Spatiotemporal heterogeneity of <i>b</i> values revealed by a data-driven approach for the 17 June 2019 <i>M</i><sub>S</sub> 6.0 Changning earthquake sequence, Sichuan, China

Abstract. The spatiotemporal heterogeneity of b values has great potential for helping in understanding the seismogenic process and assessing seismic hazard. However, there is still much controversy about whether it exists or not, an important reason that choice subjective parameters eroded foundations research. To overcome this problem, we used a recently developed non-parametric method based on data-driven concept to calculate values. major steps include (1) performing large number Voronoi tessellations Bayesian information criterion (BIC) value calculation, selecting optimal models study area, (2) using ensemble median (Q2) absolute deviation (MAD) represent final its uncertainty. We investigated variations before after 2019 Changning MS=6.0 earthquake Sichuan Basin, China. results reveal spatial volume with low pre-mainshock near mainshock source region, size corresponds roughly rupture area mainshock. anomalously high distributed NW direction epicenter were interpreted be related fluid invasion. decreases during aftershock sequence along occurrences several strong aftershocks imply could indicator stress state. In addition, found although distribution characteristics obtained from different methods investigation are qualitatively consistent, they differ significantly terms their specific values, suggesting best way heterogeneous pattern joint dimension space-time rather than separately time space. Overall, our emphasizes importance b-value studies hazards.