The Large Earthquake (~ M7) and Its Associated Tsunami of 8 November 1905 in Mt. Athos, Northern Greece

Mt. Athos, Northern Greece, is a monastic community with life since ~ 1000 AD, a UNESCO worldwide cultural heritage site that was repeatedly hit by earthquakes. On 8 November 1905, a large earthquake, with estimated magnitude ranging from 6.8 to 8.3, caused destruction in Mt. Athos, but the event remains little known since only few documentary sources have been utilized so far. We collected a set of sources including contemporary press reports, letters, manuscripts and books. We reconstructed the earthquake impact field and organized a database containing (1) assignment of macroseismic intensity in 44 observation points at epicentral distances up to ~ 660 km, and (2) identification of sites where important co-seismic ground failures were reported, e.g., landslides and rock falls. From magnitude-intensity relationships, a macroseismic magnitude of ~ 7 equivalent to Ms was estimated, which is close to recent instrumental estimates of ~ Mw 7.2. The examined sources revealed for the first time that a local but powerful tsunami with an ~ 3-m run-up was generated by earthquake-triggered landslides in southern Mt. Athos. Eleven persons were reportedly killed. Both the landslide and the tsunami were numerically simulated by a scenario of massive landslide entering the sea. The synthetic marigrams obtained from the simulation are consistent with the historical tsunami descriptions. Another little-known tsunami was reported in Mt. Athos in association to the large 1585 earthquake. We concluded that a comprehensive hazard assessment in Mt. Athos should take into account not only strong earthquakes but also associated phenomena like landslides and tsunamis.