@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{WeberHelwigBaueretal.2012, author = {Weber, Michael H. and Helwig, S. L. and Bauer, Klaus and Haberland, Christian and Koch, Olaf and Ryberg, T. and Maercklin, N. and Ritter, O. and Schulze, A.}, title = {Near-surface properties of an active fault derived by joint interpretation of different geophysical methods - the Arava/Araba Fault in the Middle East}, series = {Near surface geophysics}, volume = {10}, journal = {Near surface geophysics}, number = {5}, publisher = {European Association of Geoscientists \& Engineers}, address = {Houten}, issn = {1569-4445}, doi = {10.3997/1873-0604.2012031}, pages = {381 -- 390}, year = {2012}, abstract = {The motion of tectonic plates is accommodated at fault zones. One of the unanswered questions about fault zones relates to the role they play in controlling shallow and local hydrology. This study focuses on the Arava/Araba Fault (AF) zone, the southern portion of the Dead Sea Transform (DST) in the Middle East. We combine seismic and electromagnetic methods (EM) to image the geometry and map the petro-physical properties and water occurrence in the top 100 m of this active fault. For three profiles, P-velocity and resistivity images were derived independently. Using a neural network cluster analysis three classes with similar P-velocity and resistivities could then be determined from these images. These classes correspond to spatial domains of specific material and wetness. The first class occurs primarily east of the fault consisting of 'wet' sand (dunes) and brecciated sediments, whereas the second class composed of similar material located west of the fault is 'dry'. The third class lies at depth below ca. 50 m and is composed of highly deformed and weathered Precambrian rocks that constitute the multi-branch fault zone of the AF at this location. The combination of two independent measurements like seismics and EM linked by a stringent mathematical approach has thus shown the potential to delineate the interplay of lithology and water near active faults.}, language = {en} } @article{WeberZetscheRybergetal.2005, author = {Weber, Michael H. and Zetsche, F. and Ryberg, Trond and Schulze, A. and Spangenberg, Erik and Huenges, Ernst}, title = {Seismic detection limits of small, deep, man-made reflectors : a test at a geothermal site in northern Germany}, issn = {0037-1106}, year = {2005}, abstract = {A key question for the development of geothermal plants is the seismic detection and monitoring of fluid injections at several kilometers depth. The detection and monitoring limits are controlled by several parameters, for example, the strength of seismic sources, number of receivers, vertical stacking, and noise conditions. For a known reference reflector at 2.66 km depth at a geothermal site in northern Germany the results of a simple surface seismic experiment were therefore combined with numerical forward modeling for different injection scenarios at 3.8 km depth. The underlying idea is that changes of reflectivity from the injection at 3.8 km must be larger than the variance of the measurements to be observable. Assuming that the injection at 3.8 km depth would produce a subhorizontal disklike target with a fracture porosity of 2\% or 5\% (the critical porosity) the water injection volume has to be at least 443 and 115 m(3), respectively, to be detectable from the surface. If the injection on the other hand does not create subhorizontal but subvertical pathways or only reduces the seismic velocities via the increased pore pressure in the immediate vicinity of the bore hole, the injection is undetectable from the surface. The most promising approach is therefore to move sources and/or receivers closer to the target, that is, the use of borehole instrumentation}, language = {en} }