Waveform inversion for 3D shear velocity structure in the lowermost mantle

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K17744
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Solid earth and planetary physics
• Research Institution: The University of Tokyo
• Principal Investigator: Kawai Kenji 東京大学, 大学院理学系研究科, 准教授 (20432007)
• Research Collaborator: Borgeaud Anselme F. 東大, 院生 ; Suzuki Yuki 東大, 院生 ; Yamaya Lina 東大, 院生
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 波形インバージョン法 / 最下部マントル / プレート

Outline of Final Research Achievements

Geologists have long known that the paleo-plates subducted beneath the western margin of South and North America about 180 million years ago (Ma), but until now have not known in detail what happened when it reached the bottom of the mantle. We used waveforms of deep earthquakes recorded from 2004-2015 by the USArray, a transportable seismic array that fully covered the conterminous U.S. Their imaging revealed remnants of paleoslabs, at the base of the mantle beneath the Northern Pacific and Central America, surrounded by hotter-than-average and possibly iron-enriched material. Subduction of paleoslabs to the base of the mantle thus profoundly influences the Earth's surface environment and hence the evolution of life.

Free Research Field

固体地球物理学