大地震以自我愈合的脉冲或轻微裂的形式传播
Valère Lambert1, Nadia Lapusta2,3, Stephen Perry2
1Seismological Laboratory, California Institute of Technology, Pasadena, CA, USA. vlambert@caltech.edu.
Nature
|March 11, 2021
概括
在较低的压力水平下, 成熟的断层会发生大地震. 数字模型显示,持续弱的断层会产生类似裂的裂,与自愈脉冲不同,产生更高的辐射能量.
科学领域:
- 地质学
- 地震学
- 计算地质学
背景情况:
- 成熟断层的地震压力远低于预测的静态强度.
- 两个主要假设解释了这一点:断层在半静态上很强,但在动态上变弱,或者断层在持续性上很弱,可能是由于流体过压.
研究的目的:
- 通过数值建模来研究地震破裂动态的竞争理论.
- 模拟地震破裂与观察到的应力下降 (1-10MPa) 和有限的热量产生一致.
主要方法:
- 使用数值模型模拟地震断裂.
- 在不同的断裂强度假设下,比较破裂特性 (自愈脉冲式与裂纹式).
- 分析压力变化 (静态与动态) 和辐射能量.
主要成果:
- 几乎静态强但动态弱的断层会产生尖的,自我修复的脉冲式断裂,带有高动态应力变化.
- 持续的弱断层会产生较轻的裂纹,具有可比的静态和动态应力变化.
- 自治脉冲辐射的能量远远高于观测到的大地震事件的能量,而类似裂的断裂与观测一致.
结论:
- 持续存在的弱断层和裂类似的断层与地震观测的巨大地震一致.
- 自愈脉冲的高辐射能量可能表明它们在巨大冲击环境中很罕见,或者它们的能量被低估了.
- 这些发现挑战了当前对地震物理和地震震动的理解,
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