Russian Journal of Earth Sciences Russian Journal of Earth Sciences Russian Journal of Earth Sciences 1681-1208 115481 10.2205/2026es001128 plsnyr 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 Coseismic Multiple Cusp Signatures in VIPIR Ionograms from SKiKP-Excited Infrasound following the 2025 MW 8.8 Kamchatka Earthquake Coseismic Multiple Cusp Signatures in VIPIR Ionograms from SKiKP-Excited Infrasound following the 2025 MW 8.8 Kamchatka Earthquake https://orcid.org/0000-0002-5805-6694 Mabie Justin Mabie Justin justin.j.mabie@gmail.com https://orcid.org/0000-0003-1677-4177 Скоркина Анна Александровна Skorkina Anna Aleksandrovna skorkina.anet@gmail.com https://orcid.org/0009-0001-4832-0076 Молокова Алисия Molockova Alisiya https://orcid.org/0000-0001-9256-6105 Bullett T. Bullett T. Hollahan S. Hollahan S. Четвёртая Государственная Коммуникационная компания Шайенн США 4th State Communications Cheyenne United States of America Институт теории прогноза землетрясений и математической геофизики РАН Россия Institute of Earthquake Prediction Theory and Mathematical Geophysics RAS Russian Federation Институт теории прогноза землетрясений и математической геофизики РАН Россия Institute of Earthquake Prediction Theory and Mathematical Geophysics RAS Russian Federation Четвёртая Государственная Коммуникационная компания США 4th State Communications United States of America - США - United States of America 01 07 2026 01 07 2026 26 2 ES2018 02 02 2026 25 05 2026 https://rjes.ru/en/nauka/article/115481/view

Following the MW 8.8 Kamchatka earthquake on 29 July 2025, we observed coseismic Multiple Cusp Signatures (MCS) in successive 1-min ionograms recorded by the VIPIR ionosonde near Koror, Palau (PL407). We attribute these signatures to plasma displacements driven by three seismogenic infrasonic waves generated by teleseismic SKiKP phases. Doppler measurements reveal downward plasma displacements associated with each infrasonic wave. We further propose that the Palau barrier reef lagoon may serve as an efficient infrasonic wave generator, enabling MCS formation despite strong seismic attenuation over the ~4350 km epicentral distance.

Following the MW 8.8 Kamchatka earthquake on 29 July 2025, we observed coseismic Multiple Cusp Signatures (MCS) in successive 1-min ionograms recorded by the VIPIR ionosonde near Koror, Palau (PL407). We attribute these signatures to plasma displacements driven by three seismogenic infrasonic waves generated by teleseismic SKiKP phases. Doppler measurements reveal downward plasma displacements associated with each infrasonic wave. We further propose that the Palau barrier reef lagoon may serve as an efficient infrasonic wave generator, enabling MCS formation despite strong seismic attenuation over the ~4350 km epicentral distance.

 High altitude acoustic wave coseismic ionospheric disturbance SKiKP ScS Multiple Cusp Signature VIPIR ionosonde 2025 Kamchatka megathrust earthquake High altitude acoustic wave coseismic ionospheric disturbance SKiKP ScS Multiple Cusp Signature VIPIR ionosonde 2025 Kamchatka megathrust earthquake This work was supported by the Office of Naval Research and by ongoing institutional funding of IEPT RAS No. 075-00608-26-00. The authors thank the Coral Reef Research Foundation for field site support and the Government of the Republic of Palau for hosting our research activities. This work was supported by the Office of Naval Research and by ongoing institutional funding of IEPT RAS No. 075-00608-26-00. The authors thank the Coral Reef Research Foundation for field site support and the Government of the Republic of Palau for hosting our research activities.

Artru J., Farges T. and Lognonné P. Acoustic waves generated from seismic surface waves: propagation properties determined from Doppler sounding observations and normal-mode modelling // Geophysical Journal International. — 2004. — Vol. 158, no. 3. — P. 1067–1077. — https://doi.org/10.1111/j.1365-246x.2004.02377.x Artru J., Farges T. and Lognonné P. Acoustic waves generated from seismic surface waves: propagation properties determined from Doppler sounding observations and normal-mode modelling // Geophysical Journal International. — 2004. — Vol. 158, no. 3. — P. 1067–1077. — https://doi.org/10.1111/j.1365-246x.2004.02377.x Astafyeva E. Ionospheric detection of natural hazards // Reviews of Geophysics. — 2019. — Vol. 57, no. 4. — P. 1265– 1288. — https://doi.org/10.1029/2019rg000668 Astafyeva E. Ionospheric detection of natural hazards // Reviews of Geophysics. — 2019. — Vol. 57, no. 4. — P. 1265– 1288. — https://doi.org/10.1029/2019rg000668 Bies D. A., Hansen C. H., Howard C. Q., et al. Engineering Noise Control. — 6th. — CRC Press, 2023. — https://doi.org/10.1201/9780367814908 Bies D. A., Hansen C. H., Howard C. Q., et al. Engineering Noise Control. — 6th. — CRC Press, 2023. — https://doi.org/10.1201/9780367814908 Bilitza D., Pezzopane M., Truhlik V., et al. The International Reference Ionosphere Model: A Review and Description of an Ionospheric Benchmark // Reviews of Geophysics. — 2022. — Vol. 60, no. 4. — https://doi.org/10.1029/2022RG000792 Bilitza D., Pezzopane M., Truhlik V., et al. The International Reference Ionosphere Model: A Review and Description of an Ionospheric Benchmark // Reviews of Geophysics. — 2022. — Vol. 60, no. 4. — https://doi.org/10.1029/2022RG000792 Chum J., Hruška F., Zednik J., et al. Ionospheric disturbances (infrasound waves) over the Czech Republic excited by the 2011 Tohoku earthquake // Journal of Geophysical Research: Space Physics. — 2012. — Vol. 117, A8. — https://doi.org/10.1029/2012JA017767 Chum J., Hruška F., Zednik J., et al. Ionospheric disturbances (infrasound waves) over the Czech Republic excited by the 2011 Tohoku earthquake // Journal of Geophysical Research: Space Physics. — 2012. — Vol. 117, A8. — https://doi.org/10.1029/2012JA017767 Darwin Ch. R. The structure and distribution of coral reefs. Being the first part of the geology of the voyage of the Beagle, under the command of Capt. Fitzroy, R.N. during the years 1832 to 1836. — London : Smith, Elder, Co., 1842. Darwin Ch. R. The structure and distribution of coral reefs. Being the first part of the geology of the voyage of the Beagle, under the command of Capt. Fitzroy, R.N. during the years 1832 to 1836. — London : Smith, Elder, Co., 1842. Davies K. Ionospheric radio propagation. — U.S. Department of Commerce, National Bureau of Standards, 1965. Davies K. Ionospheric radio propagation. — U.S. Department of Commerce, National Bureau of Standards, 1965. Davies K. and Baker D. M. Ionospheric effects observed around the time of the Alaskan earthquake of March 28, 1964 // Journal of Geophysical Research. — 1965. — Vol. 70, no. 9. — P. 2251–2253. — https://doi.org/10.1029/jz070i009p02251 Davies K. and Baker D. M. Ionospheric effects observed around the time of the Alaskan earthquake of March 28, 1964 // Journal of Geophysical Research. — 1965. — Vol. 70, no. 9. — P. 2251–2253. — https://doi.org/10.1029/jz070i009p02251 Emmert J. T., Drob D. P., Picone J. M., et al. NRLMSIS 2.0: A Whole-Atmosphere Empirical Model of Temperature and Neutral Species Densities // Earth and Space Science. — 2021. — Vol. 8, no. 3. — https://doi.org/10.1029/2020ea001321 Emmert J. T., Drob D. P., Picone J. M., et al. NRLMSIS 2.0: A Whole-Atmosphere Empirical Model of Temperature and Neutral Species Densities // Earth and Space Science. — 2021. — Vol. 8, no. 3. — https://doi.org/10.1029/2020ea001321 Forsythe V. V., Bilitza D., Burrell A. G., et al. PyIRI: Whole-Globe Approach to the International Reference Ionosphere Modeling Implemented in Python // Space Weather. — 2024. — Vol. 22, no. 4. — https://doi.org/10.1029/2023sw003739 Forsythe V. V., Bilitza D., Burrell A. G., et al. PyIRI: Whole-Globe Approach to the International Reference Ionosphere Modeling Implemented in Python // Space Weather. — 2024. — Vol. 22, no. 4. — https://doi.org/10.1029/2023sw003739 Grubb R. N., Livingston R. and Bullett T. W. A new general purpose high performance HF Radar // Proceedings of XXIX General Assembly 7-16 august 2008. — Chicago, USA : URSI, 2008. Grubb R. N., Livingston R. and Bullett T. W. A new general purpose high performance HF Radar // Proceedings of XXIX General Assembly 7-16 august 2008. — Chicago, USA : URSI, 2008. Havskov J. and Lieser K. Reported Teleseismic Phase Statistics at the ISC Over the Last Four Decades // Summary of the Bulletin of the International Seismological Centre. — 2025. — Vol. 58, no. II. — P. 31–44. — https://doi.org/10.31905/qea2ygg5 Havskov J. and Lieser K. Reported Teleseismic Phase Statistics at the ISC Over the Last Four Decades // Summary of the Bulletin of the International Seismological Centre. — 2025. — Vol. 58, no. II. — P. 31–44. — https://doi.org/10.31905/qea2ygg5 Hines C. O. Internal atmospheric gravity waves at ionospheric heights // Canadian Journal of Physics. — 1960. — Vol. 38, no. 11. — P. 1441–1481. — https://doi.org/10.1139/p60-150 Hines C. O. Internal atmospheric gravity waves at ionospheric heights // Canadian Journal of Physics. — 1960. — Vol. 38, no. 11. — P. 1441–1481. — https://doi.org/10.1139/p60-150 Kakinami Yo., Kamogawa M., Tanioka Yu., et al. Tsunamigenic ionospheric hole // Geophysical Research Letters. — 2012. — Vol. 39, no. 13. — https://doi.org/10.1029/2011gl050159 Kakinami Yo., Kamogawa M., Tanioka Yu., et al. Tsunamigenic ionospheric hole // Geophysical Research Letters. — 2012. — Vol. 39, no. 13. — https://doi.org/10.1029/2011gl050159 Kennett B. L. N., Engdahl E. R. and Buland R. Constraints on seismic velocities in the Earth from traveltimes // Geophysical Journal International. — 1995. — Vol. 122, no. 1. — P. 108–124. — https://doi.org/10.1111/j.1365-246x.1995.tb03540.x Kennett B. L. N., Engdahl E. R. and Buland R. Constraints on seismic velocities in the Earth from traveltimes // Geophysical Journal International. — 1995. — Vol. 122, no. 1. — P. 108–124. — https://doi.org/10.1111/j.1365-246x.1995.tb03540.x Mabie J. Infrasound induced plasma perturbations associated with geomagnetic pulsations // Russian Journal of Earth Sciences. — 2019a. — Vol. 19, no. 3. — ES3002. — https://doi.org/10.2205/2019es000661 Mabie J. Infrasound induced plasma perturbations associated with geomagnetic pulsations // Russian Journal of Earth Sciences. — 2019a. — Vol. 19, no. 3. — ES3002. — https://doi.org/10.2205/2019es000661 Mabie J. Rocket Induced High Altitude Acoustic Waves : PhD thesis / Mabie J. — Boulder, 2019b. Mabie J. Rocket Induced High Altitude Acoustic Waves : PhD thesis / Mabie J. — Boulder, 2019b. Mabie J. and Bullett T. Infrasonic wave induced variations of ionospheric HF sounding echoes // Radio Science. — 2019. — Vol. 54, no. 10. — P. 876–887. — https://doi.org/10.1029/2019rs006826 Mabie J. and Bullett T. Infrasonic wave induced variations of ionospheric HF sounding echoes // Radio Science. — 2019. — Vol. 54, no. 10. — P. 876–887. — https://doi.org/10.1029/2019rs006826 Mabie J., Bullett T., Moore P., et al. Identification of rocket-induced acoustic waves in the ionosphere // Geophysical Research Letters. — 2016. — Vol. 43, no. 20. — https://doi.org/10.1002/2016gl070820 Mabie J., Bullett T., Moore P., et al. Identification of rocket-induced acoustic waves in the ionosphere // Geophysical Research Letters. — 2016. — Vol. 43, no. 20. — https://doi.org/10.1002/2016gl070820 Maruyama T., Tsugawa T., Kato H., et al. Rayleigh wave signature in ionograms induced by strong earthquakes // Journal of Geophysical Research: Space Physics. — 2012. — Vol. 117, A8. — https://doi.org/10.1029/2012ja017952 Maruyama T., Tsugawa T., Kato H., et al. Rayleigh wave signature in ionograms induced by strong earthquakes // Journal of Geophysical Research: Space Physics. — 2012. — Vol. 117, A8. — https://doi.org/10.1029/2012ja017952 Maruyama T., Yusupov K. and Akchurin A. Ionosonde tracking of infrasound wavefronts in the thermosphere launched by seismic waves after the 2010 M8.8 Chile earthquake // Journal of Geophysical Research: Space Physics. — 2016. — Vol. 121, no. 3. — P. 2683–2692. — https://doi.org/10.1002/2015ja022260 Maruyama T., Yusupov K. and Akchurin A. Ionosonde tracking of infrasound wavefronts in the thermosphere launched by seismic waves after the 2010 M8.8 Chile earthquake // Journal of Geophysical Research: Space Physics. — 2016. — Vol. 121, no. 3. — P. 2683–2692. — https://doi.org/10.1002/2015ja022260 Picone J. M., Hedin A. E., Drob D. P., et al. NRLMSISE-00 empirical model of the atmosphere: Statistical comparisons and scientific issues // Journal of Geophysical Research: Space Physics. — 2002. — Vol. 107, A12. — https://doi.org/10.1029/2002ja009430 Picone J. M., Hedin A. E., Drob D. P., et al. NRLMSISE-00 empirical model of the atmosphere: Statistical comparisons and scientific issues // Journal of Geophysical Research: Space Physics. — 2002. — Vol. 107, A12. — https://doi.org/10.1029/2002ja009430 Rolland L. M., Lognonné P. and Munekane H. Detection and modeling of Rayleigh wave induced patterns in the ionosphere // Journal of Geophysical Research: Space Physics. — 2011. — Vol. 116, A5. — https://doi.org/10.1029/2010ja016060 Rolland L. M., Lognonné P. and Munekane H. Detection and modeling of Rayleigh wave induced patterns in the ionosphere // Journal of Geophysical Research: Space Physics. — 2011. — Vol. 116, A5. — https://doi.org/10.1029/2010ja016060 Verhulst T. G. W. and Stankov S. M. Height-dependent sunrise and sunset: Effects and implications of the varying times of occurrence for local ionospheric processes and modelling // Advances in Space Research. — 2017. — Vol. 60, no. 8. — P. 1797–1806. — https://doi.org/10.1016/j.asr.2017.05.042 Verhulst T. G. W. and Stankov S. M. Height-dependent sunrise and sunset: Effects and implications of the varying times of occurrence for local ionospheric processes and modelling // Advances in Space Research. — 2017. — Vol. 60, no. 8. — P. 1797–1806. — https://doi.org/10.1016/j.asr.2017.05.042 Xu D., Wang W. and Ren Z. Preliminary slip distribution of the July 29, 2025 M 8.8 Kamchatka, Russia earthquake // Earthquake Research Advances. — 2025. — P. 100427. — https://doi.org/10.1016/j.eqrea.2025.100427 Xu D., Wang W. and Ren Z. Preliminary slip distribution of the July 29, 2025 M 8.8 Kamchatka, Russia earthquake // Earthquake Research Advances. — 2025. — P. 100427. — https://doi.org/10.1016/j.eqrea.2025.100427 Zabotin N. A., Wright J. W. and Zhbankov G. A. NeXtYZ: Three-dimensional electron density inversion for dynasonde ionograms // Radio Science. — 2006. — Vol. 41, no. 6. — https://doi.org/10.1029/2005rs003352 Zabotin N. A., Wright J. W. and Zhbankov G. A. NeXtYZ: Three-dimensional electron density inversion for dynasonde ionograms // Radio Science. — 2006. — Vol. 41, no. 6. — https://doi.org/10.1029/2005rs003352