Aftershocks of the 2 April 2024 Mw 7.4 Hualin, Taiwan Earthqauke

ABSTRACT A devastating Mw 7.4 earthquake occurred in Taiwan on the 2 April 2024 at 23:58:11 UTC claiming 14 human lives, injuring over 1000 and causing wide spread structural damage. Moderate aftershocks of major earthquakes tend to cause further damage to already weakened built structures. An assessment of the duration of occurrence of such aftershocks is helpful in post earthquake recovery phase. This earthquake is the most significant earthquake to have occurred after 25 years of the 21 September 1999 Mw 7.7 Chi-Chi earthquake in Taiwan. Our study indicates that there was a paucity of Mw ≥ 5 aftershocks for the Chi-Chi earthquake as only 45 such aftershocks occurred in 40 days. However, an increase in the number of Mw 4.5 earthquakes was observed compared to the background seismicity. Using Omori’s Law, we estimated the duration of Mw ≥ 4.5 aftershocks using the data of first 14 days to be 110 days, that matches quite well with the the Chi-Chi earthquake sequence. The 2 April 2024 Hualin earthquake is quite similar to the 1999 Ch-Chi earthquake. There is a paucity of Mw ≥ 5 for the Hualin earthquake. No such after shock has been recorded after 7 April 2024. However, Mw ≥ 4.5 aftershoks are continuing to occur. Our study, using the data of 14 days after the Hualin earthquake, indicates that Mw ≥ 4.5 aftershocks for the Hualin earthquake shall continue for ∼ 80 days.