[M-IS05] 南大洋・南極氷床が駆動する全球気候変動

[MIS05-P02] Vertical crustal motion induced by GIA in Lützow-Holm Bay, East Antarctica

*奥野 淳一^1,2、服部 晃久²、石輪 健樹¹、入江 芳矢¹、土井 浩一郎^1,2 (1.国立極地研究所、2.総合研究大学院大学)

キーワード：氷河性地殻均衡調整、南極氷床変動、マントル粘性率

Geodetic and geomorphological observations in the Antarctic coastal area generally indicate the uplift movement of the crust associated with the Antarctic Ice Sheet (AIS) change since the Last Glacial Maximum (LGM). This trend is called the glacial isostatic adjustment (GIA), the Earth's viscoelastic response due to the surface load changes. The current crustal motion, which the GNSS observation indicates, includes the elastic component due to the present-day surface mass balance of AIS in addition to the viscoelastic response. To reveal the secular crustal movement associated with the GIA, the separation of both components due to the current mass balance and last deglaciation is essential.
Recently geomorphological study in the Lützow-Holm Bay region, East Antarctica, reported that the rapid ice thinning of about 400 m for 3000 years has occurred in the early-to-mid Holocene. This melting may influence the crustal deformation through the viscoelastic response due to rapid ice load change. Therefore, we examine the GIA component due to this melting on the current crustal deformation rate using the numerical modeling. Results indicate that the viscoelastic relaxation due to the abrupt ice thinning depends significantly on the upper mantle viscosity profile. This presentation will discuss the dependence of the AIS retreat history and mantle viscosity structure on the GIA-induced crustal movement based on the numerical experiments.