3D seismic velocity structure of Hawaii from onshore-offshore tomography


Principal Investigators:

Juli Morgan (Rice University)

Colin Zelt (Rice University)


Paul Okubo (USGS - HVO)

Graduate Students:

Jaewoo Park

Undergraduate Students:

Leo Peters

Nathan Benesh

Funding Sources:

NSF Ocean Sciences (MG&G)


Airgun shot data from a 1998 multichannel seismic survey conducted offshore Kilauea and Mauna Loa volcanoes in Hawaii were recorded by the permanent on-land seismic array maintained by the Hawaiian Volcanoes Observatory (Figure 1).  Raypaths for extracted arrivals over the survey region sample large volumes of active volcanoes and the underlying oceanic crust, with the densest coverage near the onshore-offshore transition.  The unprecedented 3D coverage has provided a unique opportunity to image the 3D velocity structure of the active Hawaiian volcanoes of Mauna Loa, Kilauea, and the submarine Loihi.  (More information about the survey geometry and data quality can be found HERE. )



Figure 1


Using first-arrival seismic tomography, we have imaged broad regions of high seismic velocities correlated with magma cumulates beneath the volcano summits and rift zones (Figure 2 - depth slices through the velocity model).



Figure 2                                                                                              Figure 3


Previously known high velocity bodies beneath and seaward of Kilauea's summit (Figure 3, A-A'), and beneath Kilauea's East Rift Zone (Figure 3, B-B') are imaged with improved resolution.  An elongate region of high velocities occurs within the oceanic crust parallel to Loihi's rift zones (Figure 3, C-C'). Also, an extensive buried rift zone now can be recognized within Mauna Loa's southeast flank (Figure 2, Figure 3, B-B' and C-C').  Low velocity anomalies coincide with the seaward dipping Hilina and Kao'iki fault zones that bracket Kilauea's summit, and the offshore flanks of Kilauea and Mauna Loa (Figure 3, A-A' and C-C').


We are presently carrying out a joint inversion of active-source and earthquake data which will expand the coverage of the onshore portions of the volcanoes, in particular, Mauna Loa.  The resulting velocity model will be coupled with gravity and geodetic data to provide a better understanding of the dynamics and evolution of active Hawaiian volcanoes.



Park, J., Morgan, J.K., Zelt, C.A., Okubo, P.B., Peters, L., and Benesh, N., in revision, Comparative velocity structure of active Hwaiian volcanoes from 3-D onshore-offshore seismic tomography, Earth Planet. Sci. Lett.

Morgan, J.K., Park, J., Zelt, C.A., Okubo, P.B., and Smith, J.R., in preparation, Mauna Loa's hidden edifice: Rift zone abandonment and reconfiguration in Hawaii, Science.



Park, J., Morgan, J.K., Zelt, C.A., and Okubo, P. 2006, New evidence for deep magma migration in Hawaii: Seismic tomography of Kilauea  and Loihi volcanoes, AGU, 87, Fall Meet. Suppl., Abstract V23D-0653.

Park, J., J.K. Morgan, C.A. Zelt, and P.G. Okubo, 2005, Buried rift zones and seamounts in Hawaii: Implications for volcanotectonics, EOS Trans. AGU, 86, Fall Meet. Suppl., Abstract V23C-05.

Morgan, J.K., C.A. Zelt, J. Park, N. Benesh, L. Peters, and P. Okubo, 2004, Imaging the 3D volcanic structure of Hawaiian volcanoes: Onshore-offshore seismic investigations of the Island of Hawaii, EOS Trans. AGU, 85, West. Pac. Geophys. Meet. Suppl., Abstract S43A-82.

Park, J., L. Peters, J.K. Morgan, C.A. Zelt, N. Benesh, and P. Okubo, 2003, 3D onshore-offshore seismic investigation of Kilauea volcano, HI, EOS Trans. AGU, 84, Fall Meet. Suppl., Abstract V22C-0599.

Peters, L., Morgan, J., and Zelt, C., 2001, Constraints on the 3D velocity structure of the Kilauea volcano: Analysis of on-shore-offshore traveltime through forward modeling, EOS Trans. AGU, 82, Fall Meet. Suppl., 838.


Page last modified: 29-Dec-2006