Scientists measure the force of eruptions using something called the Volcanic Explosivity Index, or VEI. (I learned about this from my teenage grandson, who has an encyclopaedic knowledge of volcanoes.)
The eruption of Hunga Tonga-Hunga Ha’apai had a VEI of 5 or 6, depending on which source you believe. According to NIWA, it was the biggest atmospheric explosion recorded in more than a century. As a point of comparison, the cataclysmic Oruanui (Lake Taupo) eruption about 26,500 years ago had a VEI of 8. Krakatoa (1883) scored a 6.
