Mechanical modeling of the Father's day dike intrusion along the east rift zone of Kilauea, Hawaii, constrained from ALOS PALSAR interferometry

On June 17, 2007 a sudden increase in seismicity and rapid changes in surface deformation were detected along the east rift zone of Kilauea volcano. This seismicity was associated with a dike intrusion that aligned with the east rift zone and opened ~2 meters close to Makaopuhi crater by June 20, 2007. The surface deformation caused by the dike intrusion event was captured by ALOS PALSAR interferograms. ALOS uses an L- band signal whose wavelength is about 4 times longer than the C-band, and thus better penetrates dense vegetation, resulting in better interferometric coherence. We formed interferograms from ascending and descending orbits spanning 2007/05/05 - 2007/06/20 and 2007/02/28 - 2007/07/16, respectively. The interferograms indicate maximum line-of-sight shortening (motion towards the satellite) of ~36 cm (ascending) and ~86 cm (descending). Range increase in the summit region, suggesting summit deflation, is ~11 cm (ascending) and ~9 cm (descending). These interferograms were used to model the approximate dimensions of the dike and the deflation source at the summit. The modeled dike is sub parallel to the east rift zone of Kilauea, dips about 81 to 85 degrees to the south, and has a volume increase of ~33×106 m3. The estimated volume decrease at the summit is ~1.7×106 m3.