April 6, 1580 Tsunami: Dover Straits, England, United Kingdom

The earthquake in the Dover Straits caused rising and agitated water, sinking boats in the English Channel. A deluge of water engulfed Calais and Boulogne. The weather was calm at the time.

April 6, 1580, English Channel: Epicenter, probably submarine, near the east coast of Kent. Sandwich (51 deg 16 min N., 01 deg 21 min E) and Dover (51 deg 08 min N, 01 deg 18 min E) -- Sea much agitated, Vessels in the harbor were dashed together. (reference #43)

Effects on water were noticeable, especially since all accounts agree that at the time of the earthquake the weather was fine and calm. The agitation of the Thames is reported by Churchyard (1580) and others. In the English Channel, it was worse. At Sandwich, "the sea so foamed, that the ships tottered" (Stow, 1601). One contemporary account suggests that marine effects were more severe on the other side of the Channel. "In Calais .. . there was such a horrible and fearful trembling that a great part of the houses collapsed and even the sea flooded into the town . .. In Boulogne there was a similar earthquake and flooding by the sea" (Discours d'une ... , 1580). This may be a seismic sea-wave, but unfortunately there is some doubt about the time, and therefore about the actual relationship between earthquake and marine incursion. Elsewhere in the same document we find it stated that on the 7th April between 4 and 5 a.m. (which coincidentally is the time of the third Kent aftershock) "there occurred in these places great signs of floods". (reference #3945)

Varley (1996) states categorically that the earthquake produced a tsunami (which he refers to as a tidal wave) at Calais, Boulogne and Dover. Neilson et al (1984) are more cautious, considering that due to uncertainty about the coincidence in time of inundation and earthquake, the flooding report may have had some other cause (presumably meteorological). Melville et al (1996) are dismissive of the idea of a tsunami from this event. Evidence suggests (Melville et al 1996) that contemporary sources conflated descriptions of the earthquake with the effects of a storm that occurred very shortly afterwards. This is all the more likely since at this period it was not known that earthquakes were very short-lived phenomena, and to a 16th century writer it would have been natural to consider the seismic shock and a storm a day later as being part of the same occurrence. Undoubtedly the earthquake caused agitation of the water in harbours at Dover and Sandwich harbours (Neilson et al 1984). It is most likely that this movement was a seiche and not a tsunami as there is no evidence of any seabed displacement in the area and the strength of the earthquake (5.8 ML (Musson, 1994)) was insufficient to cause a tsunami directly. (reference #11945)

Undoubtedly the earthquake caused agitation of the water in harbours at Dover and Sandwich harbours (Neilson et al 1984). It is most likely that this movement was a seiche and not a tsunami as there is no evidence of any seabed displacement in the area and the strength of the earthquake (5.8 ML (Musson, 1994)) was insufficient to cause a tsunami directly. The well surveyed bathymetry in the Channel shows no sign of or even the potential for a large underwater landslide [studies have also ruled out the possibility that a very large cliff fall (106 m3) could generate a tsunami that would reach both sides of the channel, and an improbably large event 0.01km3 would be needed. (reference #14326)

Seismic sea effects in the Channel were certainly observed. It has been suggested that some of the strong effects attributed to the earthquake were actually caused by a storm a few days later. (reference #14327)

Reference #12345 (accessed August 2024) and Reference #4139 lists tsunami event as validity 3 (probable tsunami).