The seismogenic process of the 2016 Meinong earthquake, southwest Taiwan

Strong Wen ； Yu-Lien Yeh ； Yi-Zen Chang ； Chieh-Hung Chen

《Terrestrial, Atmospheric and Oceanic Sciences》 28卷5期 (2017/10) Pp. 651-662

https://doi.org/10.3319/TAO.2017.02.17.01

摘要

Southwest (SW) Taiwan lies on the deformation front of a plate collision zone. Most earthquakes in this region occur due to deformation of the upper crust, therefore, potential seismic hazards in this area must be considered. On 6 February 2016, a moderate, but disastrous earthquake (ML = 6.6; depth = 14.6 km) occurred in Meinong, a district in the Kaohsiung area of Taiwan. This earthquake produced three cluster-like aftershocks. Among them, two of the aftershocks clusters were not spatially correlated with the main earthquake. Additionally, the trends of these two seismic clusters were not associated with previously known faults or geological structures. Therefore, our major intention is not only to investigate the rupture process of the 2016 Meinong earthquake, but more importantly, to look into the corresponding seismogenic process. In this research, high quality strong-motion data was used to invert the slip distribution on the fault plane using the isochron method. In addition, we relocated aftershocks to further obtain focal mechanisms using a 3D velocity model. Coulomb failure stress maps are calculated for different depth ranges based on the obtained source slip distribution to verify whether the main-shock triggers nearby unknown faults or not. In conclusion, we suggest that there might exist a NWSE trending, north-dipping fault, which is located north of the source area and may have been triggered by the initial shock. We also conclude that the 2016 Meinong earthquake did trigger the pre-existing normal faults beneath Tainan City.

關鍵字

The 2016 Meinong earthquake ； Slip distribution ； Stress inversion ； Focal mechanism ； Coulomb failure stress ； Seismogenic process ； Chishan Transfer Fault Zone