Russian Journal of Earth Sciences Russian Journal of Earth Sciences Russian Journal of Earth Sciences 1681-1208 106692 10.2205/2026es001129 tcbkck KAMCHATKA EARTHQUAKE M 8.8 ON JULY 29, 2025 KAMCHATKA EARTHQUAKE M 8.8 ON JULY 29, 2025 KAMCHATKA EARTHQUAKE M 8.8 ON JULY 29, 2025 Analysis of Ionospheric Parameter Dynamics During a Strong Earthquake in Kamchatka on July 29, 2025, Based on a Complex Approach (According to the Data of Ionosphere Vertical Radio Sounding and GNSS) Analysis of Ionospheric Parameter Dynamics During a Strong Earthquake in Kamchatka on July 29, 2025, Based on a Complex Approach (According to the Data of Ionosphere Vertical Radio Sounding and GNSS) https://orcid.org/0000-0001-5718-1429 Павлов Алексей Владимирович Pavlov Aleksey Vladimirovich pavlov@ikir.ru

кандидат физико-математических наук;

candidate of physical and mathematical sciences;

 https://orcid.org/0000-0002-6172-1827 Мандрикова Оксана В. Mandrikova Oksana V. oksanam1@mail.ru https://orcid.org/0000-0003-3518-9301 Титков Николай Николаевич Titkov Nikolay Nikolaevich Институт космофизических исследований и распространения радиоволн ДВО РАН Россия Institute of Cosmophysical Research and Radio Wave Propagation FEB RAS Russian Federation Институт космофизических исследований и распространения радиоволн ДВО РАН Россия Institute of Cosmophysical Research and Radio Wave Propagation, FEB RAS Russian Federation Камчатский филиал Единой геофизической службы РАН Россия Kamchatka Branch of the Federal Research Center “Geophysical Survey of RAS” Russian Federation 01 07 2026 01 07 2026 26 2 ES2019 02 02 2026 25 05 2026 https://rjes.ru/en/nauka/article/106692/view

Using a complex of tools for data recording and analysis, the paper investigates ionospheric parameter dynamics during a strong earthquake in Kamchatka on July 29, 2025 (magnitude M = 8.8). The data of the ionospheric critical frequency foF2 of Paratunka observatory (Kamchatka, IKIR FEB RAS), and the data of the regional GNSS receiver network, located near the earthquake source, were under analysis. Using data from GNSS receivers, the values of absolute vertical total electron content (TEC) and disturbance indices of vertical TEC variations (WTEC) were studied. Data detailed analysis was realized using a new method based on wavelet transform. For the estimates, anomaly intensity measure, characterizing weak, moderate and strong ionospheric disturbances, was used. Before and during the earthquake on July 29, 2025, anomalous changes were distinguished in ionospheric parameter time series. They characterize moderate and intensive oscillation processes in the ionosphere exceeding the background level. A large-scale long (about 2 days) negative anomaly was detected three days and a half before the earthquake against the background of low geomagnetic activity according to the data of Paratunka observatory and GNSS receivers. During the development of the aftershock process, according to data from the Paratunka observatory and data from all GNSS receivers, a large-scale positive anomaly was identified, exceeding in intensity the background variations in ionospheric parameters by three times and more. The positive anomaly lasted for about 2 days. In the region of PAUJ station, the ionospheric disturbances were the most intensive and significantly exceeded in amplitude the disturbances, observed during the period under analysis when geomagnetic activity increased.

Using a complex of tools for data recording and analysis, the paper investigates ionospheric parameter dynamics during a strong earthquake in Kamchatka on July 29, 2025 (magnitude M = 8.8). The data of the ionospheric critical frequency foF2 of Paratunka observatory (Kamchatka, IKIR FEB RAS), and the data of the regional GNSS receiver network, located near the earthquake source, were under analysis. Using data from GNSS receivers, the values of absolute vertical total electron content (TEC) and disturbance indices of vertical TEC variations (WTEC) were studied. Data detailed analysis was realized using a new method based on wavelet transform. For the estimates, anomaly intensity measure, characterizing weak, moderate and strong ionospheric disturbances, was used. Before and during the earthquake on July 29, 2025, anomalous changes were distinguished in ionospheric parameter time series. They characterize moderate and intensive oscillation processes in the ionosphere exceeding the background level. A large-scale long (about 2 days) negative anomaly was detected three days and a half before the earthquake against the background of low geomagnetic activity according to the data of Paratunka observatory and GNSS receivers. During the development of the aftershock process, according to data from the Paratunka observatory and data from all GNSS receivers, a large-scale positive anomaly was identified, exceeding in intensity the background variations in ionospheric parameters by three times and more. The positive anomaly lasted for about 2 days. In the region of PAUJ station, the ionospheric disturbances were the most intensive and significantly exceeded in amplitude the disturbances, observed during the period under analysis when geomagnetic activity increased.

 Seismic activity seismo-ionospheric coupling total electron content ionospheric disturbances wavelet transform Kamchatka megathrust earthquake Seismic activity seismo-ionospheric coupling total electron content ionospheric disturbances wavelet transform Kamchatka megathrust earthquake The paper was supported by the State Task of IKIR FEB RAS (Subject Registration No. 124012300245-2). The authors thank the Kamchatka Branch of the Federal Research Center “Geophysical Survey of RAS” (Petropavlovsk-Kamchatskiy, Russia) for providing data from the regional GPS receiver network KAMNET. The authors thank the Institute of Cosmophysical Research and Radio Wave Propagation FEB RAS (Paratunka, Russia) and the World Data Center for Geomagnetism (Kyoto, Japan) for providing geomagnetic data. The authors also thank the United States Geological Survey’s (USGS) Earthquake Hazards Program for providing access to earthquake data. The paper was supported by the State Task of IKIR FEB RAS (Subject Registration No. 124012300245-2). The authors thank the Kamchatka Branch of the Federal Research Center “Geophysical Survey of RAS” (Petropavlovsk-Kamchatskiy, Russia) for providing data from the regional GPS receiver network KAMNET. The authors thank the Institute of Cosmophysical Research and Radio Wave Propagation FEB RAS (Paratunka, Russia) and the World Data Center for Geomagnetism (Kyoto, Japan) for providing geomagnetic data. The authors also thank the United States Geological Survey’s (USGS) Earthquake Hazards Program for providing access to earthquake data.

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