High-resolution micro-seismicity along the western segments of the Main Marmara Fault
Abstract
A detailed study, based on Ocean Bottom Seismometers (OBS) data from two recording periods (3.5 months in 2011 and 2 months in 2014) and on a high-resolution, 3D-velocity model, reveals wave propagation anomalies in the Western Sea of Marmara, particularly in areas where gas-prone sediment layers are known to be present. Location results indicate thatduring the recording period : i) a significant number of earthquakes occurred off-axis, with a predominantly normal focal mechanism, at depths between 2 and 6 km, along tectonically active, structural trends oriented E-W or SW-NE.; 2) a great number of earthquakes were also found to occur within the upper sediment layers (at depths < 2 km), particularly in the areas where free gas is suspected to exist, based on high-resolution 3D seismics. Part of this "ultra-shallow" seismicity appears to occur in response to deep earthquakes of intermediate (ML 4 - 5) magnitude. Resolving the depth of the shallow seismicity requires adequate experimental design ensuring source-receiver distances of the same order as hypocentral depths. To reach this objective, deep-seafloor observatories with a sufficient number of geophone sensors near the fault trace are needed.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.T13I0341G
- Keywords:
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- 7209 Earthquake dynamics;
- SEISMOLOGYDE: 7212 Earthquake ground motions and engineering seismology;
- SEISMOLOGYDE: 8110 Continental tectonics: general;
- TECTONOPHYSICSDE: 8118 Dynamics and mechanics of faulting;
- TECTONOPHYSICS