A Mw7.4 earthquake struck Taiwan at 07:58 am local time (TST) on Wednesday 3 April 2024, the strongest event on the island for 25 years. According to the United States Geological Survey (USGS), the epicenter was located on Taiwan’s eastern Philippine Sea coast, 18km southwest of the city of Hualien, at a relatively shallow depth of 34.8km (Figure 1). The rupture occurred on the convergent boundary between the Philippine and Eurasian Plates, along a northeast-to-southwest striking reverse fault in which overlying rock above the fault shifts upwards relative to the rock below.
The mainshock produced strong ground motions, reaching a Modified Mercalli Intensity (MMI) of VIII (severe), predominantly in areas near and to the north of the epicenter. Peak Ground Acceleration surpassed 0.4g, and Peak Ground Velocity exceeded 50cm/s in areas reporting these maximum MMI levels (Figure 1). Over 19 million people were exposed to shaking intensities of MMI V (moderate) or stronger, with the USGS estimating 153,000 people exposed to the highest intensity shaking.[1] A Mw6.5 aftershock occurred 13 minutes after the mainshock, and over 130 subsequent Mw5.0+ aftershocks were reported in and around Hualien over the following 8 hours.
Data source: USGS
At the time of writing, the National Land Management Agency reported over 848 cases of damage to structures in Hualien, Taipei, New Taipei, Taoyuan, and Keelung.[2] Of these, 42 have been classified as “code red” the highest level of damage. A "code red" designation refers to buildings where critical structural elements, such as columns, beams, exterior walls, floors, and foundations, have sustained significant damage or the entire structure is leaning.
Further reported impacts by Taiwan’s National Fire Agency include 16 fatalities, over 1,100 injuries, and 3 individuals missing.[3] Rescue operations faced challenges due to ongoing aftershocks, with reports of 70 people trapped in rock quarries in the aftermath, around 1,000 stranded in Taroko National Park's mountains, and more suspected to be trapped in various mountain tunnels throughout Hualien County.[4]
Due to the earthquake’s coastal location, Japan and the Philippines issued tsunami warnings immediately following the event. However, these were later downgraded and lifted, after no significant change in wave heights was recorded. A number of landslides were also noted in mountainous East Coast regions, damaging roads and rendering many routes impassable hindering rescue efforts.
It is anticipated that insured losses will remain well under $1 billion USD, as the areas close to the epicenter in Hualien County (population 340,000) are not densely populated, and the region is characterized by moderate rates of insurance coverage.
Taiwan has a long history of destructive earthquakes due to its location on a tectonic plate boundary. Including its offshore regions, Taiwan has experienced 27 earthquakes with magnitudes greater than Mw7.0 since 1900 (Figure 2). The most powerful of these, a Mw8.2 earthquake, occurred offshore of Hualien County in 1920, claiming five lives and destroying nearly 300 homes.[5] Yet despite its magnitude, this was not the most catastrophic event in Taiwan's recent seismic history. The 21st September 1999 Mw7.7 Chi-Chi earthquake in central Taiwan was far more destructive, resulting in approximately 9,000 buildings collapsing and 2,297 fatalities. Post-event investigations of the 1999 event found many building failures were due to 'soft-storey' collapse of ground floors and deviations from building codes.[6]
Data source: USGS
During the 2024 earthquake, Hualien City experienced the worst damage, yet the incidence of 'soft-story' failures was significantly lower compared to the 1999 Chi-Chi earthquake. While some buildings in Hualien were left mostly intact but leaning - a hallmark of 'soft-story' collapse - most structures performed well and remained standing after the quake.
This is a testament to the decades of work Taiwan has put into learning from previous events to improve resilience. In particular, lessons learned in the aftermath of the 1999 earthquake contributed to the relatively low damage and loss of life suffered this time around.
After the 1999 event there were multiple revisions to building regulations, leading to the retrofitting of thousands of older structures that did not comply with the updated codes, such as the strengthening of floors and walls. These efforts were backed by government funding for both the initial seismic assessments and the subsequent retrofitting. Regular building inspections are now a standard procedure after earthquakes; for example, a Mw6.4 earthquake near Hualien City in 2018 prompted the government to order a new round of inspections. Furthermore, to enhance public safety, nationwide drills and mobile alerts have been introduced to provide early warning and educate citizens on finding shelter quickly during seismic events.
While the earthquake’s location played a key role, the effect of preparedness and mitigation measures was also seen in the resilience of the semiconductor industry. Any disruption has global ramifications felt across industries.[8]
Manufacturers in Taiwan have been hardening their factories against earthquakes for decades and many use automatic shutdown systems to minimize damage to their production and tools. Taiwan's semiconductor manufacturing hubs are mainly located along its western edge, on the opposite side of the island to the recent earthquake (Figure 1). As a result, disruption following the quake was short-lived. In one case – 10 hours after the event – the island's biggest chipmaker, Taiwan Semiconductor Manufacturing Corporation, was able to report that more than 70% of its chipmaking tools were back online, and that no vital machines had been damaged.[9]
However, the event serves as a reminder of the potential risks to global supply chains posed by Taiwanese earthquakes. Large historical earthquakes in 1925 and 1941 – long before the semiconductor industry was established – struck much closer to hubs of population and industry (Figure 1). Should events like these occur again, there could be larger repercussions not only for the local semiconductor industry but also for the global economy.
