Vertical tectonic crustal movements along the Japanese coastlines inferred from late Quaternary and recent relative sea-level changes
Vertical tectonic crustal movements along the Japanese coastlines inferred from late Quaternary and recent relative sea-level changes
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DOI：
10.1016/j.quascirev.2014.03.010
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发表时间：
2014-05
影响因子：
4
通讯作者：
J. Okuno;M. Nakada;M. Ishii;H. Miura
中科院分区：
文献类型：
--
作者：
J. Okuno;M. Nakada;M. Ishii;H. Miura
观测到的相对海平面（RSL）在过去的130 kyr的变化，使人们有可能评估垂直地壳运动，由于几个构造过程，如大洋板块俯冲。在这里，我们推断构造地壳运动的平均速率沿着日本海岸线的三个典型的时间尺度为150年，16 kyr和125 kyr的基础上，验潮仪和全新世RSL观测和海洋阶地的高度形成于末次间冰期（LIG）阶段在125 ka。250年时间尺度上的速率来自验潮仪数据、海洋热膨胀引起的热位海平面变化、冰川-水均衡调整（GIA）对最后一次冰消期的预测以及最近高山冰川、格陵兰和南极冰盖的融化。1.6kyr和1.125kyr的结果是基于RSL观测和GIA模型的预测，考虑了全新世中晚期和LIG阶段海平面随时间变化的不确定性。在大多数地点，特别是沿着从北海道东部到日本东北部、四国和面向太平洋的九州南部的海岸线的地点，推断的125 kyr的速率与125 kyr的速率有显著差异。在这些地区，125 kyr和150 yr的速率分别为正值（隆起）和负值（沉降）。此外，观测到的RSL变化在12.5万年和GIA预测的RSL变化率在许多站点是一致的推断RSL变化，但不一致的150年在大多数站点，除了少数站点。这些结果表明，在一个时间尺度上的150年的速率是不代表的时间尺度超过16 kyr在大多数网站沿着日本海岸线的地壳构造运动。然而，在这些时间尺度上推断的速率可能有助于讨论其间隔为10.1 kyr的大逆冲断层地震的复发，如2011年东北太平洋沿岸的地震。
Observed relative sea-level (RSL) changes during the past ∼130 kyr make it possible to evaluate the vertical crustal movement due to several tectonic processes such as the subduction of oceanic plates. Here we infer average rates of tectonic crustal movement along the Japanese coastlines on three typical timescales of ∼50 yr, ∼6 kyr and ∼125 kyr based on tide gauge and Holocene RSL observations and the altitudes of marine terraces formed at the Last Interglacial (LIG) phase at ∼125 ka. The rates on a timescale of ∼50 yr are derived from tide gauge data, thermosteric sea-level changes due to thermal expansion of the oceans and predictions due to the glacio-hydro isostatic adjustment (GIA) for the last deglaciation and also recent melting of the mountain glaciers and Greenland and Antarctic ice sheets. Those for ∼6 kyr and ∼125 kyr are based on the RSL observations and the predictions by GIA modelling, considering uncertainties for temporal changes in eustatic sea-level for the mid- to late-Holocene and LIG phase. The inferred rates for ∼50 yr are significantly different from those for ∼125 kyr in most sites, particularly for sites along the coastline from eastern Hokkaido to northeastern Japan, Shikoku and south Kyushu facing the Pacific Ocean. In these regions, the rates for ∼125 kyr and ∼50 yr are positive (uplift) and negative (subsidence), respectively. Also, the observed RSL changes at ∼6 ka are consistent with the inferred RSL changes using the rates for ∼125 kyr and GIA-predictions in many sites, but inconsistent with those for ∼50 yr in most sites except for a few sites. These results suggest 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. However, the inferred rates on these timescales may be useful in discussing the recurrence of megathrust earthquake with its interval of ∼1 kyr such as the 2011 earthquake off the Pacific coast of Tohoku.