Bradyseism

It can persist for millennia in between eruptions and each uplift event is normally accompanied by thousands of small to moderate earthquakes.

The inflation and deflation of this caldera is especially well documented due to its seaside location and a long history of habitation and construction in the area.

These occur up to 7 metres up the columns, showing how bradyseism in the area lowered the land to at least this depth under the sea and subsequently raised it again.

[2] More recently, between 1968 and 1972, the Campi Flegrei area suffered an episode of positive bradyseism and rose by 1.7 metres.

This correlated with a shallow (4 km deep) earthquake swarm during the same period, which led to the evacuation of 30,000 people due to the perceived risk of imminent eruption.