The Mw 7.5 earthquake that struck central Papua New Guinea in 2018 was the largest event ever recorded in the region with modern seismic instruments. The ground motions associated with this event also triggered widespread landslides and affected more than 500,000 people. However, due to the absence of a local seismic and Global Positioning System network in the vicinity, the fault location, system, and slip distribution of this earthquake are not well documented. In this study, we use the subpixel offset method on the Copernicus Sentinel‐1 Synthetic Aperture Radar (SAR) images to calculate the 3D coseismic displacement of the 2018 Papua New Guinea earthquake. The results show clear fault traces that suggest coseismic slip on the Mubi fault and the Mananda fault that triggered landslides that spread out in a more than 260 km2 region. Finite‐source inversions based on the subpixel offset measurements show up to 4.1 and 6.5 m coseismic slip on the Mubi and Mananda faults, respectively. Despite higher data uncertainty (⁠∼0.4–0.8 m⁠) of the subpixel offset data, synthetic resolution tests show resolvable slip above 8 km in depth. The lack of shallower slip on the west side of the Mananda fault could be due to an inflated geothermal gradient near the dormant volcano, Mount Sisa, as a slip barrier. The result of the coulomb stress change suggests possible southeastward slip propagation from the Mananda fault to the Mubi fault. Our work successfully resolves 3D coseismic displacement in highly vegetated terrains and demonstrates the feasibility of using the subpixel offset on SAR images to help our understanding of regional active tectonic systems.

中文翻译：

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使用亚像素偏移量完善2018 Mw 7.5巴布亚新几内亚地震断层滑移模型

2018年袭击巴布亚新几内亚中部的7.5兆瓦地震是该地区有史以来使用现代地震仪器记录的最大地震。与此事件相关的地面运动也引发了广泛的山体滑坡，影响了超过500,000人。但是，由于附近没有本地地震和全球定位系统网络，因此该地震的断层位置，系统和滑动分布没有得到充分记录。在这项研究中，我们使用哥白尼前哨1合成孔径雷达（SAR）图像上的亚像素偏移方法来计算2018年巴布亚新几内亚地震的3D同震位移。结果表明，清晰的断层痕迹表明在Mubi断层和Mananda断层上发生了同震滑移，引发了滑坡，这些滑坡在260多平方公里的区域内扩散。基于亚像素偏移量测量的有限源反演分别显示了Mubi和Mananda断层的同震滑移分别为4.1 m和6.5 m。尽管亚像素偏移数据的数据不确定性更高（？〜0.4–0.8 m？），但综合分辨率测试显示深度超过8 km时可解决滑移。Mananda断层西侧缺少较浅的滑动可能是由于休眠的Sisa火山附近的地热梯度膨胀造成的。库仑应力变化的结果表明，从Mananda断层到Mubi断层可能向东南滑动。我们的工作成功地解决了高植被地形中的3D同震位移，并演示了在SAR图像上使用亚像素偏移来帮助我们了解区域活动构造系统的可行性。