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- Title
Partial Ruptures Cannot Explain the Long Recurrence Intervals of Repeating Earthquakes.
- Authors
Turner, A. R.; Hawthorne, J. C.; Cattania, C.
- Abstract
Repeating earthquakes repeatedly rupture the same fault asperities, which are likely loaded to failure by surrounding aseismic slip. However, repeaters occur less often than would be expected if these earthquakes accommodate all of the long‐term slip on the asperities. Here, we assess a possible explanation for this slip discrepancy: partial ruptures. On asperities that are much larger than the nucleation radius, a fraction of the slip could be accommodated by smaller ruptures on the same asperities. We search for partial ruptures of repeating earthquakes in Parkfield using the Northern California earthquakes catalog. We find 3991 individual repeaters which have 4468 partial ruptures. The presence of partial ruptures suggests that the asperities of repeating earthquakes are much larger than the nucleation radius. However, we find that partial ruptures could accommodate only around 25% of the slip on repeating earthquake patches. A 25% increase in the slip budget can explain only a small portion of the long recurrence intervals of repeating earthquakes. Plain Language Summary: Repeating earthquakes happen on the same fault patch over and over again. They are thought to happen on locked patches surrounded by a slowly moving section of the fault. This slow‐moving fault loads the patch to failure. However, the observed slip on the repeating earthquake patches does not match the long‐term slip on the surrounding fault. This slip deficit means the time between earthquakes is longer than expected. We explore the possibility that some of the slip deficit is explained by slip happening in smaller earthquakes ("partial ruptures") in between the time of the larger magnitude repeating earthquakes. We search for partial ruptures in Parkfield, California using the Northern California earthquakes catalog, which contains many well‐located repeating earthquake sequences. We find that partial ruptures could accommodate up to 25% of the slip on repeating earthquake patches, but this is still not enough slip to explain why small repeating earthquakes occur about five times less often than one would expect. Key Points: We search for partial ruptures of repeating earthquakes in Parkfield, CaliforniaWe find partial ruptures, which suggests repeating earthquake asperities are many times larger than the nucleation radiusIncluding partial ruptures in the slip budget does not account for the repeaters' surprisingly long recurrence intervals
- Subjects
CALIFORNIA; EARTHQUAKE magnitude; EARTHQUAKES; PALEOSEISMOLOGY
- Publication
Journal of Geophysical Research. Solid Earth, 2024, Vol 129, Issue 1, p1
- ISSN
2169-9313
- Publication type
Article
- DOI
10.1029/2023JB027870