May 7, 2007 Tsunami: Black Sea, Bulgaria

A tsunami-like sea disturbance of nonseismic origin

was observed on 7 May 2007 on the Bulgarian Black Sea

coast. The maximum wave amplitude was three meters, and

the sea oscillations lasted for several hours. The anomalous

behaviour was seen in many places of the coast of Bulgaria

and was stronger in the north. Several accounts of

eyewitnesses as well as reports of local port authorities

and three tide-gauge recordings are available and have been

collected and analysed. The tsunami could have been

produced by a submarine landslide or by atmospheric

pressure pulses. Here, we explore the former hypothesis,

i.e., the possibility that the tsunami was induced by a

landslide that may have occurred on the shelf margin off

Bulgaria. By making use of numerical modelling we find

that submarine mass movements taking place within a

certain delimited source area off Bulgaria may have

generated tsunamis compatible with the observations... The anomalous behaviour of the sea started around 9:00-9:30 am (Local Time) on 7 May 2007 and lasted with progressive attenuation for about 5 hours. Direct observations were made mostly in the two biggest towns of the coast - Balchik and Kavarna (about 13000 inhabitants each). The port authorities reported similar effects to the north, near Kaliakra cape and the village of Shabla. Slightly more to the south, the observations were documented by observers at the Varna port and the Galata oil and gas platform. The oscillations were recorded by two sea level analogue mareographs, one in Varna and one in Ahtopol (the southernmost point of the Bulgarian Black Sea coast) operated by NIGiF (Scientific Research for Geodesy and Photogrammetry, Sofia).

The tsunami caused only slight damage in the affected

areas. In Kavarna, a 25-30 ton tourist boat was rotated

violently according to his captain and was damaged near the

anchor holes and in some other parts, including the rudder.

Many small fishing boats were cast onto the beach in

Kavarna and Balchik Marinas. Debris was deposited on

the shore. Some large tetrapodes (1.2 tons each) fell into the sea from the breakwater of the Kavarna Harbour.

(above from reference #4176)