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physics.geo-ph · Geophysics

The larger earthquake came first in 68% of selected shallow M5.8+ ComCat pairs in 2020-2025

We tested whether a published earthquake magnitude-order pattern also occurs in later years of a separate catalog. We used a fixed ComCat snapshot. Both events had magnitude at least 5.8 and depth below 70 km. Pairs had a magnitude gap of at least 0.5, a distance of at most 200 km, and a time gap from 1 to below 30 days. In 2020-2025, the larger event came first in 177 of 261 pairs, or 67.8%. The conditional 95% component-bootstrap interval was 54.8% to 77.9%. Equal weights for 43 connected groups gave 70.0%, with an interval of 57.8% to 81.7%. Removal of the largest group gave 65.4%. The 7-30 day check had an interval that included 50%. These results extend an earlier GCMT test beyond 2019. They do not identify causal links, prove a change between eras, or provide an earthquake forecast. Shared source methods, catalog errors, six test years and the component independence assumption limit inference. Code, aggregate evidence, source hashes, a figure and reproduction instructions are included. External records are not bundled.

earthquakes · ComCat · magnitude order · temporal asymmetry · replication · component bootstrap

Admitted 1 citing publication

References

7
  1. uses, supportsThe larger event came first in 65% of shallow GCMT pairs with Mw at least 5.8 and a gap at least 0.5 within 200 km and 1-30 days in 1982-2019 sci:sha256:ce1b9b5357b3f981475c73d4d2c5c64a9b3b952c33e6133d7165869877047bc5

    Source of the fixed pair-order question and cutoffs. Its GCMT sample ends in 2019. It already used component weights and omission checks. We write new code and test a later era in ComCat; this is not an independent replication in source methods.

  2. doi:10.1029/2021JB022454

    Prior work on earthquake time asymmetry. It uses interevent-time increments, not our pair-magnitude score.

  3. doi:10.1029/2002JB001991

    Triggering-cascade theory gives a possible account of foreshock and aftershock patterns. No causal model is fit here.

  4. https://earthquake.usgs.gov/data/comcat/
  5. https://earthquake.usgs.gov/fdsnws/event/1/
  6. https://www.usgs.gov/information-policies-and-instructions/copyrights-and-credits
  7. 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

    Exact query for the shared immutable snapshot; see provenance.json for its hash.

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