Weather Explorer - Seismic Survey

Seismic Survey

Narrative by John Gould

We are all familiar with the role played by Ocean Weather Ships in collecting systematic meteorological information from the open ocean west of the UK and the vital value of those observations to forecasters in the pre-satellite era. The ships also collected systematic oceanographic and wave data that continue to play a vital role in understanding climate related change in the oceans. What is less well known was the OWS’s occasional use as scientific test beds.

An important example of this was aboard OWS Weather Explorer in 1949 at station Juliett (52° 30’N 20° 00’W). In the late 1930s scientists in the Department of Geodesy and Geophysics of Cambridge University (now incorporated in the Department of Earth Sciences) had started to experiment with marine seismic surveying using explosives as sound sources to reveal sub-sea geological structures – techniques that later underpinned the offshore oil industry.

The work on Weather Explorer was carried out by research students John Swallow and Maurice Hill and was the Cambridge group’s first attempt to use the technique in deep water. Hydrophones were hung below buoys located by radar and of course a loud sound source was needed. So Weather Explorer sailed with its usual bottles of compressed hydrogen for the met balloons but alongside were 300lb depth charges (as RN surplus they were presumably past their “sell by date”).

John Swallow was an enthusiastic amateur photographer and I inherited from John a box of prints and negatives that included the work on Weather Explorer as well as photographs of the routine met observations and of the officers and crew.

The work is described at http://www.carrackconservation.co.uk/2016/01/14/seismic-refraction-at-sea-instrumentation-details/#more-171 the archive of the Cambridge Earth Sciences department where the negatives and prints of the geophysical work have now been deposited.

These photos are a graphic example of scientific work at sea in a pre-Health and Safety world.

Post script. In 1950-1 John Swallow (b.1924-d.1994) used the seismic techniques on the round the world voyage of the survey ship HMS Challenger (Ritchie ,1958). He later joined the National Institute of Oceanography where he developed the neutrally buoyant float to measure deep ocean circulation. Swallow’s float was the forerunner of the modern-day Argo profiling float array (Gould, 2005). Maurice Hill (b.1919-d.1966) remained at Cambridge. Both were elected Fellows of the Royal Society; Hill (1962), Swallow (1968).

References

• Gould, W.J. 2005: From Swallow floats to Argo – the development of neutrally buoyant floats. Progress in Oceanography, 52(3/4), 529-543.

• Hill, M.N. and J.C. Swallow, 1950: Seismic experiments in the Atlantic. Nature, 165, 193-4.

• Ritchie, G.S. 1958: Challenger: The life of a survey ship. Hollis and Carter.