Elasticity and anelasticity of polycrystalline material at near solidus temperatures for seismological application

2016 Fiscal Year Final Research Report

• Project/Area Number: 26287102
• 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: The University of Tokyo
• Principal Investigator: Takei Yasuko 東京大学, 地震研究所, 教授 (30323653)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: 非弾性 / 地震波低速度域 / 地震波減衰 / プレメルティング

Outline of Final Research Achievements

Present experimental studies by using a rock analogue (organic polycrystals) has revealed that polycrystal anelasticity is significantly enhanced from just below the solidus temperature in the absence of melt (Takei et al, 2014; Yamauchi and Takei, 2016). Importantly, the amplitude of this `pre-melting effect’ is large even for the samples which can produce very small amounts (~0.4-0.5 %) of melt at the solidus temperature (Yamauchi and Takei, 2016). Therefore, the newly recognized effect can remove the difficulty to explain the seismic observations without melt or with very small amount of melt indicated by the thermal and geochemical studies. Using the temperature and seismic structures of the Pacific mantle, Priestley and McKenzie (2006, 2013) captured a steep reduction in Vs just below the dry peridotite solidus. The new anelasticity model including the pre-melting effect can explain this steep reduction qualitatively and almost quantitatively (Yamauchi and Takei, 2016).

Free Research Field

固体地球科学