地震災害風險－－效益分析於土地使用規劃之應用：應用HAZ-Taiwan系統

AN APPLICATION OF EARTHQUAKE RISK-BENEFIT ANALYSIS IN LAND USE PLANNING: USING HAZ-TAIWAN SYSTEM

本文主要目的在提出一套分析地震災害危險度與風險的方法，供規劃者評估地區災害風險現況與不同土地使用方案潛在的風險－－效益。文中應用國科會與經濟部合作開發的HAZ-Taiwan系統，以土地使用計畫圖與地震風險機率模型，進行台北市士林區的地震潛勢、危險度與風險分析。從設定之三個地震事件中，發現士林區之西南、西與南部區域為地震危險度與風險較高之區域，三個地震事件平均估計總經濟損失約為1,137億元，年預期平均損失約為0.77億元。另亦估計不同土地使用方案（圖）的地震風險－－效益，成果顯示通盤檢討案較原方案，可平均降低損失風險86億元（約降低總暴露價值之4.39%）。透過HAZ-Taiwan，可有效建立地震災害風險圖及風險－－效益評估方法，提供規劃者評估土地使用計畫與社區地震風險，以避免不妥適的規劃行為。

Local authorities rarely use risk analysis instruments, the most appropriate level of seismic hazard and risk assessment, to employ as a decision-making support system in their planning and development procedures. The main purpose of this article is to provide an available instrument and methodology for planners to accomplish such analysis. We illustrated an example of seismic risk analysis for Shilin district, using available land-use map, and a probabilistic earthquake hazard model developed by National Science Council’s HAZ-Taiwan earthquake loss estimation software. We estimated the total and annual expected loss owing to three earthquakes and the spatial distributions of risk. The analysis presented that the average total predicted loss in Shilin was NT$ 113.7 billion and the expected annual earthquake loss was NT$ 77 million per year. The risk was more accumulated in the southwest, south and west regions in Shilin. We also investigated the extent to which future land-use plan growth would change this risk. It showed that the planned growth reduce of 1.18% would cause a decreasing in risk to NT$ 8.6 billion. This paper suggests the ways in which to perform the earthquake hazard and risk evaluations. It is important for planners to evaluate whether their planning is appropriate.