@article{ArrowsmithCrosbyKorzhenkovetal.2017, author = {Arrowsmith, J. Ramon and Crosby, Christopher J. and Korzhenkov, Andrey M. and Mamyrov, Ernest and Povolotskaya, Irina and Guralnik, Benny and Landgraf, Angela}, title = {Surface rupture of the 1911 Kebin (Chon-Kemin) earthquake, Northern Tien Shan, Kyrgyzstan}, series = {Seismicity, fault rupture and earthquake hazards in slowly deforming regions}, volume = {432}, journal = {Seismicity, fault rupture and earthquake hazards in slowly deforming regions}, publisher = {The Geological Society}, address = {London}, isbn = {978-1-86239-745-3}, issn = {0305-8719}, doi = {10.1144/SP432.10}, pages = {233 -- 253}, year = {2017}, abstract = {The 1911 Chon-Kemin (Kebin) earthquake culminated c. 30 years of remarkable earthquakes in the northern Tien Shan (Kyrgyzstan and Kazakhstan). Building on prior mapping of the event, we traced its rupture in the field and measured more than 50 offset landforms. Cumulative fault rupture length is >155-195 km along 13 fault patches comprising six sections. The patches are separated by changes of dip magnitude or dip direction, or by 4-10 km-wide stepovers. One <40 km section overlaps and is parallel to the main north-dipping rupture but is 7 km north and dips opposite (south). Both ends of the rupture are along mountain front thrust faults demonstrating late Quaternary activity. We computed the moment from each fault patch using the surface fault traces, dip inferred from the traces, 20 km seismogenic thickness, rigidity of 3.3 x 10(10) N m(-2) and dip slip converted from our observations of the largely reverse sense of motion vertical offsets. The discontinuous patches with c. 3-4 m average slip and peak slip of <14 m yield a seismic moment of 4.6 x 10(20) Nm (M-w 7.78) to 7.4 x 10(20) Nm (M-w 7.91). The majority of moment was released along the inner eastern rupture segments. This geological moment is lower by a factor of 1.5 from that determined from teleseismic data.}, language = {en} } @article{KueblerStreichLuecketal.2017, author = {K{\"u}bler, Simon and Streich, R. and L{\"u}ck, Erika and Hoffmann, M. and Friedrich, A. M. and Strecker, Manfred}, title = {Active faulting in a populated low-strain setting (Lower Rhine Graben, Central Europe) identified by geomorphic, geophysical and geological analysis}, series = {Seismicity, fault rupture and earthquake hazards in slowly deforming regions}, volume = {432}, journal = {Seismicity, fault rupture and earthquake hazards in slowly deforming regions}, publisher = {The Geological Society}, address = {London}, isbn = {978-1-86239-745-3}, issn = {0305-8719}, doi = {10.1144/SP432.11}, pages = {127 -- 146}, year = {2017}, abstract = {The Lower Rhine Graben (Central Europe) is a prime example of a seismically active low-strain rift zone characterized by pronounced anthropogenic and climatic overprint of structures, and long recurrence intervals of large earthquakes. These factors render the identification of active faults and surface ruptures difficult. We investigated two fault scarps in the Lower Rhine Graben, to decipher their structural character, offset and potential seismogenic origin. Both scarps were modified by anthropogenic activity. The Hemmerich site lies c. 20 km SW of Cologne, along the Erft Fault. The Untermaubach site lies SW of Duren, where the Schafberg Fault projects into the Rur River valley. At the Hemmerich site, geomorphic and geophysical data, as well as exploratory coring reveal evidence of repeated normal faulting. Geophysical analysis and palaeoseismological excavation at the Untermaubach site reveal a complex fault zone in Holocene gravels characterized by subtle gravel deformation. Differentiation of tectonic and fluvial features was only possible with trenching, because fault structures and grain sizes of the sediments were below the resolution of the geophysical data. Despite these issues, our investigation demonstrates that valuable insight into past earthquakes and seismogenic deformation in a low-strain environment can be revealed using a multidisciplinary approach.}, language = {en} } @article{KruegerKulikovaLandgraf2017, author = {Kr{\"u}ger, Frank and Kulikova, Galina and Landgraf, Angela}, title = {Instrumental magnitude constraints for the 11 July 1889, Chilik earthquake}, series = {Seismicity, fault rupture and earthquake hazards in slowly deforming regions}, volume = {432}, journal = {Seismicity, fault rupture and earthquake hazards in slowly deforming regions}, publisher = {The Geological Society}, address = {London}, isbn = {978-1-86239-745-3}, issn = {0305-8719}, doi = {10.1144/SP432.8}, pages = {41 -- 72}, year = {2017}, abstract = {A series of large-magnitude earthquakes above 6.9 occurred in the northern Tien-Shan between 1885 and 1911. The Chilik earthquake of 11 July 1889, has been listed with a magnitude of 8.3, based on sparse macroseismic intensities, constrained by reported damage. Despite the existence of several juvenile fault scarps in the epicentral region, that are possibly associated with the 1889 earthquake, no through-going surface rupture having the dimensions expected for a magnitude 8.3 earthquake has been located - a puzzling dilemma. Could the magnitude have been overestimated? This would have major implications not only for the understanding of the earthquake series, but also for regional hazard estimates. Fortunately, a fragmentary record from an early Rebeur-Paschwitz seismometer exists for the Chilik event, recorded in Wilhelmshaven (Germany). To constrain the magnitude, we compare the late coda waves of this record with those of recent events from Central Asia, recorded on modern instruments in Germany and filtered with Rebeur-Paschwitz instrument characteristics. Additional constraints come from disturbances of historic magnetograms that exist from the Chilik and the 1911 Chon-Kemin earthquakes. Scaling of these historic records confirm a magnitude of about 8 for the 1889 Chilik earthquake, pointing towards a lower crustal contribution to the fault area.}, language = {en} } @article{LandgrafKueblerHintersbergeretal.2017, author = {Landgraf, Angela and K{\"u}bler, Simon and Hintersberger, Esther and Stein, Seth}, title = {Active tectonics, earthquakes and palaeoseismicity in slowly deforming continents}, series = {Seismicity, fault rupture and earthquake hazards in slowly deforming regions}, volume = {432}, journal = {Seismicity, fault rupture and earthquake hazards in slowly deforming regions}, number = {1}, publisher = {The Geological Society}, address = {London}, isbn = {978-1-86239-745-3}, issn = {0305-8719}, doi = {10.1144/SP432.13}, pages = {1 -- 12}, year = {2017}, language = {en} } @incollection{Bookhagen2017, author = {Bookhagen, Bodo}, title = {The influence of hydrology and glaciology on wetlands in the Himalayas}, series = {Bird migration across the Himalayas : wetland functioning amidst mountains and glaciers}, booktitle = {Bird migration across the Himalayas : wetland functioning amidst mountains and glaciers}, editor = {Prins, Herbert H.T. and Namgail, Tsewang}, publisher = {Cambridge University Press}, address = {Cambridge}, isbn = {978-1-107-11471-5}, doi = {10.1017/9781316335420}, pages = {175 -- 188}, year = {2017}, abstract = {Birds migrating across the Himalayan region fly over the highest peaks in the world, facing immense physiological and climatic challenges. The authors show the different strategies used by birds to cope with these challenges. Many wetland avian species are seen in the high-altitude lakes of the Himalayas and the adjoining Tibetan Plateau, such as Bar-Headed Geese. Ringing programmes have generated information about origins and destinations, and this book is the first to present information on the bird's exact migratory paths. Capitalising on knowledge generated through satellite telemetry, the authors describe the migratory routes of a multitude of birds flying over or skirting the Himalayas. The myriad of threats to migratory birds and the wetland system in the Central Asian Flyway are discussed, with ways to mitigate them. This volume will inform and persuade policy-makers and conservation practitioners to take appropriate measures for the long-term survival of this unique migration}, language = {en} } @article{DoraniArvinOberhaenslietal.2017, author = {Dorani, Maryam and Arvin, Mohsen and Oberh{\"a}nsli, Roland and Dargahi, Sara}, title = {P-T evolution of metapelites from the Bajgan complex in the Makran accretionary prism, south eastern Iran}, series = {Chemie der Erde : interdisciplinary journal for chemical problems of the geo-sciences and geo-ecology = Geochemistry}, volume = {77}, journal = {Chemie der Erde : interdisciplinary journal for chemical problems of the geo-sciences and geo-ecology = Geochemistry}, number = {3}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0009-2819}, doi = {10.1016/j.chemer.2017.07.004}, pages = {459 -- 475}, year = {2017}, abstract = {The Bajgan Complex, one of the basement constituents of the arc massif in Iranian Makran forms a rugged, deeply incised terrain. The complex consists of pelitic schists with minor psammitic and basic schists, calc silicate rocks, amphibolites, marbles, metavolcanosediments, mafic and felsic intrusives as well as ultramafic rocks. Metapelitic rocks show an amphibolite facies regional metamorphism and contain garnet, biotite, white mica, quartz, albite ± rutile ± apatite. Thermobarometry of garnet schist yields pressure of more than 9 kbar and temperatures between 560 and 675 °C. The geothermal gradient obtained for the peak of regional metamorphism is 19 °C/km, corresponding to a depth of ca. 31 km. Replacement of garnet by chlorite and epidote suggest greenschist facies metamorphism due to a decrease in temperature and pressure through exhumation and retrograde metamorphism (370-450 °C and 3-6 kbar). The metapelitic rocks followed a 'clockwise' P-T path during metamorphism, consistent with thermal decline following tectonic thickening. The formation of medium-pressure metamorphic rocks is related to presence of active subduction of the Neotethys Oceanic lithosphere beneath Eurasia in the Makran.}, language = {en} } @article{ToySutherlandTownendetal.2017, author = {Toy, Virginia Gail and Sutherland, Rupert and Townend, John and Allen, Michael J. and Becroft, Leeza and Boles, Austin and Boulton, Carolyn and Carpenter, Brett and Cooper, Alan and Cox, Simon C. and Daube, Christopher and Faulkner, D. R. and Halfpenny, Angela and Kato, Naoki and Keys, Stephen and Kirilova, Martina and Kometani, Yusuke and Little, Timothy and Mariani, Elisabetta and Melosh, Benjamin and Menzies, Catriona D. and Morales, Luiz and Morgan, Chance and Mori, Hiroshi and Niemeijer, Andre and Norris, Richard and Prior, David and Sauer, Katrina and Schleicher, Anja Maria and Shigematsu, Norio and Teagle, Damon A. H. and Tobin, Harold and Valdez, Robert and Williams, Jack and Yeo, Samantha and Baratin, Laura-May and Barth, Nicolas and Benson, Adrian and Boese, Carolin and C{\´e}l{\´e}rier, Bernard and Chamberlain, Calum J. and Conze, Ronald and Coussens, Jamie and Craw, Lisa and Doan, Mai-Linh and Eccles, Jennifer and Grieve, Jason and Grochowski, Julia and Gulley, Anton and Howarth, Jamie and Jacobs, Katrina and Janku-Capova, Lucie and Jeppson, Tamara and Langridge, Robert and Mallyon, Deirdre and Marx, Ray and Massiot, C{\´e}cile and Mathewson, Loren and Moore, Josephine and Nishikawa, Osamu and Pooley, Brent and Pyne, Alex and Savage, Martha K. and Schmitt, Doug and Taylor-Offord, Sam and Upton, Phaedra and Weaver, Konrad C. and Wiersberg, Thomas and Zimmer, Martin}, title = {Bedrock geology of DFDP-2B, central Alpine Fault, New Zealand}, series = {New Zealand journal of geology and geophysics : an international journal of the geoscience of New Zealand, the Pacific Rim, and Antarctica ; NZJG}, volume = {60}, journal = {New Zealand journal of geology and geophysics : an international journal of the geoscience of New Zealand, the Pacific Rim, and Antarctica ; NZJG}, number = {4}, publisher = {Taylor \& Francis}, address = {Abingdon}, organization = {DFDP-2 Sci Team}, issn = {0028-8306}, doi = {10.1080/00288306.2017.1375533}, pages = {497 -- 518}, year = {2017}, abstract = {During the second phase of the Alpine Fault, Deep Fault Drilling Project (DFDP) in the Whataroa River, South Westland, New Zealand, bedrock was encountered in the DFDP-2B borehole from 238.5-893.2 m Measured Depth (MD). Continuous sampling and meso- to microscale characterisation of whole rock cuttings established that, in sequence, the borehole sampled amphibolite facies, Torlesse Composite Terrane-derived schists, protomylonites and mylonites, terminating 200-400 m above an Alpine Fault Principal Slip Zone (PSZ) with a maximum dip of 62°. The most diagnostic structural features of increasing PSZ proximity were the occurrence of shear bands and reduction in mean quartz grain sizes. A change in composition to greater mica:quartz + feldspar, most markedly below c. 700 m MD, is inferred to result from either heterogeneous sampling or a change in lithology related to alteration. Major oxide variations suggest the fault-proximal Alpine Fault alteration zone, as previously defined in DFDP-1 core, was not sampled.}, language = {en} } @misc{KuehnSchoene2017, author = {K{\"u}hn, Michael and Sch{\"o}ne, Tim}, title = {Multivariate regression model from water level and production rate time series for the geothermal reservoir Waiwera (New Zealand)}, series = {Energy procedia}, volume = {125}, journal = {Energy procedia}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1876-6102}, doi = {10.1016/j.egypro.2017.08.196}, pages = {571 -- 579}, year = {2017}, abstract = {Water management tools are necessary to guarantee the preservation of natural resources while ensuring optimum utilization. Linear regression models are a simple and quick solution for creating prognostic capabilities. Multivariate models show higher precision than univariate models. In the case of Waiwera, implementation of individual production rates is more accurate than applying just the total production rate. A maximum of approximately 1,075 m3/day can be pumped to ensure a water level of at least 0.5 m a.s.l. in the monitoring well. The model should be renewed annually to implement new data and current water level trends to keep the quality.}, language = {en} } @misc{WetzelKempkaKuehn2017, author = {Wetzel, Maria and Kempka, Thomas and K{\"u}hn, Michael}, title = {Predicting macroscopic elastic rock properties requires detailed information on microstructure}, series = {Energy procedia}, volume = {125}, journal = {Energy procedia}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1876-6102}, doi = {10.1016/j.egypro.2017.08.195}, pages = {561 -- 570}, year = {2017}, abstract = {Predicting variations in macroscopic mechanical rock behaviour due to microstructural changes, driven by mineral precipitation and dissolution is necessary to couple chemo-mechanical processes in geological subsurface simulations. We apply 3D numerical homogenization models to estimate Young's moduli for five synthetic microstructures, and successfully validate our results for comparable geometries with the analytical Mori-Tanaka approach. Further, we demonstrate that considering specific rock microstructures is of paramount importance, since calculated elastic properties may deviate by up to 230 \% for the same mineral composition. Moreover, agreement between simulated and experimentally determined Young's moduli is significantly improved, when detailed spatial information are employed.}, language = {en} } @misc{KuehnLiNakatenetal.2017, author = {K{\"u}hn, Michael and Li, Qi and Nakaten, Natalie Christine and Kempka, Thomas}, title = {Integrated subsurface gas storage of CO2 and CH4 offers capacity and state-of-the-art technology for energy storage in China}, series = {Energy procedia}, volume = {125}, journal = {Energy procedia}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1876-6102}, doi = {10.1016/j.egypro.2017.08.039}, pages = {14 -- 18}, year = {2017}, abstract = {Integration and development of the energy supply in China and worldwide is a challenge for the years to come. The innovative idea presented here is based on an extension of the "power-to-gas-to-power" technology by establishing a closed carbon cycle. It is an implementation of a low-carbon energy system based on carbon dioxide capture and storage (CCS) to store and reuse wind and solar energy. The Chenjiacun storage project in China compares well with the German case study for the towns Potsdam and Brandenburg/Havel in the Federal State of Brandenburg based on the Ketzin pilot site for CCS.}, language = {en} } @misc{KuehnKempkadeLuciaetal.2017, author = {K{\"u}hn, Michael and Kempka, Thomas and de Lucia, Marco and Scheck-Wenderoth, Magdalena}, title = {Dissolved CO2 storage in geological formations with low pressure, low risk and large capacities}, series = {Energy procedia}, volume = {114}, journal = {Energy procedia}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1876-6102}, doi = {10.1016/j.egypro.2017.03.1607}, pages = {4722 -- 4727}, year = {2017}, abstract = {Geological CO2 storage is a mitigation technology to reduce CO2 emissions from fossil fuel combustion. However, major concerns are the pressure increase and saltwater displacement in the mainly targeted deep groundwater aquifers due to injection of supercritical CO2. The suggested solution is storage of CO2 exclusively in the dissolved state. In our exemplary regional case study of the North East German Basin based on a highly resolved temperature and pressure distribution model and a newly developed reactive transport coupling, we have quantified that 4.7 Gt of CO2 can be stored in solution compared to 1.5 Gt in the supercritical state.}, language = {en} } @article{WieczorekKolmogorovKruseetal.2017, author = {Wieczorek, Mareike and Kolmogorov, Alexei and Kruse, Stefan and Jacobsen, Inga and Nitze, Ingmar and Nikolaev, Anatoly N. and Heinrich, Ingo and Pestryakova, Luidmila Agafyevna and Herzschuh, Ulrike}, title = {Disturbance-effects on treeline larch-stands in the lower Kolyma River area (NE Siberia)}, series = {Silva Fennica : a quarterly journal for forest science}, volume = {51}, journal = {Silva Fennica : a quarterly journal for forest science}, number = {3}, publisher = {The Finnish Society of Forest Science}, address = {Helsinki}, issn = {0037-5330}, doi = {10.14214/sf.1666}, pages = {20}, year = {2017}, abstract = {Tree stands in the boreal treeline ecotone are, in addition to climate change, impacted by disturbances such as fire, water-related disturbances and logging. We aim to understand how these disturbances affect growth, age structure, and spatial patterns of larch stands in the north-eastern Siberian treeline ecotone (lower Kolyma River region), an insufficiently researched region. Stand structure of Larix cajanderi Mayr was studied at seven sites impacted by disturbances. Maximum tree age ranged from 44 to 300 years. Young to medium-aged stands had, independent of disturbance type, the highest stand densities with over 4000 larch trees per ha. These sites also had the highest growth rates for tree height and stem diameter. Overall lowest stand densities were found in a polygonal field at the northern end of the study area, with larches growing in distinct " tree islands". At all sites, saplings are significantly clustered. Differences in fire severity led to contrasting stand structures with respect to tree, recruit, and overall stand densities. While a low severity fire resulted in low-density stands with high proportions of small and young larches, high severity fires resulted in high-density stands with high proportions of big trees. At waterdisturbed sites, stand structure varied between waterlogged and drained sites and latitude. These mixed effects of climate and disturbance make it difficult to predict future stand characteristics and the treeline position.}, language = {en} } @article{HoffmannSchulzHankeAlbaetal.2017, author = {Hoffmann, Mathias and Schulz-Hanke, Maximilian and Alba, Juana Garcia and Jurisch, Nicole and Hagemann, Ulrike and Sachs, Torsten and Sommer, Michael and Augustin, J{\"u}rgen}, title = {A simple calculation algorithm to separate high-resolution CH4 flux measurements into ebullition- and diffusion-derived components}, series = {Atmospheric measurement techniques : an interactive open access journal of the European Geosciences Union}, volume = {10}, journal = {Atmospheric measurement techniques : an interactive open access journal of the European Geosciences Union}, number = {1}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1867-1381}, doi = {10.5194/amt-10-109-2017}, pages = {109 -- 118}, year = {2017}, abstract = {Processes driving the production, transformation and transport of methane (CH4 / in wetland ecosystems are highly complex. We present a simple calculation algorithm to separate open-water CH4 fluxes measured with automatic chambers into diffusion-and ebullition-derived components. This helps to reveal underlying dynamics, to identify potential environmental drivers and, thus, to calculate reliable CH4 emission estimates. The flux separation is based on identification of ebullition-related sudden concentration changes during single measurements. Therefore, a variable ebullition filter is applied, using the lower and upper quartile and the interquartile range (IQR). Automation of data processing is achieved by using an established R script, adjusted for the purpose of CH4 flux calculation. The algorithm was validated by performing a laboratory experiment and tested using flux measurement data (July to September 2013) from a former fen grassland site, which converted into a shallow lake as a result of rewetting. Ebullition and diffusion contributed equally (46 and 55 \%) to total CH4 emissions, which is comparable to ratios given in the literature. Moreover, the separation algorithm revealed a concealed shift in the diurnal trend of diffusive fluxes throughout the measurement period. The water temperature gradient was identified as one of the major drivers of diffusive CH4 emissions, whereas no significant driver was found in the case of erratic CH4 ebullition events.}, language = {en} } @article{MartinezGarzonKwiatekBohnhoffetal.2017, author = {Mart{\´i}nez-Garz{\´o}n, Patricia and Kwiatek, Grzegorz and Bohnhoff, Marco and Dresen, Georg}, title = {Volumetric components in the earthquake source related to fluid injection and stress state}, series = {Geophysical research letters}, volume = {44}, journal = {Geophysical research letters}, number = {2}, publisher = {American Geophysical Union}, address = {Washington}, issn = {0094-8276}, doi = {10.1002/2016GL071963}, pages = {800 -- 809}, year = {2017}, abstract = {We investigate source processes of fluid-induced seismicity from The Geysers geothermal reservoir in California to determine their relation with hydraulic operations and improve the corresponding seismic hazard estimates. Analysis of 869 well-constrained full moment tensors (M-w 0.8-3.5) reveals significant non-double-couple components (>25\%) for about 65\% of the events. Volumetric deformation is governed by cumulative injection rates with larger non-double-couple components observed near the wells and during high injection periods. Source mechanisms are magnitude dependent and vary significantly between faulting regimes. Normal faulting events (M-w<2) reveal substantial volumetric components indicating dilatancy in contrast to strike-slip events that have a dominant double-couple source. Volumetric components indicating closure of cracks in the source region are mostly found for reverse faulting events with M-w>2.5. Our results imply that source processes and magnitudes of fluid-induced seismic events are strongly affected by the hydraulic operations, the reservoir stress state, and the faulting regime.}, language = {en} } @misc{SchmidtJochheimKersebaumetal.2017, author = {Schmidt, Martin and Jochheim, Hubert and Kersebaum, Kurt-Christian and Lischeid, Gunnar and Nendel, Claas}, title = {Gradients of microclimate, carbon and nitrogen in transition zones of fragmented landscapes - a review}, series = {Agricultural and forest meteorology}, volume = {232}, journal = {Agricultural and forest meteorology}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0168-1923}, doi = {10.1016/j.agrformet.2016.10.022}, pages = {659 -- 671}, year = {2017}, abstract = {Fragmentation of landscapes creates a transition zone in between natural habitats or different kinds of land use. In forested and agricultural landscapes with transition zones, microclimate and matter cycling are markedly altered. This probably accelerates and is intensified by global warming. However, there is no consensus on defining transition zones and quantifying relevant variables for microclimate and matter cycling across disciplines. This article is an attempt to a) revise definitions and offer a framework for quantitative ecologists, b) review the literature on microclimate and matter cycling in transition zones and c) summarise this information using meta-analysis to better understand bio-geochemical and bio-geophysical processes and their spatial extent in transition zones. We expect altered conditions in soils of transition zones to be 10-20 m with a maximum of 50 m, and 25-50 m for above-ground space with a maximum of 125 m.}, language = {en} } @article{KnapmeyerEndrunKruegerGeissler2017, author = {Knapmeyer-Endrun, Brigitte and Kr{\"u}ger, Frank and Geissler, Wolfram H.}, title = {Upper mantle structure across the Trans-European Suture Zone imaged by S-receiver functions}, series = {Earth \& planetary science letters}, volume = {458}, journal = {Earth \& planetary science letters}, publisher = {Elsevier}, address = {Amsterdam}, organization = {PASSEQ Working Grp}, issn = {0012-821X}, doi = {10.1016/j.epsl.2016.11.011}, pages = {429 -- 441}, year = {2017}, abstract = {We present a high-resolution study of the upper mantle structure of Central Europe, including the western part of the East European Platform, based on S-receiver functions of 345 stations. A distinct contrast is found between Phanerozoic Europe and the East European Craton across the Trans-European Suture Zone. To the west, a pronounced velocity reduction with depth interpreted as lithosphere-asthenosphere boundary (LAB) is found at an average depth of 90 km. Beneath the craton, no strong and continuous LAB conversion is observed. Instead we find a distinct velocity reduction within the lithosphere, at 80-120 km depth. This mid-lithospheric discontinuity (MLD) is attributed to a compositional boundary between depleted and more fertile lithosphere created by late Proterozoic metasomatism. A potential LAB phase beneath the craton is very weak and varies in depth between 180 and 250 km, consistent with a reduced velocity contrast between the lower lithosphere and the asthenosphere. Within the Trans-European Suture Zone, lithospheric structure is characterized by strong heterogeneity. A dipping or step-wise increase to LAB depth of 150 km is imaged from Phanerozoic Europe to 20-22 degrees E, whereas no direct connection to the cratonic LAB or MLD to the east is apparent. At larger depths, a positive conversion associated with the lower boundary of the asthenosphere is imaged at 210-250 km depth beneath Phanerozoic Europe, continuing down to 300 km depth beneath the craton. Conversions from both 410 km and 660 km discontinuities are found at their nominal depth beneath Phanerozoic Europe, and the discontinuity at 410 km depth can also be traced into the craton. A potential negative conversion on top of the 410 km discontinuity found in migrated images is analyzed by modeling and attributed to interference with other converted phases.}, language = {en} } @article{SippelMeessenCacaceetal.2017, author = {Sippel, Judith and Meessen, Christian and Cacace, Mauro and Mechie, James and Fishwick, Stewart and Heine, Christian and Scheck-Wenderoth, Magdalena and Strecker, Manfred}, title = {The Kenya rift revisited}, series = {Solid earth}, volume = {8}, journal = {Solid earth}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1869-9510}, doi = {10.5194/se-8-45-2017}, pages = {45 -- 81}, year = {2017}, abstract = {We present three-dimensional (3-D) models that describe the present-day thermal and rheological state of the lithosphere of the greater Kenya rift region aiming at a better understanding of the rift evolution, with a particular focus on plume-lithosphere interactions. The key methodology applied is the 3-D integration of diverse geological and geophysical observations using gravity modelling. Accordingly, the resulting lithospheric-scale 3-D density model is consistent with (i) reviewed descriptions of lithological variations in the sedimentary and volcanic cover, (ii) known trends in crust and mantle seismic velocities as revealed by seismic and seismological data and (iii) the observed gravity field. This data-based model is the first to image a 3-D density configuration of the crystalline crust for the entire region of Kenya and northern Tanzania. An upper and a basal crustal layer are differentiated, each composed of several domains of different average densities. We interpret these domains to trace back to the Precambrian terrane amalgamation associated with the East African Orogeny and to magmatic processes during Mesozoic and Cenozoic rifting phases. In combination with seismic velocities, the densities of these crustal domains indicate compositional differences. The derived lithological trends have been used to parameterise steady-state thermal and rheological models. These models indicate that crustal and mantle temperatures decrease from the Kenya rift in the west to eastern Kenya, while the integrated strength of the lithosphere increases. Thereby, the detailed strength configuration appears strongly controlled by the complex inherited crustal structure, which may have been decisive for the onset, localisation and propagation of rifting.}, language = {en} } @article{MohrMangaWangetal.2017, author = {Mohr, Christian Heinrich and Manga, Michael and Wang, Chi-Yuen and Korup, Oliver}, title = {Regional changes in streamflow after a megathrust earthquake}, series = {Earth \& planetary science letters}, volume = {458}, journal = {Earth \& planetary science letters}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0012-821X}, doi = {10.1016/j.epsl.2016.11.013}, pages = {418 -- 428}, year = {2017}, abstract = {Moderate to large earthquakes can increase the amount of water feeding stream flows, mobilizing excess water from deep groundwater, shallow groundwater, or the vadose zone. Here we examine the regional pattern of streamflow response to the Maule M8.8 earthquake across Chile's diverse topographic and hydro-climatic gradients. We combine streamflow analyses with groundwater flow modeling and a random forest classifier, and find that, after the earthquake, at least 85 streams had a change in flow. Discharge mostly increased () shortly after the earthquake, liberating an excess water volume of >1.1 km3, which is the largest ever reported following an earthquake. Several catchments had increased discharge of >50 mm, locally exceeding seasonal streamflow discharge under undisturbed conditions. Our modeling results favor enhanced vertical permeability induced by dynamic strain as the most probable process explaining the observed changes at the regional scale. Supporting this interpretation, our random forest classification identifies peak ground velocity and elevation extremes as most important for predicting streamflow response. Given the mean recurrence interval of ∼25 yr for >M8.0 earthquakes along the Peru-Chile Trench, our observations highlight the role of earthquakes in the regional water cycle, especially in arid environments.}, language = {en} } @article{TianCaoDallmeyeretal.2017, author = {Tian, Fang and Cao, Xianyong and Dallmeyer, Anne and Zhao, Yan and Ni, Jian and Herzschuh, Ulrike}, title = {Pollen-climate relationships in time (9 ka, 6 ka, 0 ka) and space (upland vs. lowland) in eastern continental Asia}, series = {Quaternary science reviews : the international multidisciplinary research and review journal}, volume = {156}, journal = {Quaternary science reviews : the international multidisciplinary research and review journal}, publisher = {Elsevier}, address = {Oxford}, issn = {0277-3791}, doi = {10.1016/j.quascirev.2016.11.027}, pages = {1 -- 11}, year = {2017}, abstract = {Temporal and spatial stability of the vegetation climate relationship is a basic ecological assumption for pollen-based quantitative inferences of past climate change and for predicting future vegetation. We explore this assumption for the Holocene in eastern continental Asia (China, Mongolia). Boosted regression trees (BRT) between fossil pollen taxa percentages (Abies, Artemisia, Betula, Chenopodiaceae, Cyperaceae, Ephedra, Picea, Pinus, Poaceae and Quercus) and climate model outputs of mean annual precipitation (P-ann) and mean temperature of the warmest month (Mt(wa)) for 9 and 6 ka (ka = thousand years before present) were set up and results compared to those obtained from relating modern pollen to modern climate. Overall, our results reveal only slight temporal differences in the pollen climate relationships. Our analyses suggest that the importance of P-ann compared with Mt(wa) for taxa distribution is higher today than it was at 6 ka and 9 ka. In particular, the relevance of P-ann for Picea and Pinus increases and has become the main determinant. This change in the climate tree pollen relationship parallels a widespread tree pollen decrease in north-central China and the eastern Tibetan Plateau. We assume that this is at least partly related to vegetation climate disequilibrium originating from human impact. Increased atmospheric CO2 concentration may have permitted the expansion of moisture-loving herb taxa (Cyperaceae and Poaceae) during the late Holocene into arid/semi-arid areas. We furthermore find that the pollen climate relationship between north-central China and the eastern Tibetan Plateau is generally similar, but that regional differences are larger than temporal differences. In summary, vegetation climate relationships in China are generally stable in space and time, and pollen-based climate reconstructions can be applied to the Holocene. Regional differences imply the calibration-set should be restricted spatially.}, language = {en} } @article{CampfortsSchwanghartGovers2017, author = {Campforts, Benjamin and Schwanghart, Wolfgang and Govers, Gerard}, title = {Accurate simulation of transient landscape evolution by eliminating numerical diffusion}, series = {Earth surface dynamics}, volume = {5}, journal = {Earth surface dynamics}, number = {1}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {2196-6311}, doi = {10.5194/esurf-5-47-2017}, pages = {47 -- 66}, year = {2017}, abstract = {Landscape evolution models (LEMs) allow the study of earth surface responses to changing climatic and tectonic forcings. While much effort has been devoted to the development of LEMs that simulate a wide range of processes, the numerical accuracy of these models has received less attention. Most LEMs use first-order accurate numerical methods that suffer from substantial numerical diffusion. Numerical diffusion particularly affects the solution of the advection equation and thus the simulation of retreating landforms such as cliffs and river knickpoints. This has potential consequences for the integrated response of the simulated landscape. Here we test a higher-order flux-limiting finite volume method that is total variation diminishing (TVD-FVM) to solve the partial differential equations of river incision and tectonic displacement. We show that using the TVD-FVM to simulate river incision significantly influences the evolution of simulated landscapes and the spatial and temporal variability of catchment-wide erosion rates. Furthermore, a two-dimensional TVD-FVM accurately simulates the evolution of landscapes affected by lateral tectonic displacement, a process whose simulation was hitherto largely limited to LEMs with flexible spatial discretization. We implement the scheme in TTLEM (TopoToolbox Landscape Evolution Model), a spatially explicit, raster-based LEM for the study of fluvially eroding landscapes in TopoToolbox 2.}, language = {en} }