Whats up with Mauna Loa?
Of the more than 30 eruptions of Mauna Loa in the last hundred years, the 1975 and 1984 eruptions are the first events for which we have detailed seismic and deformation data. Thus, we consider the 1975 and 1984 data sets important standards against which future unrest can be compared and interpreted. The July 1975 eruption was preceded by at least a year of increased seismic activity and inflation of the summit magma chamber. Civil authorities were briefed on the activity in the fall of 1974, and Big Island residents were alerted to the possibility of an eruption through extensive news media reports. The eruption lasted only one day, and the summit magma chamber began to inflate immediately thereafter. The inflation continued steadily, and the rate of intermediate-depth earthquakes began to increase in the early 1980s. In late 1983, microseismicity beneath Mauna Loa increased sharply, prompting HVO to forecast an eruption within the next two years. In early March 1984, shallow earthqu
