17Jun2021 13:41:03
Here's yet another interesting earthquake in Tonga: a shallow magnitude mmw5.5 at 13:42:02 UTC on 17Jun2021
The recording shows 20 minutes from three seismometers: II-MSVF at Monasavu, Fiji; G-FUTU on Futuna; and IU-AFI at Afiamalu, Samoa, from left to right.
The video is in plan view: north is up, south is down, west is left, east is right. the audio is from IU-AFI, west-east in the left channel, north-south in the right.
It is sped up 240 times.
The interesting thing is the large amplitude VLF (Very Low Frequency) wave, with a period of about 10 seconds, corresponding to a frequency of 0.1 Hertz
The data was kindly provided by IRIS.
Turn it up.