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| 題名: | 印度尼西亞蘇拉威西島地震構造;Seismotectonics of Sulawesi, Indonesia |
| 作者: | 游平;Serhalawan, Yopi Ruben |
| 貢獻者: | 地球科學學系 |
| 關鍵詞: | 西里伯斯和蘇拉板塊的幾何形貌和應力狀態;早中新世碰撞;晚中新世碰撞;Geometry and stress patterns of the Celebes and Sula slabs;The Early Miocene collision;The Latest Miocene collision |
| 日期: | 2023-01-16 |
| 上傳時間: | 2023-05-09 17:37:59 (UTC+8) |
| 出版者: | 國立中央大學 |
| 摘要: | 印尼東部的蘇拉威西島位於巽他、澳大利亞和菲律賓海板塊的交界。蘇拉威西島在外觀上呈現K形，分別由往北、南、東和東南方向延伸的四個區塊組成，其特殊外形暗示在不同階段的構造演化上存在一定的複雜性; 因此，每個區塊存在不同的地震地體構造特徵。 本研究旨在使用最新的地震目錄和震源機制解以及其他相關的資料以分析蘇拉威西島的地震地體構造。 首先我們根據地震的深度將蘇拉威西島初步分為兩部分：淺部（60 公里）和深部（60-400 公里），而後淺部可再細分為六個區域並根據蘇拉威西的整體構造框架下檢驗地震分佈以及震源機制的型態。 我們認為區域 I 的西里伯斯海俯衝帶和區域 II 的帕盧-科羅斷層為蘇拉威西島淺部的兩個地震活躍帶。 然而，儘管測地研究表明這兩個構造存在較高的滑移速率，但我們發現北蘇拉威西海溝的中心和帕盧-科羅斷層北部是缺乏地震活動的。 因此我們認為前者可能存在地震空區(seismic gap)或是有無震滑移的現象，而後者可能是由於此區在望加錫和北蘇拉地塊的高相對運動區域以外。在 區域III，我們提出望加錫海峽逆衝斷層的松巴段處於累積應變的狀態，預示著未來發生大地震的可能性。 在區域 IV ，我們發現 2019 年吐露灣地震序列可能為之前未被識別的盲斷層活動所引發，而此斷層可能為珀倫斷層在近海西南方向的延伸。 在區域 V中，最大的地震為在 2001 年 坦波馬斯斷層帶西段Mw 7.5 的地震。 然而，其震源機制的方向與坦波馬斯斷層帶西段的走向不一致; 暗示此地震可能是由未知的斷層或是坦波馬斯斷層帶西段的重新活動所致。 對於蘇拉威西島的深部，我們主要研究蘇拉威西島北部兩個相反隱沒極性的板塊：西里伯斯海板塊和蘇拉板塊。 我們透過線性回歸確定了這兩個板塊的幾何形狀（走向和傾角）並投影地震的 P 軸和 T 軸，以研究西里伯斯海和蘇拉板塊的應力狀態。結果顯示，西里伯斯海以平均走向92°和平均傾角71°往南俯衝，而蘇拉板塊顯示出以更陡峭的形式向北偏西北方向俯衝，傾角和走向分別為 73°和 253°。 此外，我們發現蘇拉板塊西部 60-230 公里深的區域有較低的地震活動度，其可能為在早中新世第一階段碰撞的上部板塊分離的證據。;Sulawesi Island in eastern Indonesia is situated at the triple junction of the Sunda, Australian, and Philippine Sea plates. The peculiar K-shape of Sulawesi, comprised of four arms (North, South, East, and Southeast), represented the complex geological and tectonic development at various phases in its evolution. As a result, each arm offered different seismotectonic characteristics. This study aims to analyze the seismotectonics of Sulawesi using the updated datasets for earthquake seismicity and focal mechanisms, as well as other related supporting data. We divided Sulawesi into two parts based on the depth distribution of earthquakes: shallow (60 km) and deep (60–400 km). Sulawesi’s shallow part was grouped into six regions. The distribution of seismicity and the types of focal mechanisms were then examined in the framework of Sulawesi’s tectonic configuration. We determined the Celebes Sea subduction zone in Region I and the Palu-Koro fault in Region II as the two most seismically active zones in Sulawesi’s shallow part. Nevertheless, despite geodetic studies indicating a high slip rate for these two structures, we found a lack of seismicity near the center of the North Sulawesi Trench and in the northern Palu-Koro fault. We suggested that the former might be due to a seismic gap or aseismic slip, while the latter was due to this part being beyond the high relative motion of the Makassar and North Sula Blocks. In Region III, we proposed that the Makassar Strait Thrust Somba segment is in a silent state, indicating the possibility of a large earthquake in the future. In Region IV, we found that the 2019 Tolo Bay earthquake sequence most likely originated from the offshore southwestern continuation of the Peleng fault that was previously unidentified. The largest earthquake in Region V was represented by the 2001 earthquake Mw 7.5 near the western segment of the Tamponas Fault Zone. However, the orientation of the focal mechanism was inconsistent with the western segment of the Tamponas Fault Zone. This earthquake might be triggered by an unidentified fault or the reactivation of the western segment of the Tamponas Fault Zone. For the deep part of Sulawesi, we primarily focus on the two opposite-polarity slabs in northern Sulawesi: the Celebes Sea slab and the Sula slab. We determined the geometry (strike and dip) of these two slabs based on the linear fitting method. We then projected P- and T-axes of earthquakes into the geographic and regional frames to study the stress states of the Celebes Sea and Sula slabs. Our results displayed that the Celebes Sea was subducted southward with an average strike of 920 and dip of 710, while the Sula slab shows steeper slab subduction dipping 730 to the north-northwestward with a 2530 strike angle. Moreover, we found an absence of earthquakes in the Sula slab’s western part at 60-230 km depth, which we interpreted as the upper slab detaching at the first stage of collision in the early Miocene. |
| 顯示於類別: | [地球物理研究所] 博碩士論文
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