GIGANTIC DOWNLOAD ERROR SERIES
By integrating present-day LiDAR topographic data with existing records (including studies published in Chinese), and a series of unique archival photographs (from 1910, 1920, and 1934), we present the first inventory of coseismic landslides from the epicentral region of this catastrophic 1933 event. And yet, the attention focused on this event has failed to deliver a clear picture of landslides and their geomorphic impacts-key attributes of the Diexi earthquake and its aftermath remain obscure and debated. The Diexi earthquake is among the largest known geohazard events worldwide and is frequently cited by those studying the effects of large earthquakes. On 25 August 1933, a 7.5-magnitude earthquake struck the eastern margin of the Tibetan Plateau in Sichuan, China.
GIGANTIC DOWNLOAD ERROR VERIFICATION
Verification results demonstrated that the proposed approach could improve the efficiency and accuracy of the estimates of source material volume in debris flows and assess hazards.
The trend of the degree of erosion was consistent with that of the monthly rainfall in the XLG in 2018. The highest degree of erosion occurred in the summer, followed by spring, autumn, and winter. Higher elevation with good vegetation coverage showed the sedimentation process, while lower elevation area with little vegetation showed erosion process. Estimated erosion rate ranges from 1633 m³/(km² Continuous monitoring using InSAR could help to obtain the large-scope precise process of ground surface deformation. Considering sediment connectivity, landslides debris were interpreted using optical remote sensing, and their volume was calculated, using an empirical formula, to be about 191.01 × 104 m³. The qualitative degree of stability of the source materials was estimated with volume of approximately 91.9 × 104 m³. The objective of this study was to develop a multi-source method–including field surveys, optical remote sensing interpretation, and interferometric synthetic aperture radar (InSAR) technology–to estimate the volume of source materials in the debris flow in the Xulong Gully (XLG), China. Source materials come from channel bed sediment, nearby landslides and rilling and surface erosion of slopes.
There are three main factors controlling the formation of debris flow of these, the ability to evaluate the volume of source materials in a catchment is the most significant. (2019) with three key arguments: 1) Major profile convexities in the Diexi area, including KpMJ, are associated with landslide or debris flow deposits and there is no basis for connecting explicitly any of these to long-distance knickpoint retreat 2) the giant Diexi paleolandslide predates the debris avalanches at KpMJ, therefore the latter cannot have been the trigger for landsliding in this area and 3) the spatial distribution of 666 mapped knickpoints in the Minjiang River mainstem and tributaries is not consistent with simple long-distance propagation of an ‘incisional wave’ initiated at the Longmenshan Fault. We confront the model proposed by Zhao et al. We question this interpretation based on our high-resolution landslide mapping, an analysis of knickpoints (i.e., profile convexities > 30 m high) in the Minjiang channel network, and field observations of lacustrine sediments and epigenetic gorges associated with the Diexi landslides. They then argue that this retreating knickpoint left in its wake an inner gorge that undercut and destabilized hillslopes, triggering a series of large landslides in the Diexi area. They postulate that a major river knickpoint (KpMJ) identified by them in the middle reaches of the Minjiang River (Sichuan, China) was initiated at the Longmenshan Fault and subsequently propagated ~ 85 km to its present position upstream of the Diexi lake.
(2019) examine gigantic landslides in the Diexi area along the eastern margin of the Tibetan Plateau and propose their successive failure based on a knickpoint migration conceptual model.
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