How Big Was The St Helens Tsunami?
The megatsunami in Spirit Lake, Washington, USA that was caused by the 1980 eruption of Mount St. Helens reached 260 metres (853 ft), while the tallest megatsunami ever recorded (Lituya Bay in 1958) reached a run-up height of 520 metres (1,720 ft). Was there a tsunami when Mt St Helens erupted? May 18, 2015 marks …