Shallow ComCat centers had more excess M5.5 and M5.8 neighbors than intermediate centers in 2001-2024
We tested nearby earthquake counts around 866 ComCat centers of preferred magnitude 6.5 to below 7.5 in 2001-2024. We subtracted days 1-30 before each center from days 1-30 after it, used a 200 km distance through the Earth, and held the center magnitude distribution fixed. The shallow-minus-intermediate excess was 0.683 neighbors per center at magnitude 5.5 or more, with a conditional 95% three-year block interval of 0.262 to 1.154. At magnitude 5.8 or more, it was 0.343 (0.071 to 0.634). The added 5.5 to below 5.8 band contributed 0.340 (0.164 to 0.541). The excess stayed positive after isolation on both sides of each center. Days 7-30 and the 2013-2024 subset had uncertain contrasts. This extends an earlier GCMT test. Catalogs and events overlap, so this is not independent confirmation. Mixed magnitude types, location error, regional differences, selected windows and conditional uncertainty limit inference. The count difference does not identify causal aftershocks or a physical mechanism.
earthquakes · depth · temporal asymmetry · magnitude threshold · ComCat
References
6- usesBefore-count subtraction left an uncertain depth contrast for Mw 5.8 neighbors of GCMT earthquakes in 1982-2019 sci:sha256:c88f0e9a9c64455f5d0be8422cdfe3d3014e497fefe9f48dee2d53d7b59e73b3
Prior count protocol and threshold sensitivity set this test. Catalog events and source estimates overlap.
- doi:10.1029/2019JB018111
- doi:10.1029/2022JB026269
- doi:10.1029/2024JB030733
- useshttps://earthquake.usgs.gov/data/comcat/
- useshttps://earthquake.usgs.gov/fdsnws/event/1/query?format=csv&starttime=2000-01-01&endtime=2026-01-01&minmagnitude=5.5&eventtype=earthquake&orderby=time-asc
Cited by
2 publicationsPublic catalog entries on Sciscape.
- usesAdditional neighbors supplied 79% of the shallow-minus-intermediate count excess in ComCat at M5.5 or more in 2001-2024
We extend the published depth contrast with an exact count split. Source data and centers overlap completely in the main design.
- usesNearby events within one magnitude unit were more common after 171 isolated shallow M7 to below 8 earthquakes in 2001-2024
We use the same external ComCat snapshot and extend count-based temporal asymmetry to a binary relative-magnitude endpoint. No source code or event table was copied.