Continuous GPS measurements preceding the January 30, 1997 eruption on Kilauea volcano, Hawaii constrain the temporal evolution of deformation associated with dike propagation in unprecedented detail [Owen et al., 2000]. Figure 1 shows the horizontal displacements spanning the intrusion/eruption as determined from a combination of campaign and permanent GPS data. Rift extension due to dike emplacement and contraction due to deflation of a shallow magma chamber beneath the summit of Kilauea are clearly visible in the data. The dike inferred from nonlinear inversion of the GPS data is 2.0 m thick, aligned with the surface fissures, and dips steeply to the south. [Owen et al., 2000] showed that extension between the GPS stations NUPM and KTPM (Figure 2) began nearly coincidentally with the onset of tremor, approximately eight hours before the eruption. NUPM, located north of the ERZ, displaced to the north, while KTPM, and KAEP located south of the ERZ, displaced to the south, consistent with dike intrusion into the rift. The extension began rapidly and then slowed with time, even before the onset of the eruption. Segall, 2001 showed that the displacement time history places strong constraints on the growth of the dike prior to and during the eruption.

FIGURE 1:  Horizontal displacements spanning an intrusion/eruption of a dike on Kilauea volcano, as monitored by continuous GPS.

FIGURE 2:  Extension between the GPS stations NUPM and KTPM began nearly coincidentally with the onset of tremor, approximately eight hours before the eruption.

Owen, S., P. Segall, M. Lisowski, M. Murray, M. Bevis, and J. Foster, The January 30, 1997 eruptive event on Kilauea Volcano, Hawaii, as monitored by continuous GPS, Geophys. Res. Lett., 27, 2,757-2,760, 2000.

Segall, P. Cervelli , P., Owen S, Lisowski, M., Miklius, A., Constraints on dike propagation from continuous GPS measurements, Jour. Geophys. Res., in press, 2001.

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