Long-term evolution of post-earthquake landslides and debris flows in the epicentral area of the 2008 Wenchuan earthquake

2020 ◽  
Author(s):  
Ruilin Fan
Keyword(s):  
Wenchuan Earthquake ◽  
Debris Flows ◽  
Long Term Evolution ◽  
Epicentral Area ◽  
2008 Wenchuan Earthquake ◽  
The 2008 Wenchuan Earthquake ◽  
Term Evolution ◽  
Landslides And Debris Flows

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.

scholarly journals Maternal exposure to Wenchuan earthquake and prolonged risk of offspring birth outcomes: a natural experiment study

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Qiguo Lian ◽  
Jiaying Ni ◽  
Jun Zhang ◽  
Julian Little ◽  
Shan Luo ◽  
...  
Keyword(s):  
Wenchuan Earthquake ◽  
Birth Outcomes ◽  
Low Birthweight ◽  
Maternal Exposure ◽  
Adverse Birth Outcomes ◽  
Reproductive Outcomes ◽  
2008 Wenchuan Earthquake ◽  
The 2008 Wenchuan Earthquake ◽  
Stratified Analysis

Abstract Background The prolonged effects of disasters on reproductive outcomes among the survivors are less studied, and the findings are inconsistent. We examined the associations of maternal exposure to the 2008 Wenchuan earthquake years before conception with adverse birth outcomes. Methods We included 73,493 women who delivered in 96 hospitals in 24 provinces and autonomous regions from the 2015/16 China Labor and Delivery Survey. We weighted the multivariable logistic models based on the combination of coarsened exact matching (CEM) weight and survey weight, and performed sex-stratified analysis to test whether associations of maternal earthquake exposure with adverse birth outcomes (Stillbirth, preterm birth [PTB], low birthweight [LBW], and small for gestational age [SGA]) varied by sex. Results The bivariate models showed that the weighted incidence of each adverse birth outcome was higher in exposed group than unexposed group: stillbirth (2.00% vs. 1.33%), PTB (14.14% vs. 7.32%), LBW (10.82% vs. 5.76%), and SGA (11.32% vs. 9.52%). The multivariable models showed maternal earthquake exposure was only associated significantly with a higher risk of PTB in offspring among all births (adjusted risk ratio [aRR](95%CI):1.25(1.06–1.48), P = 0.010). The sex-stratified analysis showed the association was significant among male births (aRR (95%CI): 1.40(1.12–1.75),P = 0.002),but unsignificant among female births. The sensitivity analysis reported similar findings. Conclusions The 2008 Wenchuan earthquake exposure has a long-term effect on PTB. Maternal acute exposure to disasters could be a major monitor for long-term reproductive outcomes. More attention should be paid to the underlining reasons for disaster-related adverse birth outcomes.

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.

scholarly journals Two multi-temporal datasets that track the enhanced landsliding after the 2008 Wenchuan earthquake

2019 ◽  
Vol 11 (1) ◽  
pp. 35-55 ◽  
Author(s):  
Xuanmei Fan ◽  
Gianvito Scaringi ◽  
Guillem Domènech ◽  
Fan Yang ◽  
Xiaojun Guo ◽  
...  
Keyword(s):  
Wenchuan Earthquake ◽  
Debris Flows ◽  
Temporal Evolution ◽  
The Tibetan Plateau ◽  
Mass Wasting ◽  
Epicentral Area ◽  
2008 Wenchuan Earthquake ◽  
Rain Gauges ◽  
Multi Temporal ◽  
Coseismic Landslide

Abstract. We release two datasets that track the enhanced landsliding induced by the 2008 Mw 7.9 Wenchuan earthquake over a portion of the Longmen Mountains, at the eastern margin of the Tibetan Plateau (Sichuan, China). The first dataset is a geo-referenced multi-temporal polygon-based inventory of pre- and coseismic landslides, post-seismic remobilisations of coseismic landslide debris and post-seismic landslides (new failures). It covers 471 km2 in the earthquake's epicentral area, from 2005 to 2018. The second dataset records the debris flows that occurred from 2008 to 2017 in a larger area (∼17 000 km2), together with information on their triggering rainfall as recorded by a network of rain gauges. For some well-monitored events, we provide more detailed data on rainfall, discharge, flow depth and density. The datasets can be used to analyse, on various scales, the patterns of landsliding caused by the earthquake. They can be compared to inventories of landslides triggered by past or new earthquakes or by other triggers to reveal common or distinctive controlling factors. To our knowledge, no other inventories that track the temporal evolution of earthquake-induced mass wasting have been made freely available thus far. Our datasets can be accessed from https://doi.org/10.5281/zenodo.1405489. We also encourage other researchers to share their datasets to facilitate research on post-seismic geological hazards.

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>

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 Assessment of risks of loose landslide deposits formed by the 2008 Wenchuan earthquake

2012 ◽  
Vol 12 (5) ◽  
pp. 1381-1392 ◽  
Author(s):  
S. Zhang ◽  
L. M. Zhang ◽  
M. Peng ◽  
L. L. Zhang ◽  
H. F. Zhao ◽  
...  
Keyword(s):  
Reliability Analysis ◽  
Wenchuan Earthquake ◽  
Quantitative Risk Assessment ◽  
2008 Wenchuan Earthquake ◽  
The 2008 Wenchuan Earthquake ◽  
Loose Deposits ◽  
Calculated Probability ◽  
The Individual ◽  
Risk Assessment Methodology

Abstract. A Geographic Information System (GIS)-based quantitative risk assessment methodology was adopted to evaluate the risks of loose deposits formed by the 2008 Wenchuan earthquake along a highway near the epicenter. A total of 305 loose deposits with a total volume of 4.0 × 107 m3 has been identified. A physical model was used to determine the failure probability of these loose deposits under six rainfall scenarios, assuming the loose deposits as infinite slopes. The calculated probability of rain-induced slope failures is verified by the recorded landslides at the same site during a storm in 2010. Seventy-nine out of the 112 rain-induced loose deposit failures are predicted by the reliability analysis, with an accuracy of 71%. The results of reliability analysis and information on the consequence of these rain-induced landslides enable the estimation of the annual societal and individual risks of the loose deposits. Under the rainfall scenarios of 30 mm/12 h and 70 mm/12 h, the estimated annual societal risks reach 8.8 and 7.5, respectively, and the individual risks reach 0.05 and 0.04, respectively, which are very high compared with present risk acceptance criteria. The preliminary assessment provides a benchmark for studying the long-term risks of these loose deposits and engineering decision.

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