期刊
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
卷 121, 期 2, 页码 845-863出版社
AMER GEOPHYSICAL UNION
DOI: 10.1002/2015JB012427
关键词
megathrust earthquakes; source parameters; depth dependence; spectral variations; tsunami earthquakes; radiated energy
资金
- U.S. National Science Foundation [EAR1245717]
- Directorate For Geosciences
- Division Of Earth Sciences [1245717] Funding Source: National Science Foundation
Depth-varying characteristics of high-frequency seismic radiation for megathrust earthquakes have been inferred from several recent giant earthquakes and large tsunami earthquakes. To quantify any depth dependence more extensively, we analyzed 114 M(w)7.0 thrust-faulting earthquakes with centroid depths from 5 to 55km on circum-Pacific megathrusts using teleseismic body wave finite-fault inversions and source spectrum determinations. Large tsunami earthquakes and some other shallow events at depths less than about 18km have unusually long source durations, and low values of static stress drop (sigma(E)), V-r(3)sigma(E), and apparent stress, with relatively depleted high-frequency radiation. Deeper events have no clear global trend with source depth for moment-normalized centroid time or total duration, static stress drop, moment-scaled radiated energy, apparent stress, or radiation efficiency. Regional behavior among the 17 sampled subduction zones generally conforms to the global composite. The source spectra have high-frequency logarithmic spectral decay slopes averaging-1.6. There is relative enrichment in high-frequency spectral levels with increasing source depth manifested in reduced high-frequency spectral decay slope. The ratio of high-frequency (0.3-1Hz) radiated energy to total energy increases correspondingly. These observations suggest that overall dynamic rupture processes are relatively insensitive to source depth, but varying scale lengths of megathrust heterogeneity may contribute to modest enrichment of high-frequency seismic radiation for events deeper on the megathrust. A weak correlation of higher estimated average megathrust temperature at 30km depth with higher spectral decay rate indicates that the depth-varying pattern may in part result from frictional properties being influenced by temperature variations or by systematic reduction of average attenuation with increasing depth along the megathrust.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据