FEATURES OF THE SEISMIC PROCESS IN THE WESTERN PART OF THE ALEUTIAN SUBDUCTION ZONE AND THEIR POSSIBLE RELATIONSHIP WITH CLIMATE CHANGES IN THE ARCTIC

In the second half of the XX century, there was a pronounced increase in the average annual temperature in the troposphere surface layer of the Russian Arctic region, which led to a scaling-up in the risks of natural disasters associated with the cryolithosphere degradation. Modern integrated studies of the Arctic have revealed a significant influence of geodynamic processes on the permafrost state. Previously, a seismogenic-trigger mechanism of the occurrence of climate warming phases in the Arctic proved to be possible due to strong mechanical disturbances of the marginal region of the Arctic lithosphere, caused by major earthquakes in the Aleutian subduction zone. The authors discuss the features of the seismic cycle in the Aleutian subduction zone, characterized the presence of a pronounced tangential component of the convergence vector of lithospheric plates. The study shows that the orientation of the plate convergence vector relative to subduction zone axis can have a significant impact on the preparation and occurrence of major earthquakes in subduction zones. In particular, the analysis of the seismic activity occurring in the western part of the Aleutian island arc showed that the seismic cycles here are shorter than in the eastern part of the arc. The authors revealed that major earthquakes, repeated in the same areas of the western part of the Aleutian subduction zone, differ both in magnitude and foci length. Taking into account the oblique subduction setting, the authors propose a keyboard model for the generation of major subduction-associated earthquakes as a mechanism potentially capable to explain the reduction in the seismic cycle duration and noticeable differences in the spatial extent and the foci localization of seismic events with similar magnitudes observed in the same segment of the western half of the Aleutian subduction zone.

1. Report on climate features in the Russian Federation for 2020. Moscow, Rosgidromet, 2021, 104 p. (In Russian).

2. Veselov I. A., Chupriyan A. P. On measures of the Russian Emergencies Ministry to ensure the implementation of economic and infrastructure projects in the Arctic and the creation of a system of specialized emergency rescue centers. Arktika: ekologiya i ekonomika. [Arctic: Ecology and Economy], 2011, no. 1 (1), pp. 48—51. (In Russian).

3. Sherstyukov B. G. The climatic conditions of the Arctic and new approaches to the forecast of the climate change. Arctic and North, 2016, no. 24, pp. 39—67. DOI: 10.17238/issn2221-2898.2016.24.39. (In Russian).

4. Lobkovsky L. I. Deformable plate tectonics and regional geodynamic model of the Arctic region and Northeastern Asia. Russian Geology and Geophysics, 2016, vol. 57, no. 3, pp. 371—386. DOI: 10.1016/j.rgg.2016.03.002.

5. Lobkovsky L. I., Garagash I. A., Alekseev D. A. Geodynamic evolution model of the major structures of Amerasian basin. Doklady Earth Sciences, 2018, vol. 480, pp. 753—757. DOI: 10.1134/S1028334X18060065.

6. Lobkovsky L. I. Possible seismogenic trigger mechanism of abrupt activation of methane emission and climate warming in the Arctic. Arktika: ekologiya i ekonomika. [Arctic: Ecology and Economy], 2020, no. 3 (39), pp. 62—72. DOI: 10.25283/2223-4594-2020-3-62-72. (In Russian).

7. DeMets C., Gordon R. G., Argus D. F., Stein S. Effects of recent revisions to the geomagnetic reversal time scale on estimates of current plate motions. Geophys. Res. Lett., 1994, vol. 21, ðð. 2191—2194. DOI: 10.1029/94GL02118.

8. Boyd Th. M., Lerner-Lam A. L. Spatial distribution of turn-of-the-century seismicity along the Alaska-Aleutian arc. Bull. Seismol. Soc. Am., 1988, vol. 78, no. 2, ðð. 636—650.

9. Vikulin A. V. Variant of long-term seismic forecast for the Kamchatka Bay and the Kronotsky Peninsula. J. Volcanolog. Seismol., 1986, no. 3, pp. 72—83. (In Russian).

10. Hwang L. J., Kanamori H. Of the May 7, 1986 Andreanof Islands earthquake source parameters. Geophys. Res. Lett., 1986, vol. 13, no. 13, ðð. 1426—1429. DOI: 10.1029/GL013i013p01426.

11. Nishenko S. P., Jacob K. H. Seismic potential of the Queen Charlotte-Alaska-Aleutian seismic zone. J. Geophys. Res., 1990, vol. 95, ðð. 2511—2532. DOI: 10.1029/JB095iB03p02511.

12. Sykes L. R., Kisslinger J. B., House H., Davies J. N., Jacob K. H. Rupture zones of great earthquakes in the Alaska-Aleutian arc, 1784 to 1980. Science, 1980, vol. 210, no. 4476, ðð. 1343—1345. DOI: 10.1029/ME004P0073.

13. Johnson J. M., Tanioka Y., Ruff L. J., Satake K., Kanamori H., Sykes L. R. The 1957 great Aleutian earthquake. Pure Appl. Geophys., 1994, vol. 142, ðð. 3—28. DOI: 10.1007/BF00875966.

14. Kanamori H., Brodsky E. E. The physics of earthquakes. Reports on Progress in Physics, 2004, vol. 67, ðð. 429—1496. DOI: 10.1088/0034-4885/67/8/R03.

15. McCaffrey R. Oblique plate convergence, slip vectors, and forearc deformation. J. Geophys. Res., 1992, vol. 97, ðð. 8905—8915. DOI: 10.1029/92JB00483.

16. Avdeiko G. P., Palueva A. A. The Kamchatka subduction zone: Seismotectonic regionalization and geodynamics. J. Volcanolog. Seismol., 2011, vol. 5, no. 1, pp. 1—16. DOI: 10.1134/S0742046311010027.

17. Lobkovsky L. I., Baranov B. V., Dozorova K. A., Mazova R. K., Kiselman B. A., Baranova N. A. The Komandor seismic gap: earthquake prediction and tsunami computation. Oceanology, 2014, vol. 54, no. 4, pp. 519—531. DOI: 10.7868/S0030157414030071.

18. Davies J. N., Sykes L., House L., Jacob K. Shumagin seismic gap, Alaska: History of great earthquakes, tectonic setting and evidence for high seismic potential. J. Geophys. Res., 1981, vol. 86, ðð. 3821—3855. DOI: 10.1029/JB086iB05p03821.

19. López A. M., Okal E. A. A seismological reassessment of the source of the 1946 Aleutian ‘tsunami’ earthquake. Geophys. J. Int., 2006, vol. 165, no. 3, ðð. 835—849. DOI: 10.1111/j.1365-246X.2006.

02899.x.

20. Spence W. The Aleutian Arc: Tectonic blocks, episodic subduction, strain diffusion, and magma generation. J. Geophys. Res., 1977, vol. 82, no. 2, ðð. 213—230. DOI: 10.1029/JB082I002P00213.

21. Lay T., Kanamori H. An asperity model of large earthquake sequences. Earthquake prediction: An international review. Washington, D.C, AGU, 1981, ðð. 579—592. DOI: 10.1029/ME004P0579.

22. Fedotov S. A. About the seismic cycle, the possibility of quantitative seismic zoning and long-term seismic forecasting. Seismic zoning of the USSR. Moscow, Nauka, 1968, pp. 121—150. (In Russian).

23. Boyd Th. M., Engdahl E. R., Spence W. Seismic cycles along the Aleutian arc: Analysis of seismicity from 1957 through 1991. J. Geophys. Res., 1995, vol. 100, no. B1, ðð. 621—644. DOI: 10.1029/94JB02641.

24. Beck M. E. J. On the mechanism of tectonic transport in zones of oblique subduction. Tectonophysics, 1983, vol. 93, ðð. 1—11. DOI: 10.1016/0040-1951(83)90230-5.

25. Baranov B. V., Monin A. S. O Kurilo-Aleutskoi subduktsii. Dokl. AN SSSR, 1985, vol. 281, no 6, pp. 1328—1331. (In Russian).

26. Levina V. I., Lander A. V., Mityushkina S. V., Chebrova A. Yu. The Seismicity of the Kamchatka Region: 1962—2011. J. Volcanolog. Seismol., 2013, vol. 7, no. 1, pp. 37—57. DOI: 10.1134/S0742046313010053.

27. Lobkovsky L. I., Kerchman V. I., Baranov B. V., Pristavakina E. I. Analysis of seismotectonic processes in subduction zones from the standpoint of a keyboard model of great earthquakes. Tectonophysics, 1991, vol. 199, ðð. 211—236. DOI: 10.1016/0040-1951(91)90173-P.

28. Cormier V. F. Tectonics near the junction of the Aleutian and Kuril-Kamchatka Arcs and a mechanism for Middle Tertiary magmatism in the Kamchatka Basin. Geological Society of America Bull., 1975, vol. 86, pp. 443—453. DOI: 10.1130/0016-7606(1975)862.0.CO;2.

29. Baranov B. V., Ivanchenko A. I., Dozorova K. A. The Great 2006 and 2007 Kuril Earthquakes, Forearc Segmentation and Seismic Activity of the Central Kuril Islands Region. Pure Appl. Geophys., 2015, vol. 172, no. 12, ðð. 3509—3535. DOI: 10.1007/s00024-015-1120-z.

30. Lobkovsky L. I., Baranov B. V., Vladimirova I. S., Gabsatarov Y. V., Garagash I. A., Steblov G. M. Seismotectonic deformations related to the 2010 Maule earthquake at different stages of the seismic cycle from satellite geodetic observations. Doklady Earth Sciences, 2017, vol. 477, no. 2, pp. 1498—1503. DOI: 10.1134/S1028334X17120261.

31. Lobkovsky L. I., Vladimirova I. S., Gabsatarov Y. V., Steblov G. M. Seismotectonic deformations related to the 2011 Tohoku earthquake at different stages of the seismic cycle, based on satellite geodetic observations. Doklady Earth Sciences, 2018, vol. 481, no. 2, pp. 1060—1065. DOI: 10.1134/S1028334X18080159.

32. Vladimirova I. S., Lobkovsky L. I., Gabsatarov Y. V., Steblov G. M., Vasilenko N. F., Prytkov A. S., Frolov D. I. Patterns of the seismic cycle in the Kuril island arc from GPS observations. Pure Appl. Geophys., 2020, vol. 177, no. 8, ðð. 3599—3617. DOI: 10.1007/s00024-020-02495-z.