@book{Grund2004, author = {Grund, Volker}, title = {Zur Theorie der Multipole und ihre Anwendung bei der Schwerefeldberechnung}, publisher = {GeoForschungsZentrum}, address = {Potsdam}, pages = {59 S. : Ill., graph. Darst.}, year = {2004}, language = {de} } @article{WilkePartzschFarges2004, author = {Wilke, Max and Partzsch, G. M. and Farges, Francois}, title = {XAFS of iron in silicate melt at high temperature}, issn = {0024-4937}, year = {2004}, language = {en} } @article{BartoschWassermann2004, author = {Bartosch, Thorsten and Wassermann, Joachim}, title = {Wavelet coherence analysis of broadband array data recorded at Stromboli volcano, Italy}, issn = {0037-1106}, year = {2004}, abstract = {We present a wavelet coherence method that is capable of displaying local coherence information between two seismic stations in the sense of a spectrogram. We have analyzed the vertical components of a 20-min-long time series from four stations that were situated in the seismic near field of Stromboli volcano. Typical volcanic seismic signals recorded in the near field of Stromboli volcano consist of continuous volcanic tremor superimposed on frequent Strombolian explosion signals. The tremor exhibits a banded and frequency-stable structure, whereas the broadband explosion signals span two or three frequency decades. We demonstrate that signals related to explosion earthquakes are strongly correlated within the network over 1.5 frequency decades. Using synthetic data, we show how coherent signal portions can be extracted out of noisy data using a coherence-filtering method. A time delay analysis using coherence information results in a coarse source location estimation that lies within the crater region. With the exception of randomly fluctuating coherence peaks, low correlations have been observed in the characteristic bands that are assumed to be generated by continuous tremor. In the low-frequency band that is related to the ocean microseisms (period approximate to 4-8 sec), we observe mostly high correlation that breaks down during the appearance of explosion earthquake signals. Based on further analysis using the inverse wavelet transformation, we propose a model that describes the breakdown phenomenon as a superposition of two independent events}, language = {en} } @article{MalekJanskyNovotnyetal.2004, author = {Malek, J. and Jansky, J. and Novotny, O. and R{\"o}ßler, Dirk}, title = {Vertically inhomogeneous models of the upper crustal structure in the West-Bohemian seismoactive region inferred from the celebration 2000 refraction data}, issn = {0039-3169}, year = {2004}, abstract = {As part of the international refraction measurements in Central Europe in the year 2000, three profiles traversed the region of earthquake swarms in West-Bohemia/Vogtland. The shots were also recorded at the permanent stations of the local seismic networks. The travel times of P-waves, observed in the West-Bohemian region, are discussed and interpreted in the present paper. In general, significantly lower P-wave velocities were found in the Saxothuringian (northern) part of the studied area than in the adjacent southern parts. The observed travel times are interpreted separately for the individual geological units, in particular for the plutons, crystallinicum, and the Marianske Lazne(Marienbad) Complex. After smoothing the selected data using rational approximations, the Wiechert-Herglotz method was used to compute vertically inhomogeneous velocity models. The characteristic features of the derived models are relatively low P-wave velocities at the surface and prominent velocity increases within the uppermost crust down to a depth of about one kilometer}, language = {en} } @article{CramerBondeauSchaphoffetal.2004, author = {Cramer, Wolfgang and Bondeau, Alberte and Schaphoff, Sibyll and Lucht, Wolfgang and Smith, Benjamin and Sitch, Stephan}, title = {Tropical forests and the global carbon cycle : impacts of atmospheric carbon dioxide, climate change and rate of deforestation}, issn = {0962-8436}, year = {2004}, abstract = {The remaining carbon stocks in wet tropical forests are currently at risk because of anthropogenic deforestation, but also because of the possibility of release driven by climate change. To identify the relative roles of CO2 increase, changing temperature and rainfall, and deforestation in the future, and the magnitude of their impact on atmospheric CO2 concentrations, we have applied a dynamic global vegetation model, using multiple scenarios of tropical deforestation (extrapolated from two estimates of current rates) and multiple scenarios of changing climate (derived from four independent offline general circulation model simulations). Results show that deforestation will probably produce large losses of carbon, despite the uncertainty about the deforestation rates. Some climate models produce additional large fluxes due to increased drought stress caused by rising temperature and decreasing rainfall. One climate model, however, produces an additional carbon sink. Taken together, our estimates of additional carbon emissions during the twenty-first century, for all climate and deforestation scenarios, range from 101 to 367 Gt C, resulting in CO2 concentration increases above background values between 29 and 129 p.p.m. An evaluation of the method indicates that better estimates of tropical carbon sources and sinks require improved assessments of current and future deforestation, and more consistent precipitation scenarios from climate models. Notwithstanding the uncertainties, continued tropical deforestation will most certainly play a very large role in the build-up of future greenhouse gas concentrations}, language = {en} } @article{Timmerman2004, author = {Timmerman, Martin Jan}, title = {Timing, geodynamic setting and character of Permo-Carboniferous magmatism in the foreland of the Variscan Orogen, NW Europe}, isbn = {1-86239-152-1}, year = {2004}, language = {en} } @article{BotcharnikovKoepkeHoltzetal.2004, author = {Botcharnikov, Roman E. and Koepke, J. and Holtz, Francois and McCammon, C. and Wilke, Max}, title = {The oxidation and structural state of Fe in hydrous ferrobasaltic melt}, year = {2004}, language = {en} } @article{HeeremansTimmermanKirsteinetal.2004, author = {Heeremans, Michel and Timmerman, Martin Jan and Kirstein, Linda A. and Faleide, J. I.}, title = {The late carboniferous : early permian evolution of the central North Sea}, year = {2004}, language = {en} } @article{CarrapaDiGiulioWijbrans2004, author = {Carrapa, Barbara and Di Giulio, A. and Wijbrans, J.}, title = {The early stages of the Alpine collision : an image derived from the upper Eocene-lower Oligocene record in the Alps-Apennines junction area}, issn = {0037-0738}, year = {2004}, abstract = {The upper Eocene-lower Oligocene sediments deposited in the eastern part of the Tertiary Piedmont Basin in northern Italy provide a complete record of the unroofing of the Alpine orogenic prism during the early stages of exhumation in the Ligurian sector. From late Priabonian till late Rupelian time, the sediments in the study area were derived from two different sources, one characterised by white micas with Si<6.5 pfu and Permian Ar-40/Ar-39 ages (270 Ma), and the other characterised by white micas with S>7 pfu and Eocene-Oligocene Ar-40/Ar-39 ages (32-50 Ma). The first source is considered to be indicative of low-pressure metamorphic rocks that covered the HP rocks of the Ligurian Alps, and were completely eroded by Chattian time. From this time on, the study area started to record the first input from western Alpine sources characterised by a larger span of ages with a more frequent Eoalpine signal. Thus, sediments deposited in the eastern part of the Tertiary Piedmont Basin contain the only available evidence of rocks belonging to high crustal levels in the Alpine orogenic prism that were not affected by the Alpine overprint. These data also provide time constraints to the poorly dated first conglomerates deposited in this area. Ar-40/Ar-39 geochronology reveals a minimum age of 33 +/- 1.4 Ma for the Pianfolco Conglomerates in the type locality, and of 31.4 +/- 3.5 Ma for the Borbera Conglomerates. (C) 2004 Elsevier B.V. All rights reserved}, language = {en} } @article{WeberAbuAyyashAbueladasetal.2004, author = {Weber, Michael H. and Abu-Ayyash, Khalil and Abueladas, Abdel-Rahman and Agnon, Amotz and Al-Amoush, H. and Babeyko, Andrey and Bartov, Yosef and Baumann, M. and Ben-Avraham, Zvi and Bock, G{\"u}nter and Bribach, Jens and El-Kelani, R. and Forster, A. and F{\"o}rster, Hans-J{\"u}rgen and Frieslander, U. and Garfunkel, Zvi and Grunewald, Steffen and Gotze, Hans-J{\"u}rgen and Haak, Volker and Haberland, Christian and Hassouneh, Mohammed and Helwig, S. and Hofstetter, Alfons and Jackel, K. H. and Kesten, Dagmar and Kind, Rainer and Maercklin, Nils and Mechie, James and Mohsen, Amjad and Neubauer, F. M. and Oberh{\"a}nsli, Roland and Qabbani, I. and Ritter, O. and Rumpker, G. and Rybakov, M. and Ryberg, Trond and Scherbaum, Frank and Schmidt, J. and Schulze, A. and Sobolev, Stephan Vladimir and Stiller, M. and Th,}, title = {The crustal structure of the Dead Sea Transform}, year = {2004}, abstract = {To address one of the central questions of plate tectonics-How do large transform systems work and what are their typical features?-seismic investigations across the Dead Sea Transform (DST), the boundary between the African and Arabian plates in the Middle East, were conducted for the first time. A major component of these investigations was a combined reflection/ refraction survey across the territories of Palestine, Israel and Jordan. The main results of this study are: (1) The seismic basement is offset by 3-5 km under the DST, (2) The DST cuts through the entire crust, broadening in the lower crust, (3) Strong lower crustal reflectors are imaged only on one side of the DST, (4) The seismic velocity sections show a steady increase in the depth of the crust-mantle transition (Moho) from 26 km at the Mediterranean to 39 km under the Jordan highlands, with only a small but visible, asymmetric topography of the Moho under the DST. These observations can be linked to the left-lateral movement of 105 km of the two plates in the last 17 Myr, accompanied by strong deformation within a narrow zone cutting through the entire crust. Comparing the DST and the San Andreas Fault (SAF) system, a strong asymmetry in subhorizontal lower crustal reflectors and a deep reaching deformation zone both occur around the DST and the SAF. The fact that such lower crustal reflectors and deep deformation zones are observed in such different transform systems suggests that these structures are possibly fundamental features of large transform plate boundaries}, language = {en} } @article{BommerAbrahamsonStrasseretal.2004, author = {Bommer, Julian J. and Abrahamson, Norman A. and Strasser, F. O. and Pecker, Alain and Bard, Pierre-Yves and Bungum, Hilmar and Cotton, Fabrice Pierre and F{\"a}h, Donat and Sabetta, F. and Scherbaum, Frank and Studer, Jost}, title = {The challenge of defining upper bounds on earthquake ground motions}, issn = {0895-0695}, year = {2004}, language = {en} } @phdthesis{Kesten2004, author = {Kesten, Dagmar}, title = {Structural observations at the southern Dead Sea Transform from seismic reflection data and ASTER satellite images}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-0001807}, school = {Universit{\"a}t Potsdam}, year = {2004}, abstract = {Die folgende Arbeit ist Teil des multidisziplin{\"a}ren Projektes DESERT (DEad SEa Rift Transect), welches seit dem Jahr 2000 im Nahen Osten durchgef{\"u}hrt wird. Dabei geht es prim{\"a}r um die Struktur der s{\"u}dlichen Dead Sea Transform (DST; Tote-Meer-Transformst{\"o}rung), Plattengrenze zwischen Afrika (Sinai) und der Arabischen Mikroplatte. Seit dem Mioz{\"a}n betr{\"a}gt der sinistrale Versatz an dieser bedeutenden aktiven Blattverschiebung mehr als 100 km. Das steilwinkelseismische (NVR) Experiment von DESERT querte die DST im Arava Tal zwischen Rotem Meer und Totem Meer, wo die Hauptst{\"o}rung auch Arava Fault genannt wird. Das 100 km lange Profil erstreckte sich von Sede Boqer/Israel im Nordwesten nach Ma'an/Jordanien im S{\"u}dosten und f{\"a}llt mit dem zentralen Teil einer weitwinkelseismischen Profillinie zusammen. Steilwinkelseismische Messungen stellen bei der Bestimmung der Krustenstruktur bis zur Krusten/Mantel-Grenze ein wichtiges Instrument dar. Obwohl es kaum m{\"o}glich ist, steilstehende St{\"o}rungszonen direkt abzubilden, geben abrupte Ver{\"a}nderungen des Reflektivit{\"a}tsmuster oder pl{\"o}tzlich endende Reflektoren indirekte Hinweise auf Transformbewegung. Da bis zum DESERT Experiment keine anderen reflexionsseismischen Messungen {\"u}ber die DST ausgef{\"u}hrt worden waren, waren wichtige Aspekte dieser Transform-Plattengrenze und der damit verbundenen Krustenstruktur nicht bekannt. Mit dem Projekt sollte deshalb untersucht werden, wie sich die DST sowohl in der oberen als auch in der unteren Kruste manifestiert. Zu den Fragestellungen geh{\"o}rte unter anderem, ob sich die DST bis in den Mantel fortsetzt und ob ein Versatz der Krusten/Mantel-Grenze beobachtet werden kann. So ein Versatz ist von anderen großen Transformst{\"o}rungen bekannt. In der vorliegenden Arbeit werden zun{\"a}chst die Methode der Steilwinkelseismik und die Datenverarbeitung kurz erl{\"a}utert, bevor die Daten geologisch interpretiert werden. Bei der Interpetation werden die Ergebnisse anderer relevanter Studien ber{\"u}cksichtigt. Geologische Gel{\"a}ndearbeiten im Gebiet des NVR Profiles ergaben, dass die Arava Fault zum Teil charakterisiert ist durch niedrige Steilstufen in den neogenen Sedimenten, durch kleine Druckr{\"u}cken oder Rhomb-Gr{\"a}ben. Ein typischer Aufbau der St{\"o}rungszone mit einem St{\"o}rungskern, einer st{\"o}rungsbezogenen Deformationszone und einem undeformierten Ausgangsgestein, wie er von anderen großen St{\"o}rungszonen beschrieben worden ist, konnte nicht gefunden werden. Deshalb wurden zur Erg{\"a}nzung der Reflexionsseismik, welche vor allem die tieferen Krustenstrukturen abbildet, ASTER (Advanced Spacebourne Thermal Emission and Reflection Radiometer) Satellitendaten herangezogen, um oberfl{\"a}chennahe Deformation und neotektonische Aktivit{\"a}t zu bestimmen.}, language = {en} } @article{HilleyStrecker2004, author = {Hilley, G. E. and Strecker, Manfred}, title = {Steady state erosion of critical Coulomb wedges with applications to Taiwan and the Himalaya}, year = {2004}, abstract = {[1] Orogenic structure appears to be partially controlled by the addition to and removal of material from the mountain belt by tectonic accretion and geomorphic erosion, respectively. We developed a coupled erosion-deformation model for orogenic wedges that are in erosional steady state and deform at their Coulomb failure limit. Erosional steady state is reached when all material introduced into the wedge is removed by erosion that is limited by the rate at which rivers erode through bedrock. We found that the ultimate form of a wedge is controlled by the wedge mechanical properties, sole-out depth of the basal decollement, erosional exponents, basin geometry, and the ratio of the added material flux to the erosional constant. As this latter ratio is increased, wedge width and surface slopes increase. We applied these models to the Taiwan and Himalayan orogenic wedges and found that despite a higher flux of material entering the former, the inferred ratio was larger for the latter. Calculated values for the erodibility of each wedge showed at least an order of magnitude lower value for the Himalaya relative to Taiwan. These values are consistent with the lower precipitation regime in the Himalaya relative to Taiwan and the exposure of crystalline rocks within the Himalayan orogenic wedge. Independently determined rock erodibility estimates are consistent with the accretionary wedge sediments and metasediments and the crystalline and high-grade metamorphic rocks exposed within Taiwan and the Himalaya, respectively. Therefore differences in rock type and climate apparently lead to key differences in the erosion and hence orogenic structure of these two mountain belts}, language = {en} } @article{GottesmannFoerster2004, author = {Gottesmann, B{\"a}rbel and F{\"o}rster, Hans-J{\"u}rgen}, title = {Sekaninaite from the Satzung granite (Erzgebirge, Germany) : magmatic or xenolithic?}, issn = {0935-1221}, year = {2004}, abstract = {In the earliest emplaced granite subintrusion of the multiphase peraluminous Satzung pluton, Erzgebirge, Germany, a mineral aggregate was observed consisting of sekaninaite (X-Fe = 0.74-0.94), Zn-rich hercynite (X-Zn = 0.03- 0.11), tri- and dioctahedral layer silicates of different composition and color, and minor quartz. Geological, textural, and compositional criteria argue that the sekaninaite, hercynite, quartz, and the brown biotite are not primary or secondary granite minerals, but are of metamorphic origin representing a xenolith uptaken from the granite melt near its level of emplacement. The metamorphic origin is supported by the occurrence of this mineral assemblage in metamorphic rocks exposed locally in the Erzgebirge basement. Reaction of the polymineralic metamorphic aggregate with the surrounding melt and subsequent interaction with alkali-, F- and LILE-rich residual fluids account for the widespread decomposition of the sekaninaite and formation of several layer silicates including green biotite, muscovite, berthierine/Fe chlorite, and sericite. The observed enrichment of the relic sekaninaite and its replacement products in elements such as Na, Li, Be, Rb, Cs, and F is result of interaction of the metamorphic fragment with the surrounding melt/fluid, in accordance with the evolved nature of the Satzung magmatic-hydrothermal system}, language = {en} } @article{Hainzl2004, author = {Hainzl, Sebastian}, title = {Seismicity patterns of earthquake swarms due to fluid intrusion and stress triggering}, issn = {0956-540X}, year = {2004}, abstract = {Earthquake swarms are often assumed to result from an intrusion of fluids into the seismogenic zone, causing seismicity patterns which significantly differ from aftershock sequences. But neither the temporal evolution nor the energy release of earthquake swarms is generally well understood. Because of the lack of descriptive empirical laws, the comparison with model simulations is typically restricted to aspects of the overall behaviour such as the frequency- magnitude distribution. However, previous investigations into a large earthquake swarm which occurred in the year 2000 in Vogtland/northwest Bohemia, Central Europe, revealed some well-defined characteristics which allow a rigorous test of model assumptions. In this study, simulations are performed of a discretized fault plane embedded in a 3-D elastic half- space. Earthquakes are triggered by fluid intrusion as well as by co-seismic and post-seismic stress changes. The model is able to reproduce the main observations, such as the fractal temporal occurrence of earthquakes, embedded aftershock sequences, and a power-law increase of the average seismic moment release. All these characteristics are found to result from stress triggering, whereas fluid diffusion is manifested in the spatiotemporal spreading of the hypocentres}, language = {en} } @phdthesis{Maercklin2004, author = {Maercklin, Nils}, title = {Seismic structure of the Arava Fault, Dead Sea Transform}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-0001469}, school = {Universit{\"a}t Potsdam}, year = {2004}, abstract = {Ein transversales St{\"o}rungssystem im Nahen Osten, die Dead Sea Transform (DST), trennt die Arabische Platte von der Sinai-Mikroplatte und erstreckt sich von S{\"u}den nach Norden vom Extensionsgebiet im Roten Meer {\"u}ber das Tote Meer bis zur Taurus-Zagros Kollisionszone. Die sinistrale DST bildete sich im Mioz{\"a}n vor etwa 17 Ma und steht mit dem Aufbrechen des Afro-Arabischen Kontinents in Verbindung. Das Untersuchungsgebiet liegt im Arava Tal zwischen Totem und Rotem Meer, mittig {\"u}ber der Arava St{\"o}rung (Arava Fault, AF), die hier den Hauptast der DST bildet. Eine Reihe seismischer Experimente, aufgebaut aus k{\"u}nstlichen Quellen, linearen Profilen {\"u}ber die St{\"o}rung und entsprechend entworfenen Empf{\"a}nger-Arrays, zeigt die Untergrundstruktur in der Umgebung der AF und der Verwerfungszone selbst bis in eine Tiefe von 3-4 km. Ein tomographisch bestimmtes Modell der seismischen Geschwindigkeiten von P-Wellen zeigt einen starken Kontrast nahe der AF mit niedrigeren Geschwindigkeiten auf der westlichen Seite als im Osten. Scherwellen lokaler Erdbeben liefern ein mittleres P-zu-S Geschwindigkeitsverh{\"a}ltnis und es gibt Anzeichen f{\"u}r {\"A}nderungen {\"u}ber die St{\"o}rung hinweg. Hoch aufgel{\"o}ste tomographische Geschwindigkeitsmodelle best{\"a}tigen der Verlauf der AF und stimmen gut mit der Oberfl{\"a}chengeologie {\"u}berein. Modelle des elektrischen Widerstands aus magnetotellurischen Messungen im selben Gebiet zeigen eine leitf{\"a}hige Schicht westlich der AF, schlecht leitendes Material {\"o}stlich davon und einen starken Kontrast nahe der AF, die den Fluss von Fluiden von einer Seite zur anderen zu verhindern scheint. Die Korrelation seismischer Geschwindigkeiten und elektrischer Widerst{\"a}nde erlaubt eine Charakterisierung verschiedener Lithologien im Untergrund aus deren physikalischen Eigenschaften. Die westliche Seite l{\"a}sst sich durch eine geschichtete Struktur beschreiben, wogegen die {\"o}stliche Seite eher einheitlich erscheint. Die senkrechte Grenze zwischen den westlichen Einheiten und der {\"o}stlichen scheint gegen{\"u}ber der Oberfl{\"a}chenauspr{\"a}gung der AF nach Osten verschoben zu sein. Eine Modellierung von seismischen Reflexionen an einer St{\"o}rung deutet an, dass die Grenze zwischen niedrigen und hohen Geschwindigkeiten eher scharf ist, sich aber durch eine raue Oberfl{\"a}che auf der L{\"a}ngenskala einiger hundert Meter auszeichnen kann, was die Streuung seismischer Wellen beg{\"u}nstigte. Das verwendete Abbildungsverfahren (Migrationsverfahren) f{\"u}r seismische Streuk{\"o}rper basiert auf Array Beamforming und der Koh{\"a}renzanalyse P-zu-P gestreuter seismischer Phasen. Eine sorgf{\"a}ltige Bestimmung der Aufl{\"o}sung sichert zuverl{\"a}ssige Abbildungsergebnisse. Die niedrigen Geschwindigkeiten im Westen entsprechen der jungen sediment{\"a}ren F{\"u}llung im Arava Tal, und die hohen Geschwindigkeiten stehen mit den dortigen pr{\"a}kambrischen Magmatiten in Verbindung. Eine 7 km lange Zone seismischer Streuung (Reflektor) ist gegen{\"u}ber der an der Oberfl{\"a}che sichtbaren AF um 1 km nach Osten verschoben und l{\"a}sst sich im Tiefenbereich von 1 km bis 4 km abbilden. Dieser Reflektor markiert die Grenze zwischen zwei lithologischen Bl{\"o}cken, die vermutlich wegen des horizontalen Versatzes entlang der DST nebeneinander zu liegen kamen. Diese Interpretation als lithologische Grenze wird durch die gemeinsame Auswertung der seismischen und magnetotellurischen Modelle gest{\"u}tzt. Die Grenze ist m{\"o}glicherweise ein Ast der AF, der versetzt gegen{\"u}ber des heutigen, aktiven Asts verl{\"a}uft. Der Gesamtversatz der DST k{\"o}nnte r{\"a}umlich und zeitlich auf diese beiden {\"A}ste und m{\"o}glicherweise auch auf andere St{\"o}rungen in dem Gebiet verteilt sein.}, language = {en} } @article{KitoKruegerNegishi2004, author = {Kito, Tadashi and Kr{\"u}ger, Frank and Negishi, H.}, title = {Seismic heterogeneous structure in the lowermost mantle beneath the southwestern Pacific}, year = {2004}, abstract = {The P and S wave velocity structure of the D" layer beneath the southwestern Pacific was investigated by using short-period data from 12 deep events in the Tonga-Fiji region recorded by the J-Array and the Hi-net (two large- aperture seismic arrays) in Japan. Reflected wave beam forming (RWB) and a migration method were used to extract weak signals originating from heterogeneities in the lowermost mantle. In order to acquire high resolution a double-array method was applied to the data. The results of the RWB method indicate that seismic energy is reflected at discontinuities near the depths of 2520 and 2650 km, which have a negative P wave velocity contrast of 1\% at the most. In addition, there is a positive seismic discontinuity at a depth of 2800 km. In the case of the S wave, reflected energy is produced almost at the same depth (2550 km depth). An apparent depth shift (50 km) of the discontinuity at the depth of 2850 km may indicate that the S wave velocity reduction in the lowermost mantle is similar to2-3 times stronger than that of P. A two-dimensional cross section, constructed with the RWB method, suggests that the observed discontinuities can be characterized as intermittent lateral heterogeneities whose lateral extent is a few hundred kilometers. The migration shows weak evidence of scattering objects which belong to the seismic discontinuities detected by the RWB method. These anomalous structures may represent a part of hot plume generated beneath the southwestern Pacific in the lowermost mantle}, language = {en} } @article{BoehmKuckenHauffeetal.2004, author = {B{\"o}hm, Uwe and Kucken, M. and Hauffe, D. and Gerstengarbe, F. W. and Werner, P. C. and Flechsig, M. and Keuler, K. and Block, A. and Ahrens, W. and Nocke, T.}, title = {Reliability of regional climate model simulations of extremes and of long-term climate}, issn = {1561-8633}, year = {2004}, abstract = {We present two case studies that demonstrate how a common evaluation methodology can be used to assess the reliability of regional climate model simulations from different fields of research. In Case I, we focused on the agricultural yield loss risk for maize in Northeastern Brazil during a drought linked to an El-Nino event. In Case II, the present-day regional climatic conditions in Europe for a 10-year period are simulated. To comprehensively evaluate the model results for both kinds of investigations, we developed a general methodology. On its basis, we elaborated and implemented modules to assess the quality of model results using both advanced visualization techniques and statistical algorithms. Besides univariate approaches for individual near-surface parameters, we used multivariate statistics to investigate multiple near-surface parameters of interest together. For the latter case, we defined generalized quality measures to quantify the model's accuracy. Furthermore, we elaborated a diagnosis tool applicable for atmospheric variables to assess the model's accuracy in representing the physical processes above the surface under various aspects. By means of this evaluation approach, it could be demonstrated in Case Study I that the accuracy of the applied regional climate model resides at the same level as that we found for another regional model and a global model. Excessive precipitation during the rainy season in coastal regions could be identified as a major contribution leading to this result. In Case Study II, we also identified the accuracy of the investigated mean characteristics for near- surface temperature and precipitation to be comparable to another regional model. In this case, an artificial modulation of the used initial and boundary data during preprocessing could be identified as the major source of error in the simulation. Altogether, the achieved results for the presented investigations indicate the potential of our methodology to be applied as a common test bed to different fields of research in regional climate modeling}, language = {en} } @article{ZiemannSchmidtMirwald2004, author = {Ziemann, Martin Andreas and Schmidt, Christian and Mirwald, Peter W.}, title = {Raman spectroscopic study of the liquid-liquid transition in water}, issn = {0024-4937}, year = {2004}, language = {en} } @article{ZollerHolschneiderBenZion2004, author = {Zoller, Gert and Holschneider, Matthias and Ben-Zion, Yehuda}, title = {Quasi-static and quasi-dynamic modeling of earthquake failure at intermediate scales}, year = {2004}, abstract = {We present a model for earthquake failure at intermediate scales (space: 100 m-100 km, time: 100 m/nu(shear}, language = {en} } @phdthesis{Schodlok2004, author = {Schodlok, Martin C.}, title = {Quantitative Analysen magmatischer Gesteine mittels reflexionsspektroskopischer Infrarot-Messungen}, pages = {IX, 127 S. : graph. Darst.}, year = {2004}, language = {de} } @article{BeauvalScotti2004, author = {Beauval, C{\´e}line and Scotti, O.}, title = {Quantifying sensitivities of PSHA for France to earthquake catalog uncertainties, truncation of ground-motion variability, and magnitude limits}, issn = {0037-1106}, year = {2004}, abstract = {The results of this study clearly identify four key parameters controlling the estimation of probabilistic seismic hazard assessment (PSHA) in France in the framework of the Cornell-McGuire method. Results in terms of peak ground acceleration demonstrate the equally high impact, at all return periods, of the choice of truncation of the predicted ground-motion distribution (at + 2sigma) and of the choice between two different magnitude-intensity correlations. The choice of minimum magnitude (3.5/4.5) on hazard estimates can have an important impact at small return periods (<1000 years), whereas the maximum magnitude (6.5/7.0), on the other hand, is not a key parameter even at large return periods (10,000 years). This hierarchy of impacts is maintained at lower frequencies down to 5 Hz. Below 5 Hz, the choice of the maximum magnitude has a much greater impact, whereas the impact due to the choice of the minimum magnitude disappears. Moreover, variability due to catalog uncertainties is also quantified; these uncertainties that underly all hazard results can engender as high a variability as the controlling parameters. Parameter impacts, calculated at the centers of each source zone, show a linear trend with the seismicity models of the zone, demonstrating the lack of contributions coming from neighboring zones. Indeed, the region of influence that contributes to the PSHA estimate at a given site decreases with increasing return periods. The resulting overall variability in hazard estimates due to input uncertainties is quantified through a logic tree, obtained coefficients of variation vary between 10\% and 20\%. Until better physical models are obtained, the uncertainty on hazard estimates may be reduced by working on an appropriate magnitude-intensity correlation}, language = {en} } @book{WilsonNeumannDaviesetal.2004, author = {Wilson, M. and Neumann, Else Ragnhild and Davies, G. R. and Timmerman, Martin Jan and Heeremans, Michel and Larsen, Bjoern Tore}, title = {Permo-carboniferous magmatism and rifting in Europe}, series = {Geological Society special publication}, volume = {223}, journal = {Geological Society special publication}, publisher = {Geological Society}, address = {London}, isbn = {1-86239-152-1}, pages = {498 S.}, year = {2004}, language = {en} } @phdthesis{Demory2004, author = {Demory, Fran{\c{c}}ois}, title = {Paleomagnetic dating of climatic events in Late Quaternary sediments of Lake Baikal (Siberia)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-0001720}, school = {Universit{\"a}t Potsdam}, year = {2004}, abstract = {Der Baikalsee ist ein ideales Klimaarchiv f{\"u}r die Mitte Eurasiens. In dieser Arbeit wurde gesteinsmagnetische und paleomagnetische Analysen an hemipelagischen Sequenzen von vier Lokationen analysiert. Die Kerne erreichen ein Alter von maximal 300 ky. In Kombination mit TEM, XRD, XRF und geochemischen Analysen zeigt die gesteinsmagnetische Studie, dass detritischer Magnetit das magnetische Signal der glazialen Sedimente dominiert. Die magnetischen Signale der interglazialen Sedimente wurden durch diagenetische Prozesse ver{\"a}ndert. Mittels HIRM k{\"o}nnen H{\"a}matit und Goethit quantifiziert werden. Diese Methode eignet sich, den detritischen Eintrag in den Baikalsee abzusch{\"a}tzen. Relative Paleointensit{\"a}ten des Erdmagnetfeldes ergaben reproduizerbare Muster, welche in Korrelation mit gutdatierten Referenzproben die Ableitung eines alternativen Altersmodells f{\"u}r die Datierung der Baikalsedimente erm{\"o}glichten. Bei Anwendung des paleomagnetischen Altersmodells beobachtet man, dass die Abk{\"u}hlung im Baikalgebiet und im Oberfl{\"a}chenwasser des Nordatlantiks wie sie aus den \&\#948;18 O-Werten planktonischer Foraminiferen abgeleitet werden kann, zeitgleich ist. Wird das aus benthischen \&\#948;18 O-Werten abgeleitete Altermdodell auf den Baikalsee angewandt, ergibt sich eine deutliche Zeitverschiebung. Das benthische Altersmodell repr{\"a}sentiert die globale Ver{\"a}nderung des Eisvolumens, welche sp{\"a}ter als die V{\"a}nderung der Oberfl{\"a}chenwassertemperatur auftritt. Die Kompilation paleomagnetischer Kurven ergab eine neue relative Paleointensit{\"a}tskurve \“Baikal 200\”. Mittels Korngr{\"o}ssenanalyse des Detritus konnten drei Faziestypen mit unterschiedlicher Sedimentationsdynamik unterschieden werden: 1) Glaziale Peroiden werden durch hohe Tongehalte infolge von Windeintrag und durch grobe Sandfraktion mittels Transport durch lokale Winde {\"u}ber das Eis charakterisiert. Dieser Faziestyp deutet auf arides Klima. 2) W{\"a}hrend der Glazial/Interglazial-{\"U}berg{\"a}nge steigt die Siltfraktion an. Dies deutet auf erh{\"o}hte Feuchtigkeit und damit verbunden erh{\"o}hte Sedimentdynamik. Windtransport und in den Schnee der Eisdecke eingetragener Staub sind die vorherrschenden Prozesse, welche den Silt in hemipelagischer Position zur Ablagerung bringen. 3) W{\"a}hrend des klimatischen Optimum des Eeemian werden Gr{\"o}sse und Quantit{\"a}t des Silts minimal, was auf eine geschlossene Vegetationsdecke im Hinterland deutet.}, language = {en} } @article{ThomasFoersterRickersetal.2004, author = {Thomas, R. and F{\"o}rster, Hans-J{\"u}rgen and Rickers, Karen and Webster, J. D.}, title = {Origin and evolution of extremely F-rich hydrous melt fractions and hydrothermal fluids during differentiation of highly evolved tin-granite magmas}, issn = {0016-7037}, year = {2004}, language = {en} } @article{LetaweCourbinMagainetal.2004, author = {Letawe, G. and Courbin, F. and Magain, P. and Hilker, M. and Jablonka, P. and Jahnke, Knud and Wisotzki, Lutz}, title = {On-axis spectroscopy of the z=0.144 radio-loud quasar HE 1434-1600 : an elliptical host with a highly ionized ISM}, year = {2004}, abstract = {VLT on-axis optical spectroscopy of the z = 0.144 radio-loud quasar HE 1434-1600 is presented. The spatially resolved spectra of the host galaxy are deconvolved and separated from those of the central quasar in order to study the dynamics of the stars and gas as well as the physical conditions of the ISM. We find that the host of HE 1434-1600 is an elliptical galaxy that resides in a group of at least 5 member galaxies, and that most likely experienced a recent collision with its nearest companion. Compared with other quasar host galaxies, HE 1434-1600 has a highly ionized ISM. The ionization state corresponds to that of typical Seyferts, but the ionized regions are not distributed in a homogeneous way around the QSO, and are located preferentially several kiloparsecs away from it. While the stellar absorption lines do not show any significant velocity field, the gas emission lines do. The observed gas velocity field is hard to reconcile with dynamical models involving rotating disk. modified Hubble laws or power laws, that all require extreme central masses (M > 10(9) M-circle dot) to provide only poor fit to the data. Power law models, which best fit the data, provide a total mass of M(<10 kpc) = 9.2 x 10(10) M-\&ODOT;. We conclude that the recent interaction between HE 1434-1600 and its closest companion has strongly affected the gas velocity and ionization state, from the center of the galaxy to its most external parts}, language = {en} } @article{ScherbaumCottonSmit2004, author = {Scherbaum, Frank and Cotton, Fabrice Pierre and Smit, P.}, title = {On the use of response spectral-reference data for the selection and ranking of ground-motion models for seismic-hazard analysis in regions of moderate seismicity : the case of rock motion}, issn = {0037-1106}, year = {2004}, abstract = {The use of ground-motion-prediction equations to estimate ground shaking has become a very popular approach for seismic-hazard assessment, especially in the framework of a logic-tree approach. Owing to the large number of existing published ground-motion models, however, the selection and ranking of appropriate models for a particular target area often pose serious practical problems. Here we show how observed around-motion records can help to guide this process in a systematic and comprehensible way. A key element in this context is a new, likelihood based, goodness-of-fit measure that has the property not only to quantify the model fit but also to measure in some degree how well the underlying statistical model assumptions are met. By design, this measure naturally scales between 0 and 1, with a value of 0.5 for a situation in which the model perfectly matches the sample distribution both in terms of mean and standard deviation. We have used it in combination with other goodness-of-fit measures to derive a simple classification scheme to quantify how well a candidate ground-rnotion-prediction equation models a particular set of observed-response spectra. This scheme is demonstrated to perform well in recognizing a number of popular ground-motion models from their rock-site- recording, subsets. This indicates its potential for aiding the assignment of logic-tree weights in a consistent and reproducible way. We have applied our scheme to the border region of France, Germany, and Switzerland where the M-w 4.8 St. Die earthquake of 22 February 2003 in eastern France recently provided a small set of observed-response spectra. These records are best modeled by the ground-motion-prediction equation of Berge-Thierry et al. (2003), which is based on the analysis of predominantly European data. The fact that the Swiss model of Bay et al. (2003) is not able to model the observed records in an acceptable way may indicate general problems arising from the use of weak-motion data for strong-motion prediction}, language = {en} } @article{HinzenWeberScherbaum2004, author = {Hinzen, K. G. and Weber, B. and Scherbaum, Frank}, title = {On the resolution of H/V measurements to determine sediment thickness, a case study across a normal fault in the Lower Rhine Embayment, Germany}, issn = {1363-2469}, year = {2004}, abstract = {In recent years, H/V measurements have been increasingly used to map the thickness of sediment fill in sedimentary basins in the context of seismic hazard assessment. This parameter is believed to be an important proxy for the site effects in sedimentary basins (e.g. in the Los Angeles basin). Here we present the results of a test using this approach across an active normal fault in a structurally well known situation. Measurements on a 50 km long profile with 1 km station spacing clearly show a change in the frequency of the fundamental peak of H/V ratios with increasing thickness of the sediment layer in the eastern part of the Lower Rhine Embayment. Subsequently, a section of 10 km length across the Erft-Sprung system, a normal fault with ca. 750 m vertical offset, was measured with a station distance of 100 m. Frequencies of the first and second peaks and the first trough in the H/V spectra are used in a simple resonance model to estimate depths of the bedrock. While the frequency of the first peak shows a large scatter for sediment depths larger than ca. 500 m, the frequency of the first trough follows the changing thickness of the sediments across the fault. The lateral resolution is in the range of the station distance of 100 m. A power law for the depth dependence of the S-wave velocity derived from down hole measurements in an earlier study [Budny, 1984] and power laws inverted from dispersion analysis of micro array measurements [Scherbaum et al., 2002] agree with the results from the H/V ratios of this study}, language = {en} } @article{HolschneiderTeramoBottarietal.2004, author = {Holschneider, Matthias and Teramo, A. and Bottari, A. and Termini, D.}, title = {On the relevance of the spatial distribution of events for seismic hazard evaluation}, issn = {0921-030X}, year = {2004}, abstract = {Seismic hazard evaluation is proposed by a methodological approach that allows the study of the influence of different modelling assumptions relative to the spatial and temporal distribution of earthquakes on the maximum values of expected intensities. In particular, we show that the estimated hazard at a fixed point is very sensitive to the assumed spatial distribution of epicentres and their estimators. As we will see, the usual approach, based on uniformly distributing the epicentres inside each seismogenic zone is likely to be biased towards lower expected intensity values. This will be made more precise later. Recall that the term "bias" means, that the expectation of the estimated quantity ( taken as a random variable on the space of statistics) is different from the expectation of the quantity itself. Instead, our approach, based on an estimator that takes into account the observed clustering of events is essentially unbiased, as shown by a Monte-Carlo simulation, and is configured on a 11011-isotropic macroseismic attenuation model which is independently estimated for each zone}, language = {en} } @article{ScherbaumSchmedesCotton2004, author = {Scherbaum, Frank and Schmedes, J. and Cotton, Fabrice Pierre}, title = {On the conversion of source-to-site distance measures for extended earthquake source models}, issn = {0037-1106}, year = {2004}, abstract = {One of the major challenges in engineering seismology is the reliable prediction of site-specific ground motion for particular earthquakes, observed at specific distances. For larger events, a special problem arises, at short distances, with the source-to-site distance measure, because distance metrics based on a point-source model are no longer appropriate. As a consequence, different attenuation relations differ in the distance metric that they use. In addition to being a source of confusion, this causes problems to quantitatively compare or combine different ground- motion models; for example, in the context of Probabilistic Seismic Hazard Assessment, in cases where ground-motion models with different distance metrics occupy neighboring branches of a logic tree. In such a situation, very crude assumptions about source sizes and orientations often have to be used to be able to derive an estimate of the particular metric required. Even if this solves the problem of providing a number to put into the attenuation relation, a serious problem remains. When converting distance measures, the corresponding uncertainties map onto the estimated ground motions according to the laws of error propagation. To make matters worse, conversion of distance metrics can cause the uncertainties of the adapted ground-motion model to become magnitude and distance dependent, even if they are not in the original relation. To be able to treat this problem quantitatively, the variability increase caused by the distance metric conversion has to be quantified. For this purpose, we have used well established scaling laws to determine explicit distance conversion relations using regression analysis on simulated data. We demonstrate that, for all practical purposes, most popular distance metrics can be related to the Joyner-Boore distance using models based on gamma distributions to express the shape of some "residual function." The functional forms are magnitude and distance dependent and are expressed as polynomials. We compare the performance of these relations with manually derived individual distance estimates for the Landers, the Imperial Valley, and the Chi-Chi earthquakes}, language = {en} } @article{HalfarGodinezOrtaMuttietal.2004, author = {Halfar, Jochen and Godinez-Orta, Lucio and Mutti, Maria and Valdez-Holguin, J. E. and Borges, Jose M.}, title = {Nutrient and temperature controls on modern carbonate production : an example from the Gulf of California, Mexico}, issn = {0091-7613}, year = {2004}, abstract = {In addition to salinity and temperature, nutrient concentrations in surface waters are known to have a significant impact on distribution of carbonate-producing biota, but have never been quantitatively evaluated against different temperatures along a latitudinal transect. The western coast of the Gulf of California, Mexico, presents a natural laboratory for investigating the influence of oceanographic parameters such as salinity, temperature, and chlorophyll a, a proxy for nutrients, on the composition of a range of modern heterozoan and photozoan carbonate environments along a north-south latitudinal gradient spanning the entire warm-temperate realm (29degreesN-23degreesN). Chlorophyll a, measured in situ at half-hour resolution, is highly variable throughout the year due to short-term upwelling, and increases significantly from the southern to northern Gulf of California. Salinity, in contrast, fluctuates little and remains at an average of 35\%. From south to north, carbonate production ranges from oligotrophic- mesotrophic, coral reefdominated shallow-water areas (minimum temperature 18.6 degreesC) through mesotrophic-eutrophic, red algal-dominated, inner-shelf carbonate production in the central gulf (minimum temperature 16 degreesC), and to molluscan-bryozoan, eutrophic inner- to outer-shelf environments (minimum temperature 13.7 degreesC). The Gulf of California data, supplemented with oceanographic and compositional information from a database compiled from a spectrum of modern carbonate systems worldwide, demonstrates the significance of nutrient control in the formation of heterozoan, photozoan, and transitional heterozoan-photozoan carbonate systems and serves as a basis for more accurately interpreting fossil carbonates}, language = {en} } @article{vonSeckendorffTimmermanKrameretal.2004, author = {von Seckendorff, V. and Timmerman, Martin Jan and Kramer, W. and Wrobel, P.}, title = {New 40Ar/39Ar ages and geochemistry of late Carboniferous to early Permian lamprophyres and related volcanic rocks in the Saxothuringian Zone of the Variscan Orogen (Germany)}, year = {2004}, language = {en} } @article{BowmanKorjenkovPoratetal.2004, author = {Bowman, Dan and Korjenkov, Andrey and Porat, Naomi and Czassny, Birka}, title = {Morphological response to quaternary deformation at an intermontane basin piedmont, the northern Tien Shan, Kyrghyzstan}, issn = {0169-555X}, year = {2004}, abstract = {The Tien Shan is a most active intracontinental mountain-building range with abundant Quaternary fault-related folding. In order to improve our understanding of Quaternary intermontane basin deformation, we investigated the intermontane Issyk-Kul Lake area, an anticline that was up-warped through the piedmont cover, causing partitioning of the alluvial fan veneer. To follow the morphological scenario during the warping process, we relied on surface-exposed and trenched structures and on alluvial fans and bajadas as reference surfaces. We used air photos and satellite images to analyze the spatial -temporal morphological record and determined the age of near surface sediments by luminescence dating. We demonstrate that the up-warped Ak-Teke hills are a thrust-generated subdued anticline with strong morphological asymmetry which results from the coupling of the competing processes of up-warp and erosional feedback. The active creeks across the up-warped anticline indicate that the antecedent drainage system kept pace with the rate of uplift. The rivers which once sourced the piedmont, like the Toru-Aygyr, Kultor and the Dyuresu, became deeply entrenched and gradually transformed the study area into an abandoned morphological surface. The up-warp caused local lateral drainage diversion in front of the northern backlimb and triggered the formation of a dendritic drainage pattern upfan. Luminescence dating suggest that the period of up-warp and antecedent entrenchment started after 157 ka. The morphologically mature study area demonstrates the response of fluvial systems to growing folds on piedmont areas, induced by a propagating frontal fold at a thrust belt edge, following shortening. (C) 2004 Elsevier B.V All rights reserved}, language = {en} } @article{FoersterRhede2004, author = {F{\"o}rster, Hans-J{\"u}rgen and Rhede, Dieter}, title = {Mineralogy of the Niederschlema-Alberoda U-Se-polymetallic deposit, Erzgebirge, Germany : III. First indication of complete miscibility between tennantite and giraudite}, year = {2004}, language = {en} } @article{Foerster2004, author = {F{\"o}rster, Hans-J{\"u}rgen}, title = {Mineralogy of the Niederschlema-Alberoda U-Se-polymetallic deposit, Erzgebirge, Germany : II: Hessite, Ag2Te, and native Te (?), the first tellurium minerals}, year = {2004}, abstract = {Hessite, Ag2Te, and native tellurium (?) constitute two, previously unknown tellurium species within the complex mineral assemblage at Niederschlema-Alberoda, Erzgebirge, Germany. Hessite is always intimately associated with clausthalite and has a composition close to ideal stoichiometry. The mean empirical formula is (Ag1.98Sb0.01)(1.99)(Te0.96Se0.05)(1.01). Paragenetic relations and thermodynamic data suggest that hessite crystallized in equilibrium with clausthalite, berzelianite, and tiemannite under conditions of almost identical, high fugacitities of Se-2 and Te-2, which very locally were approached in the main selenide stage of Jurassic age. Native tellurium (?) formed as replacement product of hessite. Niederschlema-Alberoda provides the first record of hessite from an uranium deposit worldwide. Hessite and native Te are the first tellurium minerals reported from the Erzgebirge metallogenic province}, language = {en} } @article{FoersterRhedeTischendorf2004, author = {F{\"o}rster, Hans-J{\"u}rgen and Rhede, Dieter and Tischendorf, Gerhard}, title = {Mineralogy of the Niederschlema-Alberoda U-Se-polymetallic deposit, Erzgebirge, Germany : I. Jolliffeite, NiAsSe, the rare Se-dominant analogue of gersdorffite}, year = {2004}, abstract = {The Niederschlema-Alberoda uranium deposit, in the Erzgebirge region of Germany, contains an uncommon assemblage of metallic minerals, in particular selenides, sulfides, arsenides, tellurides, and native elements, in addition to uraninite and coffinite. The complex mineralogy resulted from the superposition of several mineralizing events over the time interval from the Permian to the Cretaceous; these events introduced and redeposited a great variety of metallic elements within the hydrothermal uranium deposit (Pb, Ag, Cu, Hg, Tl, Bi, Co, Ni, As, Sb, Se, S, Te). One of the exotic minerals is jolliffeite, an arsenoselenide with end-member composition NiAsSe, so far only known from Lake Athabasca, Saskatchewan, Canada. A single, small, anhedral grain of jolliffeite from Niederschlema-Alberoda is included and partly replaced by sulfurian eskebornite. Associated minerals comprise hematite, Ni-Co-Se-bearing lollingite, clausthalite, tiemannite, mercurian hakite-giraudite solid solutions, sulfurian berzelianite, sulfurian umangite, hessite, Ni-Co-As-bearing pyrite, and Se-rich chalcopyrite. The sulfurian jolliffeite has the empirical formula (Ni0.85Cu0.09Co0.05Fe0.02Ag0.01)Sigma(1.02)As(0.98)(Se0.77S0.23)(Sigma1. 00) and differs from type jolliffeite mainly by substantial substitution of Cu (2.6-3.3 wt.\%) for Ni and S (3.2-4.1 wt.\%) for Se. Substantial S-for-Se substitution in jolliffeite implies extensive and probably complete miscibility between NiAsSe and its S-dominant analogue, gersdorffite-Pa3 (NiAsS). We suggest that a localized accumulation of Ni and As in the Se-(S)-bearing hydrothermal fluid gave rise to the crystallization of jolliffeite at some rare locations at a late stage of formation of the Jurassic selenide assemblage}, language = {en} } @article{NabelekWilkeHuff2004, author = {Nabelek, Peter I. and Wilke, Max and Huff, T. A.}, title = {Methane production during metamorphism of graphitic pelites, Black Hills, USA}, issn = {0016-7037}, year = {2004}, language = {en} } @article{MalischewskyScherbaum2004, author = {Malischewsky, Peter G. and Scherbaum, Frank}, title = {Love's formula and H/V-ratio (ellipticity) of Rayleigh waves}, issn = {0165-2125}, year = {2004}, abstract = {The ellipticity of Rayleigh surface waves, which is an important parameter characterizing the propagation medium, is studied for several models with increasing complexity. While the main focus lies on theory, practical implications of the use of the horizontal to vertical component ratio (H/V-ratio) to Study the subsurface structure are considered as well. Love's approximation of the ellipticity for an incompressible layer over an incompressible half-space is critically discussed especially concerning its applicability for different impedance contrasts. The main result is an analytically exact formula of H/V for a 2-layer model of compressible media, which is a generalization of Love's formula. It turns out that for a limited range of models Love's approximation can be used also in the general case. (C) 2003 Elsevier B.V. All rights reserved}, language = {en} } @article{BowmanKorjenkovPorat2004, author = {Bowman, Dan and Korjenkov, Andrey and Porat, Naomi}, title = {Late-Pleistocene seismites from Lake Issyk-Kul, the Tien Shan Range, Kyrghyzstan}, issn = {0037-0738}, year = {2004}, abstract = {The aim of the study is to record the occurrence of sediment deformation structures in one of the tectonically most active areas on the globe, the Tien Shan range in Central Asia and to examine the significance of the deformations as indicators of palaeoseismicity. Soft-sediment deformation structures in form of balls and pseudo-nodules are exposed in the Issyk-Kul basin, within interfingering beds of shallow lacustrine, beach and fluviatile origin. Additional deformation structures that were encountered are: a complex and chaotic folded structure, giant balls and a "pillar" structure which has not been previously reported, where marl intrudes down into coarse pebbley sand and forms pillar morphology. Liquefaction features and bedforms related to storm and breaking waves were not encountered. Neither was there evidence of turbidites. Seven field criteria for relating soft-sediment deformation to palaeoseismic triggering provide strong evidence for a seismic origin of the deformation structures. Empirical relationships between magnitude and the maximum distance from an epicenter to liquefaction sites make the active epicentral zone north of Lake Issyk- Kul, with its frequent high magnitude events, the most favorable source for the deformation structures. Luminescence dating of the sediments gives a time window of 26 +/- 2.1 to 10.5 +/- 0.7 ka BP, indicating latest Pleistocene seismic activity.(C) 2003 Elsevier B.V. All rights reserved}, language = {en} } @phdthesis{Bookhagen2004, author = {Bookhagen, Bodo}, title = {Late quaternary climate changes and landscape evolution in the Northwest Himalaya : geomorphologic processes in the Indian Summer Monsoon Domain}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-0001956}, school = {Universit{\"a}t Potsdam}, year = {2004}, abstract = {The India-Eurasia continental collision zone provides a spectacular example of active mountain building and climatic forcing. In order to quantify the critically important process of mass removal, I analyzed spatial and temporal precipitation patterns of the oscillating monsoon system and their geomorphic imprints. I processed passive microwave satellite data to derive high-resolution rainfall estimates for the last decade and identified an abnormal monsoon year in 2002. During this year, precipitation migrated far into the Sutlej Valley in the northwestern part of the Himalaya and reached regions behind orographic barriers that are normally arid. There, sediment flux, mean basin denudation rates, and channel-forming processes such as erosion by debris-flows increased significantly. Similarly, during the late Pleistocene and early Holocene, solar forcing increased the strength of the Indian summer monsoon for several millennia and presumably lead to analogous precipitation distribution as were observed during 2002. However, the persistent humid conditions in the steep, high-elevation parts of the Sutlej River resulted in deep-seated landsliding. Landslides were exceptionally large, mainly due to two processes that I infer for this time: At the onset of the intensified monsoon at 9.7 ka BP heavy rainfall and high river discharge removed material stored along the river, and lowered the baselevel. Second, enhanced discharge, sediment flux, and increased pore-water pressures along the hillslopes eventually lead to exceptionally large landslides that have not been observed in other periods. The excess sediments that were removed from the upstream parts of the Sutlej Valley were rapidly deposited in the low-gradient sectors of the lower Sutlej River. Timing of downcutting correlates with centennial-long weaker monsoon periods that were characterized by lower rainfall. I explain this relationship by taking sediment flux and rainfall dynamics into account: High sediment flux derived from the upstream parts of the Sutlej River during strong monsoon phases prevents fluvial incision due to oversaturation the fluvial sediment-transport capacity. In contrast, weaker monsoons result in a lower sediment flux that allows incision in the low-elevation parts of the Sutlej River.}, language = {en} } @article{HetzelTaoStokesetal.2004, author = {Hetzel, Ralf and Tao, M. X. and Stokes, S. and Niedermann, Samuel and Ivy-Ochs, Susan and Gao, B. and Strecker, Manfred and Kubik, Peter W.}, title = {Late Pleistocene / Holocene slip rate of the Zhangye thrust (Qilian Shan, China) and implications for the active growth of the northeastern Tibetan Plateau}, issn = {0278-7407}, year = {2004}, abstract = {We derive a slip rate for a thrust at the central Qilian Shan mountain front by combining structural investigations, satellite imagery, topographic profiling, luminescence dating, and Be-10 exposure dating. The seismically active Zhangye thrust transects late Pleistocene alluvial fan deposits and forms a prominent north facing scarp. The fault consists of two segments that differ in orientation, scarp height, and age. A series of loess-covered terraces records the uplift history of the western thrust segment. Loess accumulation on all terraces started at 8.5 +/- 1.5 kyr and postdates terrace formation. Gravels from the highest terrace yielded a Be-10 exposure age of 90 +/- 11 kyr, which dates the onset of faulting. With a displacement of 55-60 m derived from fault scarp profiles, this yields a vertical slip rate of 0.64 +/- 0.08 mm yr(-1). Along the eastern thrust segment, three Be-10 ages from the uplifted alluvial fan constrain that faulting started at similar to31 +/- 5 kyr. Together with a displacement of 25-30 m this leads to a vertical faulting rate of 0.88 +/- 0.16 mm yr(-1). A dip estimate of 40degrees to 60degrees for the fault plane combined with lower and upper limits of similar to0.6 and similar to0.9 mm yr(-1) for the vertical slip rate gives minimum and maximum horizontal shortening rates of 0.4 and 1.1 mm yr(-1) across the Zhangye thrust. Our results are consistent with geologic and GPS constraints, which suggest that NNE directed shortening across the northeastern Tibetan Plateau is distributed on several active faults with a total shortening rate of 4 to 10 mm yr(-1)}, language = {en} } @article{OzawaTagamiSudo2004, author = {Ozawa, Ayako and Tagami, T. and Sudo, Masafumi}, title = {K-Ar geochronology of the temporal change of eruptive style in the eastern Izu peninsula, central Japan}, issn = {1038-4871}, year = {2004}, abstract = {A recent K-Ar study elucidated that eruptive style in the eastern Izu peninsula changed from polygenetic to monogenetic volcano at 0.3-0.2 Ma. To narrow down the time of change, we determined 10 K-Ar ages on Togasayama Andesite of Amagi volcano, the youngest polygenetic volcano in the area, and Togasayama Monogenetic Volcano, one of the oldest monogenetic volcanoes in the area, which overlies a part of the Togasayama Andesite. Dating results showed that the Togasayama Andesite effused at least from 0.34 to 0.20 Ma, whereas the Togasayama Monogenetic Volcano erupted at 0.26- 0.29 Ma, suggesting that the northern part of the Togasayama Andesite effused after the eruption of the Togasayama Monogenetic Volcano. Considering previous data, it is therefore inferred that change of eruptive style in the eastern Izu area occurred during the period 0.29-0.20 Ma, with considerable overlap of both polygenetic and monogenetic volcanism}, language = {en} } @article{KanngiesserHahnWilkeetal.2004, author = {Kanngiesser, Birgit and Hahn, O. and Wilke, Max and Nekat, B. and Malzer, Wolfgang and Erko, Alexei}, title = {Investigation of oxidation and migration processes of inorganic compounds in ink-corroded manuscripts}, issn = {0584-8547}, year = {2004}, abstract = {We studied the oxidation and migration processes of inorganic compounds in iron gall inks with a combination of micro X-ray fluorescence analysis (micro-XRF) and micro X-ray absorption near edge structure spectroscopy (micro-XANES). With elemental mapping by micro-XRF, the correlation of the minor elements in the ink to the major element Fe was investigated. Along concentration profiles of Fe, micro-XANES measurements were carried out in order to determine the oxidation state and the local environment. With the help of model inks, we could show that Cu is a further important element in the paper degradation process due to iron gall ink corrosion. (C) 2004 Elsevier B.V. All rights reserved}, language = {en} } @article{OzawaTagamiListancoetal.2004, author = {Ozawa, Ayako and Tagami, Takahiro and Listanco, Eddie L. and Arpa, Carmencita B. and Sudo, Masafumi}, title = {Initiation and propagation of subduction along the Philippine Trench : evidence from the temporal and spatial distribution of volcanoes}, issn = {1367-9120}, year = {2004}, abstract = {K-Ar ages of 37 samples collected from the Bicol peninsula, the Luzon island, Philippines, were determined by the unspiked sensitivity method in order to constrain the timing of initiation of subduction along the Philippine Trench. The measured K-Ar ages range from 0 to 7 Ma with two old outliers of 27 and 43 Ma. Together with K-Ar ages previously reported on volcanics in Leyte and eastern Mindanao, subduction volcanism has likely propagated from north to south: similar to 6.6 Ma in Bicol and similar to 3.5 Ma in Leyte and its vicinity. The temporal and spatial distribution suggests that the subduction volcanism started earlier in the north than in the south. This is consistent with the southern propagation of subduction along the Philippine Trench from similar to 8 Ma. (C) 2003 Elsevier Ltd. All rights reserved}, language = {en} } @article{WilkePartzschSchmidtetal.2004, author = {Wilke, Max and Partzsch, G. M. and Schmidt, C. and Farges, Francois}, title = {In-situ study of the iron species in silicate melts}, issn = {0016-7037}, year = {2004}, language = {en} } @article{HetzelTaoNiedermannetal.2004, author = {Hetzel, Ralf and Tao, MX and Niedermann, Samuel and Strecker, Manfred and Ivy-Ochs, Susan and Kubik, Peter W. and Gao, B.}, title = {Implications of the fault scaling law for the growth of topography : mountain ranges in the broken foreland of north-east Tibet}, issn = {0954-4879}, year = {2004}, abstract = {A fault scaling law suggests that, over eight orders of magnitude, fault length L is linearly related to maximum displacement D. Individual faults may therefore retain a constant ratio of D/L as they grow. If erosion is minor compared with tectonic uplift, the length and along-strike relief of young mountain ranges should thus reflect fault growth. Topographic profiles along the crests of mountain ranges in the actively deforming foreland of north-east Tibet exhibit a characteristic shape with maximum height near their centre and decreasing elevation toward the tips. We interpret the along-strike relief of these ranges to reflect the slip distribution on high-angle reverse faults. A geometric model illustrates that the lateral propagation rate of such mountain ranges may be deciphered if their length- to-height ratio has remained constant. As an application of the model, we reconstruct the growth of the Heli Shan using a long-term uplift rate of similar to1.3 mm yr(-1) derived from Ne-21 and Be-10 exposure dating}, language = {en} } @article{MaercklinHaberlandRybergetal.2004, author = {Maercklin, Nils and Haberland, Christian and Ryberg, Trond and Weber, Michael H. and Bartov, Yosef}, title = {Imaging the Dead Sea Transform with scattered seismic waves}, issn = {0956-540X}, year = {2004}, abstract = {With controlled seismic sources and specifically designed receiver arrays, we image a subvertical boundary between two lithological blocks at the Arava Fault (AF) in the Middle East. The AF is the main strike-slip fault of the Dead Sea Transform (DST) in the segment between the Dead Sea and the Red Sea. Our imaging (migration) method is based on array beamforming and coherence analysis of P to P scattered seismic phases. We use a 1-D background velocity model and the direct P arrival as a reference phase. Careful resolution testing is necessary, because the target volume is irregularly sampled by rays. A spread function describing energy dispersion at localized point scatterers and synthetic calculations for large planar structures provides estimates of the resolution of the images. We resolve a 7 km long steeply dipping reflector offset roughly 1 km from the surface trace of the AF. The reflector can be imaged from about 1 km down to 4 km depth. Previous and ongoing studies in this region have shown a strong contrast across the fault: low seismic velocities and electrical resistivities to the west and high velocities and resistivities to the east of it. We therefore suggest that the imaged reflector marks the contrast between young sedimentary fill in the west and Precambrian rocks in the east. If correct, the boundary between the two blocks is offset about 1 km east of the current surface trace of the AF}, language = {en} } @article{HilleyStreckerRamos2004, author = {Hilley, G. E. and Strecker, Manfred and Ramos, V. A.}, title = {Growth and erosion of fold-and-thrust belts with an application to the Aconcagua fold-and-thrust belt, Argentina}, year = {2004}, abstract = {[1] The development of topography within and erosional removal of material from an orogen exerts a primary control on its structure. We develop a model that describes the temporal development of a frontally accreting, critically growing Coulomb wedge whose topography is largely limited by bedrock fluvial incision. We present general results for arbitrary initial critical wedge geometries and investigate the temporal development of a critical wedge with no initial topography. Increasing rock erodibility and/or precipitation, decreasing mass flux accreting to the wedge front, increasing wedge sole-out depth, decreasing wedge and basal decollement overpressure, and increasing basal decollement friction lead to narrow wedges. Large power law exponent values cause the wedge geometry to quickly reach a condition in which all material accreted to the front of the wedge is removed by erosion. We apply our model to the Aconcagua fold-and-thrust belt in the central Andes of Argentina where wedge development over time is well constrained. We solve for the erosional coefficient K that is required to recreate the field-constrained wedge growth history, and these values are within the range of independently determined values in analogous rock types. Using qualitative observations of rock erodibilities within the wedge, we speculate that power law exponents of 1/3 less than or equal to m less than or equal to 0.4 and 2/3 less than or equal to n less than or equal to 1 characterize the erosional growth of the Aconcagua fold-and-thrust belt. This general model may be used to understand the development of mountain belts where orogenic wedges grow as they deform at their Coulomb failure limit}, language = {en} } @article{SchoenbohmWhippleBurchfieletal.2004, author = {Schoenbohm, Lindsay M. and Whipple, K. X. and Burchfiel, B. C. and Chen, L.}, title = {Geomorphic constraints on surface uplift, exhumation, and plateau growth in the Red River region, Yunnan Province, China}, issn = {0016-7606}, year = {2004}, abstract = {Field observations, digital elevation model (DEM) data, and longitudinal profile analysis reveal a perched low- relief upland landscape in the Red River region, Yunnan Province, China, which correlates to an uplifted, regional low- relief landscape preserved over the eastern margin of the Tibetan Plateau. As with other major rivers of the plateau margin, the Red River has deeply incised the low-relief upland landscape, which we interpret to be the remnants of a pre- uplift or relict landscape. We examine longitudinal river profiles for 97 tributaries of the Red River. Most profiles consist of three segments separated by sharp knickpoints: an upper, low-gradient channel segment, a steeper middle channel segment, and a very steep lower channel segment. Upper channel segments correspond to the relict landscape and have not yet experienced river incision. Steeper middle and lower segments indicate onset of rapid, two-phase river incision, on the basis of which changes in external forcings, such as climate or uplift, can be inferred. In terms of two end-member scenarios, two-phase incision could be the result of pulsed plateau growth, in which relatively slow uplift during the first phase is followed by rapid uplift during the second phase, or it could reflect adjustments of the main channel to changing climate conditions against the backdrop of steady plateau growth. Reconstruction of the paleo-Red River indicates 1400 m river incision, 1400-1500 m surface uplift, and a maximum of 750 m vertical displacement across the northern Red River fault, elevating the northern Ailao Shan range above the surrounding relict landscape. On the basis of stratigraphic constraints, incision along the Red River likely began in Pliocene time}, language = {en} } @article{FriedrichLeeWernickeetal.2004, author = {Friedrich, A. M. and Lee, J. and Wernicke, B. P. and Sieh, K.}, title = {Geologic context of geodetic data across a Basin and Range normal fault, Crescent Valley, Nevada}, issn = {0278-7407}, year = {2004}, abstract = {[1] Geodetic strain and late Quaternary faulting in the Basin and Range province is distributed over a region much wider than historic seismicity, which is localized near the margins of the province. In the relatively aseismic interior, both the magnitude and direction of geodetic strain may be inconsistent with the Holocene faulting record. We document the best example of such a disagreement across the NE striking, similar to55degrees NW dipping Crescent normal fault, where a NW oriented, 70 km geodetic baseline records contemporary shortening of similar to2 mm/yr orthogonal to the fault trace. In contrast, our geomorphic, paleoseismic, and geochronologic analyses of the Crescent fault suggest that a large extensional rupture occurred during the late Holocene epoch. An excavation across the fault at Fourmile Canyon reveals that the most recent event occurred at 2.8 +/- 0.1 ka, with net vertical tectonic displacement of 4.6 +/- 0.4 m at this location, corresponding to the release of similar to3 m of accumulated NW-SE extension. Measured alluvial scarp profiles suggest a minimum rupture length of 30 km along the range front for the event, implying a moment magnitude M-w of at least 6.6. No prior event occurred between similar to2.8 ka and similar to6.4 +/- 0.1 ka, the C-14 calender age of strata near the base of the exposed section. Assuming typical slip rates for Basin and Range faults (similar to0.3 mm/yr), these results imply that up to one third, or similar to1 m, of the extensional strain released in the previous earthquake could have reaccumulated across the fault since similar to2.8 ka. However, the contemporary shortening implies that the fault is unloading due to a transient process, whose duration is limited to between 6 years ( geodetic recording time) and 2.8 ka ( the age of the most recent event). These results emphasize the importance of providing accurate geologic data on the timescale of the earthquake cycle in order to evaluate geodetic measurements}, language = {en} }