Abstract
On 12 May 2008, the 8.0-magnitude Wenchuan earthquake occurred in Sichuan Province, China, triggering thousands of landslides, debris flows, and barrier lakes, leading to a substantial loss of life and damage to the local environment and infrastructure. This study aimed to monitor the status of geologic hazards and vegetation recovery in a post-earthquake disaster area using high-resolution aerial photography from 2008 to 2011, acquired from the Center for Earth Observation and Digital Earth (CEODE), Chinese Academy of Sciences. The distribution and range of hazards were identified in 15 large, representative geologic hazard areas triggered by the Wenchuan earthquake. After conducting an overlay analysis, the variations of these hazards between successive years were analyzed to reflect the geologic hazard development and vegetation recovery. The results showed that in the first year after the Wenchuan earthquake, debris flows occurred frequently with high intensity. Resultantly, with the source material becoming less available and the slope structure stabilizing, the intensity and frequency of debris flows gradually decreased with time. The development rate of debris flows between 2008 and 2011 was 3% per year. The lithology played a dominant role in the formation of debris flows, and the topography and hazard size in the earthquake affected area also had an influence on the debris flow development process. Meanwhile, the overall geologic hazard area decreased at 12% per year, and the vegetation recovery on the landslide mass was 15% to 20% per year between 2008 and 2011. The outcomes of this study provide supporting data for ecological recovery as well as debris flow control and prevention projects in hazard-prone areas.
Highlights
On 12 May 2008, the 8.0-magnitude Wenchuan earthquake occurred in Sichuan Province, China.Its epicenter was located at Yingxiu Town, Wenchuan County, in the east of the Longmenshan FaultZone on the eastern fringe of the Tibetan Plateau
We found that some artificial measures and natural vegetation recovery (Figure 9d) were important for the development of debris flows, such as the hazard prevention projects, ecological restoration projects (Figure 9a,b) and cultivated land reclamation (Figure 9c) in the earthquake affected areas slowed down the progress of debris flow in some extend
Our results demonstrate the possibility of vegetation recovery in earthquake-affected areas even under harsh conditions in some areas, and a positive correlation was found with geological hazard variation (Figure 11)
Summary
On 12 May 2008, the 8.0-magnitude Wenchuan earthquake occurred in Sichuan Province, China.Its epicenter was located at Yingxiu Town, Wenchuan County, in the east of the Longmenshan FaultZone on the eastern fringe of the Tibetan Plateau. On 12 May 2008, the 8.0-magnitude Wenchuan earthquake occurred in Sichuan Province, China. The Wenchuan earthquake caused substantial casualties and financial losses. In response to the massive energy this earthquake released, thousands of geologic failures were triggered such as landslides and debris flows, in addition to the formation of barrier lakes [1,2]. These failures caused enormous damage to the local environment and ecosystem [3], and destabilized numerous hillsides and solid masses, increasing the probability of geologic disasters [4].
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