@misc{HetenyiMolinariClintonetal.2018, author = {Hetenyi, Gyorgy and Molinari, Irene and Clinton, John and Bokelmann, Gotz and Bondar, Istvan and Crawford, Wayne C. and Dessa, Jean-Xavier and Doubre, Cecile and Friederich, Wolfgang and Fuchs, Florian and Giardini, Domenico and Graczer, Zoltan and Handy, Mark R. and Herak, Marijan and Jia, Yan and Kissling, Edi and Kopp, Heidrun and Korn, Michael and Margheriti, Lucia and Meier, Thomas and Mucciarelli, Marco and Paul, Anne and Pesaresi, Damiano and Piromallo, Claudia and Plenefisch, Thomas and Plomerova, Jaroslava and Ritter, Joachim and Rumpker, Georg and Sipka, Vesna and Spallarossa, Daniele and Thomas, Christine and Tilmann, Frederik and Wassermann, Joachim and Weber, Michael and Weber, Zoltan and Wesztergom, Viktor and Zivcic, Mladen and Abreu, Rafael and Allegretti, Ivo and Apoloner, Maria-Theresia and Aubert, Coralie and Besancon, Simon and de Berc, Maxime Bes and Brunel, Didier and Capello, Marco and Carman, Martina and Cavaliere, Adriano and Cheze, Jerome and Chiarabba, Claudio and Cougoulat, Glenn and Cristiano, Luigia and Czifra, Tibor and Danesi, Stefania and Daniel, Romuald and Dannowski, Anke and Dasovic, Iva and Deschamps, Anne and Egdorf, Sven and Fiket, Tomislav and Fischer, Kasper and Funke, Sigward and Govoni, Aladino and Groschl, Gidera and Heimers, Stefan and Heit, Ben and Herak, Davorka and Huber, Johann and Jaric, Dejan and Jedlicka, Petr and Jund, Helene and Klingen, Stefan and Klotz, Bernhard and Kolinsky, Petr and Kotek, Josef and Kuhne, Lothar and Kuk, Kreso and Lange, Dietrich and Loos, Jurgen and Lovati, Sara and Malengros, Deny and Maron, Christophe and Martin, Xavier and Massa, Marco and Mazzarini, Francesco and Metral, Laurent and Moretti, Milena and Munzarova, Helena and Nardi, Anna and Pahor, Jurij and Pequegnat, Catherine and Petersen, Florian and Piccinini, Davide and Pondrelli, Silvia and Prevolnik, Snjezan and Racine, Roman and Regnier, Marc and Reiss, Miriam and Salimbeni, Simone and Santulin, Marco and Scherer, Werner and Schippkus, Sven and Schulte-Kortnack, Detlef and Solarino, Stefano and Spieker, Kathrin and Stipcevic, Josip and Strollo, Angelo and Sule, Balint and Szanyi, Gyongyver and Szucs, Eszter and Thorwart, Martin and Ueding, Stefan and Vallocchia, Massimiliano and Vecsey, Ludek and Voigt, Rene and Weidle, Christian and Weyland, Gauthier and Wiemer, Stefan and Wolf, Felix and Wolyniec, David and Zieke, Thomas}, title = {The AlpArray seismic network}, series = {Surveys in Geophysics}, volume = {39}, journal = {Surveys in Geophysics}, number = {5}, publisher = {Springer}, address = {Dordrecht}, organization = {ETHZ SED Elect Lab AlpArray Seismic Network Team AlpArray OBS Cruise Crew AlpArray Working Grp}, issn = {0169-3298}, doi = {10.1007/s10712-018-9472-4}, pages = {1009 -- 1033}, year = {2018}, abstract = {The AlpArray programme is a multinational, European consortium to advance our understanding of orogenesis and its relationship to mantle dynamics, plate reorganizations, surface processes and seismic hazard in the Alps-Apennines-Carpathians-Dinarides orogenic system. The AlpArray Seismic Network has been deployed with contributions from 36 institutions from 11 countries to map physical properties of the lithosphere and asthenosphere in 3D and thus to obtain new, high-resolution geophysical images of structures from the surface down to the base of the mantle transition zone. With over 600 broadband stations operated for 2 years, this seismic experiment is one of the largest simultaneously operated seismological networks in the academic domain, employing hexagonal coverage with station spacing at less than 52 km. This dense and regularly spaced experiment is made possible by the coordinated coeval deployment of temporary stations from numerous national pools, including ocean-bottom seismometers, which were funded by different national agencies. They combine with permanent networks, which also required the cooperation of many different operators. Together these stations ultimately fill coverage gaps. Following a short overview of previous large-scale seismological experiments in the Alpine region, we here present the goals, construction, deployment, characteristics and data management of the AlpArray Seismic Network, which will provide data that is expected to be unprecedented in quality to image the complex Alpine mountains at depth.}, language = {en} } @article{WeberScholzSchroederRitzrauetal.2018, author = {Weber, Michael and Scholz, Denis and Schr{\"o}der-Ritzrau, Andrea and Deininger, Michael and Sp{\"o}tl, Christoph and Lugli, Federico and Mertz-Kraus, Regina and Jochum, Klaus Peter and Fohlmeister, Jens Bernd and Stumpf, Cintia F. and Riechelmann, Dana F. C.}, title = {Evidence of warm and humid interstadials in central Europe during early MISSUE 3 revealed by a multi-proxy speleothem record}, series = {Quaternary science reviews : the international multidisciplinary research and review journal}, volume = {200}, journal = {Quaternary science reviews : the international multidisciplinary research and review journal}, publisher = {Elsevier}, address = {Oxford}, issn = {0277-3791}, doi = {10.1016/j.quascirev.2018.09.045}, pages = {276 -- 286}, year = {2018}, abstract = {Marine Isotope Stage 3 (MIS 3, 57-27 ka) was characterised by numerous rapid climate oscillations (i.e., Dansgaard-Oeschger (D/O-) events), which are reflected in various climate archives. So far, MIS 3 speleothem records from central Europe have mainly been restricted to caves located beneath temperate Alpine glaciers or close to the Atlantic Ocean. Thus, MIS 3 seemed to be too cold and dry to enable speleothem growth north of the Alps in central Europe. Here we present a new speleothem record from Bunker Cave, Germany, which shows two distinct growth phases from 52.0 (+0.8, -0.5) to 50.9 (+0.6, -1.3) ka and 473 (+1.0, -0.6) to 42.8 (+/- 0.9) ka, rejecting this hypothesis. These two growth phases potentially correspond to the two warmest and most humid phases in central Europe during MIS 3, which is confirmed by pollen data from the nearby Eifel. The hiatus separating the two phases is associated with Heinrich stadial 5 (HS 5), although the growth stop precedes the onset of HS 5. The first growth phase is characterised by a fast growth rate, and Mg concentrations and Sr isotope data suggest high infiltration and the presence of soil cover above the cave. The second growth phase was characterised by drier, but still favourable conditions for speleothem growth. During this phase, the delta C-13 values show a significant decrease associated with D/O-event 12. The timing of this shift is in agreement with other MIS 3 speleothem data from Europe and Greenland ice core data. (C) 2018 Elsevier Ltd. All rights reserved.}, language = {en} } @article{MohsenKindSobolevetal.2006, author = {Mohsen, Ayman and Kind, Rainer and Sobolev, Stephan Vladimir and Weber, Michael}, title = {Thickness of the lithosphere east of the Dead Sea Transform}, series = {Geophysical journal international}, volume = {167}, journal = {Geophysical journal international}, number = {2}, publisher = {Blackwell}, address = {Oxford}, issn = {0956-540X}, doi = {10.1111/j.1365-246X.2006.03185.x}, pages = {845 -- 852}, year = {2006}, abstract = {We use the S receiver function method to study the lithosphere at the Dead Sea Transform (DST). A temporary network of 22 seismic broad-band stations was operated on both sides of the DST from 2000 to 2001 as part of the DESERT project. We also used data from six additional permanent broad-band seismic stations at the DST and in the surrounding area, that is, in Turkey, Saudi Arabia, Egypt and Cyprus. Clear S-to-P converted phases from the crust-mantle boundary (Moho) and a deeper discontinuity, which we interpret as lithosphere-asthenosphere boundary (LAB) have been observed. The Moho depth (30-38 km) obtained from S receiver functions agrees well with the results from P receiver functions and other geophysical data. We observe thinning of the lithosphere on the eastern side of the DST from 80 km in the north of the Dead Sea to about 65 km at the Gulf of Aqaba. On the western side of the DST, the few data indicate a thin LAB of about 65 km. For comparison, we found a 90-km-thick lithosphere in eastern Turkey and a 160-km-thick lithosphere under the Arabian shield, respectively. These observations support previous suggestions, based on xenolith data, heat flow observations, regional uplift history and geodynamic modelling, that the lithosphere around DST has been significantly thinned in the Late Cenozoic, likely following rifting and spreading of the Red Sea.}, language = {en} } @article{GilingStaehrGrossartetal.2017, author = {Giling, Darren P. and Staehr, Peter A. and Grossart, Hans-Peter and Andersen, Mikkel Rene and Boehrer, Bertram and Escot, Carmelo and Evrendilek, Fatih and Gomez-Gener, Lluis and Honti, Mark and Jones, Ian D. and Karakaya, Nusret and Laas, Alo and Moreno-Ostos, Enrique and Rinke, Karsten and Scharfenberger, Ulrike and Schmidt, Silke R. and Weber, Michael and Woolway, R. Iestyn and Zwart, Jacob A. and Obrador, Biel}, title = {Delving deeper: Metabolic processes in the metalimnion of stratified lakes}, series = {Limnology and oceanography}, volume = {62}, journal = {Limnology and oceanography}, publisher = {Wiley}, address = {Hoboken}, issn = {0024-3590}, doi = {10.1002/lno.10504}, pages = {1288 -- 1306}, year = {2017}, abstract = {Many lakes exhibit seasonal stratification, during which they develop strong thermal and chemical gradients. An expansion of depth-integrated monitoring programs has provided insight into the importance of organic carbon processing that occurs below the upper mixed layer. However, the chemical and physical drivers of metabolism and metabolic coupling remain unresolved, especially in the metalimnion. In this depth zone, sharp gradients in key resources such as light and temperature co-occur with dynamic physical conditions that influence metabolic processes directly and simultaneously hamper the accurate tracing of biological activity. We evaluated the drivers of metalimnetic metabolism and its associated uncertainty across 10 stratified lakes in Europe and North America. We hypothesized that the metalimnion would contribute highly to whole-lake functioning in clear oligotrophic lakes, and that metabolic rates would be highly variable in unstable polymictic lakes. Depth-integrated rates of gross primary production (GPP) and ecosystem respiration (ER) were modelled from diel dissolved oxygen curves using a Bayesian approach. Metabolic estimates were more uncertain below the epilimnion, but uncertainty was not consistently related to lake morphology or mixing regime. Metalimnetic rates exhibited high day-to-day variability in all trophic states, with the metalimnetic contribution to daily whole-lake GPP and ER ranging from 0\% to 87\% and < 1\% to 92\%, respectively. Nonetheless, the metalimnion of low-nutrient lakes contributed strongly to whole-lake metabolism on average, driven by a collinear combination of highlight, low surface-water phosphorous concentration and high metalimnetic volume. Consequently, a single-sensor approach does not necessarily reflect whole-ecosystem carbon dynamics in stratified lakes.}, language = {en} } @article{KastleWeberKrueger2017, author = {Kastle, Emanuel D. and Weber, Michael and Kr{\"u}ger, Frank}, title = {Complex Deep Structure of the African Low-Velocity Zone}, series = {Bulletin of the Seismological Society of America}, volume = {107}, journal = {Bulletin of the Seismological Society of America}, publisher = {Seismological Society of America}, address = {Albany}, issn = {0037-1106}, doi = {10.1785/0120160215}, pages = {1688 -- 1703}, year = {2017}, abstract = {We use recently deployed seismological arrays in Africa to sample a 2D cross section through the mantle down to the core-mantle boundary (CMB). By making use of travel-time residuals of S, ScS, and SKS phases, a new shear-velocity model of the African low-velocity zone (ALVZ) is derived. Our model suggests between 1.2\% shear-velocity reduction at the top and 5\% at the bottom with respect to 1D reference models. The average reduction over the whole low-velocity zone (LVZ) amounts to 2\% in the presented model and is therefore about twice as strong as values found in global tomographic models. The top of the LVZ reaches up to 1200-km depth, and its lateral extent at the CMB is about 35 degrees. We propose the existence of a gap of 300 km, splitting the structure into two blocks. Our results are based on remarkable differences in SK(K) S travel-time residuals over a few degrees distance. The complexity of the structure could provide a key to an improved understanding of the deep-mantle LVZ dynamics and composition by comparison to geodynamic models. The gap in the model might suggest that the 2D cross section is cutting through a 3D indentation in the boundary of the ALVZ but may also be interpreted as a sign of two individual plumes, rather than one large homogeneous upwelling.}, language = {en} } @article{PlanertBehrmannJokatetal.2017, author = {Planert, Lars and Behrmann, Jan H. and Jokat, Wilfried and Fromm, Tanja and Ryberg, Trond and Weber, Michael and Haberland, Christian}, title = {The wide-angle seismic image of a complex rifted margin, offshore North Namibia: Implications for the tectonics of continental breakup}, series = {Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth}, volume = {716}, journal = {Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0040-1951}, doi = {10.1016/j.tecto.2016.06.024}, pages = {130 -- 148}, year = {2017}, abstract = {Voluminous magmatism during the South Atlantic opening has been considered as a classical example for plume related continental breakup. We present a study of the crustal structure around Walvis Ridge, near the intersection with the African margin. Two wide-angle seismic profiles were acquired. One is oriented NNW-SSE, following the continent-ocean transition and crossing Walvis Ridge. A second amphibious profile runs NW-SE from the Angola Basin into continental Namibia. At the continent-ocean boundary (COB) the mafic crust beneath Walvis Ridge is up to 33 km thick, with a pronounced high-velocity lower crustal body. Towards the south there is a smooth transition to 20-25 km thick crust underlying the COB in the Walvis Basin, with a similar velocity structure, indicating a gabbroic lower crust with associated cumulates at the base. The northern boundary of Walvis Ridge towards the Angola Basin shows a sudden change to oceanic crust only 4-6 km thick, coincident with the projection of the Florianopolis Fracture Zone, one of the most prominent tectonic features of the South Atlantic ocean basin. In the amphibious profile the COB is defined by a sharp transition from oceanic to rifted continental crust, with a magmatic overprint landward of the intersection of Walvis Ridge with the Namibian margin. The continental crust beneath the Congo Craton is 40 km thick, shoaling to 35 km further SE. The velocity models show that massive high-velocity gabbroic intrusives are restricted to a narrow zone directly underneath Walvis Ridge and the COB in the south. This distribution of rift-related magmatism is not easily reconciled with models of continental breakup following the establishment of a large, axially symmetric plume in the Earth's mantle. Rift-related lithospheric stretching and associated transform faulting play an overriding role in locating magmatism, dividing the margin in a magma-dominated southern and an essentially amagmatic northern segment.}, language = {en} } @article{RybergBraeuerWeber2017, author = {Ryberg, Trond and Braeuer, Benjamin and Weber, Michael}, title = {Upper mantle structure at Walvis Ridge from P-n tomography}, series = {Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth}, volume = {716}, journal = {Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0040-1951}, doi = {10.1016/j.tecto.2016.08.009}, pages = {121 -- 129}, year = {2017}, abstract = {Passive continental margins offer the unique opportunity to study the processes involved in continental extension and break-up. Within the LISPWAL (Llthospheric Structure of the Namibian continental Passive margin at the intersection with the Walvis Ridge from amphibious seismic investigations) project, combined on- and offshore seismic experiments were designed to characterize the Southern African passive margin at the Walvis Ridge in northern Namibia. In addition to extensive analysis of the crustal structures, we carried out seismic investigations targeting the velocity structure of the upper mantle in the landfall region of the Walvis Ridge with the Namibian coast. Upper mantle P-n travel time tomography from controlled source, amphibious seismic data was used to investigate the sub-Moho upper mantle seismic velocity. We succeeded in imaging upper mantle structures potentially associated with continental break-up and/or the Tristan da Cunha hotspot track. We found mostly coast-parallel sub-Moho velocity anomalies, interpreted as structures which were created during Gondwana break-up. (C)2016 Published by Elsevier B.V.}, language = {en} } @article{FrommJokatRybergetal.2017, author = {Fromm, T. and Jokat, W. and Ryberg, T. and Behrmann, Jan H. and Haberland, C. and Weber, Michael}, title = {The onset of Walvis Ridge: Plume influence at the continental margin}, series = {Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth}, volume = {716}, journal = {Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0040-1951}, doi = {10.1016/j.tecto.2017.03.011}, pages = {90 -- 107}, year = {2017}, abstract = {The opening of the South Atlantic is a classical example for a plume related continental breakup. Flood basalts are present on both conjugate margins as well as aseismic ridges connecting them with the current plume location at Tristan da Cunha. To determine the effect of the proposed plume head on the continental crust, we acquired wide-angle seismic data at the junction of the Walvis Ridge with the African continent and modelled the P-wave velocity structure in a forward approach. The profile extends 430 km along the ridge and continues onshore to a length of 720 km. Crustal velocities beneath the Walvis Ridge vary between 5.5 km/s and 7.0 km/s, a typical range for oceanic crust. The crustal thickness of 22 km, however, is approximately three times larger than of normal oceanic crust. The continent-ocean transition is characterized by 30 km thick crust with strong lateral velocity variations in the upper crust and a high-velocity lower crust (HVLC), where velocities reach up to 7.5 km/s. The HVLC is 100 to 130 km wider at the Walvis Ridge than it is farther south, and impinges onto the continental crust of the Kaoko fold belt. Such high seismic velocities indicate Mg-rich igneous material intruded into the continental crust during the initial rifting stage. However, the remaining continental crust seems unaffected by intrusions and the root of the 40 km-thick crust of the Kaoko belt is not thermally abraded. We conclude that the plume head did not modify the continental crust on a large scale, but caused rather local effects. Thus, it seems unlikely that a plume drove or initiated the breakup process. We further propose that the plume already existed underneath the continent prior to the breakup, and ponded melt erupted at emerging rift structures providing the magma for continental flood basalts. (C) 2017 Elsevier B.V. All rights reserved.}, language = {en} } @article{KottmeierAgnonAlHalbounietal.2016, author = {Kottmeier, Christoph and Agnon, Amotz and Al-Halbouni, Djamil and Alpert, Pinhas and Corsmeier, Ulrich and Dahm, Torsten and Eshel, Adam and Geyer, Stefan and Haas, Michael and Holohan, Eoghan and Kalthoff, Norbert and Kishcha, Pavel and Krawczyk, Charlotte and Lati, Joseph and Laronne, Jonathan B. and Lott, Friederike and Mallast, Ulf and Merz, Ralf and Metzger, Jutta and Mohsen, Ayman and Morin, Efrat and Nied, Manuela and Roediger, Tino and Salameh, Elias and Sawarieh, Ali and Shannak, Benbella and Siebert, Christian and Weber, Michael}, title = {New perspectives on interdisciplinary earth science at the Dead Sea: The DESERVE project}, series = {The science of the total environment : an international journal for scientific research into the environment and its relationship with man}, volume = {544}, journal = {The science of the total environment : an international journal for scientific research into the environment and its relationship with man}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0048-9697}, doi = {10.1016/j.scitotenv.2015.12.003}, pages = {1045 -- 1058}, year = {2016}, abstract = {The Dead Sea region has faced substantial environmental challenges in recent decades, including water resource scarcity, similar to 1 m annual decreases in the water level, sinkhole development, ascending-brine freshwater pollution, and seismic disturbance risks. Natural processes are significantly affected by human interference as well as by climate change and tectonic developments over the long term. To get a deep understanding of processes and their interactions, innovative scientific approaches that integrate disciplinary research and education are required. The research project DESERVE (Helmholtz Virtual Institute Dead Sea Research Venue) addresses these challenges in an interdisciplinary approach that includes geophysics, hydrology, and meteorology. The project is implemented by a consortium of scientific institutions in neighboring countries of the Dead Sea (Israel, Jordan, Palestine Territories) and participating German Helmholtz Centres (KIT, GFZ, UFZ). A new monitoring network of meteorological, hydrological, and seismic/geodynamic stations has been established, and extensive field research and numerical simulations have been undertaken. For the first time, innovative measurement and modeling techniques have been applied to the extreme conditions of the Dead Sea and its surroundings. The preliminary results show the potential of these methods. First time ever performed eddy covariance measurements give insight into the governing factors of Dead Sea evaporation. High-resolution bathymetric investigations reveal a strong correlation between submarine springs and neo-tectonic patterns. Based on detailed studies of stratigraphy and borehole information, the extension of the subsurface drainage basin of the Dead Sea is now reliably estimated. Originality has been achieved in monitoring flash floods in an arid basin at its outlet and simultaneously in tributaries, supplemented by spatio-temporal rainfall data. Low-altitude, high resolution photogrammetry, allied to satellite image analysis and to geophysical surveys (e.g. shear-wave reflections) has enabled a more detailed characterization of sinkhole morphology and temporal development and the possible subsurface controls thereon. All the above listed efforts and scientific results take place with the interdisciplinary education of young scientists. They are invited to attend joint thematic workshops and winter schools as well as to participate in field experiments. (C) 2015 The Authors. Published by Elsevier B.V.}, language = {en} } @misc{JoussetReinschRybergetal.2018, author = {Jousset, Philippe and Reinsch, Thomas and Ryberg, Trond and Blanck, Hanna and Clarke, Andy and Aghayev, Rufat and Hersir, Gylfi P. and Henninges, Jan and Weber, Michael and Krawczyk, Charlotte M.}, title = {Dynamic strain determination using fibre-optic cables allows imaging of seismological and structural features}, series = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe}, number = {691}, doi = {10.25932/publishup-42677}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-426770}, pages = {11}, year = {2018}, abstract = {Natural hazard prediction and efficient crust exploration require dense seismic observations both in time and space. Seismological techniques provide ground-motion data, whose accuracy depends on sensor characteristics and spatial distribution. Here we demonstrate that dynamic strain determination is possible with conventional fibre-optic cables deployed for telecommunication. Extending recently distributed acoustic sensing (DAS) studies, we present high resolution spatially un-aliased broadband strain data. We recorded seismic signals from natural and man-made sources with 4-m spacing along a 15-km-long fibre-optic cable layout on Reykjanes Peninsula, SW-Iceland. We identify with unprecedented resolution structural features such as normal faults and volcanic dykes in the Reykjanes Oblique Rift, allowing us to infer new dynamic fault processes. Conventional seismometer recordings, acquired simultaneously, validate the spectral amplitude DAS response between 0.1 and 100 Hz bandwidth. We suggest that the networks of fibre-optic telecommunication lines worldwide could be used as seismometers opening a new window for Earth hazard assessment and exploration.}, language = {en} }