Abstract
The increase in the wealth of information on the seismotectonic structure of the Marmara region after two devastating earthquakes (M7.6 Izmit and M7.2 Duzce events) in the year 1999 opened the way for the reassessment of the probabilistic seismic hazard in the light of new datasets. In this connection, the most recent findings and outputs of different national and international projects concerning seismicity and fault characterization in terms of geometric and kinematic properties are exploited in the present study to build an updated seismic hazard model. A revised fault segmentation model, alternative earthquake rupture models under a Poisson and renewal assumptions, as well as recently derived global and regional ground motion prediction equations (GMPEs) are put together in the present model to assess the seismic hazard in the region. Probabilistic seismic hazard assessment (PSHA) is conducted based on characteristic earthquake modelling for the fault segments capable of producing large earthquakes and smoothed seismicity modelling for the background smaller magnitude earthquake activity. The time-independent and time-dependent seismic hazard results in terms of spatial distributions of three ground-shaking intensity measures (peak ground acceleration, PGA, and 0.2 s and 1.0 s spectral accelerations (SA) on rock having 10% and 2% probabilities of exceedance in 50 years) as well as the corresponding hazard curves for selected cities are shown and compared with previous studies.
Highlights
IntroductionDüzce earthquakes, have been a turning point in the community perception of the high seismic risk prevailing in Marmara region, which hosts several highly populated cities, among them Istanbul with its 15 million population and contributing to more than 30% of Turkish GDP
The two destructive earthquakes that occurred in the Eastern part of Marmara region at the closing of the 20th century, namely the August 17, 1999, M7.6 Izmit and November 12, 1999, M7.2Düzce earthquakes, have been a turning point in the community perception of the high seismic risk prevailing in Marmara region, which hosts several highly populated cities, among them Istanbul with its 15 million population and contributing to more than 30% of Turkish GDP
We present the Probabilistic seismic hazard assessment (PSHA) results for the Marmara region corresponding to Poisson and time-dependent earthquake rupture forecast models, first in a set of ground motion intensity distribution maps; and second as hazard curves corresponding to four major cities, Istanbul, Izmit, Tekirdag, and
Summary
Düzce earthquakes, have been a turning point in the community perception of the high seismic risk prevailing in Marmara region, which hosts several highly populated cities, among them Istanbul with its 15 million population and contributing to more than 30% of Turkish GDP. Since the 1999 earthquakes, the mitigation of the seismic risk in the Marmara region and in Istanbul has been a major aim and to this end several geological and seismological studies have been conducted for the characterization of seismic sources, especially within the Marmara Sea and for the identification of the associated earthquake potential that would enhance reliable estimations of the seismic hazard levels in the region. Following the 1999 earthquakes, in addition to the several research efforts on source characterization in Marmara region, a number of studies were conducted for the estimation of future ground motions in the region. Spagnuolo et al [16] analysed the effects of the rupture directivity on the seismic hazard in Marmara region
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