A graphic of today’s 4.0 earthquake. | USGS

Three medium to small-sized earthquakes struck a few miles off the Petrolia coast today in roughly the same spot.

The first and smallest of the earthquakes occurred at 8:57 a.m., when a 2.9-magnitude quake hit 5 miles from Petrolia.

At 12:20 p.m., a 4.0 quake shook 8 miles west of Petrolia, and was immediately followed by a 3.7-magnitude quake 6 miles west of the same location.

The USGS reports that the first earthquake occurred 9.4 miles below the earth’s surface. The stronger earthquakes from this afternoon were 6 and 3 miles deep, respectively.