(CNN) In 2018, a multitude of seismic signals were detected by earthquake monitoring agencies all over the world in May and June. They created a weird humming sound and some of the signals detected in November of that year had a duration of up to 20 minutes.

The signals and humming triggered "the curiosity of the scientific community," according to a new study that explains what happened: the formation of a new underwater volcano.

The unusual amount of earthquakes were traced to the island of Mayotte in the Indian Ocean, one of several in the Comoros archipelago found between Africa and Madagascar.

Scientists detected 7,000 tectonic earthquakes within the scope of the study. These kinds of earthquakes occur when Earth's tectonic plates become stuck as they move alongside one another. The pressure that allows them to move on causes earthquakes.

The most severe earthquakes reached a magnitude of 5.9 in May 2018.

Simone Cesca works on the modelling of magma movement.

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