Reconstructions of what the weather was like during the days SWOT picked up the signal also show that it couldn’t have been anything but a seiche. As fascinating as bizarre signals from other planets can be—teaching us about earthquakes on Mars or auroras in the skies of Jupiter—sometimes even weirder signals come from weather extremes happening right here on Earth. For nine days in 2023, an unknown seismic pulse was generated by the Earth every 90 seconds. It remained a mystery, even though studies at the time found seismic data that seemed to align with the sloshing motions of standing waves. Tsunamis are often seismic phenomena, and the very long period (VLP) seismic signal that came from the fjord was the aftermath of a tsunamigenic landslide.