Claim: The 1382 Dover Straits earthquake which had an estimated magnitude of 7.0 Ms produced significant aftershocks on 23 May and on 24 May, the latter being the strongest recorded and was also described as a "waterquake" affecting anchored ships.
Evidence: It had an estimated magnitude of 6.0 Ms and a maximum felt intensity of VII-VIII on the Mercalli intensity scale. 
1382 Dover Straits earthquake 6.0 Ms