21 research outputs found
Expected Earthquake Losses to Buildings in Istanbul and Implications for the Performance of the Turkish Catastrophe Insurance Pool
The city of Istanbul will likely experience substantial direct and indirect losses as a result of a future large earthquake. This paper reports on the expected building losses in the city in terms of probable maximum and average annualized losses and discussed the results from the perspective of the compulsory earthquake insurance scheme operational in the country
Source parameters and seismic moment-magnitude scaling for Northwestern Turkey
Abstract The source parameters of 523 aftershocks (0.5 ML 5.9) of the 1999
Kocaeli earthquake are determined by performing a two-step spectral fitting procedure.
The source spectrum, corrected for both site and propagation effects, is described
in terms of a standard x-square model multiplied by an exponential term of
frequency. The latter term is introduced to estimate the high-frequency (f 12 Hz)
fall-off of the acceleration source spectra by computing the j parameter. The seismic
moments obtained range between 1.05 1014 and 2.41 1017 N m, whereas the
Brune stress drops are between 0.002 and 40 MPa. The j value varies between 0.00
and 0.08 sec, indicating a decay of the acceleration level at the higher frequency
part of the spectrum greater than that assumed by the x 2 model. Both the stress
drop and the j parameter show the tendency of increasing with aftershock magnitude.
No evidence of self-similarity breakdown is observed between the source radius and
M0. Finally, both the seismic moment and the moment magnitude are compared with
the local magnitude to derive new moment–magnitude relationships for the area
Empirical ground-motion prediction equations for Northwestern Turkey using the aftershocks of the 1999 Kocaeli earthquake
We present ground motion models for northwestern
Turkey using the aftershocks of the Mw 7.4, 1999
Kocaeli earthquake. We consider 4047 velocity and
acceleration records for each component of motion,
from 528 earthquakes recorded by stations belonging to
regional networks. The ground motion models obtained
provide peak ground velocity, peak ground acceleration, and
spectral accelerations for 8 different frequencies between
1 and 10 Hz. The analysis of the error distribution shows
that the record-to-record component of variance is the
largest contribution to the standard deviation of the
calibrated ground- motion models. Furthermore, a clear
dependence of inter-event error on stress drop is observed.
The empirical ground-motion prediction equations, derived
for both the larger horizontal and vertical components, are
valid in the local magnitude range from 0.5 to 5.9, and for
hypocentral distances up to 190 km. Citation: Bindi, D.,
S. Parolai, H. Grosser, C. Milkereit, and E. Durukal (2007),
Empirical ground-motion prediction equations for northwestern
Turkey using the aftershocks of the 1999 Kocaeli earthquake
ML scale in Northwestern Turkey from 1999 Izmit aftershock: updates
Abstract We present an update of the local magnitude scale previously calibrated
for northwestern Turkey by Baumbach et al. (2003). The path coverage in the westernmost
part of the analyzed area has been increased, as well as the number of
amplitudes for distance greater than 110 km. Furthermore, a set of recordings from
accelerometric stations operated by the Kandilli Observatory and Earthquake Research
Institute (KOERI) has been merged with the recordings by the Sapanca-Bolu
and German Task Force seismological networks. In all, 4047 recordings from
528 earthquakes recorded by 31 seismometers and 23 accelerometers are considered
to calibrate the local magnitude scale over a hypocentral distance range from 10
to 190 km. By analyzing the unit covariance matrix and the resolution matrix, we
show how the source-to-station geometries of the seismic and strong-motion networks
affect the uncertainties of the computed station corrections, attenuation coefficients,
and magnitudes. The assumptions made concerning the reference station
correction, and the change in the amplification for the Wood–Anderson torsion seismograph
from 2800 to 2080 (Uhrhammer and Collins, 1990) introduced an offset of
about 0.34 in the magnitudes with respect to Baumbach et al. (2003), with the updated
local magnitude scale ranges from 0.50 to 5.91. The distribution of the residuals with
distance confirms that the extension of both the magnitude and distance ranges and
the improved path coverage have preserved the high quality that characterized the
data set analyzed by Baumbach et al. (2003)
ML scale in Northwestern Turkey from 1999 Izmit aftershocks: updates
We present an update of the local magnitude scale previously calibrated for Northwestern Turkey
by Baumbach et al. (2003). The path coverage in the westernmost part of the analysed area has been
increased, as well as the number of amplitudes for distance greater than 110 km. Furthermore, a set
of recordings from accelerometric stations operated by the Kandilli Observatory and Earthquake
Research Institute (KOERI) has been merged with the recordings by the Sapanca-Bolu and
GermanTaskForce seismological networks. In all, 4047 recordings from 528 earthquakes recorded
by 31 seismometers and 23 accelerometers are considered to calibrate the local magnitude scale
over a hypocentral distance range from 10 to 190 km. By analyzing the unit covariance matrix and
the resolution matrix, we show how the source-to-station geometries of the seismic and strong
motion networks affect the uncertainties of the computed station corrections, attenuation
coefficients, and magnitudes. The assumptions made concerning the reference station correction,
and the change in the amplification for the Wood-Anderson torsion seismograph from 2800 to 2080
(Uhrhammer and Collins, 1990) introduced an offset of about 0.34 in the magnitudes with respect to
Baumbach et al. (2003), with the updated local magnitude scale ranges from 0.50 to 5.91. The
distribution of the residuals with distance confirms that the extension of both the magnitude and
distance ranges and the improved path coverage have preserved the high quality that characterized
the data set analyzed by Baumbach et al. (2003)
STRONG GROUND MOTIONS AND DAMAGE PATTERNS FROM THE 1999 DUZCE EARTHQUAKE IN TURKEY
The Mw 7.1 Duzce earthquake occurred on 12 November 1999 along the North Anatolian Fault in northwestern Turkey. This paper documents observations from a field reconnaissance team, addressing two principal aspects of this significant earthquake: the recorded ground motions and the distribution and severity of the earthquake effects on the built environment. In general, the recorded ground motions from this earthquake were smaller than predicted by ground motion predictive equations available at the time of the event. One anomalous recording is presented and potential causes for this irregular motion based on observations from field reconnaissance are discussed. The effects of rupture directivity on the near-fault recordings are assessed and the effects of soil conditions on the recorded ground motions are examined. The patterns of building damage based on post-earthquake reconnaissance are presented for the most strongly shaken cities in the near-fault region: Duzce, Kaynasli, and Bolu. Damage in Duzce was concentrated in the southern part of the city, which is underlain by softer sediments. Damage in Bolu was distributed evenly throughout the city; whereas damage was concentrated on more recent alluvial sediments in Kaynasli. No evidence of liquefaction or ground failure was observed in the populated areas surveyed after the earthquake
Empirical ground-motion prediction equations for northwestern Turkey using the aftershocks of the 1999 Kocaeli earthquake
We present ground motion models for northwestern Turkey using the aftershocks of the Mw 7.4, 1999 Kocaeli earthquake. We consider 4047 velocity and acceleration records for each component of motion, from 528 earthquakes recorded by stations belonging to regional networks. The ground motion models obtained provide peak ground velocity, peak ground acceleration, and spectral accelerations for 8 different frequencies between 1 and 10 Hz. The analysis of the error distribution shows that the record-to-record component of variance is the largest contribution to the standard deviation of the calibrated ground-motion models. Furthermore, a clear dependence of inter-event error on stress drop is observed. The empirical ground-motion prediction equations, derived for both the larger horizontal and vertical components, are valid in the local magnitude range from 0.5 to 5.9, and for hypocentral distances up to 190 km
Source parameters and seismic moment-magnitude scaling for northwestern Turkey
The source parameters of 523 aftershocks (0.5 12 Hz) fall-off of the acceleration source spectra by computing the K parameter. The seismic moments obtained range between 1.05 x 10(14) and 2.41 x 10(17) N m, whereas the Brune stress drops are between 0.002 and 40 MPa. The K value varies between 0.00 and 0.08 sec, indicating a decay of the acceleration level at the higher frequency part of the spectrum greater than that assumed by the omega(-2) model. Both the stress drop and the K parameter show the tendency of increasing with aftershock magnitude. No evidence of self-similarity breakdown is observed between the source radius and M-0. Finally, both the seismic moment and the moment magnitude are compared with the local magnitude to derive new moment-magnitude relationships for the area
Empirical ground-motion prediction equations for Northwestern Turkey using the aftershocks of the 1999 Kocaeli earthquake
We present ground motion models for northwestern
Turkey using the aftershocks of the Mw 7.4, 1999
Kocaeli earthquake. We consider 4047 velocity and
acceleration records for each component of motion,
from 528 earthquakes recorded by stations belonging to
regional networks. The ground motion models obtained
provide peak ground velocity, peak ground acceleration, and
spectral accelerations for 8 different frequencies between
1 and 10 Hz. The analysis of the error distribution shows
that the record-to-record component of variance is the
largest contribution to the standard deviation of the
calibrated ground- motion models. Furthermore, a clear
dependence of inter-event error on stress drop is observed.
The empirical ground-motion prediction equations, derived
for both the larger horizontal and vertical components, are
valid in the local magnitude range from 0.5 to 5.9, and for
hypocentral distances up to 190 km. Citation: Bindi, D.,
S. Parolai, H. Grosser, C. Milkereit, and E. Durukal (2007),
Empirical ground-motion prediction equations for northwestern
Turkey using the aftershocks of the 1999 Kocaeli earthquake,PublishedL083054.1. Metodologie sismologiche per l'ingegneria sismicaJCR Journalpartially_ope