Abstract
In the past 1500 years, seven sequences of significant earthquakes have occurred on a 160-km-long segment of the North Anatolian Fault zone (NAFZ) centered on Istanbul. The most recent of these sequences will be complete with the future occurrence of one or more Mw ≥ 7.0 earthquakes near the city. From a summation of the seismic moment released by historical earthquakes between 500 and 2000 CE we calculate a mean slip deficit rate of 9.9 mm/year. Our moment summation procedure sums the seismic moment associated with known historical earthquakes in the past 1500 years based on rupture length and assumed seismogenic depth. We observed that in the 1999 Izmit earthquake, strongly coupled fault patches were associated with the highest co-seismic slip. In our calculated map of present-day slip-potential, we recognize several such patches from their low present-day rate of microseismicity, e.g. segments beneath the Kumburgaz and Eastern (Çınarcık) Marmara Basins. In contrast, intervening weakly coupled patches host high present-day background seismicity, e.g. the segment beneath the Western (Tekirdağ) Basin. This lends credibility to an interpretation of future earthquakes occurring in three seismogenic segments of the NAFZ corresponding to three deep basins in the Sea of Marmara. The present-day slip deficits reach up to 1.7 m beneath the Western (Tekirdağ Basin) segment, and 4.0 m and 5.4 m beneath the Central (Central High and Kumburgaz Basin) and Eastern (Çınarcık Basin) segments, respectively. These segments most recently ruptured in August 1766, May 1766 and October 1509 and currently have a potential to generate Mw 7.2, Mw 7.4 and Mw 7.5, earthquakes respectively. Although contiguous ruptures have not occurred historically, ruptures of contiguous segments could occur as a Mw 7.5 earthquake in the west, or a Mw 7.6 earthquake in the east or as a single through-going Mw 7.7 rupture.
| Original language | English |
|---|---|
| Pages (from-to) | 77-87 |
| Number of pages | 11 |
| Journal | Tectonophysics |
| Volume | 764 |
| DOIs | |
| Publication status | Published - 5 Aug 2019 |
Bibliographical note
Publisher Copyright:© 2019 Elsevier B.V.
Funding
The authors thank Kandilli Observatory and Earthquake Research Institute (KOERI) and Disaster and Emergency Management Authority for providing seismological data. The authors thank Kelin Wang, Roger Bilham and two anonymous reviewers for their constructive comments, and Bengisu Gelin for proofreading. The GPS data are uniformly combined in the frame of a research project, which has been funded by TUBITAK (project number: 113Y430). Slip deficit modeling and hypocenter relocations have been performed in the frame of a research project “Slip deficit along Major Seismic Gaps in Turkey”, which has been funded by Bogazici University (project number: 18T03SUP4).
| Funders | Funder number |
|---|---|
| Bogazici University | 18T03SUP4 |
| TUBITAK | 113Y430 |
Keywords
- Central and Eastern (Çınarcık) segments locked
- Forecasting earthquake slip and magnitude
- Marmara Seismic Gap
- North Anatolian Fault
- Wastern (Tekirdag) segment weakly coupled
