Question: Hi Elena. Can you please give me some facts about volcanoes? Thanks, Zaina

Elena Maters answered on 29 Jun 2020:

Hi Zaina – great question – I don’t know where to begin! Here are a few:

The loudest sound that humans have ever recorded was the 1883 eruption of Krakatau volcano in Indonesia. It was heard clearly 1000s of miles away, for example in Australia, like the sound of gunshot. It was so loud that it ruptured the eardrums of people up to 40 miles away!

Super-eruptions are larger than any experienced by human civilisation, releasing over 300 cubic kilometres of magma. For a sense of how huge this is, if a super-eruption of this size happened in Trafalgar Square in London, it would bury all of Greater London in ash up to 210 metres high – taller than the London Eye! Some famous super-eruptions were at Yellowstone, USA, 2 million years ago (2450 cubic kilometres of magma) and Toba, Indonesia, 74 000 years ago (2800 cubic kilometres of magma).

Volcanic soils, which develop from ash and lava, are some of the most fertile in the world. They are full of important nutrients for plants like potassium and phosphorous. Even though volcanic soils cover ~1 % of the world’s land surface, they support ~10% of the world’s population (for example being used for crops).

Volcanic ash can also fertilise the ocean by releasing iron into seawater. Iron is an essential nutrient for the tiny photosynthetic plankton that live in the sunlit surface layer. A large phytoplankton ‘bloom’ was seen in the Gulf of Alaska after the 2008 eruption of Kasatochi volcano.

At any moment, an average of ~20 volcanoes are erupting around the world. You can see which ones are currently active here: https://volcano.si.edu/reports_weekly.cfm