The leading geophysicist Brian Jacob, who died on November 5th aged 63, was senior professor of geophysics in the School of Cosmic Physics at the Dublin Institute for Advanced Studies (DIAS) since 1990. He was an outstanding practitioner of both active and passive seismology.
He set up and operated the Irish Network which has been passively recording worldwide events, not only earthquakes, but also artificial events including underground nuclear explosions for more than two decades. The methods used are of great importance in monitoring compliance of the Comprehensive Test Ban Treaty. Brian Jacob was also associated with the Pugwash Group, which shared the Nobel Peace Prize in 1995.
He is best known internationally for his development and application of the methods of controlled source seismology to the study of the deep Earth structure and processes beneath major geological features including the African Rift, the Alps, the Hawaiian Volcanic Chain, and the nature of the Core-Mantle Boundary. He was most proud of the successful series of RAPIDS projects (Rockall And Porcupine Irish Deep Seismic), which has greatly enhanced our understanding of the complex continent-ocean transition off the west coast of Ireland and has provided the framework needed for offshore hydrocarbon exploration.
Alfred William Brian Jacob was born on January 28th, 1938, the son of Frank and Ida (nΘe Beatt) Jacob of Cork city. He attended Portora Royal School, where he developed interests in rugby, cricket and tennis, as well as excelling in competitive sailing at Kinsale.
He entered Trinity College Dublin in 1956, graduated in physics in 1960 and completed a masters in nuclear physics in 1962. He then joined the family firm of T. E. Jacob & Co., provender millers in Cork.
After a couple of years he realised that commerce was not his forte and in 1965 became a scholar in the School of Cosmic Physics at DIAS.
Here, at the instigation of the Rev Richard Ingram SJ, director of the Seismology Observatory at Rathfarnham Castle, he started his life-long work in seismology with an investigation of the structure of the crust and upper mantle beneath a line extending from Valencia Observatory at Caherciveen to Eskdalemuir in Scotland. He then worked at the Global Seismology Unit of the Institute of Geological Sciences (now the British Geological Survey) in Edinburgh on the completion and operation of the LOWNET (Lowlands Network) earthquake recording array which he used to study local seismicity. It was here that he developed an interest in using artificial seismic sources, particularly underwater sources, for probing the Earth's interior. His success can be gauged by the fact that one signal from the North Sea was recorded at the South Pole. He was the co-leader of the international LISPB (Lithospheric Seismic Profile in Britain) experiment to determine the crustal structure from the north to the south of Britain. He left his post as a principal scientific officer of the IGS to return to DIAS as professor of geophysics in 1976 and became the senior professor in 1990.
After setting up the Irish Network, Brian Jacob started his extensive investigations of the lithosphere with the Irish Caledonian Suture Seismic Profile, work which is continuing on and offshore at the present day with the RAPIDS programmes. He led the Irish team in the major phases of the Kenya Rift International Seismic Projects which set out to understand the processes which lead to the break-up of continents. He won a major EU award for the imaginative COMBO (Core-Mantle Boundary) project to investigate the Earth's core.
Brian Jacob was an authority on the deep lithospheric structure and seismicity of Ireland and surrounding areas, notably the complex continent-ocean transition off the west coast. Internationally, he was recognised as a leading exponent in the use of both natural earthquakes and controlled underwater seismic sources to determine the internal structure and constitution of the Earth down to the core. He had a leading role in a number of major international programmes to investigate the lithospheric structure of the UK, Ireland, and Europe, the East African Rift, and most recently to study the plume beneath the Hawaiian volcanic chain.
Brian Jacob's calm efficiency and good humour endeared him to his staff as well as to his many friends and colleagues from many parts of the world. He was in demand not only to participate in major projects, but also to run international workshops in Dublin. The DIAS Communications Series in 1997 on continental rifts, and in 1999 on Active and Passive Seismic Techniques Reviewed, reflected his range of interests.
Brian Jacob was chairman of the Irish National Committee for Geodesy and Geophysics from 1996 to 1999 and a member since 1988. He was a member of the Irish Pugwash Group and the European Geophysical Society of which he was the general secretary from 1992-'96, and which awarded him a gold badge in 1997. He also served as the Irish representative on many other international bodies. He was elected an associate (honorary foreign member) of the Royal Astronomical Society in 1989 and to membership of the Royal Irish Academy in 1998.
Brian Jacob is survived by his wife Chris, whom he met while he was in Edinburgh and married in Cambridge in 1969, his sons, Stephen and Alan, and sisters, Olive and Ann.
Alfred William Brian Jacob; born 1938; died, November 2001