Rowan, Linda R. and Clayton, Robert W.
The three-dimensional structure of Kilauea Volcano, Hawaii, from travel time tomography.
Journal of Geophysical Research B, 98
- Published Version
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A linear, travel time tomography study of the most active shield volcano of the world, Kilauea Volcano, Hawaii, was undertaken to determine the lateral heterogeneities produced by its intricate magmatic and tectonic environment. Kilauea provides an ideal setting to do tomography because of its dense seismograph array and many local earthquakes that allow excellent ray coverage of complex subsurface features. Local P wave data from ∼ 12,295 events were inverted using a one-dimensional layered velocity model. Inversions were done for two cell sizes (5×5×5 km and 1×1×1 km) to resolve structural regions on different length scales. This study provided a view of the average velocity variations relative to a one-dimensional velocity model. Analysis and interpretation of the tomographic images allowed us to infer the following model. The main shallow magma reservoir is delineated by a slow velocity region southeast of the summit from 0 to 2 km depth. There is a distinct high velocity region centered northwest of the summit from 0 to 2 km depth that represents a cap of dense, intrusive dikes surrounding the magma chamber. We suggest that the shallow reservoir is a narrow, compartmentalized region of sills and dikes, centered just south-southeast of Halemaumau caldera. Below the main reservoir, the summit is imaged as a slightly fast region from 5 to 10 km in the coarse model indicating that the main conduit is structurally defined by an intrusive dike complex until about 10 km. The rift zones of Kilauea are imaged as major, high velocity entities, widening to the south with depth until 6 km. These fast anomalies are related to the sheeted dike complexes along the rifts. On a finer scale, slow anomalies suggest the presence of magma pockets centered at 0–2 km depth beneath Mauna Ulu, Makaopuhi and Puu Oo, along the east rift zone (ERZ). Two significant high velocity regions along the lower ERZ near Kalalua and Kaliu are inferred to represent intrusive barriers to magma injection along the shallow (0–4 km) ERZ conduit. The southwest rift zone may have an intrusive barrier related to a high velocity region just southwest of Mauna Iki. The Hilina and Kaoiki fault zones are imaged as slow features at shallow depths (< 5 km) related to the open fractures and scarps along the normal faults. The Koae fault system is imaged as a slightly fast shallow structure (< 6 km) possibly related to intrusive diking from the adjacent rift zones that fill and may even induce the extensional structures associated with this complex fault zone. Continued inversions with the immense amount of seismic data collected for Hawaiian events will allow the detailed development of a three-dimensional structural model for Kilauea. Such a model will be extremely useful to seismologists and petrologists alike for understanding the tectonic growth and magmatic evolution of this dynamic shield volcano.
|Additional Information:||© 1993 American Geophysical Union.
Received 30 November 1990; accepted 21 October 1992.
We would like to thank Phyllis Ho-Liu and Hua-Wei Zhou for their help and advice throughout this project. We appreciate the reviews and useful comments on the manuscript from Jim Westphal and Hiroo Kanamori. We appreciate the patient and critical reviews by two anonymous reviewers and Stuart Sipkin. We would also like to thank Carl Johnson, Bob Koyanagi and Paul Okubo for providing us with the data set for 1986 and some useful discussions on our interpretations of the tomographic images. The first author would like to add a special thanks to Robert P. Sharp for including me on a field trip to the Big Island so I could see and understand the dynamic beauty of Kilauea Volcano at least on the surface. This work was partially supported by the contracts USGS 14-08-0001-G1774 and by EAR-83-511371. Contribution No. 4942 from the Division of Geological and Planetary Sciences, Caltech. |
|Funding Agency||Grant Number|
|Subject Keywords:||Seismology: Structure of the crust; Volcanology: Magma migration; Exploration Geophysics: Oceanic structures;
Information Related to Geographic Region: Pacific Ocean;
Seismology: Body waves
|Other Numbering System:|
|Other Numbering System Name||Other Numbering System ID|
|Caltech Division of Geological and Planetary Sciences||4942|
|Official Citation:||Rowan, L. R., and R. W. Clayton (1993), The three-dimensional structure of Kilauea Volcano, Hawaii, from travel time tomography, J. Geophys. Res., 98(B3), 4355–4375, doi:10.1029/92JB02531. |
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited On:||15 Oct 2012 22:45|
|Last Modified:||31 Jan 2017 21:26|
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