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The 2025 and 1952 Kamchatka Earthquakes Viewed From Tsunami Waveforms Recorded Around the Pacific Ocean

Description: 

The July 2025 Kamchatka earthquake (Mw 8.8) generated Pacific-wide tsunamis that were recorded on DART bottom pressure gauges and coastal tide gauges. The inversion of 40 DART records around the Pacific Ocean, accounting for the elasticity of the Earth and sea water, shows large (> 9 m) slip in three subfaults at distances of 200 – 400 km SW of the epicenter with depth of 0 – 26 km below the seafloor. The average slip is 3.1 m, providing a total seismic moment of 1.87 × 10²² Nm. This solution is very similar to the USGS finite fault model based on teleseismic data. The inversion of coastal tide gauge records yields a similar result, but slightly larger average slip (3.8 m) and seismic moment (2.28 × 10²² Nm). The large slips occur at similar subfaults, but the amounts are larger (> 10 m).

In this region, a similarly great megathrust earthquake (M ~ 9) occurred in 1952. The 1952 tsunami waveforms recorded at tide gauge stations around the Pacific Ocean were very similar to those of the 2025 earthquake. Johnson and Satake (1999, Pageoph) inverted the tide gauge records and estimated the large slip at deep plate interface, without accounting for the elasticity of the Earth and sea water. We conducted the inversion of the 1952 tide gauge records for the slip distribution and clock correction at each station, considering the elasticity and station corrections obtained from the 2025 DART and tide gauge inversions. The result shows that the 1952 slip distribution was similar to that of 2025, except for the depth of the largest slip and the northern slip where foreshock and aftershocks occurred in 2025. This difference, or complementary slip, can explain the shorter interval than expected from backslip rate (~ 8 m/century) estimated from GPS analysis (Burgman et al., 2005, JGR).

Session: SSJ-SSOC-SSA Joint Session: Lessons from Recent Major Earthquake Sequences Around the World - I

Type: Oral

Date: 4/17/2026

Presentation Time: 02:45 PM (local time)

Presenting Author: Kenji Satake

Student Presenter: No

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