Global Positioning System measurements on the island of Hawai`i: 1997 through 2004

Abstract

This report summarizes GPS data and observations collected between 1997 and 2004 on the island of Hawai`i with static surveying and continuously recording instruments. On Kilauea, the long-term deformation field is dominated by steady southeastern velocities of more than 6 cm/year and uplift of about 2 cm/yr at stations on the south flank (with respect to a fixed Pacific Plate). Superimposed on this steady signal are transient displacements associated with magmatic intrusions, earthquakes, and aseismic slip events. The largest of these was the January 30, 1997 dike intrusion and eruption. GPS instruments near Kilauea's summit also record numerous additional short-term fluctuations associated with variations in magma reservoir pressure and geometry. From mid-1997 through 2001, the dominant signal at the summit was deflationary, with maximum subsidence of ~5 cm/yr south of Kilauea caldera. However, inflation of the magma system was observed from late 2001 to May 2002, and from mid-2003 through 2004. The east rift zone eruption continued at the Pu`u `O`o vent during the entire period of this report. Mauna Loa Volcano, which most recently erupted in 1984, showed low rates of contraction across the summit caldera and southeasterly motion of the southeast flank from 1997 until May 2002. Reinflation started abruptly in May 2002. Inflation continued through 2004, but at highly variable rates. Extension rates on a baseline across the summit caldera slowed in October 2002 and increased again starting in mid-2003. The most dramatic change during the inflation period, however, was a significant increase in extension rate on longer baselines, from the northwest to southeast flanks, in July 2004. GPS measurements on Hualalai volcano show no significant motion relative to the Pacific Plate.

Mitigating atmospheric noise for InSAR using a high resolution weather model

“…A second pair for 27 Jan 2003 and 12 Jan 2004 (Figures 2d–2f) spans almost exactly one year and deformation of the summit area of Mauna Loa is now significant, with vertical motions of up to ∼2 cm/yr and horizontal opening of ∼5 cm/yr across the summit measured by GPS [ Miklius et al , 2005]. The atmospheric influence for these acquisitions is lower amplitude, but shows a similar pattern to Figure 2a, although in this case the summits appear as relative lows suggesting a relative increase in high altitude water vapor for the second date.…”

“…The moisture gradient is illustrated in Figure 1 where the color pattern roughly follows the contours of the topography of Mauna Loa, and to a lesser extent, of Mauna Kea and Hualalai. The correlation of the signal with the topography and the absence of any measurable deformation with GPS for Mauna Kea and the distal regions of Mauna Loa [ Miklius et al , 2005] confirm that the pattern is an atmospheric artifact that makes it difficult to resolve the ground motion signal due to inflation under Mauna Loa's summit.…”

Spatiotemporal evolution of dike opening and décollement slip at Kīlauea Volcano, Hawai'i

“…Because of the short duration of the intrusion (about 3 days), no secular velocity is removed or estimated. The maximum secular velocities on Kīlauea are ∼7 cm/yr at coastal sites [ Owen et al , 2000b; Miklius et al , 2005]. One week of accumulated displacement at these typical velocities would amount to 1.3 mm at the fastest sites over the observation period, which is well below the ambient noise level of the kinematic GPS positions.…”

3‐D Modeling of Irregular Volcanic Sources Using Sparsity‐Promoting Inversions of Geodetic Data and Boundary Element Method

“…Simultaneously, the Pu'u O'o–Kupaianaha vents on the east rift zone experienced almost continuous eruptive activities. Starting in late 2003, the summit deformation mode switched from deflation to inflation (Miklius et al, ) due to a new surge of magma supply into shallow magma plumbing system (Poland et al, ). The summit inflation culminated in 2007, followed immediately by a small fissure eruption on the east rift zone (called the Father's Day event) and by a summit eruption in Halemaumau crater in 2008 (Patrick et al, ).…”