Paper Title, Authors, Abstract (Issue 1, Volume 2, 2008)

Pages

Retrieving Slowness Distribution of a Medium between Two Boreholes from First Arrival Traveltimes
D. Ustundag

Abstract: We study a problem of reconstruction of seismic wave speed distribution from a set of measured first arrival traveltimes in presence of strong velocity contrasts, which cause the problem to be highly non-linear. In this context, we make an attempt to improve a stable iterative reconstruction algorithm by incorporating appropriate a variable regularizing parameter and also used it for a simple synthetic borehole test after writing its algorithm in a C++ code. The simulations results support the effectiveness of the method.
 

A Seismotectonic Study for the Heraklion Basin in Crete (Southern Hellenic Arc, Greece)
E. Kokinou, M. Moisidi, I. Tsanaki, E. Tsakalaki, E. Tsiskaki, A. Sarris, F. Vallianatos

Abstract: In the context of the present work the spatial distribution of the seismic activity around Crete Island in the Southern Hellenic Arc for the period 2003-2007 is studied. Especially in the period July-October 2007 about 600 events of low and moderate magnitudes have been indicated. Most of these events are located near coast and onshore of Crete. Additionally, we studied the relation of the earthquake epicenters with specific fault zones for the Heraklion basin. GIS techniques were used for mapping the distribution of earthquake epicenters on the various topographic and geological features of the area. Maps were created through interpolation algorithms. Spatial tools and statistical analysis were exploited to examine the correlation between earthquake loci and faulting orientations. The distribution of the epicenters indicates that the near coast and onshore seismicity is closely associated to the Crete tectonics. Especially for Heraklion prefecture the epicenter distribution is related to E-W, NE-SW and NW-SE striking faults.