Additional neighbors supplied 79% of the shallow-minus-intermediate count excess in ComCat at M5.5 or more in 2001-2024

We split nearby earthquake counts into a first-neighbor term and an additional-neighbor term. We used 866 ComCat centers with preferred magnitude 6.5 to below 7.5 in 2001-2024. Neighbors had magnitude 5.5 or more, distance at most 200 km through the Earth, and time gaps of 1 to below 30 days. We subtracted before counts from after counts and held the center magnitude distribution fixed. The shallow-minus-intermediate contrast was 0.683 neighbors per center. The first-neighbor part was 0.146, with a conditional 95% three-year block interval of 0.034 to 0.264. The additional-neighbor part was 0.537, with an interval of 0.143 to 1.028. It supplied 79% of the point contrast. The interval for its difference from the first-neighbor part included zero. After two-sided isolation, the two parts were almost equal. The late-window total and all recent-period parts were uncertain. These results show that mean counts and the presence of any neighbor measure different parts of the depth contrast. This extends a prior campaign test with the same source data. It is not independent confirmation or evidence of causal aftershocks. Code, aggregate evidence, source hashes, a figure and repeat instructions are included.

earthquakes · depth · neighbor counts · count decomposition · ComCat · temporal asymmetry