Slab-derived fluid storage in the crust elucidated by earthquake swarm
Yusuke Mukuhira, Masaoki Uno, Keisuke Yoshida
Abstract
Abstract Slab-derived fluids control crustal dynamics in the subduction zone. However, the slab-derived fluid budget has never been quantified beyond a geophysical and geological spatiotemporal resolution. Here, we target an intense earthquake swarm associated with the M9 Tohoku earthquake, which represented the critical dynamic behavior of slab-derived fluid. The fluid volume involved has been quantified, with a plausible range of 10 6 −10 8 m 3 , by utilizing injection-induced seismicity insights. Comparisons with geological proxies suggest that the estimated fluid volume can be accumulated via supply from the lower crust within 10 2 –10 4 y. Our study demonstrated such amount of aqueous fluid stored at the midcrustal level, which triggered consecutive swarm activity for ~2 y with the Tohoku earthquake, suggesting a possible link between earthquake swarms to M9 class earthquakes (10 3 y cycle) and mineral veins and deposits. This study has shed light on the quantitative understanding of the dynamic slab-derived fluid budget.