Analysis of Earthquake Occurrence in Jiali Area of Tainan

• Main Authors: han-chi ho, 何漢琪
• Other Authors: Ruey-Juin Rau
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/29422872136501948421

碩士 === 國立成功大學 === 地球科學系專班 === 97 === Taiwan lies on a suture zone between the Eurasia Plate and the Philippine Sea Plate. As to the tectonic structure of Taiwan, the early tectonic structure exists in the western Taiwan. From 1991 to 2008, there were the earthquake records for the tectonic activities of Jiali Area in Tainan. By using statistical techniques to analyze the earthquake magnitudes, the earthquake hypocenter depth, the time of earthquake occurrence, and the spatial and temporal distribution of the earthquakes, the geological and the earthquake characteristic of the area are studied. According to the analysis, Jiali area can be divided into three areas. They are area1 (23º6’30”N~23º17’24”N, 119º54’E~120º5’24”E), area2 (23º15’N~23º 19’48”N, 120º6’E~120º12’E), and area3 (23º10’12”N~23º23’48”N, 120º3’E~120º6’E). The analysis shows that there are three fault structures distributing over Jiali Area of Tainan, including Sinhua Area. The three fault trends are: zone A exists about the western north 61º, zone B exists about the western north 58º, zone C exists about the western north 70º. They are all left-lateral fault structures, and especially zone B and zone C go down toward the north-east obviously. As to the earthquake occurrence, the earthquakes occurred in zone A and zone B are mainly influenced by the fluid in the stratum, and the occurrence by the fluid pops with irregular pattern. What can be told is there are two popping activities. The first popping activity, from 1991 to 1994, triggered the occurrence of sudden individual earthquakes in area1 and area2. The second popping activity caused the occurrence of sudden individual earthquake in area3 from 1995 to 1998. As to the analysis of b-value, the rate of the large earthquake occurrence goes down in Jiali Area. Especially being influenced by the 921 Earthquake, the stress of the area modulates and that makes the rate of the sudden individual earthquake occurrence and the large earthquake occurrence both go down. In addition, the earthquakes in this area occur in 10~15 km depth, which is speculated to be the depth of the tectonic structure or the depth of fluid.