Have you heard of this strange earthquake swarm that started in 2018 in Mayotte, a French Island ?
It turned out that it is caused by a baby volcano , growing under the sea.
This is now being monitored and researched, partly thanks to new Raspberry shake sensors.
The BBC has just released a podcast about that : https://www.bbc.co.uk/sounds/play/w3cswmqw
I thought that could interest you !