New constraints on seismicity in Eastern Sabah, Malaysia
Abstract
Unlike the rest of Malaysia, the state of Sabah in northern Borneo has moderate levels of seismicity. Notable earthquakes in the region include the 2015 M6 Ranau earthquake, and the 1976 M6.2 Lahad Datu earthquake, the largest Malaysian earthquake on record. Over the last 44 years the population of Sabah has increased to over 4 times what it was in 1976, yet seismic hazard in Sabah is not yet well understood. Vital to improving this state of affairs is accurate earthquake detection and location, however the ability to do this in Sabah was significantly limited prior to 2018 due to the modest number of seismometers present. The situation was subsequently transformed in 2018 due to the installation of 15 new permanent broadband seismometers as part of the Malaysian national seismic network, and a temporary (March 2018-January 2020) deployment of 46 broadband seismometers by the northern Borneo Orogeny Seismic Survey (nBOSS) project.
To efficiently detect, locate and estimate the magnitude of seismicity in Eastern Sabah, we use QuakeMigrate, an open-source Python package implementing a waveform migration and stacking technique. We provide QuakeMigrate with continuous seismic data recorded by 19 seismometers from both the nBOSS and Malaysian networks, and a new seismic velocity model derived from the joint inversion of receiver function and surface wave data. In the period March 2018 to January 2020, after manually reviewing detected events, we are able to build an earthquake catalogue that contains an order of magnitude (>50) more earthquakes than established catalogues (5 or less). This indicates that pre-existing compilations are incomplete at low magnitudes and that existing hazard and tectonic models for the area may need to be revised.- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMT014...08G
- Keywords:
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- 8149 Planetary tectonics;
- TECTONOPHYSICS;
- 8150 Plate boundary: general;
- TECTONOPHYSICS;
- 8155 Plate motions: general;
- TECTONOPHYSICS;
- 8157 Plate motions: past;
- TECTONOPHYSICS