Description: Along with cell phones and the internet, satellite navigation is an integral part of everyday life. However, satellite navigation signals provide much more than precise information on user locations. Even before the GPS was declared fully operational in 1995, the potential for these globally and continuously available navigation signals for Earth observation and geoscientific applications was recognized. Such applications include the precise monitoring of continental plate movements with sub-mm/year accuracy (now used in real-time as part of early earthquake warning systems), regional and global atmospheric and ionospheric sounding to improve weather forecasts and climate change predictions, and for monitoring of water, ice, and land surfaces. The Earth observation prospects and related spectrum of applications are continuously growing, mainly stimulated by the transition from a single constellation (GPS) to Multi-GNSS (Global Navigation Satellite System) with the Russian GLONASS, Chinese BeiDou and European Galileo satellites and by the increasing number of GNSS receivers available both on the ground and aboard Low Earth Orbiting satellites.
Description: In the deep crust, temperature, which is among the key parameters controlling lithospheric dynamics, is inferred by extrapolation from the surface using several assumptions that may fail in regions of active tectonics and fluid migration. In the rare case that temperatures of 700 °C or higher are exceeded in the upper and middle continental crust composed of quartz-rich felsic rocks, the α-β quartz transition (ABQT) will occur, generating a measurable seismic signature and offering the possibility for precisely estimating temperature from the known ABQT phase diagram. Here it is shown that all expected seismic features of the ABQT are met by the boundary between the upper and middle crust below the INDEPTH III profile in central Tibet. This finding implies that a temperature of 700 °C is achieved at a depth of 18 km under the southern Qiangtang block, which agrees with the depth to the top of a high electrical conductivity anomaly, likely representing partially melted crust. To the south in the northern Lhasa block, the ABQT is at 32 km depth, corresponding to a temperature of 800 °C. It thus appears that this seismic boundary representing the ABQT is the result of recent geologic processes rather than being a lithologic boundary.
Description: We employ finite-element thermo-mechanical modelling to study the dynamics of a continental transform boundary between the Arabian and African plates marked by the Dead Sea Transform (DST), that accommodated ca 105 km of relative transform displacement during the last 20 Myr. We show that in the initially cold lithosphere expected at the DST, shear deformation localizes in a 20–40 km wide zone where temperature-controlled mantle strength is minimal. The resulting mechanically weak decoupling zone extends sub-vertically through the entire lithosphere. One or two major faults at the top of this zone take up most of the transform displacement. These and other modelling results are consistent with geological observations and lithospheric structures imaged along the DESERT seismic line, suggesting that the Arava Valley segment of the DST is an almost pure strike-slip plate boundary with less than 3 km of transform-perpendicular extension. Modelling suggests that the location of the Arava Valley segment of the DST has been controlled by the minimum in lithospheric strength possibly associated with margin of the Arabian Shield lithosphere and/or by regionally increased crustal thickness. Models also show that heating of the Arabian Shield mantle adjacent to the DST, inferred independently by petrological and seismological studies, is required to explain asymmetric Late Cenozoic uplift in the area.
Description: The German-Indonesian Tsunami Early Warning System (GITEWS) has been established after the devastating Tsunami in the Indian Ocean on December 26, 2004. It became an integral part of the Indonesian Tsunami Early Warning System (InaTEWS) providing sensor networks and core computational components. GITEWS follows an “end-to-end” approach to cover the complete warning chain from rapid hazard detection over decision support to capacity development of communities at risk and the implementation of disaster reduction measures. PROTECTS (Project for Training, Education and Consulting for Tsunami Early Warning Systems) followed GITEWS with its main focus on system refinements, capacity building, and elaborated training measures that covered all aspects of the GITEWS Project. This paper discusses the specific challenges of Tsunami Early Warning in Indonesia, describes recent developments in instrumentation and data analysis and summarizes the system performance over the past 5 years.