A 3D Spherical ETAS Model: A Case Study in the Alaska-Aleutian Region

This study proposes a hypocentral version of the spherical epidemic-type aftershock sequence (ETAS) model by incorporating hypocentral depth information into the spherical ETAS model and applies it to earthquake data from the Alaska-Aleutian area. We validate the model using the stochastic reconstruction techniques and illustrate the rationale behind selecting the spatial probability density function. Subsequently, we estimate the 3D spatial variations of the background and offspring seismicity in the study region, revealing that the majority of clusters are located in shallow regions. We also identify an apparent temporal change in the background seismicity caused by artificial effects. Compared with the 3D-ETAS and spherical version of the epidemic-type aftershock sequence (SETAS) models, the new 3D-SETAS model provides a better description of 3D seismicity in high-latitude regions globally.