Research on mantle dynamics and tectonic crustal movement for glacial isostatic adjustment

2015 Fiscal Year Final Research Report

• Project/Area Number: 25400455
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Solid earth and planetary physics
• Research Institution: Kyushu University
• Principal Investigator: NAKADA MASAO 九州大学, 理学(系)研究科(研究院), 教授 (50207817)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: マントルレオロジー / 地球温暖化 / 氷床変動 / テクトニック運動 / 地球回転変動 / マントルダイナミクス

Outline of Final Research Achievements

We have examined mantle dynamics and tectonic crustal movements along the Japanese coastlines by considering the Earth’s deformation for glacial isostatic adjustment (GIA) due to the last deglaciation, sea level observations due to the recent global warming, Earth’s rotational variations and sea level observations at the Japanese Islands during the pat 125 kyr. The main results for mantle dynamics are as follows: (i) GIA-induced d2-dot (rate of change of degree-two harmonics of geopotential) is -(6.0-6.5)xE-11/yr, (ii) lower mantle viscosity inferred from the GIA-induce J2-dot and sea level changes at ~21 kyr BP is (5-10)x10E22 Pa s and (iii) the observed polar wander may be significantly attributed to convection motions in the mantle. As for the Japanese tectonic crustal movements, we obtained that the rates on a timescale of ~50 yr are not representative of the tectonic crustal movements for timescales longer than ~6 kyr in most sites along the Japanese coastlines.

Free Research Field

固体地球惑星物理学