Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: Geophysical Research Letters
When earthquakes break the Earth’s surface, they create surface ruptures along existing faults that are surrounded by damage zones. These damage zones are made of rocks that have fractured during past earthquakes. It is unclear how this pre-existing damage affects future earthquake ruptures. Some contend that more damage prevents energy from being stored and therefore damage inhibits earthquake rupture. Others argue that damage weakens the fault and leads to more earthquake slip.
Wu et al. [2024] measured the pre-existing damage around the surface rupture of the 2008 Mw7.9 Wenchuan earthquake in China. This unique data set allows a rare comparison between earthquake slip and pre-existing fracture damage. The data show an anti-correlation between the amount of fracture damage and the amount of near-surface slip in the earthquake. In other words, the study shows that, in this earthquake, existing damage inhibited slip.
The study implies that, as a fault accumulates near-surface damage, it may also (assuming the damage does not heal) reduce the amount of near-surface slip that can occur in future earthquakes. This also has implications for assessing hazard as the future slip distribution may be related to the distribution of existing damage – a hypothesis to be tested in additional locations.
Citation: Wu, C. H., Cui, P., Klinger, Y., Tan, X. B., Yi, S. J., & Li, Y. S. (2024). Pre-existing off-fault damage can impede coseismic on-fault slip. Geophysical Research Letters, 51, e2024GL111198. https://doi.org/10.1029/2024GL111198
—Åke Fagereng, Associate Editor, Geophysical Research Letters