论文部分内容阅读
最大地震震级(m_x)是地震危险性和风险分析中的一个关键参数。然而,最近发生的一些大地震表明,大多数现有的估算m_x的方法都存在不足。此外,m_x本身定义也不明确,因为它的意义在很大程度上取决于其使用范围,如果只使用现有的数据而不把它与时间间隔相结合,通常不能将其推断出来。在本研究中,用研究时段内的可能最大地震震级m_p(T)取代m_x。m_p(T)不仅包含震级极限的信息也包含极端事件发生率。使用锥形古登堡—里克特(TGR)分布为环太平洋俯冲带估计了m_p(T)。对两个锥形古登堡—里克特参数,即β值和角震级(mc)的估计是通过最大似然法与构造矩率约束得出的。需要较小地震的发生率来补充锥形古登堡—里克特分布。采用整个地球模型,即m≥5地震发生率的全球高分辨率估计,来估计这些发生率。通过蒙特卡罗模拟计算m_p(T)的不确定性。我们的研究结果表明,多数环太平洋俯冲带可以在250年的时间间隔生成m≥8.5的地震,在500年的时间间隔生成m≥8.8的地震,在10 000年的时间间隔生成m≥9.0的地震。利用基于浊积岩研究的10 000年古地震记录为卡斯凯迪亚俯冲带补充了有限的仪器记录地震数据。我们的结果显示,该地区500年周期预计有m≥8.8地震;1 000年周期预计有m≥9.0地震;超过10 000年的周期预计有m≥9.3地震。
The maximum earthquake magnitude (m_x) is a key parameter in seismic hazard and risk analysis. However, some recent major earthquakes show that most of the existing methods for estimating m_x are inadequate. In addition, the definition of m_x itself is also not clear, since its significance depends very much on the scope of its use, which can not usually be inferred if using only the existing data without combining it with the time interval. In this study, m_x is replaced by the maximum possible earthquake magnitude, m_p (T), over the study period. m_p (T) not only contains magnitude limit information but also extreme event rates. Estimated m_p (T) for the Pacific Rim subduction zone using the Cone Gutenberg-Richter (TGR) distribution. Estimates of the two conic Gutenberg-Ricci parameters, β and mc, are based on the maximum likelihood method and the moment-of-confinement constraint. The incidence of smaller earthquakes is needed to supplement the cone Gutenberg-Richter distribution. These rates are estimated using the global model of the Earth, a global high-resolution estimate of the incidence of m ≥ 5 earthquakes. Uncertainty of m_p (T) is calculated by Monte Carlo simulation. Our results show that most of the Pacific Rim subduction zones can generate m ≥ 8.5 earthquakes at 250-year intervals, earthquakes with m ≥8.8 at 500-year intervals and m ≥ 9.0 at 10,000-year intervals earthquake. The use of 10,000-year paleoseismic records based on turbidite studies complemented Cascadia subduction zones with limited instrumental recorded seismic data. Our results show that the m ≥8.8 earthquake is expected to occur in the 500-year cycle in this area; the m ≥ 9.0 earthquake in 1000-year cycle and the m≥9.3 earthquake in the period of more than 10,000 years.