卢显,刘杰,薛艳,晏锐,姜祥华,李祖宁,邓世广,苑争一. 2023. 台湾地区强震活动特征分析. 地震学报,45(6):996−1010. DOI: 10.11939/jass.20220221
引用本文: 卢显,刘杰,薛艳,晏锐,姜祥华,李祖宁,邓世广,苑争一. 2023. 台湾地区强震活动特征分析. 地震学报,45(6):996−1010. DOI: 10.11939/jass.20220221
Lu X,Liu J,Xue Y,Yan R,Jiang X H,Li Z N,Deng S G,Yuan Z Y. 2023. Analysis of strong earthquake activity characteristics in Taiwan. Acta Seismologica Sinica45(6):996−1010. DOI: 10.11939/jass.20220221
Citation: Lu X,Liu J,Xue Y,Yan R,Jiang X H,Li Z N,Deng S G,Yuan Z Y. 2023. Analysis of strong earthquake activity characteristics in Taiwan. Acta Seismologica Sinica45(6):996−1010. DOI: 10.11939/jass.20220221

台湾地区强震活动特征分析

Analysis of strong earthquake activity characteristics in Taiwan

  • 摘要: 基于定性分析和Morlet小波分析方法,研究了我国台湾地区的主要构造带和强震分布特征。1900年以来台湾地区MS≥7.0地震存在三个活跃时段:第一个活跃时段为1902—1925年,长达近23年;第二个活跃时段为1935—1978年,约43年;第三个活跃时段为1986—2006年,时长20年。台湾自2006年12月26日恒春海域发生MS7.2地震之后,MS≥7.0地震平静已近16年,为历史最长平静时段,存在开始新的活跃时段的可能。从区域分布看,台东地震带MS≥6.9地震具有六个活动周期,大部分活动周期平均约为16年,每个活动周期均包含活跃和平静时段,所有MS≥6.9地震均发生在活跃时段,统计显示台东地震带的活动强度自2002年进入第六个活动周期后逐渐减弱,直到2022年9月份台湾东带才再次发生MS6.9地震,可能进入了新一轮活跃时段。台湾西带MS≥6.0地震存在92年左右和14年左右的周期,1901—1993年为一个活跃-平静大周期(92年左右),1994年开始新一轮的大周期活动,同时,大周期又包含平均周期为14年左右的小周期。临近预报(nowcasting)方法计算的小震积累水平显示,台湾东带MS≥7.0地震和台湾西带MS≥6.0地震具有较高的发震背景概率,台湾地区强震在年尺度上与华南地区中强地震具有一定的对应关系。

     

    Abstract: Based on qualitative analysis and Morlet wavelet method, the distribution characteristics of the main tectonic zones and strong earthquakes in Taiwan, China are studied. The Taiwan, China can be divided into the Taidong seismic zone and the Taixi seismic zone, bounded by the Central Mountains. The former is mainly composed of the Huadong longitudinal valley fault, the coastal mountains and the sea area to the east of the coastal mountains. It is the region with the strongest seismic activity in Taiwan. The latter seismic zone mainly includes the western foothills and the western coastal plain. In addition, due to the influence of the Philippine Sea Plate pushing the Eurasian Plate towards the northwest, most earthquakes in Taiwan and surrounding waters are thrust-type earthquakes.   There have been three active periods of MS≥7.0 earthquakes in Taiwan since 1900. The first active period was from 1902 to 1925, which lasted nearly 23 years; the second was from 1935 to 1978, about 43 years; the third was from 1986 to 2006, lasting 20 years. Since the Hengchun sea area MS7.2 earthquake in Taiwan on December 26, 2006, Taiwan earthquakes above MS7.0 have been quiet for nearly 16 years, which is the longest quiet time in history, and there is a possibility of a new active period.   From the regional distribution perspective, MS≥6.9 earthquakes in the eastern Taiwan had six active cycles, most of which lasted about 16 years on average. Each active cycle included active and quiet periods, and all MS≥6.9 earthquakes occurred in active periods. Statistics show that the activity intensity of the eastern Taiwan had gradually weakened since 2002, when it entered the sixth active cycle. A new active period may have started since the Hualian MS6.9 earthquake occurred in the eastern Taiwan on September of 2022. At the same time, the Morlet wavelet method was used to calculate the period spectrum of seismic activity of the Taidong seismic zone and the significance testing. The results showed that the 3-year and 16-year periods in the region passed the 80% confidence testing, and the 16-year period could better reflect the average duration of most seismic periodic activities in the Taidong seismic zone. The 3-year period was consistent with the average occurrence interval of MS≥7.0 earthquakes with every three years in the Taidong seismic belt from 1900 to 2006. As for the western Taiwan, MS≥6.0 earthquakes have cycles of about 92 years and 14 years which passed the 80% confidence testing. 1901−1993 was a large active-quiet cycle (about 92 years) and a new round of large cycle activity began from 1994. At the same time, the large cycle also included some small cycles with an average period of 14 years. At present, the Taixi seismic belt is in the quiet period of the small cycle of 2010 to 2022. Based on the average duration of the small cycle of about 14 years, the Taixi seismic belt maybe enter a new round of the small cycle activity of MS≥6.0 earthquake in the future.   From the perspective of focal depth, the focal depth of earthquakes in Taiwan has the characteristic of gradually deepening from west to east. Among them, earthquakes in the northeast of Taiwan and nearby waters are mainly of medium to deep source earthquakes, while earthquakes in the waters of the central Taiwan are mostly distributed within the range of 20−40 kilometers, mainly located in the waters near Hualien. The distribution characteristics of source depth are consistent with the eastward dipping characteristic of the Huadong longitudinal valley fault in the region. The accumulation level of small earthquakes calculated by the Nowcasting method also shows that the MS≥7.0 earthquakes in the eastern zone of Taiwan and MS≥6.0 earthquakes in the western zone of Taiwan have a high background probability of earthquake occurrence, and the strong earthquakes in Taiwan have a certain corresponding relationship with the moderate-strong earthquakes in South China on an annual scale.

     

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