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| Titel |
Co-seismic and Post-seismic Models of the 23 October 2011 (Mw=7.2) Van Earthquake (Turkey) from GPS Measurements |
| VerfasserIn |
Deniz Oz Demir, Ugur Dogan, Ziyadin Cakir, Semih Ergintav, Seda Cetin, Alpay Ozdemir, Haluk Ozener, Robert Reilinger |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250131192
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| Publikation (Nr.) |
 EGU/EGU2016-11570.pdf |
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| Zusammenfassung |
| As there were almost no GPS stations in the epicentral region of the 2011 Van earthquake,
previous studies used the GPS data from the CORS-TR network that is rather scattered over
entire Turkey (roughly in a 50x50 km grid). We have recently obtained GPS data collected at
25 sites in the earthquake region before the earthquake by local institutions for mainly
cadastral purposes at different times. Most of the sites are located within the city and to the
south of the fault rupture. Nevertheless, the presence of some sites to the east is critical for
constraining the eastern tip of the fault rupture that is poorly known due to lack of
measurements and presence of the Erçek Lake. Sites near by the surface rupture north of the
city are also useful for constraining the fault parameters. Therefore, to estimate coseismic
displacements in the near field we conducted a field campaign and all the sites were
reoccupied and measured around 10 hours after the earthquake. Then, we modeled the
results using elastic dislocations on triangular faults embedded in a homogenous
and elastic half space. We use the same fault surfaces used by Doğan et al. (2014)
to model the postseismic GPS displacements. Estimated seismic moment, M0, is
6.4858*1019 Nm (Mw = 7.1), in good agreement with seismologically and geodetically
estimated seismic moment. Modeling predicts a simple elliptical slip patch centered
at around 8 km depth with a maximum slip of about 2.5 m, which is consistent
with the previous estimates based on InSAR measurements. However, as the GPS
measurements span a postseismic period of 47 months, our model predicts slip also on the
shallow sections of the fault, which is due to the postseismic afterslip shown by
Doğan et al. (2014). The measurements confirm that the fault splay west of the fault
that was reactivated following the earthquake did not experience any significant
coseismic slip. Modeling also confirms that the rupture does not go straight to the
east as suggested by Emre et al. (2011), but veers to the northeast in the Erçek
Lake.
The last (i.e. the tenth) postseismic GPS campaign was carried out in September
2015. Thus, we were able to obtain a long time series since November 2011 at
about every 6 months. Analysis of our time series together with the continuously
operating GPS stations nearby suggests that the postseismic relaxation has not ceased
yet. Modeling of the total postseismic displacements shows aseismic thrust slip
with left lateral component up to 65 cm, equivalent to an earthquake of Mw=6.7
(M0= 13.8822*1018 Nm) (This study is supported by TUBITAK no: 112Y109
project).
Keywords: Van earthquake, GPS, coseismic, postseismic, deformation, elastic modeling |
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