Mexico's Gulf of California has been hit by a 6.9-magnitude earthquake and at least three smaller tremors.
There have been no reports of injuries or damage.
The 6.9-magnitude tremor struck at 1259 local time (1759GMT), with its epicentre 76 miles (122km) north-east of Santa Isabel in Baja California.
There was a risk of a small, localised tsunami in the area, officials and experts warned, but no threat to America's Pacific coast.
The tremors were all centred under the bed of the Gulf of California, a narrow strip of sea between Baja California peninsula and the Mexican mainland.
Wilfredo Rivera, a manager at the Posada Santa Gemma hotel in Bahia Kino told Associated Press: "The earth was turning around really ugly. People got really scared."
The mountains and deserts of the peninsula are sparsely populated, minimising the risk of widespread damage or injuries.