熱帶氣旋的環境參數及其相關地震活動;Environmental parameters on the occurrences of tropical cyclones and the associated seismicity

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Title:	熱帶氣旋的環境參數及其相關地震活動;Environmental parameters on the occurrences of tropical cyclones and the associated seismicity
Authors:	潘瑞維;Pandey, Ravi Shankar
Contributors:	大氣科學學系
Date:	2023-01-09
Issue Date:	2024-09-19 14:10:03 (UTC+8)
Publisher:	國立中央大學
Abstract:	此論文研究熱帶氣旋的環境因素及其可能的誘發地震活動。我使用西北太平洋北部夏季（6 月、7 月、8 月：JJA）風暴頻率和累積氣旋能量 (ACE) 的進行調查。資料包括45 年，來自世界上氣旋最活躍的海盆(19772021年，每年24場風暴）的熱帶氣旋，其中42%屬於夏季，且其中約32%直接穿過太平洋菲律賓海板塊邊界。在風暴活動極高的年份(通過風暴頻率和ACE技術），西北太平洋盆地風暴與太平洋菲律賓海板塊邊界的高地震活動相關。風暴因半徑大，甚至可以在距板塊邊界幾百公里處引發地震（相關性0.70以上）。因此比直接穿過板塊邊界的風暴（0.35以上）具有更大的相關性。本研究使用皮爾遜相關係數，該係數衡量兩個變量之間的線性相關性，由它們的協方差與標準差乘積之間的比率計算得出。對於使用基於風暴頻率分類的極端 TC 活動年測量，TC（穿過板塊邊界的 TC）頻率與太平洋-菲律賓板塊邊界的地震事件之間的相關性很強（中等）且具有相關性。 0.73（0.35），從 0.75（0.43）、0.75（0.47）到 0.79（0.66）不斷增加，深度從 120 公里（大洋岩石圈厚度）、75 公里（地震岩石圈深度）到 30 公里（張裂板塊邊緣淺層地震）。對於使用基於 ACE 的分類測量的極高 TC 活動年份，跨越板塊邊界的 TC 的上述相關性提高了 37%;相關。 0.48（21%;相關性 0.52、17%;相關性 0.55、改善 20%;相關性 0.79，地震深度分別為 120 公里、75 公里、30 公里），表明風暴的動能與引發地震。作為一種巨大的自然現象，風暴甚至可以在距板塊邊界幾百公里的地方引發地震，因此提供了比直接穿過板塊邊界的風暴（0.35 以上）更大的相關性（0.70 以上）。 Fisher 的精確和雙側卡方 (χ2) 檢驗表明，ACE 和基於 TC 頻率的技術對於北方夏季大部分研究參數是可互換的。本研究亦發現相對渦度與風暴頻率最敏感。中層對流層風（850 hPa）的作用在極低颱風活動年比在極高颱風活動年更重要。垂直切變在極高颱風活動年比極低颱風活動年更為重要。我討論了所有環境因素之間的相互關聯，以及它們對風暴頻率的影響。熱帶氣旋和地震是西北太平洋的兩種自然災害，本研究提供了寶貴的初步信息。;The nature and extent of response of environmental factors and possible induced seismicity are investigated using the classifications based on the storm’s frequency and the accumulated cyclone energy (ACE) in the boreal summer season (June, July, August: JJA) in the West North Pacific (WNP) during 45 years (1977-2021) of the study period. A huge number of storms (42%) in the most cyclonically active ocean basin of the world (24 storms every year during 1977-2021) belong to boreal summer, in which around 32% directly cross the Pacific-Philippine Sea Plates’ boundary. The study uses Pearson’s correlation coefficient which is a measure of linear correlation between two variables, calculated by the ratio between their covariance and product of standard deviations. For extremely high TC activity years measured using storms frequency-based classification, the correlation between the frequency of TCs (TCs that cross the plate boundary) and earthquake events at the Pacific-Philippine plates boundary is strong (moderate) with correl. 0.73 (0.35), which keeps on increasing further from 0.75 (0.43), 0.75 (0.47) to 0.79 (0.66) with decreasing depths of 120 km (oceanic lithosphere thickness), 75 km (seismological lithosphere depth) to 30 km (mid-ocean ridges and transform margins have shallow earthquakes), respectively. For extremely high TC activity years measured using ACE-based classification, the above correlation for the TCs that cross the plates’ boundary improves by a huge 37%; correl. 0.48 (21%; correl. 0.52, 17%; correl. 0.55, 20% improvement; correl. 0.79, with earthquake depths 120 km, 75 km and 30 km, respectively), suggesting that the storm’s kinetic energy is significantly linked with the triggering the earthquakes. Being a huge size of natural phenomenon, the storms can trigger earthquakes even from a few hundred km away from the plates’ boundary, thus providing a bigger correlation (above 0.70) than the storms that directly cross the plates’ boundary (above 0.35), although it is not possible with ACE based classification because ACE is more associated with stronger storms which are more than three times less than the weaker storms. The Fisher’s Exact and Two-sided chi-square (χ2) tests reveal that both ACE and TC frequency-based techniques are interchangeable for the majority of studied parameters in boreal summer except cyclonic strength-based parameters as the ACE reflects storm’s kinetic energy. The earthquake magnitudes ranging from 4.1 to 4.9 on the Richter scale account for three-fourths (75%) of the triggered earthquakes at the plates’ boundary. Relative vorticity is found as the most sensitively linked with storms’ frequency. The role of middle-level tropospheric winds (850 hPa) is found in comparably more important for extremely low-TC activity years than in extremely high-TC activity years. Vertical shear is more crucial during extremely high-TC years than extremely low-TC years. The mutual dynamic and environmental connections among all environmental factors were discussed with their observed impact on storms frequency. Tropical cyclones (TC) and earthquakes both are the two most notorious natural hazards in the WNP-related regions, causing huge human and economic losses, while the extreme TC activity years link to flood, drought and water crises in the region. Hence, such a study is essential for the welfare of society, disaster risk-related agencies and researchers worldwide.
Appears in Collections:	[Department of Atmospheric Sciences and Graduate Institute of Atmospheric Physics ] Department of Earth Sciences

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