Late and postglacial reverse faults and seismically-induced landslides are characteristic features of deglaciated terrain in the northern Fennoscandia. The main focus of this study was to investigate the rupturing history of the reverse Vaalajärvi fault complex in Sodankylä, Finland, based on remote sensing, on-site geophysics and sedimentology in excavations trenched across the faulted terrain. In addition to the previously known NNW–SSE-trending Vaalajärvi segment, we discovered six new SW–NE-trending fault segments that probably belong to the same Vaalajärvi ‘postglacial’ fault complex. Our analysis indicate that the Vaalajärvi fault segment was triggered by stress change caused by ruptures on the surrounding SW–NE-trending reverse faults. In total, at least two to three slip events have taken place in different segments of the Vaalajärvi complex since the Early Weichselian with the most recent event(s) being postglacial in timing. By using the scaling laws of fault surface rupture length and offset and under different scenarios of which segments or systems ruptured in a single or separate event, we estimate that the Vaalajärvi complex potentially hosted an earthquake that ranged between M_w ≈ 6.7–7.0. This magnitude is comparable to the landslide-inferred magnitudes in the Vaalajärvi area.

中文翻译：

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冰川沉积物中地震引起的变形结构——Fennoscandia北部Vaalajärvi断层的断层再活化和失稳的证据

晚和冰川后的逆断层以及地震诱发的滑坡是芬诺斯坎迪亚北部的冰川地形的特征。这项研究的主要重点是基于遥感，现场地球物理和沉积学研究跨越断层地形开挖的芬兰Sodankylä反向Vaalajärvi断层复合体的破裂历史。除了先前已知的NNW–SSE趋势Vaalajärvi断层之外，我们还发现了六个新的SW–NE趋势断层，这些断层可能属于同一Vaalajärvi“冰川后”断层。我们的分析表明，Vaalajärvi断层段是由周围SW-NE趋势逆断层破裂引起的应力变化触发的。总共，自早期魏克塞勒时代以来，至少有2至3处滑移事件发生在Vaalajärvi复合体的不同部分，最近的事件在时间上是冰期之后的。通过使用断层破裂长度和偏移量的比例定律，以及在单个或单独事件中哪个段或系统破裂的不同场景下，我们估计Vaalajärvi复合体潜在地引发了一次地震，震级介于中号_W¯¯  ≈6.7-7.0。这个量级与Vaalajärvi地区滑坡推断的量级相当。