The 700-km-long Chaman fault (CF) marks the western edge of the plate boundary between India and Eurasia. Although global plate models predict 2.3–3.6 cm/yr left-lateral motion between both plates, the fault is known to have hosted few earthquakes in historical times. Recent geodetic measurements attested the presence of aseismic slip locally. To detail the interplay between fast and slow slip along the CF, we build three Interferometric Synthetic-Aperture Radar time series of ground deformation covering the whole fault length over 5 years (2014–2019). We find that most of the active fault trace slips aseismically and continuously. From south to north, we identify three creeping fault portions: the Nushki, Central, and Qalat segments of lengths between 80 and 130 km. The loading rate is 1.2 ± 0.3 cm/yr for the two southernmost portions, while it is about 0.7 ± 0.2 cm/yr for the Qalat segment. The Central segment and the nearby locked segments have hosted the largest known historical earthquakes on the CF, and three moderate magnitude earthquakes in our observation period. We image these earthquakes for which modeled slip at depth (M_w 5–5.6), time series of surface slip and deformation patterns argue toward large triggered aseismic slip. The June 2018 event displays postseismic moment 3–15 times greater than coseismic moment. Over the two decades covered by geodetic observations, continuous or triggered aseismic slip dominates along most of the fault and co-locates with earthquakes. We observe that fault geometrical complexities delimit active segments and may be responsible for the kilometer-scale intertwining between seismic and aseismic events.

中文翻译：

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InSAR照射下查曼断层地震与地震滑动的相互作用

700 公里长的查曼断层 (CF) 标志着印度和欧亚大陆之间板块边界的西部边缘。尽管全球板块模型预测两个板块之间的左侧运动为 2.3-3.6 厘米/年，但已知该断层在历史上几乎没有发生过地震。最近的大地测量证实了当地存在抗震滑动。为了详细说明沿 CF 快速滑动和慢速滑动之间的相互作用，我们构建了三个干涉合成孔径雷达时间序列，覆盖了 5 年（2014-2019 年）整个断层长度的地面变形。我们发现大部分活动断层痕迹都在抗震和连续滑动。从南到北，我们确定了三个蠕动断层部分：Nushki、Central 和 Qalat 段，长度在 80 到 130 公里之间。最南端的两个部分的加载率为 1.2 ± 0.3 cm/yr，而 Qalat 段约为 0.7 ± 0.2 cm/yr。中央段和附近的锁定段在 CF 上发生了已知最大的历史地震，在我们的观察期内发生了 3 次中等强度地震。我们对这些地震进行了成像，其中模拟了深度滑移（M _w 5-5.6)，地表滑移和变形模式的时间序列证明大的触发抗震滑移。2018 年 6 月的事件显示震后时刻是同震时刻的 3-15 倍。在大地观测所涵盖的二十年中，连续或触发的地震滑动在大部分断层上占主导地位，并与地震共存。我们观察到断层几何复杂性界定了活动段，可能是造成地震和地震事件之间千米级交织的原因。