ISSN 1028-334X, Doklady Earth Sciences, 2008, Vol. 419, No. 2, pp. 335Ð338. © Pleiades Publishing, Ltd., 2008. Original Russian Text © B.W. Levin, V.M. Kaistrenko, A.V. Rybin, M.A. Nosov, T.K. Pinegina, N.G. Razzhigaeva, E.V. Sasorova, K.S. Ganzei, T.N. Ivel’skaya, E.A. Krav- chunovskaya, S.V. Kolesov, Yu.V. Evdokimov, J. Bourgeois, B. MacInnes, B. Titzhugh, 2008, published in Doklady Akademii Nauk, 2008, Vol. 419, No. 1, pp. 118Ð122.

GEOPHYSICS

Manifestations of the on November 15, 2006, on the Central : Results of the Modeling of Run-Up Heights Corresponding Member of the RAS B. W. Levina, V. M. Kaistrenkoa, A. V. Rybina, M. A. Nosovb, T. K. Pineginac, N. G. Razzhigaevad, E. V. Sasorovae, K. S. Ganzeid, T. N. Ivel’skayaf, E. A. Kravchunovskayac, S. V. Kolesovb, Yu. V. Evdokimovc, J. Bourgeoisg, B. MacInnesg, and B. Titzhughg Received September 28, 2007

DOI: 10.1134/S1028334X08020335

On November 15, 2006, a strong earthquake with and the Presidium of the Far East Division of the Rus- magnitude Mw = 8.3 occurred in the Central Kuril seg- sian Academy of Sciences). The second expedition was ment of the KurilÐKamchatka seismic focal zone. The carried out within the NSF project Kuril Biocomplexity. earthquake source was located in the ocean opposite to The expeditions were carried out onboard the Iskatel-4 and islands. The instrumental epicen- (registry port Korsakov). The expedition included well- ter was located approximately at a distance of 85 km known tsunami specialists from different institutes of from the northern edge of Simushir Island. This was the and the United States, whose joint work at the first recording of such a powerful earthquake in this common sites provided a high level of research. region in the entire history of seismic observations. It is worth noting that many of the authors had During the period from July 1 to August 14, 2007, already visited the region of the Central Kuril Islands in two marine multidisciplinary expeditions were carried the summer of 2006. Thus, a unique possibility out in the region of the Central Kuril Islands. One of the appeared to compare the coastal regions before and goals of the expeditions was investigation of the coasts after the tsunami. Furthermore, in the summer of 2006, of the Central Kuril Islands to measure the run-up temporal GPS stations were set on Ketoi, Matua, and heights and inundation distances of tsunami, as well as islands, which recorded coseismic defor- to gather data on the geological effects of the tsunami mations caused by the November 15, 2006, and Janu- on the coasts. The first expedition was organized by the ary 13, 2007 (Mw = 8.1), earthquakes. The January event Institute of Marine Geology and Geophysics, Far East was also tsunamigenous. However, we can state on the Division of the Russian Academy of Sciences (sup- basis of a number of pressure gauge records and ported by the Russian Foundation for Basic Research obtained field data that the second tsunami was much weaker than the November one. a Institute of Marine Geology and Geophysics, During 45 days of work, the participants of the expedi- Far Eastern Division, Russian Academy of Sciences, tion investigated , Simushir, Ketoi, Yankicha, and ul. Nauki 1b, Yuzhno-Sakhalinsk, 693022 Russia Ryponkicha islands (islands of the group), as b Moscow State University, Leninskie gory, Moscow, well as the islands of and Matua (Fig. 1). 119991 Russia; e-mail: [email protected] c Institute of Volcanology and Seismology, Far East Division, The highest tsunami run-ups were found on Matua Russian Academy of Sciences, bulv. Piipa 9, Island, where their mean height exceeded 10 m. In Ainu 683006 Petropavlovsk-Kamchatskii, Russia Bay (southwestern part of Matua Island), the tsunami d Pacific Institute of Geography, Far East Division, changed the coastal morphology strongly and eroded a Russian Academy of Sciences, ul. Radio 7, Vladivostok, part of marine accumulation terrace 20Ð30 m wide. In 690041 Russia Dushnaya Bay (northeastern part of Simushir Island), e Shirshov Institute of Oceanology, Russian Academy the tsunami left numerous flood gullies on the marine of Sciences, Nakhimovskii pr. 36, Moscow, 117997 Russia terrace. In addition to erosion, accumulation was f Tsunami Center of the Hydrometeorological observed everywhere on the investigated coasts. Tsu- Service, ul. Zapadnaya 78, Yuzhno-Sakhalinsk, nami deposits are presented by sea sand, pebbles, 693000 Russia ridges, and floating material transported shoreward. g University of Washington, 301 Gerberding Hall, Vegetation was partly destroyed on steep slopes of the , WA 98195 USA coasts, and soil was also washed out by the tsunami.

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336 LEVIN et al.

145° 150° 155° E N Matua Is. Kamchatka Pen. Toporkov Is. Sakhalin Is. SEA OF Sarychevo OKHOTSK 50° Ainu Bay Is. Yuzhnaya Bay Matua Is. Ushishir Ils. Rasshua Is. SEA OF Simushir Is. Ketoi Is. Rasshua Is. Dushnaya Urup Is. Bay PACIFIC OCIAN

Hokkaido 45° 500 km Malen’kaya Simushir Is. Bay Ketoi Is. Ushishir Ils. Yuzhnyi C.

Ryponkicha Is. Spaseniya Bay

Yankicha Is. Yuzhnaya Bay 5 km N Coast intervals studied in detail

Fig. 1. Region of field works and sites of studied coasts. All islands are shown in different scales; the bar length is 5 km in each case.

N 49°

Matua Is. 48° Rasshua Is. Ushishir Ils. Ketoi Is. 10 m 47° Simushir Is.

Urup Is. 46°

45° 149° 150° 151° 152° 153° 154° 155° 156° E

Fig. 2. Calculation area and tsunami source on November 15, 2006. The isobaths are shown with a step of 1000 m. White contour lines show vertical deformation of the bottom (solid line denotes uplift; dashed line, subsidence; contour lines are shown with a step of 0.2 m). Calculated run-up heights are shown with segments oriented normal to the coastline. The segment length is proportional to the run-up height. (10 m) Scale of run-up height.

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MANIFESTATIONS OF THE TSUNAMI 337 The same Notes to measurements 0.5 m. (2) The errors of run-up and inun- 0.5 m. (2) ± ) hand level instrument, height rod, and roulette; ) hand level ing the GPS along straight line between d distance; (+2006) topographic profiles of 2006 d distance; (+2006) topographic profiles Island between the coast and line of maximal run-up ments ing material and plastic floating material and plastic on the coastal ridge for short and steep profiles The lowest and highest run-ups are excluded for long and flat profiles re usually less than of run-ups Number of measurements 816 Num- ber of profiles 2006 4 5 2006 13 30 ments Method of measure- HR, LR, HRR + 2006 Inunda- tion dis- tance, m m ± Accuracy ments, of measure- 9Ð10 1.0 30Ð40 HRR 6 14 In the strait between Toporkov Island and Matua 6Ð106Ð8 0.56Ð8 60Ð100 0.5 HR <0.5 100Ð140 HR 180Ð220 + LR 9 6 9 6 With account for the height of coastal ridges 6Ð99Ð14 The same 0.57Ð9 <0.5 35Ð65 50Ð90 <0.5 HR LR 100Ð150 + LR 17 10 17 100 The lowest and highest run-ups are excluded The same 4.2, 5 0.5 65 HR 2 2 11Ð17 <0.5 50Ð60 LR, HRR 9 16 Excluding the lowest and highest run-ups 13Ð16 <0.5 50Ð65 LR, HRR12Ð14 817Ð20 0.513Ð14 12 100Ð120 0.5 HR 200Ð400 0.5 70Ð120 HR 2 The same 2 2 2 Inundation distances based on GPS measure- 12Ð19 <0.5 80 LR, HR 3 3 Very steep profiles Run-up 6.5Ð7.5 0.5 50Ð60 HRR 5 34 Excluding lowest and highest run-ups height, m Region of observations Western coast of the island north Okhotsk side eastern part Sarychev Coast, central part Sarychev Coast, southern part Yuzhnaya Bay, eastern part Yuzhnaya Bay, western part Ainu Bay, south- eastern part Ainu Bay, cen- tral part Ainu Bay, north- western part Malen’kaya Bay 9.7 0.5Yuzhnaya Bay, 50western part HRSnorthern part Dushnaya Bay, central part Dushnaya Bay, southern part 1Spaseniya Bay 4.5Ð7 1 0.5 Determination based on the final ridge of float- 80Ð140 HR 7 8 Excluding lowest and highest run-ups " " " " " " " " " " " " Island Toporkov (east of Matua) dation distances obtained from topographic profiles are usually less than 10%; the error (sometimes correction) was estimated us dation distances obtained from topographic profiles are usually less than 10%; the error (sometimes correction) was instrument and height rod; (HRR edge and the point of maximal tsunami run-up. (3) Methods measurements: (LR) level water instrument and rod for measuring heights an (HR) hand level instrument, height rod, and step measuring survey; (HRS) hand level The number of run-up heights measured between topographic profiles. were used. (4) (2007) Date of in- vestigations Note: a in the studied regions in the sea level of the data has not been corrected based on tide tables; variations (1) Part August 8 August 2Ð3 Matua Sarychev Coast, August 2Ð4 August 6Ð7 August 2Ð5 August 11 RasshuaAugust 9 Cape Yuzhnyi, August 9 RyponkichaAugust 10 Ryponkicha Northern edge Yankicha SE coastJuly 8 Northern edge 5.7 Ketoi 12.8 10Ð11 0.5July 10Ð27 <0.5 <0.5 Yuzhnaya Bay, July 10Ð27 54 45Ð55 50 HR LR LR 1 6 1 19 1 1 Excluding lowest and highest run-ups Determination based on the large amount of August 7 August 6 August 4Ð6 August 11 July 8Ð11 July 10Ð27 Simushir Dushnaya Bay, July 12Ð19 August 2Ð5 Run-ups and inundation distances of the tsunami on November 15, 2006, studied coasts Central Kuril Islands

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338 LEVIN et al. In the southeastern part of Simushir Island, the quality of the information on ocean depths. The data of intensity of the tsunami was much smaller, while the measurements were compared with the information run-up heights did not exceed the run-ups of storm from the GEBCO atlas and GUNIO digital model of waves in the southern part of Urup Island. They were bottom topography. It was found that the GEBCO atlas not greater than 4Ð6 m and could be even smaller. The frequently overestimates the depths in the study region obtained results on run-ups and inundation of the tsu- (the error reaches 100% of the actual depth and even nami are presented in Table 1. more). The GUNIO digital model demonstrated a good After final processing, all the data gathered during correlation with the data of measurements. Since the the expeditions will be included in the Russian and digital model of the bottom topography does not cover World databases. The collected material will allow us to the entire region needed for the calculations and only test and refine the numerical models used to estimate covers areas corresponding to the sheets of marine nav- the tsunami hazard on the coasts. igation charts (scale 1 : 250 000), it was necessary to Numerical modeling of the November 15, 2006, tsu- create combined bathymetry. nami was carried out within the linear theory of long The distribution of calculated maximal wave heights waves [1]. Linearized equations of shallow water writ- is shown in Fig. 2 with gray segments oriented normal ten in the spherical coordinate system without account to the coastline. The segment length is proportional to of the Coriolis force were reduced to a wave equation the run-up height. The maximal calculated run-ups (up with respect to the displacement of the free sea surface. to 7.5 m) correspond to the Pacific coast of Simushir, The boundary condition of full reflection was specified Ketoi, Ushishir, Rasshua, and Matua islands. The near the coastline at the 10 m isobath. The condition of Okhotsk coast of the islands is influenced by waves of free flow was specified at the external boundaries of the notably smaller amplitude. The run-up heights in the calculation area. The deviation of the free water surface southern part of Simushir Island (Spaseniya Bay) from the equilibrium position was used as the initial appear much smaller as compared to its northern part condition, which was assumed identical to the vertical (Dushnaya Bay). The wave heights on the coasts of residual deformations of the bottom. The wave equa- Urup Island appear comparatively small. tion was approximated by the traditional explicit finite- We recall that the numerical model used in our work difference scheme on a rectangular grid. is a linear one. In addition, it calculates the run-up The displacement of the free water surface from the height not at the real coast but at a hypothetical vertical equilibrium position, which was assumed identical to wall set along the 10-m isobath. It is known that the the vertical deformations of the ocean bottom, was con- account for nonlinearity increases the run-up height but sidered as the initial condition. The vertical deforma- by not more than a factor of 2. The run-up height also tions were calculated from the Okada formulas accord- increases strongly in the case of the tsunami wave inci- ing to the earthquake source model developed at the dent on a flat beach. Therefore, the calculated wave U.S. Geological Survey (http://earthquake.usgs.gov/). heights are 2Ð3 times smaller than the measured values. Vertical deformations of the bottom are shown in Fig. 2 Taking into account this correction, we can conclude with white contour lines. The time step (0.75 s) was that the calculated run-up heights generally correspond determined by the Courant instability condition. The well to the measured values. calculation area extended from 149° to 156° E and from ° ° ° × 45 to 49 N. The spatial step was 0.004 (1751 ACKNOWLEDGMENTS 1001 nodes). This work was supported by the Russian Foundation Reliable data on the bottom topography (bathyme- for Basic Research (project nos. 07-05-10070k, 06-05- try) are required to model the tsunami wave propaga- 08098, 07-05-00363, 07-05-00414, and 05-05-64733), tion, especially in shallow regions. In our calculations, the Presidium of the Far East Division of the Russian we used combined bathymetry based on a 1-min digital Academy of Sciences, and the National Science Foun- GEBCO atlas (British Oceanographic Data Center, dation (project no. ARC-0508109). The authors thank http://www.ngdc.noaa.gov/mgg/gebco/) and a digital I.V. Fine for the data on the vertical deformation of the model of the bottom topography with a resolution of bottom in the tsunami source region. 0.25 angular minutes based on unclassified marine nav- igation charts presented by the Main Administration on Navigation and Oceanography of the Russian Ministry REFERENCES of Defense (GUNIO). 1. B. W. Levin and M. A. Nosov, Physics of Tsunami and During the expedition, an echo sounder survey was Similar Phenomena in the Ocean (YanusÐK, Moscow, performed on the shelf of the Kuril Islands to test the 2005) [in Russian].

DOKLADY EARTH SCIENCES Vol. 419 No. 2 2008