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What are the seismic expressions of deep thermal and thermochemical plumes?

深部热羽流和热化学羽流的地震表达是什么？

基本信息

批准号：
1565511
负责人：
Jeroen Ritsema
金额：
$ 19.42万
依托单位：
Regents of the University of Michigan - Ann Arbor
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2016
资助国家：
美国
起止时间：
2016-04-01 至 2020-03-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1565511&HistoricalAwards=false
关键词：
What seismic expressions deep thermal

项目摘要

Hawaii and Iceland are classic examples of volcanic islands associated with dynamical upwellings (i.e., plumes) from the deep mantle. Plumes form naturally and abundantly in laboratory simulations of Earth convection. Yet, there is no consensus among Earth scientists whether rising plumes exist in the Earth. The burden is on seismologists to find expressions of plumes in seismic data. This proposal is aimed at identifying how physically plausible thermal and thermochemical plumes may perturb seismic waves and how these perturbations can be found in seismic data. The project will support one PhD student. The research expands an ongoing international collaboration that provides important international experience to the PhD student at Michigan and the two students in Europe who are directly involved in the project.This proposal leverages significant investments made by the NSF in observational geophysics (including EarthScope and dedicated seismic arrays) by using the available data and providing a new, interdisciplinary investigation into the resolvability of mantle plumes by observational geophysics.By combining multidisciplinary expertise, the work in this proposal will develop high-resolution simulations of plume formation and plume morphology and it will quantify the expected plume signatures in seismic data. The research involves computer simulations of thermal and thermochemical plume ascent, mineral physics calculations of the seismic wave speed variations within plumes, and 3D simulation of the distortion of the seismic wave field by plumes. Waveform and traveltime tomography and receiver function analysis of simulated waveforms will demonstrate how plumes are imaged tomographically and whether they produce observable deflections of phase boundaries in the transition zone.

夏威夷和冰岛是火山岛的典型例子，与深部地幔的动力上升流（即羽流）有关。在地球对流的实验室模拟中，羽流自然而丰富地形成。然而，地球科学家对地球上是否存在上升的羽流尚未达成共识。地震学家的任务是在地震资料中找到羽流的表现形式。该建议旨在确定物理上合理的热羽流和热化学羽流如何干扰地震波，以及如何在地震数据中发现这些扰动。该项目将资助一名博士生。这项研究扩大了正在进行的国际合作，为密歇根大学的博士生和直接参与该项目的两名欧洲学生提供了重要的国际经验。该提案利用NSF在观测地球物理学（包括EarthScope和专用地震阵列）方面的重大投资，利用现有数据，并通过观测地球物理学对地幔柱的可解析性进行新的跨学科研究。通过结合多学科专业知识，本提案中的工作将开发羽流形成和羽流形态的高分辨率模拟，并将量化地震数据中预期的羽流特征。该研究包括热与热化学羽流上升的计算机模拟，羽流内部地震波速度变化的矿物物理计算，以及羽流对地震波场畸变的三维模拟。波形和旅行时断层扫描以及模拟波形的接收函数分析将演示如何对羽流进行断层成像，以及它们是否在过渡区产生可观察到的相位边界偏移。