Most earthquakes last only seconds. But some can go on for hours or even days. Research has discovered that slow quakes can be triggered by storms

A network of sensitive seismometers has revealed a new source of earth tremor. Rather than emanating from deep in the Earth’s crust, this disturbance comes from above and is produced by storms at sea. Researchers at Florida State University dubbed the effect a stormquake in a paper in Geophysical Research Letters.

While most earth tremors are jolts lasting a matter of seconds, there is also seismic background noise over a longer time scale. The scientists were exploring these longer-duration events and discovered a type which was highly seasonal and never occurred in summer. Normally seismic activity is indifferent to the seasons, but the meteorological connection became obvious when the researchers found the mystery quakes coincided with major hurricanes and storms.