The earthquake at Kamchatka July 30, 2025
        23:24:51 UTC, has generated significant Free Oscillations.
      
    We list a few links where you can see the response of the
    Superconducting Gravimeter OSG_054 at Onsala Space Obeservatory.
     Waveforms 
    Diagrams, acceleration in nm/s2, can be seen here: SCG-monitor
    In the fields to fill out you can easily advance at full hours by
    entering date 2025-07-30, hour 00, and dt 60 and then clicking
    on  Submit query. 
    The ringing in the light-blue curve, dP/dt in hPa/s, at
      midnight is an artefact of Fourier interpolation. It recurs
      systematically. Awaiting the re-hooking of the OSG accompanying
      barometer soon to happen, the stand-in instrument that samples at
      a lower rate is still in use, so we interpolate its record. Thanks
      to the opportunity of the mega-seismic event the problem has been
      noted---a little late though. 
    
    Spectrograms
     
    
    The spectrogram
    has been renewed daily until the 0S0
    mode waned below the noise level on Oct. 19, 2025. It's the balloon mode
    with very little energy dissipation, since sheer strain in the
    mantle is mostly confined to internal and the crust-ocean boundaries.   
    
    The event on day 43 (Sep. 9) was caused by a coldhead change.
    Periodograms showing the amplitude spectrum up to 6
        mHz and 3
        mHz with periodograms added for four-day stretches the
    week after the earthquake.
    Another
        one shows the spectrum for the period from July 31 to
    August 3 together with the situation in the week before the
    earthquake.