October 720 Earthquake: Hebrides, Scotland, United Kingdom

721 October, Ireland. This is again from the Annals of Ulster (Bale and Purcell 2003), and no details are recorded, not even a place, so one assumes Ireland as the location, but it could also be western Scotland given the links between Ulster and western Scotland at this time. Again, one cannot be sure that a seismic event is being referred to. Principia (1982) give the year as 720. DOUBTFUL event. (reference #13466)

720 Octobe. The Annals of Ulster then have the following unique record, not contained in any other extant Irish annal, as the second of nine entries for 721: Terrimotus in Octimbre. [Translated as:] An earthquake in October. The term terrimotus was a generic one, literally “earth-movement”, and could also be used to refer to landslides. It is translated here as “earthquake” because Iona lies north adjacent to the Great Glen Fault as it enters the sea on the west coast of Scotland, and experiences earthquakes […] The clear evidence of these examples is that the chronology of the various sources of the Annals of Ulster was often inconsistent with its own, which was itself incorrect in 720; and that events could be misdated by several years either side of their true occurrence by these sources. As the earthquake record of 721 is unique to the Annals of Ulster, it clearly came from “another book”, and its chronology is therefore particularly liable to be incorrect. The interpretation that it is from “another book” is re-enforced by the fact that an October entry appears as the second of nine entries for 721, suggesting chronological displacement within the events of that year, when events were recorded in strict chronological order by any individual original text. Furthermore, given medieval Irish knowledge of seismology, its essential contemporaneous relationship to the “great bursting forth of the sea” of 720 would not have been apparent to the Ulster compiler […] the conclusion that they are in fact contemporaneous appears to be overwhelmingly probable. They are therefore identified as the record of a seismic tsunami, observed at Iona in October 720. (reference #13465)