The Rupture Process of the 2018 M-w 6.9 Hawai'i Earthquake as Imaged by a Genetic Algorithm-Based Back-Projection Technique

Abstract

An episode of unrest began at Klauea in April 2018 that produced both significant volcanic output and high rates of seismicity, including a M-w 6.9 earthquake on 4 May 2018. In this study, we image the rupture process of this earthquake using a genetic algorithm-based back-projection technique. The dominant feature of the earthquake is a slowly propagating western rupture, which shares similar characteristics with the region's largest recorded event in 1975 (M-w 7.7). The location of this western segment suggests that small asperities on this section of the decollement that frequently fail as slow slip events may achieve seismic slip rates when rupture is initiated on adjacent sections of the fault. Given the interaction between volcanic and seismic activity in this region, imaging the rupture properties of these events can improve our understanding of future geologic hazards in this region. Plain Language Summary Voluminous lava flows and explosive eruptions at Klauea Volcano in Hawai?i have captured the attention of the media and general public during the past year. In the early stages of this volcanic activity, a magnitude 6.9 earthquake occurred beneath the south flank of Klauea, which was the second largest earthquake recorded by modern instrumentation in this region. The research presented in the manuscript uses a novel source imaging technique to study the fine-scale spatiotemporal evolution of the rupture that produced this event. The details of this rupture provide new insight into the relationship between fault properties, background seismicity, slow slip events, and major earthquakes in volcanic settings.