The Colchester Earthquake

Although it is generally thought that earthquakes are rare in Britain they do in fact occur quite frequently. Approximately 300 are detected each year by sophisticated monitoring equipment and of these about 30 are strong enough to be felt. Occasionally, however, Britain is shaken by an earthquake that causes structural damage.

The most destructive earthquake ever recorded in Britain occurred in Essex on the morning of 22 April 1884 and strongly shook most of the county. It is known as the Colchester Earthquake because the greatest damage was caused to Colchester, Wivenhoe and the towns and villages nearby. The tremor was felt over much of southern England and parts of France and Belgium, and its magnitude has been estimated at 5.2 on the Richter scale.

The number of casualties is difficult to estimate, but it is doubtful whether any deaths or serious injuries can be attributed to the earthquake. There was, however, considerable damage to over 1,200 buildings in Essex. The earthquake was probably due to movement along a fault in the ancient Palaeozoic rocks under Essex, which would have affected the overlying cover of Cretaceous and Tertiary strata.

An extensive study of the effects of the earthquake was carried out shortly afterwards by the Essex Field Club and the resulting report, entitled 'Report on the East Anglian Earthquake of April 22nd 1884', was published in 1885. It is a fascinating and extremely valuable account and copies are available for reference at Colchester and Chelmsford libraries.