P波規模之估計於印尼爪哇島西部地區之地震預警系統開發

Abstract

地震預警（Earthquake Early Warning, EEW）系統中，快速且準確的地震規模估算是一個關鍵組成部分，特別是在印尼這樣構造活動頻繁的地區。然而，目前印尼尚未建立區域專屬的 P波地震規模計算公式。本研究探討了P波位移峰值（P-waves Peak Displacement, Pd）參數在地震規模之估算。Pd 定義為 P 波到時後前 3 秒內的最大垂直位移峰值。本研究以西爪哇地區 56 起規模 M ≥ 5 的事件為基礎，建立了一個經驗關係式。迴歸分析結果顯示，Pd、震源距離 (R) 與印尼氣象、氣候與地球物理局（BMKG）目錄規模之間具有高度相關性，均方根誤差（RMSE）為 0.23。 針對 31 起內陸地震的進一步分析則顯示出更佳的表現，RMSE 為0.16，與測站距震源較近的情況一致。相比之下，τc 參數的可靠性低於 Pd。儘管透過設定峰值加速度（Pa）閾值對 τc 值進行篩選以提升訊噪比，在本研究條件下，τc 的估算結果仍顯示較低的穩健性。此外，Pd 與 PGV 之間呈現高度相關性，其均方根誤差（RMSE）為 0.47，顯示 Pd 具有應用於快速地動估計的潛力。本研究證實 Pd 是一個可靠的快速地震規模估算參數，能夠支持印尼地震預警系統的發展。

Rapid and accurate magnitude estimation is a crucial component of earthquake early warning (EEW), particularly in tectonically active regions such as Indonesia. However, a region-specific formulation for Indonesia has not yet been established. This study investigates the effectiveness of the P-wave peak amplitude of displacement (Pd) parameter, defined as the maximum values of vertical ground displacement following the first three seconds after the P-wave arrival, for estimating earthquake magnitude in the western part of Java. An empirical relationship was developed using 56 events with magnitudes M ≥ 5. The regression analysis showed a strong correlation between Pd, hypocentral distance (R), and catalog magnitudes from BMKG with root mean square error (RMSE) of 0.23. An additional analysis of 31 inland earthquakes demonstrated the better performance, with an RMSE of 0.16, which aligns with the closer stations recorded. In contrast, τc parameter exhibits lower reliability compared to Pd. Although τc values were filtered using a peak amplitude of acceleration (Pa) threshold to enhance signal-to-noise ratios, τc estimates remain less robust under the studied conditions. Additionally, Pd shows a strong correlation with PGV, with a RMSE of 0.47, indicating its potential for rapid ground motion estimation. This study confirms that Pd is a reliable parameter for rapid magnitude estimation and can support the development of earthquake early warning systems in Indonesia.