Fig. 6: DDSS record of the April 2, 2024, MW 7.4 Hualien earthquake in Hole-A.

This earthquake occurred approximately 20 km from the DDSS array with a peak ground acceleration of about 0.32 m/s2 from the nearest strong motion station. The signal saturated a few seconds after initial arrivals, but overall, the recording system performed adequately, although attention needs to be paid to address the signal saturation. Similar to the smaller local events (Fig. 4) and the teleseismic events (Fig. 5), waveforms exhibit noticeable amplification in the depth range of the MFZ from the first motion on, distinguishing this amplification effect from other fault-zone-related amplification effects such as trapped waves or interface waves.