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Detailed structure of the top of the melt body beneath the East Pacific Rise at 9°40′N from waveform inversion of seismic reflection data
- Source :
- Journal of Geophysical Research: Solid Earth. 102:20287-20304
- Publication Year :
- 1997
- Publisher :
- American Geophysical Union (AGU), 1997.
-
Abstract
- We have applied waveform inversion to multichannel seismic reflection data collected at the East Pacific Rise at 9°40'N in order to determine the precise velocity structure of the magma body causing the axial magma chamber reflection. Our analysis supports the idea of a molten sill as previously suggested from forward modeling of seismic data from this location. Our inverted solution has a 30-m-thick sill with a P wave seismic velocity of 2.6 km s -1 . Although not well constrained by the data we believe that the S wave velocity in the sill is not significantly different from 0.0 km s -1 . The low P- and S- wave velocities in the sill imply that it contains less than 30% crystals. The molten sill is underlain by a velocity gradient in which the P wave velocity increases from 2.6 to 3.5 km s -1 over a vertical distance of 50-m. The shape of our velocity-depth profile implies that accretion of material to the roof of the sill is minor compared to accretion to the floor. The underlying velocity gradient zone may represent crystal settling under gravity. We suggest that only material from the 30-m-thick layer can erupt.
- Subjects :
- Atmospheric Science
Soil Science
Magma chamber
Aquatic Science
Oceanography
Sill
Geochemistry and Petrology
S-wave
Earth and Planetary Sciences (miscellaneous)
P-wave
Earth-Surface Processes
Water Science and Technology
geography
geography.geographical_feature_category
Ecology
Accretion (meteorology)
Velocity gradient
Paleontology
Forestry
Geophysics
Space and Planetary Science
Magma
Reflection (physics)
Geology
Seismology
Subjects
Details
- ISSN :
- 01480227
- Volume :
- 102
- Database :
- OpenAIRE
- Journal :
- Journal of Geophysical Research: Solid Earth
- Accession number :
- edsair.doi...........9ba8ff0dcde50374974137950930b397