A magnitude-8.3 earthquake struck in the Pacific Ocean off the coast of Chile on Wednesday, September 16, causing a 15-foot tsunami along the coast. The earthquake killed at least 10 people and triggered tsunami advisories for Hawaii, Southern California, and other parts of the Pacific Ocean. The tsunami spread across much of the Pacific, with the worst of its effects expected to be centered in French Polynesia.

The Pacific Typhoon Warning Center issued a tsunami advisory for Hawaii. It does not expect a major tsunami, but it was predicting sea level changes and strong currents that could be dangerous for swimmers and boaters. Officials encouraged people to stay off beaches and out of the water. Initial tsunami waves had a magnitude of 3 feet in Hilo; 2.2 feet in Kahului, Maui; and a 2- to 3-inch rise in Honolulu.

The National Tsunami Warning Center issued a tsunami advisory for coastal areas in San Luis Obispo, Santa Barbara, Ventura, Los Angeles, Orange, and San Diego Counties in Southern California. People are urged to stay away from the water until the danger subsides. Initial tsunami waves were detected on the morning of September 17 in Santa Monica, La Jolla, and Monterey Harbor. People were advised to stay off beaches, harbor areas, and jetties until the advisory is lifted. No evacuations were ordered.

Tsunami advisories were posted for American Samoa. Tsunami waves were reported in French Polynesia and the Chatham Islands east of New Zealand. Three tsunami waves of at least 13 feet were reported off Coquimbo, Chile. Smaller tsunami waves were reported in several other cities along the coast of Chile. The waves caused flooding in some areas.

Peru’s military issued a tsunami warning for the country’s entire coastline. Ecuador warned of dangerous currents but did not issue a tsunami warning. The U.S. government’s Pacific Tsunami Warning Center said tsunami waves could reach one to three feet above normal in both Peru and Ecuador.

The earthquake struck 34 miles west of Illapel, Chile and 145 miles north-northwest of Santiago. It was the strongest earthquake reported anywhere in the world so far this year. A tsunami warning was issued for the country’s entire coastline, advising people near the coast to move to higher ground. The warning was lifted for Chile’s two southernmost regions Wednesday after 11 p.m.

The earthquake was so strong that shaking was felt throughout much of South America. Severe shaking that registered at level VIII on the 12-point Mercalli scale was recorded in Coquimbo and La Serena. Level IX shaking, which is considered violent, was reported in Illapel.

The earthquake caused widespread power outages, the collapse of cellular phone networks, and landslides near the epicenter. Low-lying areas along the Pacific shore were evacuated, and the main airport in Santiago was evacuated as a precaution. Many houses collapsed in Illapel, forcing people to sleep outside. Strong aftershocks were also recorded.

In 2010, a magnitude-8.8 earthquake and a subsequent tsunami in south-central Chile killed over 500 people and destroyed 220,000 homes and other structures along the coastline. The earthquake released so much energy that it changed the Earth’s rotation and shortened the day by a fraction of a second. The earthquake and tsunami led Chile to improve its alert systems.

Chile is one of the Earth’s regions at greatest risk for earthquakes because the Nazca tectonic plate plunges beneath the South American plate just off the coast. The strongest earthquake ever recorded struck Chile in 1960. It had a magnitude of 9.5 and killed over 5,000 people.