R. MAZOVA 1, L.LOBKOVSKY 2, L.KATAEVA 1
1 Nizhny Novgorod State Technical University,
Nizhny Novgorod, Russia (e-mail: raissamazova@mail.nnov.ru)
2 P.P.Shirshov Institute of Oceanology, Russian Academy of Science, 36
Nakhimovsky avenue, 117997, Moscow, Russia
As known, tsunami formation depends on character and dynamics of shifts in earthquake source zone or more concretely on initial ocean floor shifts. It is also known that the island-arc wedge consists of separated large segments. Such cutting to blocks of frontal parts of islands and active continental margins determines structurally the strong earthquake source size. The presence of transcurrent faults have led to necessity of introducing of new, more small elements of interaction, so-called keyboard blocks (~ 100 km) with frontal side of overriding plate (Lobkovsky, 1988; Lobkovsky et al., 2004). The earthquake source can extend to not one but several seismogeneous keyboard blocks and in such a case the extension of the rupture zone increases. The similar scenario of events was realized in recent catastrophe at Sumatra Island on 26 December 2004. Its source has an extension more than 1000 km and includes a lot of keyboard blocks. In this work, in frames of nonlinear shallow water equations, it is performed a numerical simulation of tsunami generation by Sumatra earthquake and its propagation up to nearest coasts. There were considered various scenarios of tsunami wave generation. The length of source was from 1000 to 1400 km with width from 100 to 150 km and the number of blocks was from 3 to 14. It was considered the vertical block motion up as well as down. The velocity of block motion was taken in agreement with characteristic motion time in the earthquake source. In result, it was obtained that tsunami waves generated by various combination of keyboard block motion have an essentially different character which fact leads to different picture of maximum run-up distribution along the coast. Taking into account the oblique character of subduction zone characteristic for Sumatra- Andaman earthquake on 26 December 2004 permits most accurately to reproduce processes occurring at nearest coasts and thus describe processes occurring in the earthquake source in more details. Such a model can also account for the tsunami wave field character in other regions of Indian and Pacific Oceans basin as well. (This work is supported by RFBR grant No. 05-05-64685 and by grant of EU Project 502247 - COMSHELFRISKS).