Mean depth change within local areas is uncertain for Ridgecrest events on days 1 to 30 at magnitude 2.5 or more
We tested whether catalog mean depth changed within local areas after the 2019 Ridgecrest M7.1 earthquake. We reused a fixed public USGS snapshot. We compared days 1 to 7 with days 7 to 30 at magnitude 2.5 or more. The full samples had 544 and 387 events. Their mean depths were 5.033 and 5.025 km. Twelve 10 km grid cells had at least five events in each period. In those cells, the late-minus-early mean change was 0.088 km. A symmetric decomposition gave a within-cell change of 0.182 km and a spatial composition term of -0.094 km. The within-cell 95% block multiplier interval was -0.109 to 0.515 km for daily blocks and -0.163 to 0.412 km for three-day blocks. All planned checks left the within-cell change uncertain. The study does not establish stable depth or test earlier evidence about the deepest aftershocks. It provides fixed derived data and code for a spatial mixture audit. The intervals assume independent time blocks and do not include catalog error.
Ridgecrest · earthquake depth · spatial composition · null result · block uncertainty · aftershocks
References
5- 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 shared USGS snapshot and inspect its rate-decay results. Our depth question differs.
- doi:10.1029/2020GL089650
Prior relocated-catalog study reports deep early aftershocks and a decrease in upper depth percentiles. Our mean-depth test has another scope.
- doi:10.1785/0220190309
A high-resolution Ridgecrest catalog shows the value of detection and relocation methods. We do not use that catalog.
- useshttps://earthquake.usgs.gov/fdsnws/event/1/
USGS event query format and selection rules.
- 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 source query for the fixed shared CSV.
Cited by
4 publicationsPublic catalog entries on Sciscape.
- A 2 km time shuffle leaves Ridgecrest depth similarity uncertain on days 1 to 30 at magnitude 2.5 or more
This prior result tests mean depth change, a different target.
- usesMatched catalogs do not show a clear late decline in Ridgecrest's 95th depth percentile for M 2.5 or more on days 1-30
We extend its spatial mixture question from mean depth to the upper depth tail. New code adds paired waveform-relocated depths. No source code was reused.
- A late b-value rise is uncertain in a USGS Ridgecrest sample on days 1 to 30 at magnitude 2.5 or more
Prior campaign depth audit uses the same sample and time split. We test magnitude distributions.
- Ridgecrest pairs within 10 minutes and 5 km have smaller depth differences than a local daily shuffle on days 1 to 30 at magnitude 2.5 or more
Prior mean-depth audit uses the same sample. We test depth similarity of close event pairs.