Title: Surface Rupture of the 2008 Wenchuan, China, Earthquake in the Qingping Stepover Determined from Geomorphologic Surveying and Excavation, and Its Tectonic Implications
Abstract:The Wenchuan Mw 7.9 earthquake of 12 May 2008 caused the rupture of the Longmen Shan thrust belt, which bounds the eastern margin of the Tibetan plateau, and generated a very complex surface rupture. ...The Wenchuan Mw 7.9 earthquake of 12 May 2008 caused the rupture of the Longmen Shan thrust belt, which bounds the eastern margin of the Tibetan plateau, and generated a very complex surface rupture. The Beichuan-Yingxiu fault (BYF )w as themainseismogenicfaultandformedtwodistinctivelydifferentsurfacerupturezones separated by the Qingping and Gaochuan stepovers. Real-time kinematic (RTK) sur- veying of alluvial terrace sequences indicates that terraces T1-T3 and river floodplain T0 have the same vertical displacement associated with the Wenchuan earthquake. Trench excavation and optical stimulated luminescence (OSL) dating of alluvial depos- its indicate that only the deformation of the Wenchuan earthquake was recorded in the Qingping stepover since at least ∼20 ka. Other deformations since ∼20 ka probably occurred in other places or did not reach the surface. This can be meaningful to analyze the completeness of paleoearthquakes in trench excavation on thrust faults. The width of the Qingping stepover is ∼1 km and it is not strong enough to form a barrier to arrest the propagation of rupture in the 2008 Wenchuan earthquake. The Gaochuan stepover is ∼7 km wide and it is a barrier to separate the two surface rupture zones associated with the Wenchuan earthquake along the BYF. The empirical rela- tionship of rupture displacement and stepover dimensions on strike-slip faults is prob- ably suitable for the large thrust fault zone with a strike-slip component. This may be beneficial to the study of cascade rupture sections and seismic hazard assessment on large thrust faults.Read More
Publication Year: 2010
Publication Date: 2010-10-19
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 17
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Title: $Surface Rupture of the 2008 Wenchuan, China, Earthquake in the Qingping Stepover Determined from Geomorphologic Surveying and Excavation, and Its Tectonic Implications
Abstract: The Wenchuan Mw 7.9 earthquake of 12 May 2008 caused the rupture of the Longmen Shan thrust belt, which bounds the eastern margin of the Tibetan plateau, and generated a very complex surface rupture. The Beichuan-Yingxiu fault (BYF )w as themainseismogenicfaultandformedtwodistinctivelydifferentsurfacerupturezones separated by the Qingping and Gaochuan stepovers. Real-time kinematic (RTK) sur- veying of alluvial terrace sequences indicates that terraces T1-T3 and river floodplain T0 have the same vertical displacement associated with the Wenchuan earthquake. Trench excavation and optical stimulated luminescence (OSL) dating of alluvial depos- its indicate that only the deformation of the Wenchuan earthquake was recorded in the Qingping stepover since at least ∼20 ka. Other deformations since ∼20 ka probably occurred in other places or did not reach the surface. This can be meaningful to analyze the completeness of paleoearthquakes in trench excavation on thrust faults. The width of the Qingping stepover is ∼1 km and it is not strong enough to form a barrier to arrest the propagation of rupture in the 2008 Wenchuan earthquake. The Gaochuan stepover is ∼7 km wide and it is a barrier to separate the two surface rupture zones associated with the Wenchuan earthquake along the BYF. The empirical rela- tionship of rupture displacement and stepover dimensions on strike-slip faults is prob- ably suitable for the large thrust fault zone with a strike-slip component. This may be beneficial to the study of cascade rupture sections and seismic hazard assessment on large thrust faults.