臺灣位處於菲律賓海板塊與歐亞大陸板塊交界帶，該區域斷層與海溝分布極為複雜，屬於環太平洋地震帶上具高度地震與海嘯潛勢之地區。歷史記錄顯示，臺灣沿海曾多次遭受海嘯侵襲，顯示其地理位置所帶來之天然災害風險不容忽視。隨著近年觀測技術之進展，地震中心已於臺灣周邊海域部署多條海底電纜監測系統，提供極高時空解析度之觀測資料，為地震及其引發之海嘯研究開啟全新契機。 本計畫運用地震中心所建置之豐富海底電纜觀測資料，結合 COMCOT 海嘯數值模式進行模擬與分析，探討外海電纜所記錄之海嘯波形與臺灣主要港口所受海嘯影響之關聯性。進一步分析海嘯源規模變化對外海電纜觀測與港口波高之對應關係，建立可供預警應用之量化關係模型。透過本研究，期能建立外海即時觀測資料與沿岸衝擊之量化轉換關係，使交通部中央氣象署得以在海嘯發生初期，即利用海底電纜即時資料輔助判斷沿岸港口潛在衝擊程度，提升海嘯預警發布之即時性與可靠性，強化國家整體海嘯防災決策能力。 更利用多年連續海纜資料，建立台灣外海深海背景噪訊基準模型，並解析噪訊能量與海象因子之間的物理關聯性，以量化海況對地震與海嘯監測性能的影響。我們採用國際標準之 PSD/PDF 分析框架，建立不同季節、海況與水深條件下的噪訊統計圖集，辨識如infragravity waves、微震能量與環境因子的耦合關係。進一步透過互相關（CCF）與頻譜相干性（MSC）分析，探討局地風浪與遠端湧浪的相對貢獻，並評估極端海象對偵測閾值與長週期訊號擷取的影響。 本研究將補足過去短期 OBS實驗無法呈現的年際變化，建立首套台灣外海深海噪訊基準與動態偵測能力評估模型，對提升海嘯預警參數化、海纜站位布局及外海地震監測效能具有重要科學與實務價值。 ;Taiwan is located at the convergent boundary between the Philippine Sea Plate and the Eurasian Plate, where the distribution of faults and trenches is highly complex. This region is part of the seismically active Pacific Ring of Fire and is considered to have a high potential for both earthquakes and tsunamis. Historical records indicate that Taiwan's coastal areas have been affected by tsunamis multiple times, underscoring the significant natural disaster risk posed by its geographic location. With advancements in observational technology in recent years, the Central Weather Administration has deployed multiple submarine cable monitoring systems in the waters surrounding Taiwan. These systems provide high-resolution spatiotemporal data, offering new opportunities for advancing the study of earthquakes and tsunami generation. This project aims to utilize the extensive submarine cable observation data established by the seismic monitoring network and integrate it with the COMCOT tsunami numerical model to conduct simulations and analyses. The goal is to investigate the correlation between offshore tsunami waveforms recorded by submarine cables and the tsunami impacts observed at major ports in Taiwan. Furthermore, the project will analyze how variations in tsunami source magnitude influence the relationship between offshore cable observations and port wave heights, with the objective of developing a quantitative correlation model applicable to early warning systems. Through this research, we seek to enhance scientific understanding of tsunami hazards under diverse seismic source scenarios and provide more accurate and reliable data to support operational tsunami early warning and decision-making at the Central Weather Administration. This study uses multi-year submarine-cable seismic data to establish a deep-ocean ambient noise baseline for offshore Taiwan and to quantify how ocean conditions influence seismic and tsunami monitoring performance. Using the PSD/PDF framework, we construct seasonal and depth-dependent noise statistics and identify the roles of infragravity waves, microseisms, and environmental forcing. Cross-correlation (CCF) and magnitude-squared coherence (MSC) analyses further distinguish the contributions of local wind waves and remote swells, and assess how extreme sea states affect detection thresholds. This work fills the gap left by short-term OBS deployments and provides the first long-term noise baseline and detection capability assessment for Taiwan’s offshore region, supporting improved tsunami warning and cable-station planning.
