| PKPdif波-内核低速层存在的地震学证据 |
| |
| 引用本文： | 许健生,徐小明,隗永刚,周建超,郭祥云. PKPdif波-内核低速层存在的地震学证据[J]. 地震工程学报, 2019, 41(1): 131-137 |
| |
| 作者姓名： | 许健生 徐小明 隗永刚 周建超 郭祥云 |
| |
| 作者单位： | 中国地震局地球物理所北京地震台, 北京 100095;北京白家疃地球科学国家野外科学观测研究站, 北京 1000095,中国地震局地球物理所北京地震台, 北京 100095;北京白家疃地球科学国家野外科学观测研究站, 北京 1000095,中国地震局地球物理所北京地震台, 北京 100095;北京白家疃地球科学国家野外科学观测研究站, 北京 1000095,中国地震局地球物理所北京地震台, 北京 100095;北京白家疃地球科学国家野外科学观测研究站, 北京 1000095,中国地震局地球物理所, 北京 100095 |
| |
| 基金项目： | 中国地震局地球物理研究所中央级公益性科研院所基本科研业务专项项目（DQJB13B17）;中国地震局专项0718204资助 |
| |
| 摘 要： | 通过对中国数字地震仪台网(CDSN)11个台1993—2012年间30个极远震记录的分析,识别出了PKP波入射到内外核界面(ICB)上的衍射波PKPdif波。PKPdif波在震中距120°左右时出现在PKIKP波之前,在震中距150°以后出现在PKIKP波之后,是一个长周期波。为了解释PKPdif波超前于PKIKP波的原因,设想在距地面约5 156.1～5 372.2 km的深度,即内外核界面下有可能存在一个PKIKP波的低速层(厚度约216.1 km)。该设想符合Jeffreys速度模型,给出的PKPdif波在震中距119.4°～176.1°间的走时表填补了目前使用的《IASPEI1991地震波走时表》的空白。讨论PKPdif波的运动学特征有助于对内外核界面物理性质的认识,有助于提高分析震相的水平和积累震相分析经验。
|
| 关 键 词： | PKPdif波 内核低速层 运动学特征 PKPdif波走时表 |
| 收稿时间： | 2014-08-20 |
PKPdif Wave may Indicate Existence of Low-velocityLayer in Earth's Inner Core |
| |
| XU Jiansheng,XU Xiaoming,WEI Yonggang,ZHOU Jianchao and GUO Xiangyun. PKPdif Wave may Indicate Existence of Low-velocityLayer in Earth's Inner Core[J]. China Earthguake Engineering Journal, 2019, 41(1): 131-137 |
| |
| Authors: | XU Jiansheng XU Xiaoming WEI Yonggang ZHOU Jianchao GUO Xiangyun |
| |
| Affiliation: | Beijing Seismic Station of Institute of Geophysics, China Earthquake Agency, Beijing 100095, China;Beijing Baijiatuan Earth Science State Geophysical Observatory, Beijing 100095, China,Beijing Seismic Station of Institute of Geophysics, China Earthquake Agency, Beijing 100095, China;Beijing Baijiatuan Earth Science State Geophysical Observatory, Beijing 100095, China,Beijing Seismic Station of Institute of Geophysics, China Earthquake Agency, Beijing 100095, China;Beijing Baijiatuan Earth Science State Geophysical Observatory, Beijing 100095, China,Beijing Seismic Station of Institute of Geophysics, China Earthquake Agency, Beijing 100095, China;Beijing Baijiatuan Earth Science State Geophysical Observatory, Beijing 100095, China and Institute of Geophysics, CEA, Beijing 1000095, China |
| |
| Abstract: | In this study, we analyzed the records of 30 earthquakes recorded from 11 stations in the China Digital Seismographic Network (CDSN) during 1993-2012. We could observe a PKPdif phase at the epicentral distance from about 120°. The travel-time of a PKPdif wave was shorter than that of a PKIKP wave in the epicentral distance range of 120° to 150°, but longer for epicentral distances of more than 150°. We regarded PKPdif waves as diffracted PKP waves with a long period at the inner core boundary. We discussed the cause and propagation mechanism of PKPdif waves and proposed an assumption, in agreement with the Jeffreys model that a low-velocity layer of a PKIKP wave exists at a depth range of 5 156.1-5 372.2 km under the Earth''s surface. We suggested the kinematic characteristics of the PKPdif waves recorded by the CDSN stations. We defined the relationship between the PKPdif travel-time and the epicentral distance, which filled the gap in the current "IASPEI1991 Seismological Tables". We constructed a travel-time table of PKPdif waves within an epicentral range of 119.4° to 176.1°. We also discussed the kinematic characteristics of PKPdif waves to better understand the physical properties of the ICB, improve phase identification, and accumulate analytical experience regarding the seismic phase. |
| |
| Keywords: | PKPdif wave low-velocity layer in Earth''s inner core kinematic characteristics travel-time table of PKPdif wave |
| 本文献已被 CNKI 等数据库收录！ |
| 点击此处可从《地震工程学报》浏览原始摘要信息 |
|
点击此处可从《地震工程学报》下载免费的PDF全文 |
|
