Mapping the 650 Discontinuity Beneath the Tonga Subduction  Zone
{'Code': '06030204', 'Directorate': {'Abbreviation': 'GEO', 'LongName': 'Directorate For Geosciences'}, 'Division': {'Abbreviation': 'EAR', 'LongName': 'Division Of Earth Sciences'}}
{'SignBlockName': 'James H. Whitcomb', 'PO_EMAI': None, 'PO_PHON': None}
Interaction of subducted slabs with either a phase change or               a chemical boundary, or both, at 650 km may determine important                 aspects of mantle convection and mixing in the mantle.                          Observations of S-P conversion from the discontinuity provide a                 means to map deformation, or disturbance of the discontinuity                   beneath seismically active zones.  The research proposed here is                primarily an extensive and detailed study of the phase S650P                    beneath Tonga and other western-Pacific subduction zones.                            The phase S65oP has been tentatively observed by other                     researchers, using the short period Warramunga Seismic Array (WRA)              in central Australia, from deep events beneath Tonga and the Izu-               Bonin arc.  A much larger data set from  WRA, including more than               300 deep events from Tonga, has been collected.  With this 8-fold               increase in high quality data, the following exciting results have              been obtained from preliminary analysis: (1) much clearer                       observation of S650P than before, (2) geographical variation in                 the apparent depth of the discontinuity (deformation), between 650              and 720 km, and (3) observation of other possible converted                     phases.
{'FirstName': 'Mark', 'LastName': 'Richards', 'PI_MID_INIT': 'A', 'PI_SUFX_NAME': None, 'PI_FULL_NAME': 'Mark A Richards', 'EmailAddress': 'markrich@uw.edu', 'NSF_ID': '000367645', 'StartDate': '02/01/1988', 'EndDate': None, 'RoleCode': 'Principal Investigator'}
{'Name': 'University of Oregon Eugene', 'CityName': 'EUGENE', 'ZipCode': '974031905', 'PhoneNumber': '5413465131', 'StreetAddress': '1776 E 13TH AVE', 'StreetAddress2': None, 'CountryName': 'United States', 'StateName': 'Oregon', 'StateCode': 'OR', 'CONGRESSDISTRICT': '04', 'CONGRESS_DISTRICT_ORG': 'OR04', 'ORG_UEI_NUM': 'Z3FGN9MF92U2', 'ORG_LGL_BUS_NAME': 'UNIVERSITY OF OREGON', 'ORG_PRNT_UEI_NUM': 'Z3FGN9MF92U2'}
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{'Code': '1574', 'Text': 'Geophysics'}
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