Lower edge of locked Main Himalayan Thrust unzipped by the 2015 Gorkha earthquake

Large earthquakes are thought to release strain on previously locked faults. However, the details of how earthquakes are initiated, grow and terminate in relation to pre-seismically locked and creeping patches is unclear ^1-4. The 2015 Mw 7.8 Gorkha, Nepal earthquake occurred close to Kathmandu in a region where the prior pattern of fault locking is well documented ^5. Here we analyze this event using seismological records measured at teleseismic distances and Synthetic Aperture Radar imagery. We show that the earthquake originated northwest of Kathmandu within a cluster of background seismicity that fringes the bottom of the locked portion of the Main Himalayan Thrust fault (MHT). The rupture propagated eastwards for about 140 km, unzipping the lower edge of the locked portion of the fault. High-frequency seismic waves radiated continuously as the slip pulse propagated at about 2.8 km s-1 along this zone of presumably high and heterogeneous pre-¬seismic stress at the seismic-aseismic transition. Eastward unzipping of the fault resumed during the Mw 7.3 aftershock on May 12. The transfer of stress to neighbouring regions during the Gorkha earthquake should facilitate future rupture of the areas of the MHT adjacent and up-dip of the Gorkha earthquake rupture.This is the author accepted manuscript. The final version is available from Nature Publishing Group via http://dx.doi.org/10.1038/ngeo251

Darstellung und Verarbeitung hoeherdimensionaler Signale mit Hilfe von Schnittbildsequenzen

Copy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

TOMOGRAPHIC SAR INVERSION FROM MIXED REPEAT- AND SINGLE-PASS DATA STACKS – THE TERRASAR-X/TANDEM-X CASE

This paper presents the first demonstration of high precision very high resolution tomographic SAR inversion with the assistance of TanDEM-X data. The data quality of TerraSAR-X and TanDEM-X is investigated. TomoSAR algorithms such as SVD-Wiener, Nonlinear Least Squares and SL1MMER are extended for mixed repeat- and single-pass data stacks. A systematic approach is proposed for the fusion of TerraSAR-X and TanDEM-X data in which the different data quality provided by the TerraSAR-X and TanDEM-X data are taken into account by introducing a weighting according to the noise covariance matrix. The proposed approach is evaluated with simulated data. The simulation result shows that the reconstruction accuracy of tomographic SAR inversion can be improved significantly by using jointly fused TerraSAR-X and TanDEM-X data

X-SAR Radiometric Calibration and Data Quality

In April and October 1994 the X-SAR was flown as part of the SIR-C/X-SAR space radar laboratory missions (SRL-1/2) on the Space Shuttle. Amongst other activities DLR is responsible for the calibration of all X-SAR data products and is running the German Processing and Archiving Facility (D-PAF)

Wide band SAR sub-band splitting and inter-band coherence measurements

Range resolution of SAR images is determined by transmitted radar signal bandwidth. Most recent SAR sensors use wide band signals in order to achieve metric range resolution, whereas metric azimuth resolution can be achieved in spotlight mode. As an example, ENVISAT ASAR sensor uses a 15-MHz bandwidth chirp whereas TerraSAR-X spotlight mode uses signals having a 150-MHz bandwidth leading to a potentially 10 times higher resolution. One can also take advantage of wide band to split the full band into sub-bands and generate several lower resolution images from a single acquisition, each being centred on slightly different frequencies. These sub-images can then be used in a classical interferometric process to measure inter-band coherence of a given scene. This inter-band coherence reveals scatterers keeping a stable-phase behaviour along with frequency shift. A simple coherence model derived from Zebker model for randomly distributed surface scatterers is proposed. Examples are presented, showing that scatterers can have a behaviour that deviates from the model, leading to a new information channel.WiMCA - Wide Band interferometric Multichromatic Analysi

Correcting Motion Compensation Induced Height Errors in Airborne SAR Interferometry

For the motion compensation in airborne SAR processing the imaged terrain is generally assumed to be flat at some reference level. For SAR interferometry this introduces differential phase errors leading to distortions of the estimated heights above the assumed reference level. This contribution presents a correction approach which avoids a reprocessing of the interferometric SAR image pair

Correcting Motion Compensation Induced Height Errors in Airborne SAR Interferometry

For the motion compensation in airborne SAR processing the imaged terrain is generally assumed to be flat at some reference level. For SAR interferometry this introduces differential phase errors leading to distortions of the estimated heights above the assumed reference level. This contribution presents a correction approach which avoids a reprocessing of the interferometric SAR image pair