Strong Ground Motions and Site Amplifications in the Near-source Region of the 2016 Mw 6.5 Meinong Earthquake, Taiwan

Strong Ground Motions and Site Amplifications in the Near-source Region of the 2016 Mw 6.5 Meinong Earthquake, Taiwan

On February 6, 2016, an earthquake of MW 6.5 occurred in Meinong, Taiwan. The maximum observed peak ground acceleration(PGA) and peak ground velocity(PGV) were 445 gal and 76 cm/s, respectively. Major damage occurred in areas with PGAs greater than 200 gal and PGVs greater than 30 cm/s. A strong source effect due to forward rupture directivity was observed in Tainan City within an azimuth of 105° during this earthquake. Pulse-like velocities can be recognized at 27 stations where all the observed PGVs were greater than 25 cm/s on the largest horizontal component. The pulse-like velocities are categorized into two groups based on the pulse directions:(1) a north–south direction in central to northern Tainan, and(2) an east–west direction in central and western Tainan. The velocity pulses were caused by two faults. The effects of site amplification and source rupture on the PGA in a near-source region with a hypocentral distance of 30 km, are calculated to be 3.1 and 5.4, respectively.