In the early hours of Sunday, 30 October, a huge rock block detached from a rocky face and struck a beachside hotel near Ierapetra, at southeast Crete. One woman was killed, a child was injured, and part of the hotel was swept away.
The area comprises of sedimentary rocks of the Pliocene series and fluvial torrential deposits. The material at the detachment area is conglomerate with a general dip of 5 to 20o. It is affected by differential weathering, resulting to marginally stable outcrops. In addition, two weeks before the incident, significant rainfalls affected the area. The detached block that reached the beach was a trapezoidal prism, with an approximate volume of 35m3.
A drone video became available in local media shortly after the incident (https://www.youtube.com/@SarantosNikos). It was analyzed by our team with a structure-from-motion (SfM) software to produce a 3D digital mesh model, with a fair degree of accuracy. This model was then imported into a 3D rockfall simulation software allowing for a preliminary analysis of the incident.
Making rational assumptions, the 3D analysis resembled the incident closely. No impact or sliding traces are visible in the proximity of the hotel in the upslope direction, indicating that the block landed onto the hotel room, which is in accordance with the magnitude of the damage and the scatter of the debris. This is well captured by our analysis since the block travels in the air at that position. In addition, the trajectory endpoint is precisely found by our preliminary analysis.
Besides the tragedy and the devastating effects, this incident reveals an opportunity for relevant research. The availability of high-quality data immediately after an incident along with the advanced simulation tools, facilitate the study of natural disasters enhanced with critical information, further advancing our understanding of such complex phenomena.