Understanding the Earthquake Cycle along the North Anatolian Fault integrating seismological and geodetic observations
Abstract
Large earthquakes represent the occasional catastrophic failure of plate-boundary and intra-plate fault zones accommodating permanent tectonic deformation and elastic-rebound strains. Failure occurs when accumulated tectonic deformation exceeds the frictional strength in the Earth's heterogeneous crust. Due to the physical complexity of this system, earthquake forecasting efforts worldwide have not yet yielded a consistent set of precursory phenomena. However, tectonic deformation in the Earth's crust leads to pre-earthquake symptoms in seismological and geodetic data at critical stages of the earthquake generation process. In this study, we integrate long-term microseismicity and near-fault geodetic observations to elaborate on earthquake cycle. The test ground, the North Anatolian Fault in NW Turkey, has accommodated three major earthquakes over the last two decades, which has been monitored by dense seismic and geodetic networks since early 80s. Although the fault zone has substantially failed during the last century, it did not complete its failure in NW Turkey and therefore left several segments at different physical stages. The results show that the 1999 M7.4 Izmit and the 2014 M6.9 Aegean earthquakes were preceded by almost a decade-long period of enhanced micro-earthquake activity representing a brittle process preparing the failure. This interpretation is supported by observed lateral migration of micro-earthquakes towards the mainshock hypocenter within a time scale of roughly a decade. The enhanced microseismicity is reflected to the surface deformation in a couple of months as an accelerated near-fault movement. This delayed surface response suggests an unlocking of the fault due to decrease in frictional strength at seismogenic depths. The Sea of Marmara segments of the North Anatolian Fault show a rather temporally uniform seismicity and geodetic trends leading to the conclusion that those segments are still not in the preparation stage for a large earthquake.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMMR41B2703B
- Keywords:
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- 3902 Creep and deformation;
- MINERAL PHYSICSDE: 7230 Seismicity and tectonics;
- SEISMOLOGYDE: 8118 Dynamics and mechanics of faulting;
- TECTONOPHYSICSDE: 8163 Rheology and friction of fault zones;
- TECTONOPHYSICS