January 9, 1821 Tsunami: Ionian Sea, Greece

1821, January 6 (9). Ionian Sea, Ionian Islands and Gulf of Patras. A strong earthquake occurred on the Ionian Islands and in the district of Morea within continental Greece with its source located, possibly, between the Island of Zakythos and the north-western extremity of Peloponnesus. Serious damage was done to villages around the town of Zakynthos. The town of Sali (Lalas) in Morea was destroyed almost completely, people were killed under the ruins. (ref #2130).

Reference #2427 lists Jan 9, 1821, Patras Gulf. Destructive inundation.

1821, January 6. 37o48' N, 21o18' E, earthquake magnitude 6.5, intensity X, tsunami intensity 4, reliability 4. On January 6, at Zakyntos and Morea several shocks, the main at 6 p.m. Severe damage in many villages. The town of Sala in Morea was almost entirely destroyed and numbers of people perished (Mallet, r16). According to Mallet, on January the 9th the waters of the Alcyonic Sea, part of the Gulf of Corinth, rose suddenly, inundating the country and carrying away houses (Mallet, r16). In Patras the harbour facilities and a number of houses near the sea front were severely damaged. The water overflowed the shores and covered the ancient Temple of Demeter, dedicated to St. Andrew. Severe damage caused by the wave (Antonopoulos, r417); Galanopoulos, r433). Further references: Papadopoulos (r80, r570), Soloviev (r414), Galanopoulos (r479), Antonopoulos (r573, 392), Ambraseys (r391), Heck (r78). (ref #4139)

1821, January 6. Severe damage at Patras by a seismic sea wave set off by a very strong aftershock centered between Zante and Ells (ref #109)

1821, January 6, 37.8 N 21.3 E. Probable tsunami (ref #11164, v.2)

On 6 January 1821 a strong aftershock occurred. A slight sea disturbance and a sea-quake were reported in Zakynthos in association with the first earthquake (Barbiani and Barbiani, 1864). Some authors, however, confused the stormy weather prevailing at the time of the earthquake occurrence with a possible, destructive tsunami associating the earthquake. For example, Papazachos and Papazachou (1989, 1997) reported that "...6people died and 29 were injured. Two people were drown by the flood which followed" giving the impression that the earthquake and the flooding were associated. They estimated a tsunami intensity of III + in a six-grade scale. However, from the documentation cited by Barbiani and Barbiani (1864) and Konomos (1970), it becomes clear that flooding following both the main shock of 29 December 1820 and its aftershock of 6 January 1821, as well as the reported people to be drowned after the first event, were due to a heavy rainfall. […] There is no good reason to associate the 6 January 1821 earthquake with the sea- wave of 9 January 1821, by assuming that the date of the latter is an erroneous writing of 6 January 1821. The date of 9 January 1821 could be accepted with less scepticism with respect to the date of 6 January 1821 as an alternative […] In Pouqueville's (1824) description one may observe that the wave was associated with thunders and a storm concluding with the appearance of a rainbow, which implies that the wave was rather a storm surge than a real tsunami event.(ref #13472)

Reference #9116 lists and earthquake on 1821 January 06 (Zakynthos) with no mention of tsunami. Reference #9116 states the following for 1821 January 09, (Alcyonic Sea): The level of the Alcyonic Sea (Gulf of Aegosthena, the easternmost part of the Gulf of Corinth) rose suddenly inundating the country, washing away houses in some places that are not named. This happened without an earthquake. Modern writers consider this to be a seismic sea wave, which they attribute to the earthquake that shook Zakynthos three days earlier, which happened 200 km away from the Alcyonic Sea. As a matter of fact the earthquake in Zakynthos was not felt in the Gulf of Aegoosthena 210 km away.