Richard Dixon Oldham
|Richard Dixon Oldham|
Richard Dixon Oldham
|Born||31 July 1858|
|Died||15 July 1936|
|Known for||measuring Earth's core; separate arrival of seismic phases|
Richard Dixon Oldham FRS (31 July 1858 – 15 July 1936) was a British geologist who made the first clear identification of the separate arrivals of P-waves, S-waves and surface waves on seismograms and the first clear evidence that the Earth has a central core.
In 1879 Oldham became an assistant-superintendent with the Geological Survey of India, working in the Himalayas. He wrote about 40 publications for the Survey on geological subjects including hot springs, the geology of the Son Valley and the structure of the Himalayas and the Ganges plain. His most famous work was in seismology. His report on the 1897 Assam earthquake went far beyond reports of previous earthquakes. It included a description of the Chedrang fault, with uplift up to 35 feet and reported accelerations of the ground that had exceeded the Earth's gravitational acceleration. His most important contribution to seismology was the first clear identification of the separate arrivals of P-waves, S-waves and surface waves on seismograms. Since these observations agreed with theory for elastic waves, they showed that the Earth could be treated as elastic in studies of seismic waves.
In 1903, Oldham resigned from the GSI in 1903 due to ill-health and returned to the United Kingdom, living in Kew and various parts of Wales. In 1906 he wrote a paper analyzing seismic arrival times of various recorded earthquakes. He concluded that the earth had a core and estimated its radius to be less than 0.4 times the radius of the Earth.
|Wikisource has original works written by or about:
- Oldham, R. D. (1899). "Report of the great earthquake of 12th June, 1897". Memoirs of the Geological Society of India 29. K. Paul, Trench, Trübner & co.
- Oldham, R. D. (1900). "On the Propagation of Earthquake Motion to Great Distances". Philosophical Transactions of the Royal Society A 194: 135–174. Bibcode:1900RSPTA.194..135O. doi:10.1098/rsta.1900.0015.
- Oldham, R. D. (1906). "The Constitution of the Interior of the Earth, as Revealed by Earthquakes". Quarterly Journal of the Geological Society 62 (1-4): 456–475. doi:10.1144/GSL.JGS.1906.062.01-04.21.
- Harold Jeffreys – showed that the outer core is liquid
- Inge Lehmann – showed that the inner core is solid
- List of geophysicists
- Bragg, W. (1936). "Tribute to deceased fellows of the Royal Society". Science 84 (2190): 539–546. Bibcode:1936Sci....84..539B. doi:10.1126/science.84.2190.539. PMID 17834950.
- "Oldham, Richard Dixon". Complete Dictionary of Scientific Biography 10. Charles Scribner's Sons. 2008. p. 203.
- Davison 1936, p. 110
- Bragg 1936
- Oldham 1906
- Davison, C. (1936). "Richard Dixon Oldham. 1858-1936". Obituary Notices of Fellows of the Royal Society 2 (5): 111–113. doi:10.1098/rsbm.1936.0008.
- Davison 1936, p. 113