Global S&T Development Trend Analysis Platform of Resources and Environment
DOI | 10.1029/2019GL085665 |
Metastable Olivine Wedge Beneath the Japan Sea Imaged by Seismic Interferometry | |
Shen, Zhichao; Zhan, Zhongwen | |
2020-03-28 | |
发表期刊 | GEOPHYSICAL RESEARCH LETTERS |
ISSN | 0094-8276 |
EISSN | 1944-8007 |
出版年 | 2020 |
卷号 | 47期号:6 |
文章类型 | Article |
语种 | 英语 |
国家 | USA |
英文摘要 | The metastable olivine wedge (MOW) within subducted slabs has long been hypothesized to host deep-focus earthquakes (>300 km). Its presence would also rule out hydrous slabs being subducted into the mantle transition zone. However, the existence and dimensions of MOW remain debatable. Here, we apply inter-source interferometry, which converts deep earthquakes into virtual seismometers, to detect the seismic signature of MOW without influence from shallow heterogeneities. With data from the Hi-net, we confirm the existence of MOW beneath the Japan Sea and constrain its geometry to be similar to 30 km thick at 410-km depth and gradually thinning to a depth of 580 km at least. Our result supports transformational faulting of metastable olivine as the initiation mechanism of deep earthquakes, although large events (M7.0+) probably rupture beyond the wedge. Furthermore, the slab core must be dehydrated at shallower depth and only transports negligible amount of water into the transition zone. Plain Language Summary Most earthquakes occur within the top tens of kilometers of the Earth, but some can be more than 300 km deep. These deep earthquakes are puzzling, because they are not supposed to happen given the high pressure and temperature there. Scientists hypothesize that they might be caused by sudden phase changes of the mineral olivine, which should have broken down at the depth but survived metastably by hiding in the cold core of subducted plates. However, detecting the "surviving" metastable olivine has been difficult because of its small size and remoteness. Here we apply a novel method that can turn some deep earthquakes into virtual sensors closer to our target. Seismic waveforms recorded by these virtual sensors not only provide clear evidence for the metastable olivine but also constrain it dimension much better than before: a wedge 30 km thick at 410-km depth and extending down to 580-km depth at least. This finding supports the phase change hypothesis for deep earthquakes and also means that the slab core must be extremely dry, because even a small amount of water can break the "surviving" olivine mineral. |
英文关键词 | metastable olivine inter-source interferometry deep earthquake mechanism dry slab core mantle transition zone |
领域 | 气候变化 |
收录类别 | SCI-E |
WOS记录号 | WOS:000529097700023 |
WOS关键词 | SUBDUCTING PACIFIC SLAB ; DEEP-FOCUS EARTHQUAKES ; WAVE-GUIDE ; WATER ; ZONE ; CONSTRAINTS ; RUPTURE ; DEPTH ; PHASE ; EARTH |
WOS类目 | Geosciences, Multidisciplinary |
WOS研究方向 | Geology |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/279838 |
专题 | 气候变化 |
作者单位 | CALTECH, Seismol Lab, Pasadena, CA 91125 USA |
推荐引用方式 GB/T 7714 | Shen, Zhichao,Zhan, Zhongwen. Metastable Olivine Wedge Beneath the Japan Sea Imaged by Seismic Interferometry[J]. GEOPHYSICAL RESEARCH LETTERS,2020,47(6). |
APA | Shen, Zhichao,&Zhan, Zhongwen.(2020).Metastable Olivine Wedge Beneath the Japan Sea Imaged by Seismic Interferometry.GEOPHYSICAL RESEARCH LETTERS,47(6). |
MLA | Shen, Zhichao,et al."Metastable Olivine Wedge Beneath the Japan Sea Imaged by Seismic Interferometry".GEOPHYSICAL RESEARCH LETTERS 47.6(2020). |
条目包含的文件 | 条目无相关文件。 |
除非特别说明,本系统中所有内容都受版权保护,并保留所有权利。
修改评论