Relation between Earth surface phenomena and deep mantle structure inferred from a hybrid P-wave tomography

2015 Fiscal Year Final Research Report

• Project/Area Number: 25287116
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Solid earth and planetary physics
• Research Institution: Japan Agency for Marine-Earth Science and Technology
• Principal Investigator: OBAYASHI Masayuki 国立研究開発法人海洋研究開発機構, 地球深部ダイナミクス研究分野, 主任研究員 (30359179)
• Co-Investigator(Renkei-kenkyūsha): YOSHIMITSU Junko 国立研究開発法人海洋研究開発機構, 地球深部ダイナミクス研究分野, 技術副主任 (70392941)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 地震波トモグラフィー / 火山現象 / テクトニクス / 地球内部構造 / 沈み込むスラブ / マントルプルーム / ホットスポット

Outline of Final Research Achievements

We developed a P-wave mantle tomography, using ray theory for onset times and finite frequency kernels for broadband waveform data. We applied this new method to investigate mantle structures in Northeastern Asia and French Polynesia and succeeded to obtain detail structures.
The tomography image shows slow anomalies below the Cenozoic volcanoes around the Songliao basin. In the mantle transition zone, no extended flatten slab is observed beneath the basin while it is observed to the north and south. It looks like a hole of the stagnant slab. The hole of the stagnant slab may be related with the volcanism of Changbaishan. Below the French Polynesia, the image shows that a strong large-scale (~1000 km in diameter) slow anomalies from the core-mantle boundary do not extend straight to the surface but become small and weak in the depth range about 550 - 900 km. The small-scale slow anomalies seem to shape a circle connecting the Society, Marquesas, Pitcairn and MacDonald hotspots.

Free Research Field

地震学