L.LOBKOVSKY 1, R.MAZOVA 2, L.KATAEVA 2
1 P.P.Shirshov Institute of Oceanology,
Russian Academy of Science, 36 Nakhimovsky avenue, 117997, Moscow, Russia (e-mail:
llobkovsky@geo.sio.rssi.ru)
2 Nizhny Novgorod State Technical University, Nizhny Novgorod, Russia
The deep-sea trench with ocean side of south Kurile islands permits to consider the region of Kurile islands as potential seismically dangerous zone, moreover underwater earthquakes in subduction zone appears to be mostly tsunamigenic. The appearence of tsunami at such earthquakes is dangerous for coastal regions of Okhotsk Sea including Sakhalin Island where there are intensive developments of infrastructure of oil and gas industry. During the history there were fixed several cases of tsunami attacks at Sakhalin coast produced by earthquakes in the region of Kurile Islands. In sourth and north parts of Kurile islands, because of small keyblock structure of deep-sea trench, the elastic energy release during the subduction occurs gradually last time while in the middle- Kurile region the process of the elastic energy release can lead to strong underwater earthquake which in its turn can lead to tsunami with great destructive power. In present work, it is performed a complex study of possibility of strong tsunami generation in the ‘seismic gap’ region in subduction zone of Kurile islands on the basis of instrumental study performed during recent ocean scientific-research expedition in the region of ‘seismic gap’ of Kurile-Kamchatka arc. The first aim is a situative numerical simulation of possible source of tsunamigenic earthquake and analysis of possible scenarios of tsunami wave generation which can lead to catastrophic sequences at Okhotsk Sea coast. For numerical simulation of possible earthquakes and tsunami there were considered two types of hypotetic earthquake source with length of order 400 km and width of order 100 km located between Bussol strait and Shiashkotan Island. So, mean distance between source and Kurile islands was about 35 km. There was considered a various number of keyboard blocks (from 3 to 8) moving up and down from 5 to 14 m with block motion time from 10 to 60 sec. The analysis performed demonstrates that at realization of various scenarios of tsunami source formation by given seismic sources, the wave height distribution can be from 15 m at islands of Kurile-Kamchatka arc to 8,5 m at a number of parts of Sakhalin island coast. (The work was supported by RFBR grant No. 05-05-64685 and by grant of EU Project 502247 - COMSHELFRISKS)