利用SAR干涉測量研究菲律賓雷伊泰Tongonan地熱場抽提地熱水引起的地面沉降

Abstract

菲律賓群島自成立以來，一直在經歷複雜的地質過程，如俯衝，碰撞和主要的走滑斷層。具體而言，菲律賓構造板塊在菲律賓東部的歐亞板塊下俯衝。這些板塊在菲律賓南部的摩盧卡斯海相撞，主要的走滑斷層發生在菲律賓斷裂帶（PFZ）群島的中心。菲律賓位於太平洋火環西部，經歷頻繁的地震和火山活動。沿著活躍的構造塊體廣泛的火山活動為菲律賓提供了高熱流，可以用作地熱資源的替代能源。這符合菲律賓政府想要增加可再生能源，特別是地熱能的能力的想法。截至2015年12月，菲律賓處理的裝機容量為1,906兆瓦，這使得菲律賓聲稱它在安裝世界地熱能力方面位居全國第二。到2030年，他們希望將地熱容量增加約1,371兆瓦。在菲律賓中部，雷伊泰中部高地的雷伊泰地熱田（LGF）仍然是該國主要的地熱能源生產國。它總共產生約710兆瓦的電力，佔菲律賓總裝機容量的37％左右。Tongonan地熱田（TGF）是菲律賓最古老和最大的地熱發電廠之一，位於PFZ區附近的Leyte島。為了達到地熱能力目標，需要增加勘探和開採。不僅如此，我們還必須維護和監控菲律賓已有的發電廠。在這種情況下，有必要對土地移位的危險採取預防措施，包括沉降和隆起。在用PS-InSAR方法分析後，我們發現在TGF周圍區域經歷了沉降，特別是在生產井周圍發生了嚴重的沉降，高達37.5 mm / yr。這種下沉是由於過多的地下水開採造成的，這可能會損壞發電廠本身。

The Philippines Archipelago has been undergoing complex geologic processes such an subduction, collision and major strike-slip faulting since it was formed. Specifically, the Philippines Tectonic Plate subducted under the Eurasian Plate on the eastern part of The Philippines. The plates collided in the Moluccas Sea, in the southern part of the Philippines and major strike-slip faulting took place at the center of the archipelago, the Philippines Fault Zone (PFZ). Situated in the western part of the Pacific Ring of Fire, the Philippines experiences frequent seismic and volcanic activity. The widespread volcanic activity along the active tectonic blocks provides the Philippines with high heat flow that can be used as an alternative source of energy from the geothermal resources. This is in line with the thoughts of the Government of the Philippines who want to add the capacity of the renewable energy resources, especially geothermal energy. As of December 2015, the Philippines processes 1,906 MW installed capacity which sustains the Philippines claim that it is ranked second among the nations in the installation of the world’s geothermal capacity. By 2030 they want to increase the geothermal capacity by approximately 1,371 MW. In Central Philippines, the Leyte Geothermal Field (LGF) in the central highlands of Leyte remains as the leading producer of geothermal energy in the country. It produces a total of around 710 megawatts and provides about 37% of the total installed geothermal capacity in the Philippines. Tongonan Geothermal Field (TGF) is one of the oldest and largest geothermal power plants fields in the Philippines, placed in Leyte Island near the PFZ zone. In order to reach the geothermal capacity target, its need increase the exploration and the exploitation. Not only that we also have to maintain and monitor the power plant which already exists in the Philippines. In this case it is necessary to take a preventive action about the danger of land displacement both subsidence and uplift. After analyzing with PS-InSAR method, we found in the area around TGF experiencing subsidence especially a severe subsidence happened around the production well area with up to 37.5 mm/yr LOS displacement. This subsidence is caused by excessive groundwater extraction which can damage the power plant itself.