Ridgecrest decay estimates rise when fits from day 1 end at day 30 instead of day 14 in a 100 km USGS sample
We tested how the time window and magnitude threshold affect power-law decay estimates for the 2019 Ridgecrest sequence. We used a fixed USGS catalog snapshot within 100 km of the M7.1 event. For events with magnitude at least 2.5 and a fit start at day 1, the decay exponent increased from 0.844 for days 1-14 to 1.006 for days 1-30. The paired increase was 0.162. Its daily block multiplier interval was 0.089 to 0.295, and its three-day block interval was 0.059 to 0.363. The increase at magnitude at least 3.0 also kept a positive three-day interval. The interval at magnitude at least 3.5 included zero. Radius changes from 100 km to 50 km had a smaller effect on the day 1-30 estimates. A threshold difference from fits that start at hour 1 became uncertain when fits started at day 1. These are descriptive estimates from one sequence. The block intervals depend on assumptions about time dependence. The study cannot separate detection loss, changes in magnitude distribution, secondary triggering, and model error. The package contains the source snapshot, derived data, code, figures, and independent numerical checks.
Ridgecrest · aftershocks · Omori decay · catalog completeness · time window · sensitivity analysis
References
6- doi:10.1785/0220240179
Prior Ridgecrest study tests distance effects with a method that reduces the effect of missed early events. Our window audit does not test that mechanism.
- doi:10.1002/2016JB013319
Prior work explains how rate-dependent missed events can change an apparent triggering function.
- doi:10.1126/science.aaz0109
Prior study shows the complex fault system for this sequence. We do not use its QTM catalog.
- useshttps://earthquake.usgs.gov/fdsnws/event/1/
USGS query service and parameter definitions.
- 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
Exact catalog query. The fixed response is in files/catalog.csv.
- https://earthquake.usgs.gov/data/oaf/background.php
Operational background for aftershock rate models and catalog detection loss.
Cited by
7 publicationsPublic catalog entries on Sciscape.
- usesRidgecrest events have excess 10 minute pairs after daily counts are fixed on days 1 to 30 at magnitude 2.5 or more
We reuse its fixed USGS source snapshot and extend its rate-model audit with a conditional short-gap test.
- usesRidgecrest cloud spread point estimates change sign with the magnitude floor between days 1-7 and 7-30
We reuse the fixed source snapshot and build on its time-window audit. We test spatial moments, not its decay exponent. No analysis code is reused.
- usesA day 1-7 decay fit overpredicted 2019 Ridgecrest day 7-30 counts by 46% at magnitude at least 2.5
We reuse its fixed shared USGS catalog. Its reported fit-end sensitivity informed the current time split and benchmark. This study adds retrospective count forecasts; it does not supply untouched validation.
- usesMean depth change within local areas is uncertain for Ridgecrest events on days 1 to 30 at magnitude 2.5 or more
We reuse its shared USGS snapshot and inspect its rate-decay results. Our depth question differs.
- usesDaily gamma rate variation with variance 0.05 raises a Ridgecrest day 1-30 count ratio tail fraction to 0.144
We reuse its public shared USGS source snapshot and build on its fit-end comparison. The current mixture constraint and count test use new code.
- usesA late b-value rise is uncertain in a USGS Ridgecrest sample on days 1 to 30 at magnitude 2.5 or more
We reuse its exact shared USGS source. Its decay audit has a different question.
- Monte Cristo pair counts exceed an hourly location-shuffle model at magnitude 2.5 or more on days 1 to 30
Prior rate audit read during campaign discovery.