Complex fault system associated with the Molucca Sea Divergent double subduction zone revealed by the 2019 Mw 6.9 and Mw 7.1 Earthquakes

IF 2.7 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics Pub Date : 2024-08-30 DOI:10.1016/j.tecto.2024.230493

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引用次数: 0

Abstract

GNSS (Global Navigation Satellite System) data in northern Sulawesi and western Halmahera reveals a pattern of coseismic displacement that was caused by the 7 July 2019 (Mw 6.9) and 14 November 2019 (Mw 7.1) Molucca Sea earthquakes. The coseismic slip of these earthquakes are obtained via inversion on rectangular fault planes of surface GNSS coseismic deformation offsets. The 7 July 2019 earthquake ruptured on an east-dipping fault with a maximum slip of ∼35 cm located at ∼4 km depth and ∼ 100 km north-west of the epicenter. The 14 November 2019 earthquake also ruptured on an east-dipping fault, which has a maximum slip of ∼64 cm located at ∼22 km depth and ∼ 20 km south-west of the epicenter. The coseismic slip distribution of the 14 November earthquake is spatially aligned to that of an earthquake of similar magnitude that took place on 15 November 2014 in the same region. This observation points to the possibility of synchronization, thus raising the prospect of a future earthquake exceeding magnitude 7. If the stress was completely released during the 2014 event, it would have been necessary to reload that portion of the fault at a rate significantly larger than the observed convergence rate of ∼5.8 cm/yr. This suggests that partial ruptures are likely controlling the recurrence time of large earthquakes in the region.

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2019 年 6.9 级和 7.1 级地震揭示的与摩鹿加海发散型双俯冲带有关的复杂断层系统

苏拉威西岛北部和哈尔马海拉岛西部的全球导航卫星系统（GNSS）数据揭示了由 2019 年 7 月 7 日（Mw 6.9）和 2019 年 11 月 14 日（Mw 7.1）摩鹿加海地震引起的共震位移模式。这些地震的共震滑移是通过对地表 GNSS 共震变形偏移的矩形断层平面进行反演获得的。2019 年 7 月 7 日地震发生在一条东倾断层上，最大滑移量为 35 厘米，位于震中西北方向 100 公里处，震源深度为 4 公里。2019 年 11 月 14 日地震也发生在一条东倾断层上，该断层的最大滑移量为∼64 厘米，位于震源深度∼22 公里处，震中西南方向∼20 公里处。11 月 14 日地震的共震滑移分布与 2014 年 11 月 15 日在同一地区发生的类似震级地震的滑移分布在空间上是一致的。这一观察结果表明了同步的可能性，从而提高了未来发生超过 7 级地震的可能性。如果应力在 2014 年的地震中被完全释放，那么该部分断层的重载速度将远远大于观测到的 5.8 厘米/年的收敛速度。这表明，部分断裂很可能控制着该地区大地震的复发时间。

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来源期刊

Tectonophysics 地学-地球化学与地球物理

CiteScore

4.90

自引率

6.90%

发文量

300

审稿时长

6 months

期刊介绍： The prime focus of Tectonophysics will be high-impact original research and reviews in the fields of kinematics, structure, composition, and dynamics of the solid arth at all scales. Tectonophysics particularly encourages submission of papers based on the integration of a multitude of geophysical, geological, geochemical, geodynamic, and geotectonic methods