HR: 10:40h
AN: V21F-02    [PDF]
TI: Joint inversion of short- and long-period P traveltimes reveals a variety of plumes in the mantle.
AU: * Montelli, R
EM: montelli@princeton.edu
AF: Department of Geosciences, Guyot Hall, Princeton University, Princeton, NJ 08544 United States
AU: Nolet, G
EM: nolet@princeton.edu
AF: Department of Geosciences, Guyot Hall, Princeton University, Princeton, NJ 08544 United States
AU: Dahlen, F
EM: fad@princeton.edu
AF: Department of Geosciences, Guyot Hall, Princeton University, Princeton, NJ 08544 United States
AU: Masters, G
AF: IGPP, University California San Diego, La Jolla, CA 92093 United States
AU: Engdahl, R
EM: engdahl@armstrong.colorado.edu
AF: Department of Physics, University of Colorado, boulder, CO 80309 United States
AU: Hung, S
EM: shung@ccms.ntu.edu.tw
AF: Department of Geosciences, National Taiwan University, Taipei, 106 Taiwan
AB: Diffraction theory predicts that traveltimes of finite-frequency waves are affected by heterogeneities within a narrow region around the ray-theoretical path, called Fresnel zone. Because of wavefront healing, heterogeneities whose scale-length is smaller then the size of the Fresnel zone do not significantly affect the traveltimes. Dahlen et al. (GJI, Vol 141, 157, 2000) show how to correct for wavefront healing effects with a method we refer to as finite-frequency modeling. We perform a global tomographic study by using the finite-frequency modeling, which allows to combine data of different dominant frequencies. To enhance the resolution, we combine long- and short-period data, and we introduce an irregular model parameterization. Our new tomographic model shows a strong correlation between low velocity anomalies and the location of a large number of known hotspots. To test the reliability of these anomalies, an extensive resolution analysis was performed. As result, we can confidently say that deep mantle plumes are located beneath Ascension, Azores, Canary, Easter, Hawaii, Samoa and Tahiti. Other plumes, among which is Iceland, originate at much shallower depth. Newly discovered plumes-like features are located beneath the Mid-Atlantic Ridge, the Southeast Indian Ridge, beneath the Seychelles and the Coral Sea.
DE: 6982 Tomography and imaging
DE: 8121 Dynamics, convection currents and mantle plumes
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting