And on the morning of September 19, another magnitude 5.7 earthquake occurred in Hualien County. During two consecutive days, earthquakes occurred frequently in Taiwan.
It is worth noting that neighboring provinces also felt the tremor of the Taitung earthquake . According to media reports, on the afternoon of September 18, many places in Fujian Province on the other side of the strait also experienced a short period of shaking. According to reports from media on the island, the Taiwan Disaster Response Center said that in the next week, it is not ruled out that aftershocks above magnitude 5 will occur on the island.
Taiwan Province, China is a frequent earthquake. According to data, the earliest record of earthquakes in Taiwan was on January 30, 1736, when the earthquake was magnitude 6.5, killing 372 people. According to statistics, from 1901 to 2000, 91 major earthquakes occurred in Taiwan, of which 48 caused life losses. The latest major earthquake was the "9/21 Earthquake", which occurred on September 21, 1999, killing 2,415 people. And three major earthquakes occurred in 2022. In the history of earthquakes on the island, there are dozens of earthquakes above magnitude 6, the largest of which was the magnitude 8.3 earthquake in 1910, followed by the magnitude 8.2 earthquake in Hualien County in 1920.
So the question is, why are earthquakes frequent on Taiwan? According to the "plate drift theory" of German geographer Wegener , Taiwan is located in the world's largest seismic zone - the Pacific Rim seismic zone , and is located on the collision zone with significant subduction and uplift motion between the Asia-European plate and the Pacific plate. The two major plates move towards each other, contact and collide with each other, causing complex and violent movements in the earth's crust, thus forming an eastern seismic belt of the "loop seismic belt". In this "loop seismic belt", earthquakes occur almost every day, but the earthquake size is different.
For tens of thousands of years, the instability of the plate structure and the continuous movement of the plate edges have caused the squeeze and collision movement of the Asia-European plate and the Pacific plate under the seas near Taiwan Island . This is also an important source of frequent earthquakes in Taiwan Province, China.
Taiwan earthquake zone can be divided into western, eastern and northeastern. Among them, there are fewer earthquakes in the west and shallower focal sources, while the eastern and northeast are in the Pacific Rim volcanic belt. The plate boundaries are mostly polymerizable, the focal sources are deeper, and the number of times is more frequent. The plates generate huge power when they move, which can trigger earthquakes, volcanic eruptions and tsunamis.
. Taitung and Hualien, which occurred in this earthquake, belong to the eastern seismic belt. The eastern seismic belt starts from the seabed in the northeast of Yilan County , passes through Hualien to Taitung, and extends southward to Luzon Island ; the northern end of this belt is connected from Yilan and the Pacific Rim seismic belt to the seabed in the western Pacific, and the southern end is connected to the Philippine seismic belt. This zone is approximately arc-oriented towards the Pacific Ocean, and is parallel to Taiwan's island, 130 kilometers wide, characterized by a large number of earthquakes. Usually, the focal source is deeper than the western one.
According to the past earthquake distribution and earthquake damage situations in Taiwan Province, the damage degree of Taiwan earthquake is divided into four districts from light to strong, Taitung County belongs to the third district, and Hualien County belongs to the fourth district, so it is no wonder that the earthquake in Taitung and Hualien this time will have a great impact, and even the bridge is broken.
Therefore, there are two points that need to be taken into account when designing the architectural design on the island. One is to prevent shock and the other is to prevent typhoons . Given that Taiwan is in a frequent crustal activity zone, for example, the high-speed railway system on the island is designed with integrated automatic safety devices that can safely stop all trains when major earthquakes are detected. Given that Taiwan Island is in an extremely sensitive active crust zone, earthquakes in Taiwan will continue to occur in the future, which requires better and more comprehensive earthquake monitoring and planning to minimize the losses of the people on the island.
