We present the results of a paleoseismic survey of the Incapuquio Fault System, a prominent transpressional fault system cutting the forearc of South Perú. High-resolution Digital Elevation Models, optical satellite imagery, radiocarbon dating, and paleoseismic trenching indicate that at least 2–3 m of net slip occurred on the Incapuquio Fault generating a complex, ∼100-km long set of segmented fault scarps in the early 15th century (∼1400–1440 CE). We interpret the consistent along-strike pattern of fault scarp heights, geometries and kinematics to reflect a surface rupture generated by a single M_w 7.4–7.7 earthquake, suggesting that brittle failure of the forearc poses a significant, yet mostly overlooked, seismic hazard to the communities in coastal areas of Perú. The timing of this earthquake coincides with the collapse of the Chiribaya civilization in ∼1360–1400 CE, and we present evidence of damaged buildings along the fault trace that may be of Chiribayas age. Our surface faulting observations, when combined with observations of deformation in the forearc from geodesy and seismology, also demonstrate that the forearc in South Perú experiences a complex, time-varying pattern of permanent strain, with evidence for trench-parallel shortening, trench-parallel extension, and trench-perpendicular shortening all in close proximity but in different periods of the megathrust earthquake cycle. The kinematics of recent slip on the Incapuquio Fault are consistent with the sense of interseismic strain within the forearc measured by GPS, suggesting the fault is loaded toward failure between megathrust earthquakes.

中文翻译：

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秘鲁前弧发生 Mw 7 前西班牙地震的古地震证据

我们展示了 Incapuquio 断层系统的古地震调查结果，这是一个切割南秘鲁前弧的显着横压断层系统。高分辨率数字高程模型、光学卫星图像、放射性碳测年和古地震挖沟表明 Incapuquio 断层上发生了至少 2-3 m 的净滑移，在早期产生了复杂的、约 100 公里长的分段断层陡崖15 世纪（约公元 1400-1440 年）。我们解释了断层陡坡高度、几何形状和运动学的一致沿走向模式，以反映由单个M _w产生的表面破裂7.4-7.7 级地震，表明前弧的脆性破坏对秘鲁沿海地区的社区构成了重大但大多被忽视的地震危害。这次地震发生的时间与公元 1360-1400 年 Chiribaya 文明的崩溃相吻合，我们提供了沿断层痕迹损坏建筑物的证据，可能是 Chiribayas 时代。我们的地表断层观测与大地测量学和地震学对弧前变形的观察相结合，也表明秘鲁南部的弧前经历了复杂的、随时间变化的永久应变模式，有证据表明与沟渠平行的缩短、平行沟渠延伸和海沟垂直缩短都非常接近，但发生在大地震周期的不同时期。