A Moment-bounded Epidemic type aftershock sequence model (ETAS)

Kelian Dascher-Cousineau, & Rishav Mallick

Submitted August 30, 2026, SCEC Contribution #15570, 2026 SCEC Annual Meeting Poster #207

We present a moment-bounded spatiotemporal epidemic-type aftershock sequence (ETAS) model. Tectonic loading replenishes the available moment; earthquakes locally deplete it. The evolving and spatially variable moment budget constrains the maximum earthquake size. Our principle here is to faithfully model earthquake occurrence at the scale of geophysical measurements. We handle sub-scale processes empirically with ETAS and system-scale processes physically with rupture constraints. Efficient sampling lets us explore the parameter space with hundred-million-event sequence. In addition to eliminating many of ETAS’s statistical pathologies, the simple constraint produces a rich set of features, many of which are documented in nature: quasi-periodic recurrence of system-spanning events, rare explosive (supercritical) precursory activity, b-value fluctuations, swarms, and corona-like quiescence after great events. This phenomenology is tied to the largest events, whose moment depletes the budget enough to shift the maximum-magnitude. The long-run maximum magnitude that emerges represents a quantifiable tradeoff between the tectonic loading rate and the branching process. Finally, we outline strategies for inference, for assimilating geodetic and geological measurements, and for integrating rupture physics into this tested-statistical framework.

Key Words
ETAS, Precursor, Earthquake Cycle, Geodesy, Slip Rate, Moment

Citation
Dascher-Cousineau, K., & Mallick, R. (2026, 08). A Moment-bounded Epidemic type aftershock sequence model (ETAS). Poster Presentation at 2026 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Forecasting and Predictability (EFP)