本研究利用8個位於新化斷層及後甲里斷層區域之中央地質調查所GPS連續觀測站，於2006年6月至2007年3月間之每日解所得時間序列，來探討台南地區之地殼變形。所得結果顯示，相對於中國大陸邊緣，台南地區向西移動趨勢明顯，速度平均約10 mm/yr。在這10個月期間，雖有明顯的往西移動，但其並非持續的位移，而是間歇性移動，最大有一月間移動5 mm以上之幅度，也有一整月不曾位移之時。尤其在後甲里斷層及新化斷層以西及以北地區，曾在十日中瞬間向西移動達3~5 mm，地殼變形並有受力回彈的現象發生，證明了此地區的地殼變動並無一定速率，經常發生間歇性移動，且變化以後甲里斷層連接新化斷層以西以北地區為分界而發生。主因推論台南地區發生豪雨後雨水滲流使斷層溼潤，增加岩層間孔隙水壓使有效正向壓應力減少，加上菲律賓海板塊持續擠壓歐亞大陸板塊的力量，造成迅速位移至一臨界距離，使得動摩擦轉回靜摩擦強度。

We used eight GPS continuous stations from Central Geological Survey to investigate the crustal deformation of the Tainan area. We used Bernese 4.2 software to calculate the velocity of the above-mentioned GPS stations form June 2006 to March 2007. These GPS measurements have provided the complete velocity field relative to the Paisha station (S01R) of the Penghu islands, which is situated on the Chinese continental shelf. Analysis of crustal deformation of the Tainan area indicates instable horizontal motions. A greatest displacement of 5 mm occurred within 10 days in late September 2006 for stations west of the Houchiali fault. We confirm that there is no consistent velocity in the crustal deformation of this area, and the intermittent movement often takes place. The pattern changes across the boundary between Houchiali fault and Shinhua fault. Because the influent rainwater makes the fault moist after the heavy rain, the crustal deformation reaches a critical distance which changes the intensity of the friction.

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