Using the 2011 Mw 9.0 off the Pacific coast of Tohoku Earthquake to test the Coulomb stress triggering hypothesis and to calculate faults brought closer to failure
Using the 2011 Mw 9.0 off the Pacific coast of Tohoku Earthquake to test the Coulomb stress triggering hypothesis and to calculate faults brought closer to failure
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DOI：
10.5047/eps.2011.05.010
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发表时间：
2011-09
期刊：
影响因子：
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通讯作者：
S. Toda;Jian Lin;R. Stein
中科院分区：
文献类型：
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作者：
S. Toda;Jian Lin;R. Stein
2011 年 3 月 11 日的东北地震对库仑应力传递在多大程度上控制余震的触发提供了前所未有的考验。 3月11日至31日期间，发生了177次具有震源机制的余震，因此可以在余震节面上解析由破裂引起的库仑应力变化，以了解它们是否更接近失败。许多主震震源模型都是根据地震、大地测量和海啸观测结果反演的。在这里，我们表明，在六个测试的震源模型中，正应力余震机制比作为对照组的背景地震（1997 年至 2011 年 3 月 10 日）平均增加了 47%。发现余震断层摩擦力 0.4 比 0.0 或 0.8 更适合数据，在所有测试模型中，Wei 和 Sladen (2011) 的增益最大，达到 63%。我们还计算出，七次大型、异国情调或远程余震中至少有 5 次距离失败更近 ≥0.3 巴。通过这些测试作为确认，我们计算出日本海沟巨型逆冲断层、外海沟斜坡正断层、东京下方的关东碎片以及糸鱼川-静冈构造线的大部分区域也距离破坏更近了 ≥0.3 条。
The 11 March 2011 Tohoku Earthquake provides an unprecedented test of the extent to which Coulomb stress transfer governs the triggering of aftershocks. During 11–31 March, there were 177 aftershocks with focal mechanisms, and so the Coulomb stress change imparted by the rupture can be resolved on the aftershock nodal planes to learn whether they were brought closer to failure. Numerous source models for the mainshock have been inverted from seismic, geodetic, and tsunami observations. Here, we show that, among six tested source models, there is a mean 47% gain in positively-stressed aftershock mechanisms over that for the background (1997–10 March 2011) earthquakes, which serve as the control group. An aftershock fault friction of 0.4 is found to fit the data better than 0.0 or 0.8, and among all the tested models, Wei and Sladen (2011) produced the largest gain, 63%. We also calculate that at least 5 of the seven large, exotic, or remote aftershocks were brought ≥0.3 bars closer to failure. With these tests as confirmation, we calculate that large sections of the Japan trench megathrust, the outer trench slope normal faults, the Kanto fragment beneath Tokyo, and the Itoigawa-Shizuoka Tectonic Line, were also brought ≥0.3 bars closer to failure.