A high-resolution model of P-wave anisotropic tomography beneath Mainland China and surrounding regions is determined using a large number of arrival-time data recorded by the China seismic network, the International Seismological Centre (ISC) and temporary seismic arrays deployed on the Tibetan Plateau. Our results provide important new insights into the subducted Indian plate and mantle dynamics in East Asia. Our tomographic images show that the northern limit of the subducting Indian plate has reached the Jinsha River suture in eastern Tibet. A striking variation of P-wave azimuthal anisotropy is revealed in the Indian lithosphere: the fast velocity direction (FVD) is NE-SW beneath the Indian continent, whereas the FVD is arc parallel beneath the Himalaya and Tibetan Plateau, which may reflect re-orientation of minerals due to lithospheric extension, in response to the India-Eurasia collision. There are multiple anisotropic layers with variable FVDs in some parts of the Tibetan Plateau, which may be the cause of the dominant null splitting measurements in these regions. A circular pattern of FVDs is revealed around the Philippine Sea slab beneath SE China, which reflects asthenospheric strain caused by toroidal mantle flow around the edge of the subducting slab.

No abstract

Following the 2008 Wenchuan M8 earthquake, the seismic risk of the northeastern section of the Longmenshan fault zone and the adjacent Hanzhong basin has become an issue that receives much concern. It is facing, however, the problem of a lack of sufficient data because of little previous work in these regions. The northeastern section of the Longmenshan fault zone includes three major faults: the Qingchuan fault, Chaba‐Lin'ansi fault, and Liangshan south margin fault, with the Hanzhong basin at the northern end. This paper presents investigations of the geometry, motion nature, and activity ages of these three faults, and reveals that they are strike slip with normal faulting, with latest activity in the Late Pleistocene. It implies that this section of the Longmenshan fault zone has been in an extensional setting, probably associated with the influence of the Hanzhong basin. Through analysis of the tectonic relationship between the Longmenshan fault zone and the Hanzhong basin, this work verifies that the Qingchuan fault played an important role in the evolution of the Hanzhong basin, and further studies the evolution model of this basin. Finally, with consideration of the tectonic setting of the Longmenshan fault zone and the Hanzhong basin as well as seismicity of surrounding areas, this work suggests that this region has no tectonic conditions for great earthquakes and only potential strong events in the future.

Background: The Gorkha, Nepal Mw 7.8 earthquake of 25 April 2015 triggered a large number of coseismic landslides in a broad area. Two highways, Araniko Highway and Pasang Lhamu Highway, that connect Tibet of China and Nepal, were affected seriously by these landslides. The purpose of this study was to investigate the landslide damage along the two highways, construct a detailed and complete inventory of coseismic landslides in the 5-km buffer area of the Araniko Highway, and perform a regional assessment of landslide hazard in the affected area. Findings: Based on visual interpretation of high-resolution satellite images, field investigations, and GIS technology, we investigated the coseismic landslides along the Araniko Highway and Pasang Lhamu Highway. A detailed pointbased inventory of coseismic landslides was constructed and spatial distributions of the landslides were analyzed. Correlations between the landslides and five controlling factors, i.e. elevation, slope angle, slope aspect, lithology, and seismic intensity, were illustrated statistically which permitted to assess landslides hazard in a larger rectangle area.

No abstract

No abstract

No abstract

No abstract