User:Mikenorton/sandbox/British Institutions Reflection Profiling Syndicate

The British Institutions Reflection Profiling Syndicate, better known by its acronym BIRPS, was set up to acquire deep seismic reflection profiles around the United Kingdom Continental Shelf (UKCS). It was formed, initially as BURPS, the British Universities Reflection Profiling Syndicate, involving geophysicists from the Natural Environment Research Council (NERC) and British Universities. After the involvement of other institutions the name was changed to BIRPS and by February 1981 NERC had approved funding for a four-year programme. The next ten years saw the collection of 12,000 km of deep seismic profiles around the British Isles. By the time NERC stopped funding the program in 1997, more than 20,000 km of data had been acquired.

Formation
In the mid 1970s, the technique of seismic reflection profiling, which had become a standard exploration tool in the oil and gas industry, was first applied to investigate the structure of the Earth's crust. The Consortium for Continental Reflection Profiling (COCORP) was set up in the US and from 1975 began acquiring data. The success of this approach in addressing the problems of deep crustal geometry across structures such as the Appalachians, led the Royal Society to set up a working group to investigate how a similar approach could be used in the United Kingdom. Drummond (Drum) Matthews and Derek Blundell were tasked with formulating a deep profiling program for the United Kingdom by the British Universities Reflection Profiling Syndicate (BURPS). After initially considering onshore profiles similar to those acquired by COCORP, the group were persuaded of the benefits of data acquisition offshore. An initial four-year program was approved in February 1981 by NERC and the group was officially inaugurated in November 1981 as the British Institutions Reflection Profiling Syndicate (BIRPS).

Acquisition
The first profile to be acquired was the Moine and Outer Isle Seismic Traverse (MOIST). This roughly 185 km long line ran west-east, north of the Scottish mainland, intending to image the main Caledonian structures known onshore, such as the Outer Isles Fault Zone and the Moine Thrust Belt. The line was acquired in March 1981 by Western Geophysical and processing was complete by October of that year.

Interpretation
The MOIST profile shows a series of deep half-graben basins, bounded to the west by easterly dipping extensional faults, part of the West Orkney Basin. The faults coincide with major east-dipping zones of relectivity extending down to the lower crust. These have been interpreted to be Caledonian thrust structures, with the Outer Isles Fault clearly imaged. No direct correlation was possible between the Moine Thrust Belt onshore and the offshore structure. The MOIST line was also interpreted to show whole lithosphere extensional faulting, although later interpretation suggested that the major normal faults did not pass through the Moho.

The lower crust is observed to be quite reflective and bounded at its base by a clear reflection Moho event. Towards the western end of the line, east-dipping reflections are seen extending well into the mantle, the first time that undoubted mantle reflectivity had been imaged. This mantle structure was named the Flannan Thrust.

Acquisition
The Western Isles-North Channel (WINCH) profiles were shot partly within the foreland of the Caledonian orogenic belt and partly across the Great Glen Fault. WINCH1 was a short west-east profile about 12 km north of the western end of the MOIST line. WINCH2 started just south of the eastern end of WINCH 1 continuing just north and west of the Outer Hebrides before running in a southeasterly direction down the North Channel, finishing just west of the Isle of Man.

Acquisition
The South West Approaches Traverse (SWAT) consisted of a series of eleven profiles acquired between September and November 1983 by Seismic Profilers Ltd, with a total length of 1600 km. The profiles were shot across the North and South Celtic Sea Basins, the Western Approaches Basin and the Western and Eastern Channel Basins. Processing was carried out by Seismograph Services Ltd. (SSL).

SALT
Two short profiles, named for the Zechstein salt layer found over large parts of the North Sea that had caused problems with deep seismic penetration, were acquired to test the feasibility of deep profiling over the area in preparation for the much larger NSDP survey.

Acquisition
The two profiles, SALT 1 and SALT 2 were shot in 1983 along parts of a previously acquired seismic refraction profile.

Interpretation
When this survey was shot, sufficient deep reflection data had been acquired to establish a pattern of reflectivity for the crust of the North Sea, with the Moho interpreted at the base of a band of reflections. The SALT survey showed that this was consistent with the Moho interpreted from earlier seismic refraction data.

Acquisition
The DRUM profile was named as an acronym for Deep Reflections in the Upper Mantle and for Drummond (Drum) Matthews the BIRPS scientific director. It was acquired and processed in 1984 by GECO, with an unprecedented record length of 30 seconds two-way travel time.

NSDP
A set of ten seismic profiles shot to investigate the deep structure of the North Sea.

Acquisition
The NSDP profiles were acquired in 1984 and 1985 by GECO as a group shoot, involving the oil industry and BIRPS. The first five were shot in the Northern North Sea in 1984 and are named NSDP 84-1,2,3,4 and 5. The second set of profiles were shot in the central and southern North Sea in 1985 and are named NSDP 85-6, 7, 8, 9 and 10. The total line length for the survey is about 3,000 km. The record length for the survey was 15 seconds of two-way travel time. The data were initially processed by GECO as an unmigrated stack and the data were reprocessed by BIRPS.

Acquisition
The GRID profiles were acquired to provide a better coverage of structures already identified off the north coast of Scotland by MOIST and DRUM. The SLAVE profile was a two-ship wide-aperture experiment that formed part of the overall grid of lines. The data was recorded to record lengths of between 15 and 60 seconds of two-way travel time (TWTT).

SHET
The SHET survey consisted of four profiles, totalling 830 km, acquired around the Shetland Islands in August 1984.

Acquisition
The SHET profiles were shot by GECO to a record length of 15 seconds TWTT. The data were also processed by GECO using similar processing parameters to those used on earlier BIRPS profiles.

Interpretation
The most important observation from the SHET survey was that the Moho was apparently offset by the Walls Boundary Fault, a major strike-slip fault formed during the later part of the Caledonian Orogeny, thought to be part of the Great Glen Fault system.

Acquisition
The 237 km long North East Coast (NEC) profile was shot in October 1985 by GECO, with processing carried out by SSL. It ran from near Montrose in Scotland to near Hartlepool in England. The record length varied between 15 and 16 seconds TWTT, imaging down to an estimated 50 km. It was designed to provide information on the collision zone between the microcontinent of Avalonia and Laurentia, particularly the location and geometry of the Iapetus Suture.

WAM
The WAM (Western Approaches Margin) profile was shot in 1985 to investigate the structure of part of the UK continental margin.

WIRE
The WIRE (West of IREland) profiles were shot in 1987.

MOBIL
The MOBIL (Measurements Over Basins Imaging the Lithosphere) dataset was acquired after a gift of shiptime on the Mobil Search seismic vessel in 1987.

WISPA
The WISPA (Wearside Integrated S‐wave and P‐wave Analysis) experiment was acquired in 1988. This was the only entirely onshore seismic experiment carried out by the BIRPS group.

BABEL
The BABEL ((Baltic and Bothnian Echoes from the Lithosphere) profiles were acquired in 1989 by a consortium of scientific institutions from Sweden, Denmark, Finland, Germany and the United Kingdom (the BIRPS group).

SWABS
The SWABS (Seismic Wide-Angle and Broadband Survey) was a two-ship seismic experiment shot in 1992 in the North Sea.

TIMOR & DAMAR
The TIMOR and DAMAR surveys were shot in 1992 across the Banda Arc.

MONA LISA
The MONA LISA (Marine and Onshore North Sea Acquisition for Lithospheric Seismic Analysis) were a set of four normal incidence seismic reflection profiles and associated wide-angle data shot in 1993.

CHIX
The CHIX survey was a set of three profiles shot in 1996 across the Chicxulub crater.

ARAD
The ARAD (Anatomy of a Ridge-Axis Discontinuity) experiment was a 3D seismic survey carried out by investigators at Scripps Institute of Oceanography and the University of Cambridge in 1997 with funding from the RIDGE program of the National Science Foundation, BIRPS and the NERC.