The 1714 Bhutan earthquake was one of the largest in the Himalaya in the last millennium. Nevertheless, until few years ago, Bhutan Himalaya were regarded as a seismic gap with a large potential for slip. We show that the surface rupture caused by this earthquake was at least 175 km long, with slip exceeding 11 m at our study site. The age of the surface rupture was constrained by combination of radiocarbon and traditional optically stimulated luminescence dating of affected river sediments. Computations using empirical scaling relationships yielded plausible magnitude of Mw 8.1 ± 0.4, and placed the epicentre of the 1714 Bhutan earthquake on the flat segment of the Main Himalayan Thrust (MHT), the basal décollement of the Himalayan orogen. Calculations of Coulomb stress transfer indicate that large earthquakes along the proximal part of the MHT would cause surface rupture. In contrast, distal earthquakes would not immediately trigger surface rupture although they would increase the stresses in the proximal part facilitating future surface-rupturing earthquakes. Distal, blind earthquakes would also transfer stress into the foreland basin facilitating southward propagation of the MHT in form of a blind basal décollement. In conclusion, studies of surface rupturing events alone, likely underestimate the seismic slip along the Himalayan megathrust.

中文翻译：

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关闭地震间隙：新喜马拉雅主锋冲断沟的古地震学发现增加了 1714 年不丹地震的范围

1714 年的不丹地震是过去一千年中喜马拉雅地区最大的地震之一。尽管如此，直到几年前，不丹喜马拉雅还被认为是一个具有很大滑移潜力的地震裂隙。我们表明，这次地震引起的地表破裂至少有 175 公里长，在我们的研究地点滑移超过 11 m。地表破裂的年龄受放射性碳和受影响河流沉积物的传统光刺激发光测年的组合限制。使用经验比例关系的计算得出 Mw 8.1 ± 0.4 的合理震级，并将 1714 年不丹地震的震中放置在喜马拉雅造山带的基底断层（MHT）的平坦部分。库仑应力传递的计算表明，沿 MHT 近端的大地震会导致地表破裂。相比之下，远端地震不会立即引发地表破裂，尽管它们会增加近端部分的应力，促进未来地表破裂地震。远端的盲地震也会将应力转移到前陆盆地，促进 MHT 以盲基底塌陷的形式向南传播。总之，仅对地表破裂事件的研究可能低估了沿喜马拉雅大逆冲断层的地震滑动。盲地震也会将应力转移到前陆盆地，促进 MHT 以盲基底分离的形式向南传播。总之，仅对地表破裂事件的研究可能低估了沿喜马拉雅大逆冲断层的地震滑动。盲地震也会将应力转移到前陆盆地，促进 MHT 以盲基底分离的形式向南传播。总之，仅对地表破裂事件的研究可能低估了沿喜马拉雅大逆冲断层的地震滑动。