a Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM 87131, United States b Earthquake Science Center, U.S. Geological Survey, Pasadena, CA 91106, United States c Seismological Laboratory, California Institute of Technology, Caltech 252-21, Pasadena, CA 91125, United States d Department of Geology and Geophysics, The University of Utah, Salt Lake City, UT 8411...

I review the progress that has been made in our understanding of the physics of the upper boundary layer of the Sun, its influence on frequencies of five-minute oscillations , and its role in excitation of the oscillations. I also discuss approaches to seismological diagnosis of the properties of the layer, important information about which will be obtained from MDI high-resolution data.

Barbara A. Romanowicz,1 Mark P. Panning,2 Yuancheng Gung3 and Yann Capdeville4 1Berkeley Seismological Laboratory, University of California, Berkeley, CA 94720, USA. E-mail: [email protected] 2Department of Geosciences, Princeton University, Princeton, NJ 08544, USA 3Department of Geosciences, National Taiwan University, Taipei 10617, Taiwan 4Institut de Physique du Globe, 75252 Paris...

Recent high-pressure experiments have led to the conclusion that water release from subducted sediments lying under continents in subduction regions occurs at about 220 km depth. This dehydration reaction is in good agreement with the seismological signature of the discontinuity indicating that sediment dehydration causes the Lehmann discontinuity in

a Department of Oceanfloor Network System Development for Earthquakes and Tsunamis (DONET), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokohama 236-0001, Japan b Seismological Laboratory, California Institute of Technology, Pasadena, California 91125-2100, USA c Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku Universi...