25,000 Years Long Earthquake Cycle in Slow Deforming Continental Region: The M7 1967 Mogod (Mongolia) Event
Abstract
Slow Deforming Continental Regions (SDCR) are often considered devoid of large earthquakes. Tectonic blocs are considered rigid and forces apply primarily on bounding faults, while strain-rates inside SDCR are very low. Tectonic blocs, however, are not formed by pristine continental crust, but are rather lacerated with inherited geological scares. Hence, each of these geological weaknesses can be the preferential location of a slow stress build-up, eventually leading to large earthquakes affecting the SDCR.
Unlike in active tectonic regions, where cumulative deformation points to active geological structures, earthquakes in SDCR seem to occur randomly in space and time, questioning classical fault behavior models and posing paramount issues for seismic hazard assessment. Here, investigating the M7, 1967, Mogod earthquake, in Mongolia, a typical SDCR, despite almost total absence of visible cumulative deformation at surface, we show that a least 3 significant earthquakes occurred on the same fault system during the last 50,000 years. It demonstrates that even in SDCR with very low strain rate, faults localize deformation and distribution of large earthquakes is not random. Thus, it emphasizes the need for mapping potential seismogenic structures in SDCR, and the incorporation of such structures in seismic hazard models.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.T13H0318K
- Keywords:
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- 1242 Seismic cycle related deformations;
- GEODESY AND GRAVITY;
- 7209 Earthquake dynamics;
- SEISMOLOGY;
- 7221 Paleoseismology;
- SEISMOLOGY;
- 7290 Computational seismology;
- SEISMOLOGY