Collaborative Research: Investigation of Sources of Intraplate Volcanism Using PASSCAL Broadband Instruments in Madagascar, The Comores, and Mozambique (MACOMO)

该项目将涉及从安装在马达加斯加、科摩罗群岛和莫桑比克的宽带地震仪网络获取和分析地震数据，以确定该区域板内火山活动的起源。没有现代地震调查马达加斯加，世界？这座岛屿是有史以来形成的第四大岛，火山活动的来源并不靠近任何板块边界，目前尚不清楚。这项研究旨在确定火山活动是否与巨大的下地幔大低剪切速度区（LLSVP）或任何上地幔热点，如阿法尔或留尼汪下面。从IRIS PASSCAL仪器库借来的地震仪将部署在两个装置中：2011年夏季18个（在马达加斯加、科摩罗和莫桑比克），2012年夏季15个（全部在马达加斯加）。所有地震仪将于2013年夏季收回。将使用几种技术分析宽带地震数据，以确定该区域的地下结构。面波和体波数据都将用于生成地壳和地幔的三维层析图像;剪切波分裂将用于检查各向异性结构; P波到S波转换将用于生成接收器函数，以确定莫霍面和其他地下不连续面的地形。非洲LLSVP是地球内部最大的地震异常;作为地幔和地核之间的巨大热化学边界层，它在控制地幔内垂直质量通量的性质方面起着至关重要的作用，因此，地幔对流及其在地表表现为板块构造。非洲LLSVP被认为在非洲板块上大量发生热点火山活动中发挥了重要作用，但由于南半球该位置的数据采样极其有限，因此这种情况发生的机制尚不清楚。进一步研究非洲次低层潜势将引起许多学科的地球科学家的兴趣，并将提供对马达加斯加次表层地质的首次研究。该项目将有助于培训美国研究生以及马达加斯加和莫桑比克的科学家，并将有助于加强这三个国家之间的科学联系。该项目还将成为非洲阵列的科学合作伙伴，非洲阵列一直是非洲科学和善意的统一积极力量。该奖项由NSF国际科学与工程办公室共同资助。

This project will involve the acquisition and analysis of seismic data from a network of broadband seismometers installed in Madagascar, the Comores Islands, and Mozambique in order to determine the origin of intraplate volcanism in the region. No modern seismic investigation of Madagascar, the world?s 4th largest island, has ever been made, and the source of the volcanism, not near any plate boundary, is unknown. This study seeks to determine if the volcanism is connected with either the giant lower mantle large low-shear velocity province (LLSVP) or with any of the upper mantle hot spots such as those beneath Afar or Reunion. The seismometers, borrowed from the IRIS PASSCAL pool of instruments, will be deployed in two installations: 18 in the summer of 2011 (in Madagascar, the Comores, and Mozambique), and 15 in the summer of 2012 (all in Madagascar). All seismometers will be retrieved in the summer of 2013. The broadband seismic data will be analyzed using several techniques in order to determine the sub-surface structure of the region. Both surface and body wave data will be use to generate 3D tomographic images of the crust and mantle; shear-wave splitting will be used to examine anisotropic fabric; P-to-S-wave conversions will be used to generate receiver functions for determining topography on the Moho and other sub-surface discontinuities. The African LLSVP is the largest seismic anomaly within the earth; as an enormous thermochemical boundary layer between the mantle and core, it plays a vitally important role in controlling the nature of vertical mass flux within the mantle, and therefore of both mantle convection and its manifestation at the surface as plate tectonics. The African LLSVP is thought to play an important role in the abundant occurrence of hot spot volcanism on the African plate, but the mechanism by which this occurs is not known due to the extremely limited data sampling available at this location in the Southern Hemisphere. Further study of the sub-African LLSVP will be of interest to earth scientists in many disciplines, as will providing the first study of the sub-surface geology of Madagascar. This project will help in the training of U.S. graduate students as well as scientists in Madagascar and Mozambique, and will help strengthen the scientific ties between these three countries. This project will also be a scientific partner with AfricaArray, which has been a unifying positive force of science and good will in Africa. This award is co-funded by NSF's Office of International Science and Engineering.