A powerful earthquake that struck off the coast of Russia generated tsunami warnings and advisories for a broad section of the Pacific, including Alaska, Hawaii and the US West Coast.
The quake registered a magnitude of 8.8 and was centered off the coast of the Kamchatka Peninsula, according to the US Geological Survey. The temblor struck early Wednesday local time, which was still Tuesday in the US.
Here’s what to know about tsunamis and their warnings:
Tsunamis are waves triggered by earthquakes, underwater volcanic eruptions and submarine landslides. After an underwater earthquake, the seafloor rises and drops, which lifts water up and down. The energy from this pushes sea water that transfers to waves.
Many people think of tsunamis as one wave. But they are typically multiple waves that rush ashore like a fast-rising tide.
Some tsunamis are small and don’t cause damage. Others can cause massive destruction. In 2004, a 9.1 magnitude earthquake struck off the coast of Indonesia, causing waves that leveled remote villages, ports and tourist resorts along the Indian Ocean across Southeast and South Asia. Some 230,000 people died.
In Hawaii, emergency authorities blast alerts to people’s cellphones, on TV and radio and sound a network of sirens.
In Alaska, some communities have sirens and information is also available on weather radio or public radio broadcasts. Official accounts on social media and cellphone push alerts spread the word. In some places, local officials have relayed warnings door to door.
Earlier this month, after another earthquake off Alaska’s Aleutian Islands, public safety departments in King Cove and Unalaska sent alerts urging those in coastal areas or those that could see inundation to seek higher ground.
Authorities urge people to move to higher ground when they have indications a tsunami will arrive.
In Hawaii, the state’s emergency management agency directs people to check maps and to evacuate if they are in a tsunami hazard zone. It also tells people to stay at least 100ft (30m) away from inland waterways and marinas connected to the ocean due to the possibility of wave surges and flooding.
Some communities have buildings designated on higher ground as meetup points during tsunami warnings, such as a school, while others might simply urge residents to retreat up a hillside.
In the US, the National Weather Service has different levels of alerts:
— A warning means a tsunami that may cause widespread flooding is expected or occurring. Evacuation is recommend and people should move to high ground or inland.
