Limitation of the Predominant-Period Estimator for Earthquake Early Warning and the Initial Rupture of Earthquakes
Limitation of the Predominant-Period Estimator for Earthquake Early Warning and the Initial Rupture of Earthquakes
复制标题
DOI：
10.1785/0120080144
复制
发表时间：
2008-12-01
影响因子：
3
通讯作者：
Ide, Satoshi
中科院分区：
文献类型：
--
作者：
Yamada, Takuji;Ide, Satoshi
我们研究了代表 P 波主要周期的参数 tau(p) (t) 的特征和局限性。我们分析了时间窗 (TW) 长度、低通滤波器和滞弹性衰减的影响以及源过程的复杂性，以阐明 tau(max)(p) 值或 tau(p)(t) 的时间相关最大值是否与地震物理量有直接关系。我们发现 tau(max)(p) 的值有上限和下限。对于震源持续时间长于 TW 的较大地震，tau(max)(p) 值具有取决于 TW 的上限。另一方面，较小地震的值具有与采样间隔成正比的下限。对于中型地震，tau(max)(p) 值与其典型震源持续时间接近，并且由于震源过程的复杂性，其变化范围可能很大。这两个限制和中型地震的斜率在很宽的震级范围内产生了 tau(max)(p) 的明显最终大小依赖性。因此，tau(max)(p)对地震最终规模的依赖性并不表明地震的最终规模是由破裂初始部分的过程控制的。从 tau(max)(p) 对地震最终大小的依赖关系无法断定地震是否是确定性的。这是因为 tau(max)(p) 并不总是与地震物理量有直接关系。
We investigate the characteristics and limitations of the parameter tau(p) (t), which represents the predominant period of the P wave. We analyze the effects of the length of the time window (TW), low-pass filter, and anelastic attenuation as well as the complexity of the source process to elucidate whether values of tau(max)(p), or the time-dependent maximum value of tau(p)(t), have direct relationships to the physical quantities of earthquakes. We find that values of tau(max)(p) have upper and lower limits. For larger earthquakes with source durations longer than the TW, the values of tau(max)(p) have an upper limit that depends on the TW. On the other hand, the values for smaller earthquakes have a lower limit that is proportional to the sampling interval. For intermediate earthquakes, the values of tau(max)(p) are close to their typical source durations and can have a large variety due to the complexity of the source process. These two limits and the slope for intermediate earthquakes yield an apparent final size dependence of tau(max)(p) in a wide magnitude range. As a result, the dependence of tau(max)(p) on the final size of earthquakes does not suggest that the final size of an earthquake is controlled by processes in the initial part of rupture. It is impossible to conclude whether the earthquake is deterministic or not from the dependence of tau(max)(p) on the final size of earthquakes. This is because tau(max)(p) does not always have a direct relation to the physical quantities of earthquakes.