scholarly journals Using Google Earth Engine to monitor co-seismic landslide recovery after the 2008 Wenchuan earthquake

2020 ◽  
Author(s):  
Wentao Yang ◽  
Wenwen Qi ◽  
Jian Fang
Keyword(s):  
Wenchuan Earthquake ◽  
Debris Flows ◽  
Google Earth ◽  
Mean Annual Precipitation ◽  
2008 Wenchuan Earthquake ◽  
Computing Platform ◽  
Seismic Landslides ◽  
The 2008 Wenchuan Earthquake ◽  
Vegetation Condition ◽  
Google Earth Engine

Abstract. Earthquake-triggered landslides can pose serious threats to mountain communities by remobilizing and providing loose materials for debris flows in post-seismic years. However, how long co-seismic landslides recover remains elusive due to limited observations. Using vegetation dynamics, we studied surface recovery of co-seismic landslides induced by the 2008 Wenchuan earthquake from May 2008 to July 2019 for over 20,000 km2. Landsat derived vegetation recovery on all co-seismic landslides has been assessed based on the Google Earth Engine, a cloud-based computing platform. We found most co-seismic landslides have been recovering after the earthquake but the spatial pattern is heterogeneous. The epicentre region with low elevations along the bottom of the Min River valley has the best landslide recovery, whereas many landslides on the high Longmen Mountain are poorly recovered ten years after the earthquake. These unrecovered hillslopes and gullies together with widespread loose debris indicate that surface processes on high mountains may still active and may provide source materials for debris flows, threatening communities at low elevations. To decipher possible mechanisms, we further analysed the relations between landslide recovery and twelve influencing factors, including slope, pre-seismic vegetation condition, landslide depth, landslide area, elevation, ground peak acceleration of the earthquake, aspect, slope curvatures, topographic positions, mean annual precipitation, ground cohesion strength and vegetation types. We found elevation, topographic position and pre-seismic vegetation condition are the most important factors that influence landslide recovery over all others. This work also demonstrates the efficiency of the Google Earth Engine for continuously monitoring landslide dynamics over large areas.

The remobilisation of seismically-sourced sediment by debris flows in Wenchuan: A grain size perspective

2020 ◽  
Author(s):  
Erin Harvey ◽  
Xuanmei Fan ◽  
Tristram Hales ◽  
Daniel Hobley ◽  
Jie Liu ◽  
...  
Keyword(s):  
Grain Size ◽  
Debris Flow ◽  
Wenchuan Earthquake ◽  
Debris Flows ◽  
Real Field ◽  
Saturation State ◽  
2008 Wenchuan Earthquake ◽  
Seismic Landslides ◽  
The 2008 Wenchuan Earthquake

<p>Co-seismic landslides can mobilise up to 3 km<sup>3</sup> of loose sediment within minutes. However, the export rate of this sediment is largely unconstrained. For example, it is estimated that a decade after the 2008 Wenchuan earthquake at least 90% of the co-seismic sediment remains stored on the hillslope. Post-earthquake debris flows are the main conduit by which such hillslope debris reaches the fluvial network but the mechanics that govern the triggering and runout of such flows remain unclear and as such they appear to behave largely unpredictably.  Material grain size is a key control on both triggering and runout, since it affects both hydrological (e.g. water loss during flow; saturation state before triggering) and frictional properties of the system. However, our understanding of the role of grain size in the genesis and evolution of debris flows remains poorly explored, largely due to limitations in real field data. Existing estimates for landslide and debris flow deposit grain size distributions (GSDs) are currently limited by 1. inconsistency of applied methods; 2. the very poor sorting of these sediments; 3. inaccessibility, and 4. inherent intra-deposit variability in GSD. </p><p>Our research aims to better understand the role of grain size using an unprecedentedly detailed set of field-constrained GSDs across the post-seismic landslides and debris flows of the 2008 Wenchuan earthquake. Here we present data quantifying the grain size distribution across two debris flows using two different techniques. The two debris flows occurred in response to prolonged rainfall in August 2019 and mobilised co-seismic debris from the 2008 earthquake. In the field, we selected four to eight 1 m x 1 m x 0.5 m pits along the centre line of each debris flow at regular intervals and sieved the pit material into 8 cm, 4 cm, 2 cm and 1 cm fractions at 10 cm depth increments. Boulders >8 cm were measured and weighed individually. Smaller samples were then collected from the finer fraction (<1 cm) and sieved further in the laboratory. The coarse fraction was independently constrained from calibrated photogrammetry, and this was coupled to drone surveying to ensure the coarsest fraction (≥1 m) was correctly represented. This study presents a detailed estimate of post-earthquake debris flow GSDs with the overarching aim to better understand sediment transport and deposition from debris flows in the years following an earthquake.</p>

scholarly journals The 13 August 2010 catastrophic debris flows after the 2008 Wenchuan earthquake, China

2012 ◽  
Vol 12 (1) ◽  
pp. 201-216 ◽  
Author(s):  
Q. Xu ◽  
S. Zhang ◽  
W. L. Li ◽  
Th. W. J. van Asch
Keyword(s):  
Wenchuan Earthquake ◽  
Debris Flows ◽  
Drainage System ◽  
Preventive Measure ◽  
Simultaneous Occurrence ◽  
2008 Wenchuan Earthquake ◽  
The 2008 Wenchuan Earthquake ◽  
Seismic Fault ◽  
Loose Deposits

Abstract. From 12 to 14 August 2010, heavy rainstorms occurred in the Sichuan province in SW China in areas which were affected by the 2008 Wenchuan Earthquake, inducing catastrophic debris flows. This disaster is named as "the 8.13 debris flows". The results of the research presented in this paper show that the 8.13 debris flows are characterized by a simultaneous occurrence, rapid-onsets, destructive impacts, and disaster chain effects. They are located along the seismic fault, because the source materials mainly originate from loose deposits of landslides which were triggered by the Wenchuan Earthquake. The presence of large amounts of these loose materials on the slopes and the development of high intensity rainfall events are the main causes for the formation of these debris flows. The study of the 8.13 debris flows can provide a benchmark for the analysis of the long-term evolution of these debris flows in order to make proper engineering decisions. A flexible drainage system is proposed in this paper as a preventive measure to mitigate the increasing activity of these debris flows in the earthquake-affected area.

The formation and development of debris flows in large watersheds after the 2008 Wenchuan Earthquake

Landslides ◽  
2014 ◽  
Vol 13 (1) ◽  
pp. 25-37 ◽  
Author(s):  
Xiaojun Guo ◽  
Peng Cui ◽  
Yong Li ◽  
Qiang Zou ◽  
Yingde Kong
Keyword(s):  
Wenchuan Earthquake ◽  
Debris Flows ◽  
2008 Wenchuan Earthquake ◽  
The 2008 Wenchuan Earthquake

scholarly journals Emerging Trends and New Developments in Disaster Research after the 2008 Wenchuan Earthquake

2018 ◽  
Vol 16 (1) ◽  
pp. 29 ◽  
Author(s):  
Cailin Wang ◽  
Jidong Wu ◽  
Xin He ◽  
Mengqi Ye ◽  
Wenhui Liu ◽  
...  
Keyword(s):  
Wenchuan Earthquake ◽  
Scientific Basis ◽  
Google Earth ◽  
Mitigation Strategies ◽  
Disaster Research ◽  
2008 Wenchuan Earthquake ◽  
The 2008 Wenchuan Earthquake ◽  
Research Fields ◽  
Emerging Trends ◽  
Disaster Science

On the tenth anniversary of the 2008 Wenchuan Earthquake, investigating the evolution of disaster science is worthwhile and can be used to improve the future execution of disaster risk management. Based on more than 55,786 articles on the relative topic of “Disaster” derived from the Web of Science Core Collection from 1999–2017, this study employs CiteSpace and Google Earth to identify and visualize the spatial distribution of publications, bursts of keywords and categories, highly cited references, and interdisciplinary levels and then identify the emerging trends of disaster research over the past 20 years. The results show that the earthquake indeed jumpstarted a massive wave of disaster research around the world and increased international cooperation over the last decade. However, in terms of both the quantity and quality of publications in disaster research fields, China is lagging behind the U.S. and European countries. Moreover, although designing disaster prevention and mitigation strategies is a new popular field of disaster science, geological environment changes and geologic hazards triggered by earthquakes are more popular research topics than disaster emergency and recovery. In addition, the transdisciplinary level of disaster science increased after the earthquake. This interdisciplinary characteristic of disaster science gradually increased in popularity, which demonstrates that people can learn from catastrophes. These emerging trends could serve as a scientific basis to clearly understand disaster science progress over the last 20 years and provide a reference for rapidly identifying frontier issues in disaster science.

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