The height of Taiwan’s Central Mountain Range is slowly increasing, as the tectonic plates on either side frequently push against each other during seismic activity, a seismologist said Wednesday.
As the central mountains rise, “Taiwan will become thinner” over centuries, said Hsu Ya-ju (許雅儒), a research fellow at the Institute of Earth Sciences at Academia Sinica and head of the Taiwan Earthquake Research Center (TEC).
Currently, the movement of the tectonic plates east and west of Taiwan is pushing up the Central Mountain Range by 2-3 centimeters per year, but the actual sustained increase in height will have to be determined based also on other factors such as the erosion rate of the mountains, Hsu said.
Meanwhile, it cannot be said that “Taiwan is shifting farther away from China” as a result of tectonic plate movement, Hsu said, addressing concerns expressed by netizens about displacement of the island due to seismic activity.
The issue caught the public’s attention after the Central Weather Bureau (CWB) on Monday posted two maps on its Facebook page, showing Taiwan’s movement on the Earth’s surface between 2009 and 2018 due to tectonic action.
The maps showed fault motions during, before and after earthquakes in Taiwan over the nine-year period, which prompted some netizens to speculate on whether Taiwan was moving farther away from China.
According to Hsu, however, that is not the case, as there are both eastward and westward shifts of equal size under Taiwan.
While Taiwan sits on a compressive tectonic boundary between the Eurasian and Philippine Sea tectonic plates, it is also affected by the movements of the Okinawa Trough, a back arc basin behind the Ryukyu trench-arc system in waters northeast of Taiwan, Hsu explained.
Meanwhile, she said, it was difficult to determine whether the two large earthquakes – magnitude 6.4 and 6.8 – that hit Taitung County in September were associated with the Central Mountain Range fault.
Current research is aimed at helping to assess where large earthquakes are likely to occur, based on historical records, Hsu said.
Taiwan has been keeping earthquake records for only about 100 years, which makes it difficult to predict when and where a major quake might strike, as the period between large temblors could stretch for hundreds or even thousands of years, she said.
Source: Focus Taiwan News Channel