When a volcano erupts, the magma created by melting rocks rises and pushes through vents and fissures to the Earth’s surface. Sometimes the magma flows out in the form of lava, however, if the pressure of gas and steam under the Earth’s surface is high enough the magma shoots into the air, covering everything around it in fiery lava and ash. When a volcano underwater explodes, it can create a tsunami.
The volcano near Tonga in the Pacific Ocean exploded with huge amounts of gas and steam blasting into the air and having a widespread impact.
The impact of the eruption was measured in foreign and local weather stations at the following Thai time:
NARIT said this information can be used to determine the impact of the eruption and a similar system can be used for other natural phenomena, such as working out the impact of an asteroid.
More details can be found at http://weather.narit.or.th/