Parts of California, including San Francisco, Santa Cruz and Crescent City, are bracing for waves in the aftermath of the powerful earthquake to slam into their beachfronts.
Waves are expected to hit San Francisco just before noon eastern time. Orange County is closing its beaches and position lifeguards and other emergency personnel to prevent swimmers from going in the water, Fox News reported.
Los Angeles, meanwhile, is not expected to close its beaches yet, officials told Fox News.
Wave heights in parts of the state could reach three feet. No evacuation orders are in effect thus far.
President Obama offered condolences to the people of Japan.
"The United States stands ready to help the Japanese people in this time of great trial," he said. "The friendship and alliance between our two nations is unshakeable, and only strengthens our resolve to stand with the people of Japan as they over come this tragedy."
Obama also said U.S. states were making the necessary preparations for its aftermath.
"We will continue to closely monitor tsunamis around Japan and the Pacific going forward and we are asking all our citizens in the affected region to listen to their state and local officials as I have instructed FEMA to be ready to assist Hawaii and the rest of the U.S. states and territories that could be affected," he added.
A tsunami warning is in effect for Chile, too. The Associated Press is reporting that the country's Easter Island, in the remote South Pacific, could be the first affected. It is about 2,175 miles east of the capital of Santiago, where people planned to evacuate.
Chile has been rocked by earthquakes twice in a little more than a year.
Latin American governments ordered islanders and coastal residents to head for higher ground, the AP reported. In Ecuador, President Rafael Correa declared a state of emergency.
The earthquake that triggered the waves is the fifth strongest since 1900. In May 1960, Chile was hit with the strongest earthquake – it registered 9.5 on the Richter scale – in the last century.
More than 1,700 people were killed and the city's downtown was destroyed.
In 1946, a tsunami caused by a 8.1 earthquake near Alaska killed 165 people, mostly in Hawaii.