Scientific Report for NERC Geophysical Equipment Facility Loan 841
SEIS-UK provided an initial loan of 27 broadband seismic systems (23 x CMGESP, 3 x CMG3T and 1 CMG6TD) for a period of between 16 and 24 months, for deployment in a network that extended more than 500 km across northern Ethiopia, centred on the Afar Depression. The SEIS-UK deployment was coeval with an NSF funded deployment of 14 CMG40T seismometers in the central part of Afar. The initial network ran from September 2007 until October 2009. These systems recorded continuously at 50Hz with relatively minor data losses due to equipment problems. All data have been archived with IRIS (Incorporated Research Institutions for Seismology) and is a key dataset in the NERC Afar Consortium Project. Teleseismic tomography has been used to deliver P and S-wave velocity models for the upper mantle. These show focussed, melt related, anomalies in the top 100km of the lithosphere with broad upwellings below. Crustal structure across Afar and on the Western Plateau are constrained with P-wave receiver functions and surface wave dispersion, providing understanding on the breakup history of Afar and showing that the lower crust contains large amounts of melt.
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