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。根據文獻報告，在規模較大的地震發生前，震央附近重力基點的重力值有變化的情形，因此，重力重複觀測可作為地震前兆現象研究項目之一。本計畫選擇橫跨觸口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。今年度的測量中，位在觸口斷層上盤的重力點有較明顯的重力改變，可能與嘉義地區的地震有關；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. The repeated microgravity survey along profile across known active fault is one of the items included in the earthquake precursor research program. Repeated microgravity survey will be made to detect the gravity variation across the Chukou fault. In the year, remarkable gravity changes in the hanging-wall side at the Chukou fault were maybe associated with the earthquake occurred in Chiayi area. ; 研究期間 9701 ~ 9712
