The Reflections Under the Scottish Highlands (RUSH II) Experiment: Broadband Definition of Upper Mantle Structure

Twenty-four broadband seismometers (Streckeisen STS-2 sensors and REFTEK recorders) were deployed during the summer of 2001 across the Scottish Highlands to (1) determine the regional extent of major mantle reflectors beneath the mainland Scotland, and (2) examine the geometrical relationship of these upper mantle reflectors with known lithospheric-scale structures of Paleozoic age. Stations were deployed in a series of roughly rectilinear arrays with an average station spacing of 15 km, to form a 2.5-D network across the Great Glen fault. Access to the more southerly Iapetus suture was compromised by the foot and mouth epidemic in the United Kingdom. The upper mantle reflectors (Flannan and W) of northern Scotland have been clearly imaged and mapped in the offshore region of Scotland through marine seismic reflection data and marine wide-angle data but have not been reliably traced beneath the Scottish mainland. The experiment is the continuation of a pilot phase (RUSH I) conducted in 1999, which involved the deployment of a small array of nine broadband stations and analysis of existing short-period data from the United Kingdom Seismic Network. Installation of the equipment was completed in August, 2001 and recording of continuous data streams (1 and 20 samples per second) will continue for a period of two-years. Initial data recovered from the network includes teleseismic events from Northern Chile (07/24, Mw=6.3), Aegean Sea, (07/26, ME=7.0), and South Alaska, (07/28, Mw 6.6). Although our next service run is scheduled to be completed by the end of November 2001, just several weeks prior to the AGU meeting, preliminary receiver function analysis of selected teleseismic events across the array will be presented.