Laboratoire de Géologie, École Normale Supérieure, CNRS UMR 8538, PSL Université, Paris, France.
Institut Universitaire de France, Paris, France.
Sci Adv. 2023 Apr 21;9(16):eadd7235. doi: 10.1126/sciadv.add7235. Epub 2023 Apr 19.
Along a plate boundary, why deformation and seismic hazard distributes across multiple active faults or along a single major structure remains unknown. The transpressive Chaman plate boundary (CPB) is a wide faulted region of distributed deformation and seismicity that accommodates the differential motion between India and Eurasia at 30 mm/year. However, main identified faults, including the Chaman fault, only accommodate 12 to 18 mm/year of relative motion and large earthquakes ( > 7) occurred east of them. We use Interferometric Synthetic Aperture Radar to locate the missing strain and identify active structures. The current displacement is partitioned between the Chaman fault, Ghazaband fault and a recent, immature but fast fault zone to the east. Such partitioning matches known seismic ruptures and results in the ongoing widening of the plate boundary, potentially controlled by the depth of the brittle-ductile transition. The CPB illustrates the impact of geological time scale deformation on today's seismic activity.
沿板块边界，为什么变形和地震危险分布在多个活动断层上或沿单个主要构造分布，这仍然未知。具有挤压性质的查曼板块边界（CPB）是一个变形和地震活动分布广泛的断裂区，可适应印度和欧亚板块每年 30 毫米的差异运动。然而，主要识别出的断层，包括查曼断层，仅可容纳 12 至 18 毫米/年的相对运动，并且大地震（>7 级）发生在它们的东部。我们使用干涉合成孔径雷达定位缺失的应变并识别活动构造。当前的位移在查曼断层、加扎班德断层和东部最近的、不成熟但快速的断层带之间分配。这种分配与已知的地震破裂相匹配，并导致板块边界的持续变宽，可能受到脆性-韧性转变深度的控制。CPB 说明了地质时间尺度变形对当今地震活动的影响。
