CAJ | 학술논문

下地幔间断面是地球内部结构研究的重要课题,对于理解地球深部的动力过程具有重要意义.美国西部密集地震台网记录到的南美洲太平洋地区深震的短周期波形资料有利于震源下方下地幔间断面的研究.本文收集了美国西北太平洋地震台网和犹他大学地震台网所记录的南美洲西部俯冲地区15个深震的19组短周期垂向台网资料,并利用4次根倾斜叠加方法提取震源下方下地幔中速度界面上发生转换的次生震相SdP,据此发现南美洲西部下方下地幔中800～1200 km深度范围内存在明显的转换点集中,主要分布在900,1000和1100 km三个深度附近,三个速度界面具有不同的起伏形态,应为在研究区域双层地幔对流中边界层.
하지만간단면시지구내부결구연구적중요과제,대우리해지구심부적동력과정구유중요의의.미국서부밀집지진태망기록도적남미주태평양지구심진적단주기파형자료유리우진원하방하지만간단면적연구.본문수집료미국서북태평양지진태망화유타대학지진태망소기록적남미주서부부충지구15개심진적19조단주기수향태망자료,병이용4차근경사첩가방법제취진원하방하지만중속도계면상발생전환적차생진상SdP,거차발현남미주서부하방하지만중800～1200 km심도범위내존재명현적전환점집중,주요분포재900,1000화1100 km삼개심도부근,삼개속도계면구유불동적기복형태,응위재연구구역쌍층지만대류중변계층.
The lower mantle discontinuities are an important part of the structure of Earth's interior and very important for understanding the dynamic process of the deep part of the Earth. The waveform data of the deep events of South America recorded by the dense stations at western part of USA are suitable for studying lower mantle discontinuities beneath the events. In the paper, 19 sets waveform data of vertical short period component from 15 events beneath South America recorded by the PNSN and UUSS of USA were retrieved and processed with 4-th root slant stack method for picking the SdP phases from the lower mantle interfaces. With the SdPs,the conversion points related to SdPs are found to be concentrated between 800 and 1200 km and mainly distribute at the depths of 900, 1000 and 1100 km. In addition, the topography of the three layers is different. The interfaces may relate to the mid-boundary of the two-layer mantle convection.