Modeling the three-dimensional structure of macroscopic magma transport systems: Application to Kilauea volcano, Hawaii
We report the results of modeling the three-dimensional internal structure of Kilauea's magmatic passageways. The approach uses a clear plexiglass model containing equally-spaced levels upon which well-located seismic hypocenters are plotted. Application of constraining geologic and geophysical criteria to this distributed volume of earthquakes permits the interpretation of seismic structures produced by fracturing in response to locally high fluid pressures. Four magma transport and storage structures produce have been identified within and beneath Kilauea: (1) Primary conduit. The conduit transporting magma into Kilauea's summit storage reservoir rises from the model base (14.6 km) to 6.5 km depth level. It is a zone of intense fracturing and inferred intrusion, whose horizontal sections are elliptical in planform. Over its height, the average major axis of component horizontal section is 3.3 km, with an average minor axis of 1.7 km. This yields an aspect ratio of xi = 0.52. At the 14.6 km level, the strike of the major axis is N67 /sup 0/E. During passage from the upper mantle through the oceanic crust, this axis rotates in a right-handed sense, until the strike is N41 /sup 0/W at the 6.5 km level. (2) Magma chamber complex floor. The interval from 6.5 to 5.7 km, immediately over the primary conduit, is aseismic. This suggests differentially high fluid-to-rock ratios, and relatively weak pathways for further vertical transport into higher levels of the storage complex, as well as lateral leakage eastward into the Mauna Ulu staging area: for later vertical ascent beneath the upper east rift zone. Seismicity within the immediately subjacent rocks that form the top of the primary conduit (at 6.5 km) suggests that this inferred magma-rich horizon forms the effective floor of the summit storage complex. (3) Magma chamber crown. Intense seismicity over the 1.1--1.9 km depth interval defines an elliptical region in plan view.
- Research Organization:
- Department of Mineral Sciences, Museum of Natural History, Smithsonian Institution, Washington, D. C. 20560
- OSTI ID:
- 5875421
- Journal Information:
- J. Geophys. Res.; (United States), Vol. 86:B8
- Country of Publication:
- United States
- Language:
- English
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