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浅源地震是山区地壳抬升的主要驱动力(Avouac,2008)。然而,浅源大地震也触发大范围的同震滑坡,造成显著、但在空间上不均匀的侵蚀(Keefer,1994;Malamud et al,2004;Larsen et al,2010)。因此地壳抬升与同震滑坡的分布及规模间的相互作用就引发了一个根本的问题,即大地震及其相关的滑坡是创生还是消毁了山区地形。2008年中国四川MW7.9汶川地震触发了超过56 000处滑坡(Dai et al,2011),其空间分布仅仅部分与构造变形样式有关(Shen et al,2009)。通过将滑坡面积-体积标度关系(Larsen et al,2010;Guzzetti et al,2009)应用于高分辨率卫星影像,我们仔细检查了造山方量的潜在变化。我们估计,同震滑坡产生了约5~15km3的可侵蚀物质,大于2.6±1.2km3(de Michele et al,2010)的同震地壳抬升净方量。这种差异表明,在可能的2000~4000年的地震复发周期中(Shen et al,2009),即使只有小部分滑坡物质从造山带中运移走,汶川地震也会在龙门山导致物质净亏损。我们的结果对长期以来广泛持有的大倾滑或走滑地震能造山的观点提出了挑战,并希望引起对同震滑移、滑坡量与地形生成之间的关系更多的思考研究。
Shallow source earthquakes are the main driving force for uplift of the mountainous crust (Avouac, 2008). However, the Great Asiatic earthquake also triggers a wide range of coseismic landslides, resulting in significant but spatially uneven erosion (Keefer, 1994; Malamud et al., 2004; Larsen et al., 2010). Therefore, the underlying problem of the distribution and scale of the crustal uplift and the coseismic landslide raises the fundamental question of whether the major earthquakes and their related landslides created or destroyed the mountainous terrain. In 2008, more than 56,000 landslides triggered by the Wenchuan earthquake of MW7.9 in Sichuan Province, China (Dai et al., 2011), whose spatial distribution is only partially related to the deformation pattern (Shen et al., 2009). By applying the landslide area-volume scale relationship (Larsen et al., 2010; Guzzetti et al., 2009) to high-resolution satellite images, we carefully examined the potential changes in the amount of orogen. We estimate that the coseismic landslides produced erodible material of about 5-15 km 3, which is larger than the net amount of crustal uplift of 2.6 ± 1.2 km 3 (de Michele et al., 2010). This difference indicates that during a possible earthquake recurrence period of 2000-4000 (Shen et al., 2009), the Wenchuan earthquake caused a net material loss at Longmenshan even though only a small part of the landslide material migrated away from the orogenic belt . Our results challenged the widely held view of large or slippery earthquakes that could orogen, and hoped to give rise to more thoughtful research on the relationship between the coseismic slip, landslide quantities and topography.