Time Response of River Evacuation of Great Earthquake-Induced Landslide Mass in the Longmenshan Region: A Cast Study of the 2008 Wenchuan Great Earthquake
详细信息
- 责任者：Liu Feng (Key Laboratory of the Earth’s Deep Interior ; CAS ; Institute of Geology and Geophysics ; Chinese Academy of Sciences ; Beijing 100029 ; China) ; Fu Bihong
- 刊名：Chinese Journal of Geophysics
- 出版年：2013
- 卷期：56(5)
- 关键词：搬运作用 ; sediment transport ; 地貌旋回 ; geomorphic cycle ; 均衡补偿 ; isostatic compensation ; 龙门山 ; Longmen Mountains
- 页码：p.1517-1525
- 图表：illus., 62 refs.
- 分类号：1400
- issnNo：ISSN0001-5733
- isbnNo：CN11-2074/P
摘要
Great earthquakes play an active role in geomorphic evolution of orogenic belts,and the time response of river evacuation of landslide mass induced by great earthquakes is a key aspect in the field of tectonic geomorphology.Here we quantitatively estimate the time response of unloading of the coseimsic landslide mass and sediments due to the 2008 Wenchuan great earthquake by the Minjiang River,flowing across the NE-trending Longmen Shan belt in easternmost Tibet.Assuming a steady state transport capacity of landslide mass the same as that of the modern Minjiang River,our results indicate that a full withdrawal of the landslide mass generated by the Wenchuan earthquake needs to take 3100 years.This timescale is similar to the recurrence interval of great seismic events(~3000 years) like the 2008 Wenchuan earthquake in central Longmen Shan.Such consistency suggests an approximate balance between production and erosion of coseismic landslide mass within the recurrence interval of great seismic events in this region.This process of mass unloading may also cause isostatic rebound of the crust beneath this region in addition to other surface processes.The consequent uplift,together with the tectonic shortening and uplift caused by repeated large seismic events,collectively result in the steepest topographic margin in the eastern margin of the Tibetan plateau.Recent geophysical imaging shows a potential of upwelling of asthenospheric materials beneath this region that we interpret as a result of rapid surface unloading induced by repeated great earthquakes.
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