Volcano‐earthquake interaction at Mauna Loa volcano, Hawaii

Abstract

[1] The activity at Mauna Loa volcano, Hawaii, is characterized by eruptive fissures that propagate into the Southwest Rift Zone (SWRZ) or into the Northeast Rift Zone (NERZ) and by large earthquakes at the basal decollement fault. In this paper we examine the historic eruption and earthquake catalogues, and we test the hypothesis that the events are interconnected in time and space. Earthquakes in the Kaoiki area occur in sequence with eruptions from the NERZ, and earthquakes in the Kona and Hilea areas occur in sequence with eruptions from the SWRZ. Using three-dimensional numerical models, we demonstrate that elastic stress transfer can explain the observed volcano-earthquake interaction. We examine stress changes due to typical intrusions and earthquakes. We find that intrusions change the Coulomb failure stress along the decollement fault so that NERZ intrusions encourage Kaoiki earthquakes and SWRZ intrusions encourage Kona and Hilea earthquakes. On the other hand, earthquakes decompress the magma chamber and unclamp part of the Mauna Loa rift zone, i.e., Kaoiki earthquakes encourage NERZ intrusions, whereas Kona and Hilea earthquakes encourage SWRZ intrusions. We discuss how changes of the static stress field affect the occurrence of earthquakes as well as the occurrence, location, and volume of dikes and of associated eruptions and also the lava composition and fumarolic activity.

Volcano‐tectonic implications of 3‐D velocity structures derived from joint active and passive source tomography of the island of Hawaii

“…Although the average perturbations of the hypocentral relocation are relatively small, we found that some earthquake clusters, previously addressed by various studies [Klein et al, 1987;Denlinger and Okubo, 1995;Gillard et al, 1996;Endo, 1985;Walter and Amelung, 2006] have spatial correlations with the resolved velocity structures and connections with geodetic flank motions (Figure 11). We infer that the relationships between seismicity and volcanic structure might provide us with a better understanding of volcano-tectonic processes.…”

“…However, seismic activity is substantial within and beneath the southeast flank of Mauna Loa (Figure 11), particularly in the low-velocity regions referred to as the Kao'iki and Hilea seismic zones [Endo, 1985]. The deeper earthquakes in these seismic zones (9 -13 km) form a background of seismicity, with larger earthquake magnitude, in contrast to the shallow seismic events [Thurber et al, 1989;Walter and Amelung, 2006]. This observation suggests that the deep earthquakes have a volcano-tectonic rather than magmatic origin [Koyanagi et al, 1988[Koyanagi et al, , 1989Jackson et al, 1992], i.e., due to seaward sliding of Mauna Loa's volcanic edifice over a basal decollement zone [Endo, 1985].…”

“…[54] The deeper ($10 km) earthquakes around the western flank of Mauna Loa (Figures 9d and 11) lie in an area referred to as the Kona seismic zone [Walter and Amelung, 2006;Wolfe et al, 2004], characterized by low-angle, west directed thrust earthquakes. This focal mechanism is consistent with seaward slip of the western flank away from Mauna Loa's SWRZ, probably along a basal decollement, similar to that modeled for the southeastern flank [Walter and Amelung, 2006].…”

SAR Data Analysis in Solid Earth Geophysics: From Science to Risk Management

“…The stress variation analysis has been successfully adopted also in a volcanic context, to study the interaction among sources of different nature: magma chambers, dykes, faults [67][68] [50]. Though these analyses are always conducted a posteriori, after the event occurrence, they contribute to support the stress-transfer reliability.…”

InSAR-Based Mapping to Support Decision-Making after an Earthquake

“…In the case of volcanic triggering by unclamping of the magmatic chamber, variations of 0.1 bar have been demonstrated to be influential on the eruptive processes, while the lower value (0.01 bar) is a reasonable threshold to infer a moderate influence from a conservative hazard estimation point of view [58][59][60][61]. Note that a global agreement about the exact values of stress separating triggering from not triggering does not exist and therefore the exact values for our intervals were determined by expert judgment based on our experience and bibliography.…”