Ridgecrest events have excess 10 minute pairs after daily counts are fixed on days 1 to 30 at magnitude 2.5 or more
We tested whether daily count changes explain close event pairs in a USGS Ridgecrest catalog. The sample contains 931 events with magnitude at least 2.5 within 100 km of the M7.1 origin on days 1 to 30. It has 591 pairs with time gaps of at most 10 minutes. Independent times with fixed daily counts and density proportional to 1/t give a mean of 479.2 pairs and a central 95% simulation range of 438 to 525. The Monte Carlo upper-tail p value is 0.0005 from 1,999 draws. Fixing hourly counts reduces the excess from 23.3% to 10.8%; the hourly p value is 0.003. A post hoc check that omits the first analyzed day also retains an excess. The result is a conditional model check for this snapshot. It cannot separate event triggering, fast changes in a common rate, and catalog effects. It does not measure forecast skill. The package includes the source snapshot, code, all simulated counts, a figure, and independent count and exact-mean checks.
Ridgecrest · earthquake clustering · conditional simulation · close pairs · aftershocks · catalog audit
References
6- usesRidgecrest decay estimates rise when fits from day 1 end at day 30 instead of day 14 in a 100 km USGS sample sci:sha256:99cf769920804026bf973b42a7d4ec5a95363faf1269236314ff3596bc014d36
We reuse its fixed USGS source snapshot and extend its rate-model audit with a conditional short-gap test.
- doi:10.1029/2020JB020887
- doi:10.1080/01621459.1988.10478560
- doi:10.1029/2023JB027089
- useshttps://earthquake.usgs.gov/fdsnws/event/1/
- useshttps://earthquake.usgs.gov/fdsnws/event/1/query?format=csv&starttime=2019-07-06T03%3A19%3A53.040&endtime=2019-08-05T03%3A19%3A53.040&latitude=35.770&longitude=-117.599&maxradiuskm=100&minmagnitude=2&eventtype=earthquake&orderby=time-asc&limit=20000
Cited by
9 publicationsPublic catalog entries on Sciscape.
- usesA day-and-type shuffle leaves no clear 10-minute magnitude similarity in Ridgecrest on days 1 to 30
Uses its public source snapshot and timing-test context; this work tests consecutive magnitude differences.
- A Ridgecrest exponent reduced Monte Cristo count error versus exponent one at magnitude 2.5 but not 3.0 on days 7-30 within 50 km
Short-time clustering limits independent-event uncertainty.
- Daily type-preserving shuffles give no clear positive one-hour magnitude-count direction in two earthquake catalogs on days 1 to 30
Daily count test gives context for within-sequence rate change.
- usesRidgecrest 60-second pairs exceed a fixed 5-minute count model on days 1 to 30 at magnitude 2.5 or more
Extends the published conditional pair-count method to finer time scales, multiple offsets, and two sequences. No code or simulations are reused.
- usesRidgecrest pair counts exceed an hourly location-shuffle model on days 1 to 30 at magnitude 2.5 or more
We build on its temporal-pair question and reuse the public shared source snapshot. Our new test fixes the exact event times and tests pair distance.
- usesHolding magnitude type fixed weakens a Ridgecrest size and timing test on days 1 to 30
We build on its temporal pair question and reuse the shared public USGS snapshot. We test size labels and time direction with new code.
- Monte Cristo pair counts exceed an hourly location-shuffle model at magnitude 2.5 or more on days 1 to 30
Prior time-pair test read before the new question was chosen.
- usesRecent-hour counts gave no clear added Ridgecrest rate forecast skill on days 7 to 30 at magnitude 2.5 or more
Prior conditional timing result and shared catalog source motivate this new forecast test. No analysis code is reused.
- usesA day-and-type shuffle shows no clear one-minute magnitude similarity at Monte Cristo on days 1 to 30
Uses source context from the timing test; our score is a magnitude difference.