
Another powerful earthquake struck Taiwan on Monday morning, this time with the epicenter in Hualien’s Zhuoxi Township. Seismologists say the magnitude-5.9 temblor was just one of dozens of aftershocks of a 6.8 earthquake that struck Taitung on Sunday afternoon. They say that, since Taiwan has already experienced eight earthquakes with magnitudes of at least 6 this year, 2023 could be a calmer year, seismically speaking.
People flee Chunri Elementary School in Hualien, as landslides rush down from the mountain opposite the school’s playground, taking onlookers by surprise. Taitung’s Guanshan and Chishang townships were struck by two earthquakes with magnitudes above 6 over the weekend, followed by continuous aftershocks. Then on Monday, Hualien’s Zhouxi Township was the epicenter of a magnitude-5.9 earthquake. The weather bureau’s seismologists say more large earthquakes are unlikely in the short term.
Chen Kuo-chang
Central Weather Bureau
I think that these concentrated aftershocks should be nearly over — already they are not so frequent any more. Also, I think the chances of another large aftershock are quite low.
Experts say Taiwan is currently in a period of heightened seismic activity. In Taiwan, the year 1999 recorded 15 earthquakes with a magnitude of at least 6. That’s the most recorded in one year. That’s followed by 1951 with 13 big quakes, and this year with eight recorded so far. However, if history is any indicator, next year should see an obvious reduction in seismic activity.
Kuo Kai-wen
Former seismologist
We’ve already had eight large-scale quakes this year, so that has dissipated most of that built-up energy. So, I’m hopeful that next year will be fairly quiet.
The weekend’s large earthquakes in Taitung occurred along a fault line under the Central Mountain Range that was not previously a focus of attention. Researchers have now discovered dense seismic zones on the eastern side of the mountain range.
Wu Yi-min
National Taiwan University
The fault under the Central Mountain Range is on the west side of the rift valley. That means it slopes eastward, but it doesn’t reach the surface, so seismologists didn’t list it as an active fault.
Researchers say this type of blind thrust fault may cause large earthquakes, even though it is not exposed on the surface. They also advise paying more attention to similar faults in Chiayi Couty and Tainan, which is a potential high-risk area given how seldom the faults there release energy.
台東關山和池上,週六日兩起規模超過6的強震後,餘震不斷、至少150起,花蓮卓溪上午10點多,還出現規模5.9的餘震。地震測報中心研判,密集餘震的階段已經接近尾聲,後續不太會有大的餘震。學者分析,這次台東強震,發生在從來沒被標示的中央山脈底下斷層,雖然地表上看不到痕跡,也可能誘發大地震。
現場人員倉皇逃離春日國小,操場對面的山頭,土石瞬間崩落坍塌,嚇壞不少民眾。台東關山和池上,週末連兩起,規模超過6的強震後,餘震不斷,週一上午花蓮卓溪地牛翻身、規模還有5.9。幸好,測報中心研判,後續發生大餘震的機率低。
[[氣象局地震測報中心主任 陳國昌]]
“我個人覺得所謂的密集發生餘震的階段,應該是接近尾聲了,已經不會算是密集發生,然後大的餘震我覺得可能性偏低。”
有專家說,目前正值地震活躍期,根據規模6以上的地震次數高低統計,1999年有15次最多,再來是1951年的13次,而今年已有8起,為史上第三多。不過,高峰後的隔年,強震數量都會明顯降低。
[[前氣象局地震測報中心主任 郭鎧紋]]
“我們現在已經發生8個規模6以上的地震,所以等於是把能量清得比較乾淨,所以我期盼說,明年是個地靜人安的一年。”
這次台東強震,發生在從來沒被標示的中央山脈底下斷層。有研究團隊最近在中央山脈東側,發現地震密集帶。
[[台大地質科學系教授 吳逸民]]
“中央山脈(底下)斷層,它是在縱谷的西側,縱谷的西側,那它向東傾斜的一條斷層,只是它沒有出露到地表,所以像地質調查所就沒有把這條斷層列為活動斷層。”
學者解釋,像這樣的"盲斷層",雖然地表上看不到痕跡,但也可能引發大地震。而嘉南地區,也被專家列為重點觀察,當地斷層因為較少能量釋放,屬於高風險潛勢地區,必須加強關注。
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