Five-Year Evolution of Regional Seismicity and Deficit of Internal Crustal Displacements According to GNSS Data in Connection With the Kamchatka Megathrust Earthquake of 2025
1 RUDN University, Moscow, Russia
2 Geophysical Center of the Russian Academy of Sciences, Moscow, Russia
3 Кamchatka branch of Geophysical Survey of the Russian Academy of Sciences, Petropavlovsk-Кamchatsky, Russia
Abstract
Synoptic animation demonstrates the behavior of regional seismicity and deficit of internal crustal movements, the assessment of which was carried out based on continuous GNSS observations for more than five years with a daily time resolution. The characteristic of the deficit of internal movements is the modulus of the vector of horizontal displacements of GNSS stations in the internal reference system, not associated with conditionally fixed points in the territories of a particular tectonic plate. The orientation of the vectors of internal displacements preserves the orientation of the global coordinate reference system. The values of the horizontal displacement vector components are counted from the general average of the entire set of displacement vectors of GNSS stations in the global coordinate reference system. Thus, the general regional displacement is excluded from the entire set of control points, i.e. the resultant of external forces is excluded from the movement of the general mechanical system. The residual internal forces are associated with mutual elastic stresses within the monitored territory. Areas of small internal displacements, close in magnitude to the measurement errors, indicate the position of locked zones in the earth’s crust, which represent an increased seismic hazard.
To obtain the animation, time series of GNSS station coordinates were used, obtained from the processing results of the Kamchatka branch of the Federal Research Center «Geophysical Service of Russian Academy of Sciences», as well as surrounding stations in the northwest of the Pacific-Asian region, presented in the data archive of the Nevada Geodetic Laboratory (USA, Reno) [Blewitt et al., 2018].
Observing the behavior of seismicity and displacement deficit (dark brown areas) we can see interesting features and patterns. About a year and a half after the initial observation epoch, the deficit zone covered the entire territory along the Kuril-Kamchatka Trench, demonstrating the concentration of increased seismic hazard in this area. It is important to understand that the observation network here is too sparse and describes the field of horizontal crustal movements with low spatial resolution. Nevertheless, the shapes of the frontal zone of internal movement deficit and the Kuril-Kamchatka arc coincide regularly. Long-term experience of recording the deficit of internal movements shows that strong earthquakes are concentrated within its regions (California, Northern and Eastern Anatolia), but in the subduction regions, earthquakes gravitate towards the marginal zone of the deficit anomaly (Japan, Taiwan). This is due to the predominantly reverse mechanism of strong seismic events in subduction zones. Here, the strongest earthquakes occur where the strength of the earth’s crust is previously violated by preceding strong and moderate foreshocks, or «slow earthquakes». Observing the occurrence of strong (M ≥ 6) earthquakes on synoptic animation, one can see that, in many cases, moderate or strong shocks have already occurred in the epicentral zones before them. It can be seen that 9 days and a month and a half before the Kamchatka megathrust earthquake on July 29, 2025, at least two strong events with M ≥ 7 occurred near its epicenter. Note that an M7.3 event and a series of M6 and moderate events occurred near the epicentral zone approximately two days before the Tohoku megathrust earthquake. This resembles the situation under study. The presented animation shows how strong and moderate earthquakes regularly destroy the marginal zone of internal motion deficit. The destruction area narrows and moves to the northwest, correlating with the elongated strip of M4.5—8.8 earthquake epicenters. Along its axis, the zone of motion deficit is marked by moderate earthquakes. As a result, the Kamchatka megathrust earthquake of 2025 and its strong foreshocks consistently destroy the general zone of motion deficit in the southwest direction up to the islands of the Japanese archipelago. At the same time, the territory of the Kamchatka Peninsula, northwest of the mega-earthquake epicentral zone, which suffered the least damage, is of concern. However, the minimum magnitude of the displacement module here is of the order of 0.2 m, while the strongest events occurred in the area of accumulated displacements of the order of 0.08 m.
Database creation date: 2025; Publication date: September 2025
Contributor:
Geophysical Center of the Russian Academy of Sciences, Moscow, Russia
Institution: Geophysical Center of the Russian Academy of Sciences, Moscow, Russia
Publisher: Geophysical Center of the Russian Academy of Sciences (GC RAS), Moscow, Russia (http://www.gcras.ru/eng/)
Data format: .mp4 (M4V File Format)
doi: 10.2205/esdb-kamchatka-2025
Citation: Dokukin P. A., Kaftan V. I., Titkov N. N., Chebrov D. V. (2025) Five-Year Evolution of Regional Seismicity and Deficit of Internal Crustal Displacements According to Gnss Data in Connection with the Kamchatka Megathrust Earthquake of 2025, GCRAS, Moscow, https://doi.org/10.2205/esdb-kamchatka-2025
References:
- Blewitt, G., Hammond, W. C., Kreemer C. Harnessing the GPS data explosion for interdisciplinary science. Eos, 99 (2018) https://doi.org/10.1029/2018EO104623.
License: 
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
URL for downloading: http://esdb.wdcb.ru/doi/2025/esdb-kamchatka-2025/esdb-kamchatka-2025.mp4
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