Using Three-Dimensional Earth Models
Global Test of Seismic Event Locations Using Three Dimensional Earth Models. By Qi-fu Chen and Raymond J. Willemann.
Greg Houseman. Geodynamics and Seismology
The Harvard Seismology Group carries out a broad range of projects with topics including mapping the interior of the earth, characterizing the seismic sources and global seismicity. The seismology group includes faculty, research associates, and students from the Department of Earth & Planetary Sciences.
The first major global tomographic study was made by Professor Dziewonski in early 70's. The idea of this study was that the travel time anomalies observed for many ray paths, criss-crossing the Earth between various points near the Earth's surface and reaching different depths in its interior, could be resolved formally into a three-dimensional (3-D) model. This is now called `seismic tomography', as it conceptually resembles the medical CAT-scan. The early results were reported orally in 1974 and 1975 by Dziewonski and a full report was published in January 1977 (Dziewonski et al., 1977). A more detailed description can be found a statement written by Professor Dziewonski. The motivation for studying 3-D structure of the Earth's interior is that it may offer the best information on the dynamic processes in the deep interior of the Earth. As the seismic wave speeds change with temperature, it is plausible to obtain 3-D snapshots of the convection pattern in the Earth. By performing waveform and travel time inversions using long period seismic records, we have obtained global models for the long wavelength 3-D velocity structure of the Earth.
IRIS is a consortium of over 120 US universities dedicated to the operation of science facilities for the acquisition, management, and distribution of seismological data.
IRIS is a 501 (c) (3) nonprofit organization incorporated in the state of Delaware with its primary headquarters office located in Washington, DC. IRIS is governed according to By-laws.
IRIS provides seismic equipment and access to seismic and other data sets for researchers worldwide.
The International Association of Seismology and Physics of the Earth’s Interior (IASPEI). It is one of the eight Associations that comprise the International Union of Geodesy and Geophysics (IUGG).
IASPEI promotes the study of earthquakes and other seismic sources, the propagation of seismic waves, and the Earth's internal structure, properties, and processes. Scientists participating in IASPEI initiate and co-ordinate research and scientific exchanges that demand co-operation among countries. Work on specific topics is carried out through commissions, committees, task and working groups formed to meet specific needs of new, exciting problems as they emerge.
Project IDA is a global network of broadband seismometers operated by the Cecil H. and Ida M. Green Institute of Geophysics and Planetary Physics at the Scripps Institution of Oceanography, University of California, San Diego. IDA is an element of the IRIS / USGS Global Seismographic Network (GSN) financially supported by the US National Science Foundation and the Cecil and Ida Green Foundation for Earth Science. There are currently 41 broadband stations deployed worldwide.