Sonar image of the Molowai volcano. Source:

by Brendan

Many more active volcanoes exist beneath the surface of the world’s oceans than do above the surface, though much less is known about these submarine volcanoes.  There are numerous marine geologists who love to spend their time out on ships using techniques such as sonar and LIDAR to monitor and map these volcanoes. One recent expedition consisting of British, German and New Zealand scientists mapped a dramatic increase in size of the Molowai volcano, which lies on the Tonga-Kermadec Arc between NZ and Tonga. The BBC reports that in a single fortnight the expeditioners recorded almost 20 metres of the summit collapsing while “new lava flows had raised another area by 79.1m. Most striking was the creation of an entirely new volcanic cone…Only Vesuvius and Mount St Helen’s have recorded larger growth rates.”

You can view the report and some spectacular sonar images on the BBC website, while the full article can be found in Nature Geoscience. And who says geologists don’t have their fingers on the pulse?