The 220-km-long Palu–Koro Fault, Central Sulawesi, is a major fault with prominent expression in Eastern Indonesia. Many studies about the Palu–Koro Fault have shown its capability of generating large earthquakes, but how the Palu–Koro Fault has evolved remains enigmatic. This study is to investigate the geomorphology of NW Palu Valley based on DEMNAS (Digital Elevation Model of Indonesia) and field observations to understand the development of the Palu–Koro Fault. The study area comprises a high mountain in the west and a valley in the east. There are two major normal faults and a strike–slip fault observed in NW Palu Valley. The western normal fault is a basin-bounding fault, which marks the topographic break between mountain and valley. To the east, another normal fault is observed cutting the old alluvial fans and expressed by planar fault scarps. The strike–slip fault is observed within the basin and crosses the distal part alluvial fans. It is expressed by intra-basin ridges in places which are slightly uplifted from the adjacent surface. The surface rupture of the 2018 Mw 7.5 Palu earthquake in NW Palu Valley also shows left-lateral movement up to 4 m. We consider that the development of the Palu–Koro Fault in NW Palu Valley is characterized by toward-central-basin migration of faulting activity from basin-bounding fault to intra-basin fault.

中文翻译：

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印度尼西亚西北帕卢河谷帕卢–科罗断裂的发展

苏拉威西中部长220公里的帕鲁–科罗断裂带是印度尼西亚东部的一个主要断裂带，表现突出。关于帕卢克-科罗断裂的许多研究表明，它具有产生大地震的能力，但是帕卢克-科罗断裂的演化方式仍然是个谜。这项研究的目的是根据DEMNAS（印度尼西亚数字高程模型）调查西北帕卢河谷的地貌，并通过实地观察了解帕卢－科罗断裂的发展。研究区域包括西部的高山和东部的山谷。在西北帕卢河谷发现了两个主要的正断层和一条走滑断层。西部正断层是盆地边界的断层，标志着山脉和山谷之间的地形断裂。在东方，观察到的另一个正常断层是切割旧的冲积扇，并表现为平面断层陡峭。在盆地内观察到走滑断层，并穿过了远端的冲积扇。它由盆地内的山脊所表达，这些山脊从邻近表面略微隆起。西北帕卢河谷2018年瓦鲁7.5瓦卢地震的地表破裂也显示了向左移动达4 m。我们认为西北帕卢河谷帕卢-科罗断裂的发展特征是断层活动从盆地边界断层向盆地内部断层向中央盆地转移。NW Palu山谷的5 Palu地震也显示了向左移动达4 m。我们认为西北帕卢河谷帕卢-科罗断裂的发展特征是断层活动从盆地边界断层向盆地内部断层向中央盆地转移。NW Palu山谷的5 Palu地震也显示了向左移动达4 m。我们认为西北帕卢河谷帕卢-科罗断裂的发展特征是断层活动从盆地边界断层向盆地内部断层向中央盆地转移。