the Greenland tsunami you're referring to likely relates to a seismic event caused by a glacia collapse or landslide that triggered a massive wave breaking news headlines such events in Greenland are rare but have been occurring more frequently due to the effects of climate change where melting ice destabilizes glacia increasing the likelihood of landslides or ice carving into the ocean how it shook the Earth for 9 days seismic waves the collapse or Landslide would have generated seismic waves that propagated through the Earth's crust these waves are like ripples in a pond after a stone is thrown in but on a massive scale size MERS even those far away can detect such disturbances for an extended period depending on the event strength energy relased the energy from this type of event depending on its size can be equivalent to a significant earthquake the seismic waves generated can bounce within the Earth creating aftershocks or prolonged seismic activity that lasts for days which is what likely happened in this case Landslide induced tsunami one of the more well-known Greenland tsunamis occurred in June 2017 when a landslide caused a massive wave that affected local communities to strin homes and killing several people these types of tsunamis are relatively unusual but devastating when they happen duration of shaking the 9-day period of continued Tremors would have been caused by the large initial seismic shock followed by aftershocks and smaller vibrations as the Earth's crust settled this is similar to what happens after large earthquakes where the ground can continue to sh shake for days or weeks afterward due to the Readjustment of tectonic forces this type of seismic activity from glacia collapses or landslides in polar regions is becoming more of a concern with the increasing rate of ice lust due to global warming