| 摘要: | 索羅門群島位於太平洋板塊與澳洲板塊之交界，長年大小地震不斷，然而由於其居住地多位於沿海平坦地帶，且建物多為低矮之鐵皮屋或茅草屋，因此海嘯發生時往往對當地造成嚴重危害。為瞭解索羅門群島之海嘯潛勢，本研究以康乃爾大學所研發之COMCOT多重網格海嘯模式為基礎進行分析，並以模擬索羅門群島重大歷史海嘯作為模式驗證與討論。本研究將數值模擬成果與調查資料及美國國家海洋暨大氣總署之太平洋實驗室 (NOAA PMEL, National Oceanic and Atmospheric Administration Pacific Marine Environmental Laboratory) 模擬結果與兩則歷史案例進行比對。
第一案例為2007發生於索羅門西省之地震海嘯事件，本事件主要肇因於伍德拉克板塊、澳洲板塊以及太平洋板塊交界破裂發生規模8.1之地震。模擬結果發現海嘯主要由南向北傳遞，並於吉卓島(Gizo Island)與辛博島(Simbo Island)造成嚴重破壞。根據模擬結果，吉卓島出現高達5公尺之浪高。透過索羅門群島當地之災害調查資料，可比對海嘯波高與溢淹程度。第二案例為2013發生於索羅門東部聖克魯斯群島(Santa Cruz)之地震海嘯事件，海嘯由位於聖克魯斯群島西側聖克立托巴海溝(San Cristobal trench)破裂之地震所引發，該地震規模8.0，所引發之海嘯主要由西朝聖克魯斯群島行進，並於恩德島(Nendo Island)造成嚴重破壞。模擬結果顯示，海嘯波高於恩德島為4.6公尺，並於地震後4分鐘抵達。
本研究採用海嘯影響強度分析法（Impact Intensity Analysis ,IIA）針對索羅門群島海嘯潛勢進行分析。由於索羅門群島位於海溝邊緣，其地震型海嘯多具有垂直於海溝方向之特性。因此本研究亦搭配海嘯到時分析法（Tsunami Arrival-Time Analysis ,TATA），以納入海溝走向之影響。研究結果顯示，位於索羅門群島西省之吉卓(Gizo)及蒙達(Munda)為海嘯發生之高危險區，其海嘯威脅主要來源為南方伍德拉板塊與太平洋板塊交界於西省南方之海溝帶。而首都荷尼阿拉市(Honiara)由於位於群島之內海，受到地震型海嘯之衝擊較小，但仍需注意發生於南方旺烏努島(Vangunu Island)及瓜達爾卡納爾島(Guadalcanal Island)之間之地震海嘯。本研究將索羅門群島南部之新不列顛海溝(New Britain trench)以及聖克立托巴海溝設定6個可能之海嘯情境，以利後續海嘯災防之用。由於索羅門群島位於火山地震帶，因此本研究亦針對群島內之全新世火山進行火山型海嘯之模擬與分析。由模擬結果可知，若位於首都西北側之薩沃島(Savo Island)火山噴發，產生之火山型海嘯可能對首都荷尼阿拉市造成1公尺以上之波高，由於首都市中心皆位於沿海，因此必須小心防範。
臺灣同樣位於太平洋火環帶上，在歷史紀錄中曾經發生多起海嘯事件，其中1867年基隆海嘯為官方確認之歷史海嘯事件，且基隆地區坐擁三座核電廠，鄰近首都人口稠密，若於此地再發生海嘯事件其影響不可小覷。
本研究採用海嘯影響強度分析法（Impact Intensity Analysis ,IIA）針對台灣東北海岸進行海嘯潛勢分析。從IIA結果來看，棉花峽谷南方可能為1867基隆海嘯之源頭。本研究亦對臺灣東北海域多個火山島嶼進行山崩海嘯情境模擬，其中基隆嶼、基隆海底火山、花瓶嶼對基隆以及金山之影響較為顯著，龜山島之情境則是對宜蘭地區產生相當大之影響。
;Solomon Islands is located at the boundary between the Pacific Plate and the Australian Plate in the Pacific Ocean. It experiences frequent earthquakes of varying magnitudes. However, due to the majority of residential areas being situated in coastal flatlands and the prevalence of low-lying structures such as tin houses or thatched huts, tsunamis often pose severe threats to the local population. To understand the tsunami potential in Solomon Islands, this study utilizes the COMCOT multi-grid tsunami model developed by Cornell University for analysis. It also validates and discusses the model by simulating significant historical tsunamis in Solomon Islands and comparing the results with survey data and simulations conducted by the National Oceanic and Atmospheric Administration Pacific Marine Environmental Laboratory (NOAA PMEL).
The first case study focuses on the earthquake and tsunami event that occurred in the Western Province of Solomon Islands in 2007. This event was primarily caused by an earthquake of magnitude 8.1 along the boundary of the Woodlark Plate, the Australian Plate, and the Pacific Plate. The simulation results reveal that the tsunami propagated mainly from south to north, causing severe damage to Gizo Island and Simbo Island. According to the simulation, Gizo Island experienced wave heights of up to 5 meters. By comparing the tsunami wave heights and inundation levels with local disaster investigation data, the findings can be validated.
The second case study examines the earthquake and tsunami event that took place in the Santa Cruz Islands, located on the eastern part of Solomon Islands, in 2013. The tsunami was triggered by an earthquake of magnitude 8.0 along the San Cristobal Trench on the western side of the Santa Cruz Islands. The simulation results indicate that the tsunami primarily traveled westward towards the Santa Cruz Islands, causing significant destruction on Nendo Island. The wave height simulation shows a height of 4.6 meters on Nendo Island, reaching the island approximately 4 minutes after the earthquake.
This study employs the Impact Intensity Analysis (IIA) method to analyze the tsunami potential in Solomon Islands. As Solomon Islands is located near the trench edge, most earthquake-generated tsunamis exhibit characteristics perpendicular to the trench direction. Therefore, the study also incorporates the Tsunami Arrival-Time Analysis (TATA) to account for the influence of trench orientation. The research findings identify Gizo and Munda in the Western Province of Solomon Islands as high-risk areas for tsunamis, mainly due to the interaction between the southern Woodlark Plate and the Pacific Plate in the southern trench zone of the province. Honiara, the capital city situated within the island group, experiences relatively smaller impacts from earthquake-generated tsunamis due to its location in an enclosed sea. However, it still needs to be cautious of tsunamis occurring between Vangunu Island and Guadalcanal Island to the south. This study considers six possible tsunami scenarios for the New Britain Trench and San Cristobal Trench in the southern part of Solomon Islands to aid in future tsunami disaster prevention. Additionally, due to the presence of volcanic seismic zones in Solomon Islands, the study also simulates and analyzes volcano-generated tsunamis from Holocene volcanoes within the island group. The simulation results suggest that a volcanic eruption from Savo Island, located northwest of the capital city, could produce a tsunami with wave heights exceeding 1 meter in Honiara. Given that the city center is situated along the coast, precautionary measures need to be taken.
Taiwan, likewise located within the Pacific Ring of Fire, has a history of tsunamis, including the confirmed historical event of the Keelung tsunami in 1867. With three nuclear power plants located in the Keelung area and its proximity to the densely populated capital, the impact of a tsunami event in this area should not be underestimated.
This study adopts the Impact Intensity Analysis (IIA) method to analyze the tsunami potential along the northeast coast of Taiwan. The IIA results suggest that the southern region of the Mianhua Canyon may be the source of the 1867 Keelung tsunami. The study also simulates various landslide tsunami scenarios in the waters off the northeast coast of Taiwan, with notable impacts on Keelung Island, Keelung Submarine Volcano, and Hua-vase Island affecting Keelung and Jinshan. The scenario involving Turtle Island shows significant effects on the Yilan area. |
