Surface displacements and megathrust slip of the M8.8 2025 Kamchatka earthquake from Sentinel-1 and ALOS-2 InSAR

Gareth J. Funning, & Axel J. Periollat

Submitted September 7, 2025, SCEC Contribution #14921, 2025 SCEC Annual Meeting Poster #TBD

The M8.8 July 30th, 2025 Kamchatka earthquake was the largest event to occur globally in the last decade, and one of the ten largest events ever recorded instrumentally. It occurred offshore of the southeastern coast of the Kamchatka Peninsula, in a similar area to the inferred source location of the great 1952 M9.0 Kamchatka earthquake, and in the vicinity of an area of subduction interface locking that we have identified from boundary element modeling of interseismic GNSS velocities (Periollat and Funning, this meeting).

Here we present preliminary inversion results from analysis of coseismic InSAR data from the Kamchatka region. The region is covered by multiple ascending and descending tracks of Sentinel-1 Interferometric Wideswath (IW) and ALOS-2 Interferometric Widemode (WD1) data. We process all available data using the JPL/Caltech ISCE2 software, using the Copernicus DEM to correct for elevation. Despite the vegetated terrain, which can be challenging for C-band InSAR, we obtain usable coherence in our Sentinel-1 data, and identify line-of-sight displacement of up to ~1 m towards the satellite; our ALOS-2 data have good coherence, but are strongly affected by ionospheric noise. Our plan is to invert the InSAR displacements using the same fault geometry that we use for our studies of interseismic locking. This will allow us to gauge the level of agreement between our locking models and the pattern of coseismic slip on the megathrust implied by the InSAR data, and how well the InSAR data can be fitted by the accumulated slip deficit between the 1952 and 2025 earthquakes predicted by our locking model.

Key Words
earthquake, InSAR, locking

Citation
Funning, G. J., & Periollat, A. J. (2025, 09). Surface displacements and megathrust slip of the M8.8 2025 Kamchatka earthquake from Sentinel-1 and ALOS-2 InSAR. Poster Presentation at 2025 SCEC Annual Meeting.

Related Projects & Working Groups
Tectonic Geodesy