The East African Rift System is literally and figuratively one of the world’s geological “hot spots” for scientists wanting to understand the process of plate tectonics, and how the world’s continents formed and diverged by the splitting of a single, supercontinental landmass, known as Pangaea, 200 million years ago.  It is the only place on earth where we may now be witnessing a continent in the act of splitting.

The rift, thought to be the birthplace of Home sapiens, is also the place where Prof. Emeritus, Aftab Khan has left his most substantial mark as a geophysicist. Described by Prof. Mike Lovell, Head of the Department of Geology at University of Leicester in the UK as “a superb ambassador for geophysics worldwide…with an enormous drive”, Prof. Khan has dedicated his professional life to the advancement of this field through his teaching and research, as well as his leadership in the area of seismology.

With a career that spans over four decades, he remains enthusiastic and embedded in his work, which has involved groundbreaking geophysical investigations of the Kenyan segment of the African Rift, as well as the island of Cyprus. His achievements have earned him the high esteem of his peers in the international scientific community.

Geophysics is a major branch of earth science that applies the principles and methods of physics to the study of the earth’s structure and physical properties. It includes seismology, gravity, geomagnetism and geoelectricity, meteorology, and oceanography.  The methods of geophysics are vital in the exploration for energy, water, and mineral resources. It is also integral in monitoring environmental impact and change, in the assessment of natural and man-made hazards, forensic science, and in subsurface investigations for engineering and archaeology.

With the emergence of the plate tectonic hypothesis in the early 1960s, and the observation from satellites of rift-like features on other planets, earth and planetary scientists joined forces to investigate the deep structure and origin of the East African Rift.  Technological advances since the 1950s were making it possible to obtain high quality information about the Earth’s subsurface from geophysical observations on the earth’s surface, in boreholes and from ships aircraft, and satellites.

An international team of geophysicists was formed to study the Kenyan segment of the rift in detail. The Kenya Rift International Seismic Project (KRISP) ran from 1985 – 1995 with Prof. Khan as its Scientific Coordinator. The team of experts with tens of scientists from the UK, Europe, the USA and Africa, equipped with hundreds of portable seismographs, undertook high-resolution seismic surveys, using explosions up to two tonnes in boreholes and underwater as well as earthquakes as sources. Seismic waves from the shots were recorded at distances of over 400 km and used to determine the deep structure of the rift down to depths of over 100 km⁶⁹. The success of this sophisticated programme in remote areas of Africa with its huge logistical problems was a substantial achievement. The first results were published in Nature, the most prestigious scientific journal in the world and in a special issue of the journal Tectonophysics, which was the most cited earth science publication of 1995.

The seismic data obtained were combined with gravity observations made over three decades at over 10,000 stations across Kenya to produce the geophysical model of the deep structure. The team concluded that the rift was formed by the rise of hot material beneath it, resulting in uplift, faulting and extensive lava flows from large volcanoes. It revealed the process responsible for the breakup of Africa starting 30 million years ago with the opening of the Red Sea and Gulf of Aden, which are two junior oceans. This process is continuing today into Afar in Ethiopia, which was investigated by another international project in 2000, EAGLE (Ethiopia Afar Geoscientific Lithosphere Experiment) in which Prof. Khan participated as the manager of the shooting teams.

Another significant output from KRISP was a gravity map of Kenya, which provides information on the density and composition of rocks at various depths and is utilized in the exploration for oil, minerals, water and geothermal energy. Kenya is the first African nation to utilise geothermal sources for power, and this venture aims eventually to provide 25% of the country’s electricity needs.

Prof. Khan also conducted research on the unique island of Cyprus, which is a wedge of the deep ocean floor thrust above sea level by the forces closing the Mediterranean Sea and forming the Alpine and Himalayan mountain chains. It is the best place in the world to see what the mantle below the sea floor comprises. For 30 years, he carried out surveys, comparing these findings against theories about the mantle. The culmination was the large scale IANGASS (Investigations Around North Troodos from Gravity And Seismic Surveys) project, which confirmed that the seismic structure of Cyprus was the same as that beneath the oceans.

He has also experimented with geophysical methods of exploration for minerals, notably in Cyprus, which literally means copper. The deposits there were formed at an ocean ridge by the interaction between seawater and hot material rising from beneath the ridge. For many years, he took undergraduate and Ph.D students there for field training, testing and developing electrical and electromagnetic methods of exploration.

Prof. Khan’s contribution to education in geophysics was also pioneering. He is commended for introducing in the 1960s the first university BSc degree course in geophysics in the UK, within the new geology department at the University of Leicester. This led the way for similar programmes being introduced in 12 UK universities, with Khan serving as the external examiner in most of them. By the time he retired in 1998, he had developed prestigious teaching and research programmes in geophysics, been Head of Department twice, and served on the major university boards and committees. In the last decade, he was also involved in the initiation of the highly successful geoscience degree programme at The University of the West Indies (UWI) in St Augustine, and was its external examiner for the first five years.

He has served as Chairman of the British Geophysical Association, and was a Vice-President of the Royal Astronomical Society. At the international level, he was the Managing Editor of the Geophysical Journal International; Chairman of the Governing Board of the School of Cosmic Physics of the Dublin Institute for Advanced Studies; co-leader of UNESCO Project 400 on the Geodynamics of Continental Rifts; and Scientific Coordinator of the British-USSR Seismic Verification Project, which showed it was possible to use seismology to detect and identify underground nuclear explosions and distinguish them from earthquakes, and thus verify a Comprehensive Test Ban Treaty.

Khan has written and co-authored over 100 scientific papers; supervised 25 research students and has obtained over 20 major grants to support his research.  One of his most cited papers is on the use the anisotropy of magnetic susceptibility to determine rock fabric. In 2000, he wrote a geophysics textbook with his colleague and friend, Alan Mussett entitled, Looking into the Earth, and is working on a 2^nd edition. In 2006, he was the recipient of the Royal Astronomical Society’s prestigious Award for Services to Geophysics. The Society described him as “a stalwart servant of UK Geophysics for over 50 years …who has been singularly devoted to the promotion and promulgation of his science to all facets of our society.” In 2012, Khan received a NIHERST Award for Excellence in Science and Technology.

Aftab Khan’s long journey as a scientist began in Trinidad. He was born in Rio Claro in 1933, the third of seven sons of Abrahim Khan, once a poultry farmer and later an insurance underwriter, and his wife Ayesha. These young intelligent parents had not been able to access good secondary education themselves, but they worked hard and made many sacrifices to ensure that their sons went even beyond secondary to tertiary education and, indeed, six eventually attended top universities abroad. The difficulties that financial constraints brought did not stop the brothers from enjoying the loving and stable family life their parents provided as they were growing up.

Khan was an excellent student from the outset. He attended Curepe CM School and was usually near the top of his class. In 1944, he passed the entrance exam for Queen’s Royal College. In the School Certificate Examination taken in Form 5, he won the school mathematics prize and placed fifth in the island, winning a house scholarship, which enabled him to complete his secondary school education for free. He studied physics, mathematics and chemistry at A level, and was fourth in the stiff competition for the one national science scholarship offered annually. This was good enough though for him to be offered a scholarship to attend university in the UK, funded by the Trinidad Petroleum Development Company (later BP), where he had spent nine months learning about the exploration and production side of the oil industry.

He enrolled at the University of Birmingham in 1953, to do a degree in petroleum engineering in which he also had to study geology, a new subject which fascinated him. He was inspired by the lecturers – geologist, Prof. Donald Griffiths and physicist, Roy King, and switched from engineering to geology with physics and mathematics, with the intention of pursuing a career in geophysical exploration for oil. However, on completing his degree, Khan was offered a place at the university to pursue a Ph.D. in palaeomagnetism, under the supervision of the pre-eminent Prof. P.M.S Blackett, the 1948 physics Nobel Laureate and President of the Royal Society. Blackett was interested in the origin and history of the earth’s magnetic field and particularly in the reversals of polarity. Khan was directed to investigate the magnetic properties of the tertiary igneous rocks of the Isle of Skye, where there are over 40 well-preserved lava flows. He found they were all reversely magnetised, i.e. in the opposite direction to that of the present day magnetic field. This supported the controversial hypothesis that the earth’s magnetic field had reversed spontaneously in the past from time to time due to electric currents in the molten metallic core.   When asked about the future of geophysics, he cites from an education report of his: “With the growing demands of industry and government service, there is a severe shortage of trained UK graduates with geophysics skills. The population in the industry is aging while the number of students enrolling in programmes is falling and in many instances, courses are being discontinued. If the current rates of decline continue, there will be no geophysics undergraduates by 2030. The problem is global.”

“Ambassador” Khan therefore seizes every chance to encourage young people not just into his particular field but to understand the sciences generally. “Science involves solving problems daily. There are scientific, mathematical, computing, logistic, financial, legal, safety and administrative problems associated with working in remote areas. One has to be patient and understanding. Everyone should have some natural science and mathematics in their education. Conversely, scientists and engineers need to appreciate the arts and literature. Balance is very important.”

He certainly practises what he preaches, and it was, in fact, through his interests in theatre and music during his time at Birmingham, that Khan met his wife Diana, an actress whom he describes as his greatest supporter and mentor. He is a past president and Life Vice-President of the Leicester Literary and Philosophical Society (founded in 1835), which serves to advance education in literature, science and the arts for the benefit of all people. In his remaining free time, he potters around his garden, plays golf, and listens to classical music – grand opera especially – at home or at concerts as often as he can.