Ground deformation associated with the 1975 magnitude-7.2 earthquake and resulting changes in activity of Kilauea Volcano, Hawaii

87:6364 A singleforce model for the 1975 Kalapana, Hawaii, earthquake

“…Observed horizontal extensions increased steadily seaward over the south flank, from about 1 m at the summit to 8 m at the coast; again, the maximum extension was in the vicinity of Halape beach [Lipman et al, 1985]. Ground cracking was observed along 25 km of, the Hilina fault system, with a maximum displacement of about 1.5 m downdropped to the south, which is consistent with the overall sense of -motion on the Hilina faults.…”

“…An excellent observational summary of the earthquake was proVided by Tilling et al [1976], and deformations have been discussed by Lipman et al [1985]. The accompanying tsunami .has been described by Hatori [1976] and Cox [1980].…”

“…Previous studies of the earthquake propose either that the event was triggered by a growing compressional stress over the south flank due to steady magma injection into the east rift zone [Ando, 1979;Furumoto and Kovach;1979;Crosson and Endo, 1981] or that the driving force was the inherent gravitational instability of the poorly consolidated and growing volcanic pile [Nakamura, 1980]. The prevolcanic oceanic crust, located at about 7 km depth and lubricated by an accumulation of deep-sea sediments, has been suggested as the slide plane [Furumoto and Kovach, 1978;Crosson and Endo, 1982;Lipman et al, 1985]. Swanson et al [1976] noted that the entire south flank of Kilauea is mobile and had undergone extensions of several meters in the la.st century previous to the 1975 earthquake.…”

“…Kanamori and Given [1982] noted that the Love waves had a two-lobed radiation pattern which could not be explained by a double-couple source and that the Love wave pattern was rotated 90° Figure 2. Map of the observed horizontal (vectors) and vertical (dashed contours) displacements associated with the Kalapana earthquake, adapted from Lipman et al [1985].…”

A single‐force model for the 1975 Kalapana, Hawaii, Earthquake

“…In this view, the Hilina fault system .is a s_hallow feature that bounds large superficial landslide .blocks, which are a readjustment to a more deepseated slippage. However, Lipman et al [1985] proposed that the Hilina faults become listric at depth and join with the . volcano-crust interface, providing.…”