Tsunami advisories are in effect for Hawaii and Southern California after a powerful magnitude-8.3 earthquake struck the Pacific Ocean waters just off the coast of Chile Wednesday afternoon, generating a dangerous 15-foot tsunami along parts of the Chilean coast.
Chileans continued to assess the damage as strong aftershocks continued deep into the night, and authorities said at least five people died as a result of earthquake-related incidents.
The tsunami is expected to fan out across much of the Pacific Ocean, though the worst of its power is expected to be focused westward toward French Polynesia, including Tahiti.
Nonetheless, the two U.S. government agencies responsible for tsunami forecasting say tsunami waves of 1 to 3 feet may reach Hawaii early Thursday morning, while a tsunami of less than 1 foot is expected to reach southern California around the same time.
Update Coquimbo tide gage : appears that largest tsunami wave (4+ m) arrived more than one hour after initial wave pic.twitter.com/z58PdMHmgJ
— Jascha Polet (@CPPGeophysics) September 17, 2015
The gauge in Coquimbo, Chile, recorded three tsunami waves of at least 4 meters (13 feet) each, including a maximum tsunami wave height 15.1 feet above normal tide levels. Several other Chilean coastal cities have recorded tsunami waves as well, though none nearly as dramatic as those in Coquimbo.
Video posted to social media shows flooding from the tsunami invading the resort city of Concón in Valparaiso Province.
— Periódico La Mirada (@DiarioLaMirada) September 17, 2015
Tsunami warnings are also in effect for Peru while agencies across the rest of the Pacific Rim evaluate the potential of a Pacific-wide tsunami.
The U.S. Geological Survey said the main shock struck at 7:54 p.m. Chile time (6:54 p.m. EDT in the U.S.) about 34 miles (54 km) west of Illapel, Chile, or about 145 miles (233 km) north-northwest of Santiago, Chile’s largest city. It is the planet’s strongest quake of 2015 thus far.
Officials in Chile issued a tsunami warning for the entire coastline of the country, advising everyone near the coast to move to higher ground. The tsunami warning was dropped for Chile’s two southernmost regions shortly after 11 p.m. local time.
Shaking was reported in Santiago and across most of central Chile. The strongest shaking was reported in Coquimbo and La Serena, where the ground motions registered at level VIII (eight) on the 12-point Mercalli scale according to Chilean authorities. Such shaking is classified as “severe” and can cause severe damage in poorly built structures.
The USGS “Did You Feel It?” website received reports of level IX (nine) shaking, considered “violent” on the Mercalli scale, in Illapel.
ALERTA CHILE Reportan daños en el shooping de La Serena pic.twitter.com/Lb1j2qwhV2
— Angel Flores (@angelflores62) September 17, 2015
Widespread power outages have been reported near the epicenter, and Chile’s emergency management network, Red Nacional de Emergencia, said cellular phone networks have “collapsed” in some regions. RNE also said it has received reports of landslides in hilly sections of Salamancas, Coquimbo, and Los Vilos, in the region closest to the quake epicenter.
Officials ordered people to evacuate low-lying areas along the 2,400 miles (3,900 kilometers) of Chile’s Pacific shore, from Puerto Aysen in the south to Arica in the north. Fishing boats headed out to sea and cars streamed inland carrying people to higher ground. Santiago’s main airport was evacuated as a precaution.
Authorities said some adobe houses collapsed in the inland city of Illapel, about 175 miles (280 kilometers) north of Santiago.
Illapel’s mayor, Denis Cortes, told a local TV station that a woman had been killed in the city but declined to give any details.
Electricity was knocked out, leaving the city in darkness. “We are very scared. Our city panicked,” Cortes said.
The quake was immediately followed by four aftershocks of 6.0 or greater magnitude within 30 minutes. The tremors measured 6.3, 6.1, 6.2 and 7.0, striking at 7:59, 8:03, 8:16 and 8:18 local time, respectively. Additional strong aftershocks struck at 10:41 p.m. Wednesday (magnitude 6.4) and at 12:55 and 1:10 a.m. Thursday (magnitudes 6.2 and 6.3, respectively).
At least seven other aftershocks registering between 5.0 and 5.9 on the moment magnitude scale had occurred by 1:15 a.m. local time, according to the USGS.
Other South American Nations on Alert
North of Chile, the Peruvian military issued a tsunami warning for the entire coast of Peru. Sea level monitoring sites in Callao and Matarani both recorded tsunami waves of less than 1 foot (0.3 meter) late Wednesday evening.
However, the seismological agency in Ecuador, INOCAR, said the Chilean quake “does not have the characteristics necessary to generate a tsunami,” and did not issue a tsunami warning for its coastline. It instead warned of dangerous currents.
The U.S. government’s Pacific Tsunami Warning Center placed both Peru and Ecuador among the countries where tsunami waves could reach 0.3 to 1 meter (1 to 3 feet) above normal tide levels.
Pacific-Wide Tsunami Expected; U.S. Threat Believed Modest
Tsunami waves are expected to propagate across much of the Pacific Ocean as a result of Wednesday’s earthquake.
The brunt of the wave energy is expected to travel toward the west toward French Polynesia, including Tahiti. Tsunami waves of 1 to 3 meters (3 to 10 feet) are possible there, according to the PTWC.
In the U.S., the PTWC has issued a tsunami advisory for Hawaii. The bulletin said a major tsunami is not expected, but “sea level changes and strong currents” may endanger swimmers and boaters Thursday.
The agency projects the first tsunami waves to arrive around 3:11 a.m. Hawaiian time (9:11 a.m. EDT) Thursday. Tsunami waves around Hawaii are expected to be in the 0.3- to 1-meter (1- to 3-foot) range.
The Hawaii Emergency Management Agency said state officials are standing by, awaiting updates from the warning center.
On the Big Island, officials were bracing to be the first island affected, county spokesman Ilihia Gionson said. Officials were gathered Wednesday in the county’s emergency operations center in Hilo, he said.
“It’s too early to tell,” he said. “This early it’s best to just stay informed.”
The U.S. government’s National Tsunami Warning Center has issued a tsunami warning for southern California, including coastal areas of the counties of San Luis Obispo, Santa Barbara, Ventura, Los Angeles, Orange and San Diego. NTWC said tsunami waves of less than 1 foot above normal tide levels can be expected.
Such waves are not a danger to those on land, but they can create unusual and dangerous currents posing a danger to swimmers and boaters. People along the coast of southern California are advised to avoid the water until the tsunami threat subsides.
NTWC projects the first of the small tsunami waves to reach Newport Beach, California, at 4:46 a.m. PDT, and Los Angeles Harbor at 4:47 a.m. PDT.
Chile’s Earthquake History
A magnitude-8.8 quake and ensuing tsunami in south-central Chile in 2010 killed more than 500 people, destroyed 220,000 homes, and washed away docks, riverfronts and seaside resorts. That quake released so much energy, it actually it shortened the Earth’s day by a fraction of a second by changing the planet’s rotation.
The quake had huge ramifications, both political and practical, prompting the Andean nation to improve its alert systems for both quakes and tsunamis.
Chile is one of the world’s most earthquake-prone countries because just off the coast, the Nazca tectonic plate plunges beneath the South American plate, pushing the towering Andes cordillera to ever-higher altitudes.
The strongest earthquake ever recorded on Earth happened in Chile – a magnitude-9.5 tremor in 1960 that killed more than 5,000 people.