scholarly journals Analysing post-earthquake landslide activity using multi-temporal landslide inventories near the epicentral area of the 2008 Wenchuan earthquake

2016 ◽  
Author(s):  
Chenxiao Tang ◽  
Cees J. Van Westen ◽  
Hakan Tanyaş ◽  
Victor G. Jetten
Keyword(s):  
Wenchuan Earthquake ◽  
Image Interpretation ◽  
Extreme Rainfall ◽  
Visual Image ◽  
Extreme Rainfall Events ◽  
Epicentral Area ◽  
2008 Wenchuan Earthquake ◽  
Landslide Activity ◽  
Mountainous Regions ◽  
Seismic Landslide

Abstract. Large earthquakes in mountainous regions may trigger thousands of landslides, some active for years. We analysed the changes in landslide activity near 2008 Wenchuan earthquake epicentre, generating five landslide inventories for different years through stereoscopic digital visual image interpretation. From May 2008 to April 2015, 660 new landslides occurred outside the co-seismic landslide areas. In April 2015, the number of active landslides had gone down to 66, less than 1 % of the co-seismic landslides, still much higher than the pre-earthquake situation. We expect that the landslide activity will continue to decay, but may be halted if extreme rainfall events occur.

scholarly journals Analysing post-earthquake landslide activity using multi-temporal landslide inventories near the epicentral area of the 2008 Wenchuan earthquake

2016 ◽  
Vol 16 (12) ◽  
pp. 2641-2655 ◽  
Author(s):  
Chenxiao Tang ◽  
Cees J. Van Westen ◽  
Hakan Tanyas ◽  
Victor G. Jetten
Keyword(s):  
Wenchuan Earthquake ◽  
Image Interpretation ◽  
Extreme Rainfall ◽  
Visual Image ◽  
Extreme Rainfall Events ◽  
Epicentral Area ◽  
2008 Wenchuan Earthquake ◽  
Landslide Activity ◽  
Mountainous Regions ◽  
The 2008 Wenchuan Earthquake

Abstract. Large earthquakes in mountainous regions may trigger thousands of landslides, some active for years. We analysed the changes in landslide activity near the epicentre of the 2008 Wenchuan earthquake by generating five landslide inventories for different years through stereoscopic digital visual image interpretation. From May 2008 to April 2015, 660 new landslides occurred outside the co-seismic landslide areas. In April 2015, the number of active landslides had gone down to 66, less than 1 % of the co-seismic landslides, but still much higher than the pre-earthquake levels. We expect that the landslide activity will continue to decay, but may be halted if extreme rainfall events occur.

scholarly journals Analysis of changes in post-seismic landslide distribution and its effect on building reconstruction

2015 ◽  
Vol 15 (4) ◽  
pp. 817-825 ◽  
Author(s):  
W. T. Yang ◽  
M. Wang ◽  
N. Kerle ◽  
C. J. Van Westen ◽  
L. Y. Liu ◽  
...  
Keyword(s):  
Wenchuan Earthquake ◽  
Dynamic Process ◽  
Flash Floods ◽  
Mountainous Regions ◽  
Environment Exposure ◽  
High Resolution Images ◽  
Local Residents ◽  
Seismic Landslide ◽  
Landslide Debris

Abstract. Six years after the devastating Ms 8.0 Wenchuan earthquake, new landslides, debris flows, and flash floods still occur frequently in the earthquake-stricken regions. This shows that the geological hazards that occur after a major earthquake in a mountainous environment can be a long-term threat. However, post-earthquake reconstruction and relocation of local residents often neglect this evolving threat, and its interaction with existing and rebuilt houses has not been well studied. Here we show that the evolving mountain environment, including the changed geographic distribution of new landslides and the continuously uplifting riverbed, creates emerging risks for existing and rebuilt houses. We use spatial analysis of landslide debris and the location of houses from high-resolution images and field survey in the study area and find that new landslides and the houses rebuilt after the Wenchuan earthquake have a similar trend of moving to lower elevations, gentler slopes, and closer to rivers. This study confirms that the persistent downward movement of landslide debris has rapidly filled up riverbeds over the past 6 years. The elevated riverbeds make the study area extremely susceptible to flash floods, creating further risks to newly rebuilt houses that are closer to the river. We highlight the often neglected dynamic process that involves changes in the natural environment and man-made constructions and their interaction. This dynamic process requires long-term monitoring and adaptive management of mountainous regions after major earthquakes that can fully consider the sophisticated evolving risks caused by the changing environment, exposure, and vulnerability in the region.

scholarly journals Monitoring of the reconstruction process in a high mountainous area affected by a major earthquake and subsequent hazards

2020 ◽  
Vol 20 (4) ◽  
pp. 1163-1186 ◽  
Author(s):  
Chenxiao Tang ◽  
Xinlei Liu ◽  
Yinghua Cai ◽  
Cees Van Westen ◽  
Yu Yang ◽  
...  
Keyword(s):  
Wenchuan Earthquake ◽  
Economic Value ◽  
Image Interpretation ◽  
Economic Loss ◽  
Field Investigation ◽  
Mitigation Measures ◽  
Mountainous Area ◽  
Reconstruction Process ◽  
2008 Wenchuan Earthquake ◽  
Recovery Planning

Abstract. Recovering from major earthquakes is a challenge, especially in mountainous environments where postearthquake hazards may cause substantial impacts for prolonged periods of time. Although such impacts were reported in the 1923 Great Kantō earthquake and the 1999 Chi-Chi earthquake, careless reconstruction in hazard-prone areas and consequently huge losses were witnessed following the 2008 Wenchuan earthquake in the Sichuan province of China, as several reconstructed settlements were severely damaged by mass movements and floods. In order to summarize experiences and identify problems in the reconstruction planning, a monitoring of one of the settlements, the town of Longchi, was carried out by image interpretation and field investigation. Seven inventories containing buildings, farmlands, roads and mitigation measures were made to study the dynamics of elements at risk and exposure over a period of 11 years. It was found that the total economic value of the newly reconstructed buildings was several times more than in the preearthquake situation in 2007, because of enormous governmental investment. Postseismic hazards were not sufficiently taken into consideration in the recovery planning before the catastrophic debris flow disaster in 2010. As a result, the direct economic loss from postseismic disasters was slightly more than the loss caused by the Wenchuan earthquake itself. The society showed an impact-adapt pattern, experiencing losses from disasters and then gaining resistance by abandoning buildings in hazard-prone areas and installing mitigation measures. The locations potentially exposed to postearthquake hazards were summarized, and a possible timetable for reconstruction was proposed. Problems might be encountered in hazard assessment, and possible solutions were discussed.

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.

scholarly journals Ambient noise and ERT data provide insights into the structure of co-seismic rock avalanche deposits in Sichuan (China)

2021 ◽  
Author(s):  
V. Del Gaudio ◽  
J. Wasowski ◽  
W. Hu ◽  
P. Capone ◽  
N. Venisti ◽  
...  
Keyword(s):  
Wenchuan Earthquake ◽  
Ambient Noise ◽  
Rock Avalanche ◽  
S Wave ◽  
Seismic Surveys ◽  
2008 Wenchuan Earthquake ◽  
Single Station ◽  
Resonance Properties ◽  
History Of ◽  
Seismic Landslide

AbstractThe post-seismic history of the 2008 Mw7.9 Wenchuan earthquake shows that marginally stable deposits of large co-seismic landslide dams can pose persistent debris flow hazards for the downstream areas. Here, we combine analyses of single-station recordings of ambient noise with electrical resistivity tomography (ERT) surveys to explore the potential of drawing information on structure and geometry of the deposit of a large rock avalanche triggered by the Mw 7.9 2008 Wenchuan earthquake, which dammed the Yangjia stream in the Sichuan Province (China). The substantial thickness and heterogeneity of this kind of deposits limit the application of standard geophysical techniques, like active seismic surveys, which require highly energetic sources and long linear geophone arrays to reach adequate investigation depths. Passive single-station methods, relying on ambient noise recordings to determine site resonance properties, controlled by the contrast between soft surface layers and a stiffer substratum, offer the opportunity of investigating subsoil properties down to larger depths. In particular, we use a recently developed technique, which isolates the contribution of Rayleigh waves to ambient noise and draws information on sub-soil properties from the inversion of Rayleigh wave ellipticity curves plotted as function of frequency. In this framework, the ERT data can support the ellipticity curve inversion, typically affected by highly non-univocal solutions, by providing constraints for defining of the thickness of the uppermost surficial layers. The results allowed inferring the overlap of different layers within the 2008 rock avalanche deposit, as well as estimating lateral variations in their thickness and S-wave (Vs) velocities.

scholarly journals Interactions between deforestation, landscape rejuvenation, and shallow landslides in the North Tanganyika – Kivu Rift region, Africa

2020 ◽  
Author(s):  
Arthur Depicker ◽  
Gerard Govers ◽  
Liesbet Jacobs ◽  
Benjamin Campforts ◽  
Judith Uwihirwe ◽  
...  
Keyword(s):  
Slope Failure ◽  
Land Use Changes ◽  
Extreme Rainfall ◽  
Google Earth ◽  
Shallow Landslides ◽  
Extreme Rainfall Events ◽  
Landslide Activity ◽  
Erosion Rates ◽  
The North ◽  
The Impact

Abstract. Deforestation increases landslide activity over short, contemporary timescales. However, over longer timescales the location and timing of landsliding is controlled by the interaction between uplift and fluvial incision. Yet, the interaction between (human-induced) deforestation and landscape evolution has hitherto not been explicitly considered. We address this issue in the North Tanganyika-Kivu Rift region (East African Rift). In recent decades, the regional population has grown exponentially and the associated expansion of cultivated and urban land has resulted in widespread deforestation. On a much longer time scale, tectonic uplift has forged two parallel mountainous Rift shoulders that are continuously rejuvenated through knickpoint retreat, enforcing topographic steepening. In order to link deforestation and rejuvenation to landslide erosion, we compiled an inventory of nearly 8,000 recent shallow landslides in Google Earth© imagery from 2000–2019. To accurately calculate landslide erosion rates, we developed a new methodology to remediate inventory biases linked to the spatial and temporal inconsistency of this satellite imagery. We find that erosion rates in rejuvenated landscapes are roughly 40 % higher than in the surrounding relict landscapes, upstream of retreating knickpoints and outside of the Rift shoulders. This difference is due to the generally steeper relief in rejuvenated landscapes which more than compensates for the fact that rejuvenated slopes, when compared to similarly angled slopes in relict zones, often display a somewhat lower landslide erosion rate. These lower rates in the rejuvenated landscapes could be the result of a drier climate, the omission of earthquake-induced landslide events in our landslide inventory, and potentially a smaller regolith stock. More frequent extreme rainfall events in the relict zones, and possibly the presence of a thicker regolith, cause a stronger landslide response to deforestation compared to rejuvenated landscapes. Overall, deforestation initiates a landslide peak that lasts approximately 15 years and increases landslide erosion by a factor 2 to 8. Eventually, landslide erosion in deforested land falls back to a level similar to that observed under forest conditions, most likely due to the depletion of the most unstable regolith. Landslides are not only more abundant in rejuvenated landscapes but are also smaller in size, which may be a consequence of the seismic activity that fractures the bedrock and reduces the minimal critical area for slope failure. With this paper, we highlight the importance of considering the geomorphological context when studying the impact of recent land use changes on landslide activity.

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