Images showing sediment remobilized after the 2008 Wenchuan earthquake, China.
Images showing sediment remobilized after the 2008 Wenchuan earthquake, China. They show examples of landslides and debris flows that moved sediment down-slope after the earthquake. These images were produced using imagery from Google Earth and Maxar Technologies. Credit: Francis et al. [2022], Figure 2a-d
Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: Journal of Geophysical Research: Earth Surface

Large earth-surface disturbances such as an earthquake, volcanic eruption, or dam failure can profoundly affect the rates and processes of sediment movement across a landscape. Understanding how sedimentary systems respond to such large-scale perturbations can help scientists and managers determine how to plan for emergency response, managing or rebuilding infrastructure (such as reservoirs), and ecosystem recovery.

Francis et al. [2022] tracked sedimentary processes after the Mw 7.9 2008 Wenchuan earthquake, China. Using imagery, channel surveys, and a simulation exercise, the authors developed a sediment budget—an accounting of sediment sources, transported quantities, and deposited amounts—spanning 10 years after the earthquake. They determined that the Wenchuan earthquake mobilized 531 million tons of sediment. A decade later, in 2018, the great majority of that sediment (88%, 470 million tons) remained on local hillslopes. Debris flows were the primary process that mobilized the other 12% of earthquake-generated sediment; in 10 years just 7% of the sediment reached the Min Jiang, the major river draining the affected region.

These findings and other, related studies indicate that time scales of landscape recovery after a major seismic disturbance are long, likely lasting well over a decade. Debris flows may continue to move earthquake-produced sediment downslope to rivers even long after the earthquake, with potential consequences for downstream hazards, infrastructure, and ecosystems.

Citation: Francis, O., Fan, X., Hales, T., Hobley, D., Xu, Q., & Huang, R. (2022). The fate of sediment after a large earthquake. Journal of Geophysical Research: Earth Surface, 127, e2021JF006352.

—Amy East, Editor in Chief, JGR: Earth Surface

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