TY  - JOUR
A1  - Thomas, Ch.
A1  - Igel, Heiner
A1  - Weber, Michael H.
A1  - Scherbaum, Frank
T1  - Acoustic simulation of P-wave propagation in a heterogeneous spherical earth : numerical method and application to precursor waves to PKPdf
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Ewald, Michael
A1  - Igel, Heiner
A1  - Hinzen, Klaus-Günther
A1  - Scherbaum, Frank
T1  - Basin-related effects on ground motion for earthquake scenarios in the Lower Rhine Embayment
N2  - The deterministic calculation of earthquake scenarios using complete waveform modelling plays an increasingly important role in estimating shaking hazard in seismically active regions. Here we apply 3-D numerical modelling of seismic wave propagation to M 6+ earthquake scenarios in the area of the Lower Rhine Embayment, one of the seismically most active regions in central Europe. Using a 3-D basin model derived from geology, borehole information and seismic experiments, we aim at demonstrating the strong dependence of ground shaking on hypocentre location and basin structure. The simulations are carried out up to frequencies of ca. 1 Hz. As expected, the basin structure leads to strong lateral variations in peak ground motion, amplification and shaking duration. Depending on source-basin-receiver geometry, the effects correlate with basin depth and the slope of the basin flanks; yet, the basin also affects peak ground motion and estimated shaking hazard thereof outside the basin. Comparison with measured seismograms for one of the earthquakes shows that some of the main characteristics of the wave motion are reproduced. Cumulating the derived seismic intensities from the three modelled earthquake scenarios leads to a predominantly basin correlated intensity distribution for our study area
Y1  - 2006
UR  - http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-246X
U6  - https://doi.org/10.1111/j.1365-246X.2006.02909.x
SN  - 0956-540X
ER  - 
TY  - JOUR
A1  - Suryanto, Wiwit
A1  - Igel, Heiner
A1  - Wassermann, Joachim
A1  - Cochard, Alain
A1  - Schuberth, B. S. A.
A1  - Vollmer, Daniel
A1  - Scherbaum, Frank
A1  - Schreiber, U.
A1  - Velikoseltsev, A.
T1  - First comparison of array-derived rotational ground motions with direct ring laser measurements
JF  - Bulletin of the Seismological Society of America
N2  - Recently, ring laser technology has provided the first consistent observations of rotational ground motions around a vertical axis induced by earthquakes. "Consistent," in this context, implies that the observed waveforms and amplitudes are compatible with collocated recordings of translational ground motions. In particular, transverse accelerations should be in phase with rotation rate and their ratio proportional to local horizontal phase velocity assuming plane-wave propagation. The ring laser installed at the Fundamental station Wettzell in the Bavarian Forest, Southeast Germany, is recording the rotation rate around a vertical axis, theoretically a linear combination of the space derivatives of the horizontal components of motion. This suggests that, in principle, rotation can be derived from seismic-array experiments by "finite differencing." This has been attempted previously in several studies; however, the accuracy of these observations could never be tested in the absence of direct measurements. We installed a double cross-shaped array of nine stations from December 2003 to March 2004 around the ring laser instrument and observed several large earthquakes on both the ring laser and the seismic array. Here we present for the first time a comparison of array-derived rotations with direct measurements of rotations for ground motions induced by the M 6.3 Al Hoceima, Morocco, earthquake of 24 February 2004. With complete 3D synthetic seismograms calculated for this event we show that even low levels of noise may considerably influence the accuracy of the array-derived rotations when the minimum number of required stations (three) is used. Nevertheless, when using all nine stations, the overall fit between direct and array-derived measurements is surprisingly good (maximum correlation coefficient of 0.94).
Y1  - 2006
U6  - https://doi.org/10.1785/0120060004
SN  - 0037-1106
SN  - 1943-3573
VL  - 96
IS  - 6
SP  - 2059
EP  - 2071
PB  - GeoScienceWorld
CY  - Alexandria, Va.
ER  -