First insight in OBS data and shallow tremor detection at the Guerrero Gap, Mexico.
Abstract
In recent years, many different slow earthquakes activity has been reported near the Guerrero Gap, at the Mexican subduction zone. Slow Slip Events, tectonic tremors and low frequency earthquakes have been occurring periodically in the down dip sections of the Guerrero Gap, at approximately 200 km away from the trench and at a depth of around 40 km. Even when these seismic events are frequent in the region, until now there is no evidence of slow earthquake activity at the shallow portion of the Guerrero Gap close the trench, probably because inland seismic stations could not provide enough resolution to study this area. To provide better observations, an Ocean Bottom Seismograph array was deployed at the shallow part of the subduction zone of the Guerrero Gap, in November 2017 and recorded data for one year. Noise curves and horizontal orientations for each OBS stations were estimated and analyzed. Afterwards, a modified correlation method was applied in search of shallow tectonic tremors near the trench. Over 100 detections where done. Detections show bursts of events occurring at concentrated areas close to the trench and with approximately three months recurrence period. These bursts of seismic events do not show any migration. Seismic signals of these detections do not have a clear arrival of P or S wave. Additionally, they are deficient at frequencies above 10 Hz attenuating rapidly but are efficient at a frequency band between 2 and 8 Hz. After removing the possibility of T-phase in our detections, the likelihood of tremor activity is high. Understanding the nature of this seismic events is an important task required to understand their influence in the complex seismic cycle of Guerrero.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.S13F0499P
- Keywords:
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- 7209 Earthquake dynamics;
- SEISMOLOGY;
- 7215 Earthquake source observations;
- SEISMOLOGY;
- 7230 Seismicity and tectonics;
- SEISMOLOGY;
- 8170 Subduction zone processes;
- TECTONOPHYSICS