Abstract
The 2022 eruption at Mauna Loa, Hawai‘i, marked the first extrusive
activity from the volcano after 38 years of quiescence. The eruption was
preceded by several years of seismic unrest in the vicinity of the
volcano’s summit. Characterizing the structure and dynamics of
seismogenic features within Mauna Loa during this pre-eruptive interval
may provide insights into how pre- and co-eruptive processes manifest
seismically at the volcano. In particular, the extent to which
seismicity may be used to forecast the location and timing of future
eruptions is unclear. To address these questions, we construct a catalog
of relocated seismicity on Mauna Loa spanning 2011-2023. Our earthquake
locations image complex, sub-kilometer-scale seismogenic structures in
the caldera and southwest rift zone. We additionally identify a set of
streaks of seismicity in the volcano’s northwest flank that are
radially oriented about the summit. Using a rate-and-state friction
model for earthquake occurrences, we demonstrate that the seismicity
rate in this region can be modeled as a function of the stressing
history caused by magma accumulation beneath the summit. Finally, we
observe a mid-2019 step change in the seismicity rate in the Ka‘oiki
region that may have altered the stress state of the northeast rift zone
in the three years before the eruption. Our observations provide a
framework for interpreting future seismic unrest at Mauna Loa.