ISSN 0747-9239, Seismic Instruments, 2010, Vol. 46, No. 3, pp. 275–285. © Allerton Press, Inc., 2010. Original Russian Text © V.N. Chebrov, A.A. Gusev, V.K. Gusyakov, V.N. Mishatkin, A.A. Poplavskii, 2010, published in Seismicheskie Pribory, 2009, Vol. 45, no. 4, pp. 41–57. 275 INTRODUCTION Tsunamis are dangerous natural phenomena that can lead to mass deaths, destruction of populations, and economic damage. In the 20th century alone, powerful tsunamis repeatedly struck Russia’s Pacific coast (1923, 1952, 1959, 1969, and 1994). The main factor causing tsunami waves (approximately 85%) are underwater earthquakes. Historic and geological data reliably substantiate a high level of tsunami and earth- quake danger for the Russian Far East; it is certain that these natural hazards will be repeated here systemati- cally in the future [Solov’ev, 1972; Levin, 2005]. The Tsunami Warning Service (TWS) was estab- lished in the Russian Far East after the destructive 1952 tsunami struck the Kamchatka Peninsula and Kurile Islands. Using the data of three-component recording of seismic signals, it is possible to find epi- center coordinates and magnitude, i.e., to determine the origin and energy of the earthquake. Estimation of the probability of a tsunami from these parameters is the essence of the magnitude–geographic criterion, which continues to be the basis of the TWS’ work [Savarenskii, 1956; Poplavskii et al., 1997]. So that a tsunami warning will be timely, the loca- tion of the epicenter and earthquake power should be determined with minimal delay after its onset. For this TWS seismic stations were equipped with specially designed seismic apparatus, which was their basic equipment [Kirnos and Rykov, 1961]. These are stan- dard mechanical seismographs with small amplifica- tion and UBOPE (Ustroistvo dlya Bystrogo OPrede- leniya Epicentra; Device for Rapid Determination of Epicenter), specially designed for operational work with amplification from 1 to 30. The range of recorded periods is T = 2 to 4 s at a level of 0.9 [Apparatura…, 1974]. These mechanical installations, intended for recording strong earthquakes at epicentral distances of 150 to 2000 km in a narrow range of periods of 0.2–4.0 s, became obsolete long ago, but are still used in the TWS at the Severo-Kuril’sk and Petropavlovsk-Kam- chatskii seismic stations. At the Yuzhno-Sakhalinsk seismic station, they were removed in the late 1980s. In the 1960s, standard Kirnos system devices were additionally installed at the stations; the natural oscil- lation period of pendulums was T S = 12 s [Appa- ratura…, 1974]. Due to the small dynamic recording range of these devices, they can be used only for more distant or relatively weak nearby earthquakes. In the Kirnos devices, the seismic signals were recorded on photographic paper, which made it impossible to use them for operationally estimating the azimuth of the epicenter. In the 1970s, seismographs with recording on ther- mal paper SKD-UP-SPR (T = 20 s; V = 1000, 200, 50, and 10) [Apparatura…, 1974] were installed at the stations. Their use for recording strong nearby earth- quakes was limited by magnitudes of M = 6.0–6.5 due Concept for Developing a Seismologic Observation System for Tsunami Warning in the Russian Far East V. N. Chebrov a , A. A. Gusev a,b , V. K. Gusyakov c , V. N. Mishatkin d , and A. A. Poplavskii e, f a Kamchatka Division of Geophysical Service, Russian Academy of Sciences, Petropavlovsk-Kamchatskii, Russia b Institute of Volcanology and Seismology, Far East Division, Russian Academy of Sciences, Petropavlovsk-Kamchatskii, Russia c Institute of Computational Mathematics and Mathematical Geophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia d Geophysical Service, Russian Academy of Sciences, Obninsk, Kaluga oblast, Russia e Institute of Marine Geology and Geophysics, Far East Division, Russian Academy of Sciences, Yuzhno-Sakhalinsk, Russia f Geophysical Service, Sakhalin Division, Russian Academy of Sciences, Yuzhno-Sakhalinsk, Russia Abstract—The initial information and requirements for developing a seismologic observation system and data-processing and transfer tools for a tsunami warning system and its functions and tasks are considered. The structure of the seismologic observation system for the tsunami warning service (TWS) in the Russian Far East is proposed. A study of general technical and methodological problems is carried out to increase the effi- ciency for urgent tsunami prediction from continuous seismic monitoring data of territories of the Russian Far East and the world. Special attention is paid to the problem of tsunami prediction from seismologic data on strong earthquakes in near zone of a protected territory (up to 200 km). Key words: seismology, tsunami, seismologic observation system, operative tsunami prediction, near zone. DOI: 10.3103/S0747923910030096