Akademik Veri Yönetim Sistemi
European Seismological Commission 32nd General Assembly, Montpellier, Fransa, 6 - 10 Eylül 2010, ss.258-259
Turkey has long been affected by damaging
earthquakes. The recent Tunceli (27.01.2003),
Izmir (10.04.2003 and 17-21.10.2005),
Bingol (01.05.2003, 12-14.03.2005 and
06.06.2005), Denizli (23.07.2003), Elazig
(11.08.2004, 27.12.2007 and 08.03.2010),
Antalya (24.01.2005), Hakkari (25.01.2005)
and Ankara (20-27.12.2007) earthquakes
caused severe damage to life and property
in the country. The Izmit and Duzce earthquakes
(Ms7.4, Ms7.2; August and November
1999) of the NW Anatolia have increased
awareness of the need for seismic disaster
mitigation in Marmara region. Thus, no
part of Turkey is free from earthquake hazard.
Marmara database compiled from
homogeneous earthquake catalogue of Turkey
(Kalafat et al., 2007; KOERI) spans the
time period 1950-2008 in a rectangular area
between 26.0-31.5oE longitudes and 40.0-
41.5oN latitudes. One of the basic seismicity
parameters used to describe an ensemble
of earthquakes is the a- and b-values in the
Gutenberg-Richter frequency magnitude relation.
They characterize the distribution
of earthquakes over the observed range of
magnitudes, and are important parameter
in seismology for its association with several
tectonic features of an area (Scholz, 1968,
Wiemer and Wyss, 1997). It is important to
understand the frequency–magnitude relation
and seismicity parameters (a- and bvalues)
in assessing the earthquake hazard
of a tectonically active region. Starting from
the necessities and views, we performed a
statistical analysis in the Marmara region
following by Gutenberg-Richter magnitudefrequency
distribution. Study area has been
divided into the seven sub-zones according
to the seismotectonic patterns. We detected
a spatial correlation of 2.26-3.79 for aparameter
as indicative for more clustered
events in the region, while the b-value of
0.69-1.18 implies a high tectonic activity in
the region. This result suggests structural
variability and high heterogeneous tectonic
elements in the region. Acknowledgement:
The authors are grateful to the National
Earthquake Observation Center (UDIM) of
the Kandilli Observatory and Earthquake
Research Institute (KOERI), and to Dr. Dogan
Kalafat for accessing earthquake database
via internet (www.koeri.edu.tr). References:
Kalafat, D., Gunes, Y., Kara, M., Deniz,
P., Kekovali, K., Kuleli, H.S., Gulen, L., Yilmazer,
M. & Ozel, N. 2007. A Revised and
Extended Earthquake Catalogue for Turkey
Since 1900 (M≥4.0), Bogazici University Library
Cataloging, ISBN 978-975-518-281-0,
Istanbul-Turkey, 572p Wiemer, S., and Wyss,
M., 1997. Mapping the frequency-magnitude
distribution in asperities: An improved technique
to calculate recurrence times, Journal
Geophysical Research 102, 15.115-15.128
Scholz, C.H., 1968. The frequency–magnitude
relation of micro fracturing in rock and
its relation to earthquakes, Bulletin Seismological
Society America 58, 399-415