engleski

The source of the 2007 Ist meteotsunami (Adriatic Sea)

This paper investigates generating force of the extraordinary tsunami-like sea level oscillations, having crest-to-through height of around 4 m, which flooded Široka Bay on the island of Ist in the afternoon hours of 22 August 2007. This extreme event began when sudden ebb dried out shallow harbor, leaving most of the ships aground. A few minutes later water rushed back in, flooding basements, houses and much of the local village and carrying with it previously stranded ships, landing some of them ashore. Data analysis indicates that the flood was provoked through the double resonance mechanism, being initiated by a pronounced atmospheric disturbance traveling with the speed of about 21-24 m/s over the Adriatic shelf, which generated open ocean waves through the Proudman resonance. The waves then further amplified inside the affected bay. The source of this meteotsunami event, i.e. the traveling air pressure disturbance, was investigated through both data analysis and atmospheric numerical modeling. Apparently, the air pressure disturbance was a surface manifestation of a ducted gravity wave which propagated through the atmosphere from the Apennines to the eastern Adriatic coast over the northern Adriatic. According to the modeling results, the wave was trapped in the stable layer adjacent to the ground, which was capped by a dynamically unstable layer with the wind speeds of about 22 m/s. This made the unstable layer also a critical layer for the gravity waves propagating with the same speed, and allowed for the ducting of the gravity waves in the layer below.

meteotsunami; Adriatic Sea

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