Abstract This study focuses on the seismicity and stress inversion analysis of the Simav region in western Turkey. The latest moderate-size earthquake was recorded on May 19, 2011 (M w 5.9), with a dense aftershock sequence of more than 5,000 earthquakes in 6 months. Between 2004 and 2018, data from earthquake events with magnitudes greater than 0.7 were compiled from 86 seismic stations. The source mechanism of 54 earthquakes with moment magnitudes greater than 3.5 was derived by using a moment tensor inversion. Normal faults with oblique-slip motions are dominant being compatible with the NE-SW extension direction of western Turkey. The regional stress field is assessed from focal mechanisms. Vertically oriented maximum compressional stress (σ1) is consistent with the extensional regime in the region. The σ1 and σ3 stress axes suggest the WNW-ESE compression and the NNE-SSW dilatation. The principal stress orientations support the movement direction of the NE-SW extension consistent with the mainly observed normal faulting motions.

中文翻译：

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土耳其西部 Simav 地区的地震活动、震源机制和应力张量分析

摘要 本研究的重点是土耳其西部 Simav 地区的地震活动性和应力反演分析。最近一次中级地震记录于2011年5月19日（M w 5.9），6个月内发生了5000多次地震的密集余震序列。2004 年至 2018 年期间，86 个地震台站收集了 0.7 级以上地震事件的数据。利用矩张量反演推导出了54次震级大于3.5级地震的震源机制。具有斜滑运动的正断层占主导地位，与土耳其西部的 NE-SW 延伸方向兼容。从震源机制评估区域应力场。垂直方向的最大压缩应力 (σ1) 与该区域的拉伸状态一致。σ1 和 σ3 应力轴表明 WNW-ESE 压缩和 NNE-SSW 膨胀。主应力方向支持与主要观察到的正常断层运动一致的 NE-SW 延伸的运动方向。