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. https://doi.org/10.1029/2021JF006352
—Amy East, Editor in Chief, JGR: Earth Surface