On Saturday 15 January, a volcano erupted near Tonga, with devastating effects. The immense eruption catapulted ash, particles and gases apparently deep into the stratosphere, with estimates up to 30 km height. Besides the disastrous impact on humans, the environment, infrastructure, the eruption sent also a pressure wave around the world, detectable by measurements of atmospheric pressure (e.g., in Belgium). We can even detect this signal in the recordings of the atmospheric pressure inside our nephelometer, running at Princess Elisabeth station - see image below. The eruption took place around 4am UTC (or 5pm local time Tonga). The pressure wave took around 9 hours (for the around 17000 km to the station. A first variation of the pressure of about 2 hPa was detected at 13 UT and a second one of about 1hPa at 15 UT (one wave took the one way around the globe, the other one the other way round).
