Scientific Report to the NERC Geophysical Equipment Facility for Seis-UK loan 885

Abstract

SEIS‐UK provided a loan of 12 broadband seismic systems (12 x CMGESP), for deployment in a network of approximately 200km x 300km in the central and northern portions of the Afar depression. The network (loan 885) ran from October 2009 ‐ October 2011, and was extended until January 2012 under an extension application. These systems recorded continuously at 50Hz with relatively minor data losses due to equipment problems. These data have been used to constrain locations, moment tensors and time series of seismicity during the May 2010 intrusion in the Dabbahu segment in Afar. The data show the intrusion was sourced from a segment centred reservoir and spread to both the north and south along the rift axis. Moment tensor inversion shows the earthquakes are normal dip slip faults. In addition, data has been used to understand pre‐co, and post eruption deformation associated with the June 2011 eruption of Nabro volcano. Initial results demonstrate activity started around March 2011, and peaked during the 12 June 2011 during the eruption. Teleseismic data is being used to constrain lithosphere and asthenosphere structure beneath Afar, the Red Sea, Gulf of Aden and Yemen using surface‐wave tomography. Results show segmented low velocity zones beneath the ocean ridges suggested segmented upwelling and partial melting of asthenosphere. In addition, teleseismic data is being used to constrain seismic structure of the transition zone beneath the region using body‐wave teleseismic tomography and receiver function analysis. Results show Data was also incorporated into crustal receiver function, teleseismic body‐wave tomography, Pn tomography, and SKS splitting analysis reported for SEIS‐UK loan xxx.