MEXICO CITY -- A powerful earthquake Monday shook fishing villages along Mexico's Gulf of California, prompting alarm as far away as Phoenix, but there were no immediate reports of injuries or damage.
The U.S. National Earthquake Information Center said the 6.9-magnitude quake struck at 12:59 p.m. (1:59 EDT, 17:59 GMT) and was centered 76 miles (122 kilometers) north-northeast of Santa Isabel in Baja California and 331 miles (533 kilometers) southeast of the border city of Tijuana.
It was the strongest of four quakes of 5.0-magnitude or greater that struck the area over a 45-minute period late Monday morning.
Phoenix Fire Department spokesman Alex Rangel said a high-rise near downtown shook violently enough that workers evacuated but there were no reports of injuries or damage. The quake was located about 460 miles from downtown Phoenix.
Wilfredo Rivera, a manager at the Posada Santa Gemma hotel in Bahia Kino near the coast, said doors slammed as the ground rocked.
"The earth was turning around really ugly," he said. "People got really scared."
Civil protection officials in the two states on either side of the quake - Baja California and Sonora - said there were no reports of damage or injury.
The quakes were all centered in the middle of the narrow slice of sea between the Baja peninsula and Mexico's mainland, which reduced its chances of causing major damage, said Don Blakeman, an analyst at the center.
U.S. authorities said there was no tsunami threat to Hawaii or the Pacific coast of the United States. The Gulf of California coast was put on alert for large waves, said Alfredo Escobedo, the director of the Baja California civil protection service.
Scientists say some areas where strong shaking occurred may experience local underwater landslides.
The Gulf of California, also known as the Sea of Cortez, is believed to have come into being millions of years ago when tectonic forces shifted the Baja California peninsula off the North American Plate.
Called the "world's aquarium" by undersea explorer Jacques Cousteau, the sea has a unique ecosystem and is home to hammerhead sharks, whale sharks, orca whales, dolphins and giant Pacific manta rays.