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| Titel |
19 May 2011 Simav Earthquake Sequence : Western Turkey |
| VerfasserIn |
D. Kalafat, R. Polat, S. Altuncu Poyraz, K. Kekovali, M. F. Akkoyunlu |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250070558
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| Zusammenfassung |
| ABSTRACT In Western Anatolia as a result of the current tectonic regime normal faults
occured and they are good examples of extensional tectonic regime. The earthquake which
occured on the 19 May 2011 at local time 23:00 (Ml=5.9) in NE of Simav caused destructive
damage in this town. After the earthquake for a 1 month period only 1250 earthquakes are
located and thousands of micro earthquakes occured in the region. As they are examined
seismotectonically Simav earthquake has shallow epicenter which is characterized by dip slip
fault. The dominant direction of the fault plane is W-NW/E-SE, which is characterized
with S-SW downthrown normal fault. The depth of the earthquakes show that the
seismogenic zone is changed 5-10 km. The aftershocks recorded between 19 May-20
June 2011 dates occured on the SW block of the W-NW/E-SE aligned fault. The
19 focal mechanism solutions show the system is in an extensional regime. The
solutions from the fault parameters of these 19 earthquakes show that Tmax axis is
on N-S dominant direction and Pmax axis is on E-W direction. In the region the
M=5.0 earthquake occured on the 17 February 2009 have almost the same properties
however from the aftershock distribution it is seen that it has a character of the
north dipping normal fault character. The magnitude completeness of the current
network in the region is Mc=2.7, the b-value which shows the seismic activity is
b=1.57. The high b value value shows that the stress release is fast. b-value shows that
the seismic activity is high, the stress is releasing continuosly. In other words, the
region is subject to frequent earthquakes and the energy of the earthquakes are
frequently released. There are many fault segments defined by many researchers and in
general all these active fault segments are evaluated within Simav Fault Zone (SFZ).
Mainly the whole part of Simav is graben which is surrounded by active faults. In the
north there are listric normal faults parallel to each other which are aligned on E-W
direction and fault segments in different directions were triggered by earthquake
sequences and this caused higher earthquake activity than normal. As result of the
19 May Simav earthquake the dynamic strain and the dense earthquake activity
as a result of it is good example of the faulting trigger mechanism system. This
affected the aftershock process and caused the occurrense of the earthquakes for a
long time. Simav earthquake shows that the N-S extentional regime in the Western
Anatolia is recently active and is a good example of the evolution of the graben
system.
Key Words : extensional tectonic, T max., Simav Fault Zone |
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