The M5.0 Suining-Tongnan (China) earthquake of 31 January 2010:A destructive earthquake occurring in sedimentary cover

• 来源期刊: 科学通报(英文版)
• 学科: 地球科学
• 关键词: 沉积盖层 地震发生 破坏性地震 中国边境 遂宁 震源深度 结晶基底 强烈地震
• 年，卷（期）: 2011,（6）
• 页码范围: 522-526
• 页数: 5页
• 分类号: P315
• 语种: 中文

摘要

Usually, only crystalline basement is strong enough to store the massive strain energy that can be released in a damaging earthquake. By contrast, sedimentary cover is weak, because of its relatively high porosity and fluids. Therefore, it generally cannot accumulate enough energy for strong earthquakes. On January 31, 2010, a M5.0 earthquake occurred near the border of Suining and Tongnan in China. It excited strong short-period Rayleigh waves Rg, indicative of its shallow focal depth. The focal depth is constrained to less than 4 km, most probably in the range of 1-3 km, by modeling amplitude dependence on the frequency and waveforms of teleseismic depth phases (pP, sP). Because the local Mesozoic sedimentary cover is about 6 km thick, this earthquake should have occurred in the sedimentary cover. Though some shallow earthquakes with magnitudes up to M4 occur in Paleozoic sediments, this earthquake is the first M5 event studied in Mesozoic sedimentary cover. This event provides a rare opportunity to study seismogenic processes of damaging earthquakes in sedimentary basins.