Hunga Tonga 2.JPG

The large HTHH volcanic explosion created fast low-frequency pressure waves that penetrated about 3.1 miles/5 kilometers into the shallow crust (shown in yellow). Wind and small explosions (shown in blue) create shorter pressure waves that only penetrate down about 328 feet/100 meters. Earthquakes create variable-frequency seismic waves (shown in green) that travel through the entire crust but leave a blurry “picture” of the top 3.1 miles/5 kilometers (5000 meters).