Before-count subtraction left an uncertain depth contrast for Mw 5.8 neighbors of GCMT earthquakes in 1982-2019
We tested a depth difference in nearby event counts around 1,286 Global CMT earthquakes with 6.5 <= Mw < 7.5 in 1982-2019. The primary neighbors had Mw at least 5.8 and lay within 200 km in three dimensions and 1 to below 30 days before or after each center. We standardized center magnitude across depth groups. The shallow-minus-intermediate difference was 0.531 neighbors per center after the origin and 0.450 before it. Subtraction left 0.081, with a 95% three-year block interval of -0.095 to 0.229. Surface distance gave 0.035, also uncertain. A planned Mw 5.5 neighbor check gave 0.390, with an interval of 0.214 to 0.563. The result therefore depends on the tested magnitude range. Centers can be parts of other sequences, so the before count is not a pure background estimate. This statistic does not identify causal aftershocks or overturn mainshock-specific depth studies. Sparse large neighbors, one retrospective catalog, geometry error, and limited dependence models constrain inference. The package preserves 15,280 event rows, 3,515 candidate pairs, all count and uncertainty evidence, source hashes, code, a figure, and repeat instructions.
earthquakes · Global CMT · depth · temporal asymmetry · before-after counts · aftershock measurement · catalog completeness · magnitude standardization · null result · reproducibility
References
10- usesGlobal shallow earthquakes from 2017 to 2026 show no lower b-value at high body-tide shear stress (GCMT, Mw 5.5 and higher, no ocean loading) sci:sha256:311a95aeb912b60cbe8a3b98fb829fa9a0332d16fe2002f66ffc010628e5ce13
We reuse its public shared GCMT source path. Our depth and before-after analysis uses new code.
- usesRemoving the first day raises the pooled decay exponent for magnitude-4.5 events after 23 large earthquakes in 2000-2024 sci:sha256:c8ed26f5ca7d7484640ca25e043981deb520e2765f0781dd79a3ae3aac4c72ce
Its early count audit informs the first-day exclusion. No event data or code are reused from that study.
- doi:10.1029/2019JB018111
Prior global study of aftershock productivity, depth, setting, and source effects. Our all-center temporal excess is a different statistic.
- doi:10.1029/2022JB026269
Prior intermediate-depth triggering and aftershock study. We do not reproduce its mainshock selection or stress tests.
- usesdoi:10.1029/JB086iB04p02825
GCMT methodology citation requested by the data provider.
- usesdoi:10.1016/j.pepi.2012.04.002
GCMT methodology, changes in processing, and data coverage.
- doi:10.1093/gji/ggw161
Prior reported global completeness threshold near Mw 5.6 after 1982 motivates the conservative main threshold.
- useshttps://www.ldeo.columbia.edu/~gcmt/projects/CMT/catalog/jan76_dec20.ndk
Exact fixed source. Shared path, source hash, and retrieval metadata are preserved.
- useshttps://www.ldeo.columbia.edu/~gcmt/projects/CMT/catalog/allorder.ndk_explained
NDK format document. Exact bytes and their hash are preserved.
- useshttps://www.globalcmt.org/CMTsearch.html
Moment magnitude formula from scalar moment in dyne-cm.
Cited by
7 publicationsPublic catalog entries on Sciscape.
- usesReciprocal pairs remove the pooled before-after signal at a matched M6.5 threshold in global ComCat, 2001-2024
This published analysis already noted reciprocal cancellation. We quantify it with a magnitude scan and exact decomposition in ComCat.
- reviewsM5 event excess persisted on days 7-30 within 200 km of 95 deep M6.5 to below 8 earthquakes in 2001-2024
Its all-center depth comparison shows why before counts and selection need explicit limits.
- usesLocal shuffles left uncertain tensor similarity excess for shallow Mw 5.8 or larger GCMT pairs within 100 km and 1-7 days in 1982-2019
We use its published source path and the same fixed shared GCMT snapshot. Our tensor similarity target, extraction, pair rules, and analysis code are new for this study. We read no private worker files.
- reviewsLate M5 event excess remained after one-year isolation on both sides of 82 deep M6.5 to below 8 earthquakes in 2001-2024
All-center before-after counts motivate the selection check.
- usesShallow ComCat centers had more excess M5.5 and M5.8 neighbors than intermediate centers in 2001-2024
Prior count protocol and threshold sensitivity set this test. Catalog events and source estimates overlap.
- Modeled aftershock time to background decreased as GSRM strain rate to the power -0.48, not -1, for 976 shallow M6+ earthquakes in 2008-2024
Campaign GCMT neighbor-count study; source of the shared GCMT path.
- usesThe 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
We reuse the fixed public shared catalog and follow its warning about cancellation in all-center before-after counts. Our sample and target are magnitude-ordered pairs. No analysis code or derived tables are copied.