Triggered seismicity associated with the 1990 Nicoya, Costa Rica, Mw = 7.0 earthquake
Triggered seismicity associated with the 1990 Nicoya, Costa Rica, Mw = 7.0 earthquake
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与 1990 年哥斯达黎加尼科亚 Mw = 7.0 地震相关的触发地震活动
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
C. Bertelloni
中科院分区：
文献类型：
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作者：
S. Bilek;Candy E. Elliott;C. Bertelloni
1990年3月25日（Mw = 7.0）发生在哥斯达黎加尼科亚半岛近海的俯冲大逆冲断层地震，如预期的那样，在俯冲板块界面上产生了大量余震，并在内陆75公里处发生了一系列不寻常的地震，这一系列地震有两个显著增加的时期，一个在主震之后的60-90天，另一个在主震之后的270天左右。考虑到它们的空间和时间距离，这种内陆事件序列通常不会属于余震的分类，我们在这里表明，这种序列可能是由3月25日的主震触发的。我们使用一个简单的半空间模型以及一个包含可变流变特性的二维有限元模型来计算内陆地区代表性断层上的应力变化。半空间模型预测库仑应力变化的小幅增加和该区域的大量松开，可能足以触发内陆右行走滑断层。包括粘弹性响应的模型还指示可能与触发相关的应力增加，特别是与时间延迟相关的应力增加。内陆人口密集区的灾害评估应考虑沿哥斯达黎加沿着俯冲带逆冲的地震，因为弧前区已绘制了几组走滑断层。
The 25 March 1990 (Mw = 7.0) subduction megathrust earthquake that occurred offshore the Nicoya Peninsula, Costa Rica, produced a large number of aftershocks on the subduction plate interface as expected and preceded an unusual sequence of earthquakes 75 km inland that had two periods of significant increase, one at 60–90 days and one near 270 days, following the main shock. This inland sequence of events would not typically fall within the classification of aftershocks given their spatial and temporal distance, and we show here that this sequence was likely triggered by the 25 March main shock. We compute stress changes on representative faults within this inland region using both a simple half‐space model as well as with a 2‐D finite element model that incorporates variable rheologic properties. The half‐space model predicts a minor increase in Coulomb stress changes and a large amount of unclamping in this region, likely enough to cause triggering on the inland right‐lateral strike‐slip faults. Models that include a viscoelastic response also indicate stress increases that may link to triggering, particularly related to the time delay. Earthquakes on the subduction zone thrust along Costa Rica should be considered in hazard assessments for the inland populated region as several sets of strike‐slip faults have been mapped in the fore‐arc region.