Federal officials say nuclear plants from North Carolina to Michigan are under increased scrutiny after a 5.8 magnitude earthquake rocked the East Coast.

Twelve nuclear plants declared what regulators call "unusual events" after Tuesday's earthquake, which was centered 40 miles northwest of Richmond, Va.

Two nuclear reactors at Virginia's North Anna Power Station, in the same county as the epicenter, were automatically taken off line by safety systems. No damage was reported at the plant, which is being powered by emergency diesel generators.

The quake was also felt at the Surry nuclear plant near Newport News, but a spokesman said both reactors there continued to operate safely.

Besides Surry, nuclear plants in Maryland, Michigan, New Jersey, North Carolina and Pennsylvania were placed under increased scrutiny, but continued to operate.