許多大地震發生之前，都可以偵測到地磁與重力的改變。當岩層受到應力作用，因岩石脹容(Rock dilatancy)現象會造成地表變形；另外應力作用也可能使岩層有質量轉移(Mass transfer)的現象，這些現象都會造成地表重力值的改變。四年前的921大地震後，我們檢視全省磁力連續觀測資料發現，位於車籠埔斷層兩端的磁力站—鯉魚潭站及灣丘站，都觀測到磁力異常訊號，這些異常訊號與地震的發生有時間上的巧合。本計畫將分兩部份進行，重力方面選擇橫跨斷層的重力基點進行重複觀測，以監測該斷層活動所衍生的重力變化；磁力方面將藉由全省地磁連續觀測網，分析磁力變化與地震發生的關聯性。 Local changes in gravity field can be expected from changes in elevation for the rock dilatancy and the redistribution of mass of earth's crust due to the tectonic stresses. Many examples of gravity changes accompanying both seismic and aseismic deformations have been reported. After the Chi-Chi earthquake (four years ago), we analyzed the recorded data of geomagnetic network. On this occasion, geomagnetic fluctuations were clearly recorded at geomagnetic stations on the northern and southern extremities of the Chelungpu fault, both prior to and following the earthquake and even at the LY and TW geomagnetic stations. The goals of this proposal will investigate the temporal variations of geomagnetic and gravity, as well as their associated with earthquake occurrences and changes in tectonic stress. We also try to understand the physical mechanisms during earthquake and temperature distribution beneath Taiwan. 研究期間：9401 ~ 9412
