Vol. 6$.~\ THE SWANSEA EARTHQUAKE OF 1906. 351 



23. The Swansea Earthquake of June 27th, 1906. By Charles 

 Davison, Sc.D., F.G.S. '(Read June 19th, 1907.) 



[Plate XXV— Map.] 



I. Introduction. 



Local earthquakes in the mining districts of South Wales are not 

 uncommon. They are probably due to slight fault-slips precipitated 

 by mining operations, and, if so, are partly of artificial origin. 1 

 True tectonic earthquakes are of less frequent occurrence, and 

 none, I believe, is recorded from December 30th and 31st, 1832, 

 until June 27th, 1906, when one of the strongest shocks of the 

 last twenty years disturbed all Wales, the West of England, and 

 the south-eastern corner of Ireland. 2 



Besides this earthquake, which occurred at 9.45 a.m., several 

 others of less intensity are reported on the authority of single 

 observers ; but, in the absence of corroborative records, they should, 

 I think, be regarded as of doubtful seismic origin. They occurred 

 at the following times : — 



June 26th, about 8 p.m. : Aberavon. — A slight shock. 



June 26th, about 11.30 p.m.: Ferryside. — An unusual sound was heard, as if 



coming from the earth. 

 June 27th, about 12.45 a.m. : Ferryside. — The same. 

 June 27th, about 1 a.m. : Aberavon. — A slight shock. 

 June 27th, about 2 a.m. : Llandeilo. — A slight shock, with a rumbling noise 



like thunder. 



1 ' On Earth-Shakes in Mining Districts ' Geol. Mag. dee. 5, vol. ii (1905) 

 pp. 219-23. 



2 In studying this important earthquake, I have relied as usual on the 

 courteous assistance of many observers and correspondents. I am indebted to 

 Prof. John Milne, F.R.S., for a valuable series of newspaper-cuttings relating 

 to the earthquake ; to Mr. J. Lomas, F.G.S., Dr. H. E. Mill, and Dr. W.N, 

 Shaw, F.R.S., Director of the Meteorological Office, for accounts received by 

 them from different parts of the disturbed area ; and to Dr. A. Strahan, F.R.S., 

 for information as to the geology of the epicentral area. Mr. L. Lindsay, 

 Chief Constable, of Canton, Cardiff, communicated more than fifty descriptions 

 by officers under his command. For many records, I also beg to thank 

 Captain J. E. Acland, J.P., of Dorchester ; Miss Benger, head-mistress of the 

 High School for Girls, Swansea ; Mr. J. Burnell, of Bampton ; Mr. G-. Child, 

 B.Sc, head-master of the Higher Grade School, Ferndale ; Dr. J. Ho wells, of 

 Bridgend ; Dr. J. D. Jenkins, of Pentre, Rhondda ; Mr. Walter Lewis, Hon. 

 Secretary, and the Council of the Boyal Institution of South Wales, Swansea ; 

 and Dr. M. T. Ritchings and Mr. Iltid E. Thomas, of Swansea. Mr. J. P. 

 Gibbon, of North's Navigation Collieries, Maesteg, and the Secretary of the 

 Ocean Collieries Co., Ltd., Treorchy, made numerous enquiries among the 

 miners employed by them, which have added considerably to our knowledge of 

 the nature of the earthquake in mines. To the courtesy of the editors of ' The 

 Times,' the ' South Wales Daily News ' and the ' Western Mail ' (Cardiff), the 

 ' Western Morning News ' (Plymouth), and many other newspapers, in 

 publishing my letters of enquiry, I am indebted for many valuable accounts. 

 The expenses of the investigation were defrayed from a grant received from the 

 Government Research-Fund. 



