LIHUE — If a tsunami hits Kauai, go to higher ground.
The Pacific Tsunami Warning Center issued a tsunami watch, later downgraded to an advisory, for the state of Hawaii Wednesday due to an 8.3 magnitude earthquake almost five miles underwater in the Pacific Ocean off the coast of northern Chile.
“In this case, an earthquake in Chile, it’s several hours before it’d reach Hawaii,” said Stephen Taylor, a professor at Kauai Community College who teaches geology and oceanography. “Earthquakes in Chile happen quite often.”
According to the National Weather Service, if a tsunami is going to impact Hawaii as a result of the quake, the first wave, perhaps one meter, was projected to reach the beach about 3 a.m. today. Wave action may continue for three to four hours.
Sea-level changes and dangerous currents could pose a threat to those in or near the water. People were asked to stay out of the water and advised to avoid coastal waters, beaches and rocky shorelines from 3 to 7 a.m.
The Department of Land and Natural Resources will keep closed its coastal and low-lying state parks and forest areas (including wildlife sanctuaries, natural area reserves and game management areas) on all islands this morning until staff can monitor adjacent ocean conditions for safety before reopening them.
State small boat harbors will remain open for boat owners who may choose to take their vessels out, DLNR said.
The Kauai Civil Defense Agency said that as a precautionary measure, the Jetty Road at Nawiliwili was closed at 6 p.m. Wednesday and will reopen when the threat of a tsunami has passed.
An issued watch means a tsunami reaching Kauai is possible, but it’s not necessarily going to happen. In the case of a watch, it’s a good idea to stay tuned in to local emergency management outlets, like the Kauai Civil Defense Agency, as well as the National Weather Service.
If a warning is issued, that means there’s an indication it will happen, or is happening. Those same emergency management outlets will provide information on who should evacuate and where to go if there is a tsunami warning.
People are advised to remain at least 100 feet away from inland waterways and marinas connected to the ocean in the event of a warning. It’s also a good idea to keep an eye on traffic and be prepared for a gridlock situation. That means if there’s too much traffic, you might have to walk to higher ground.
A tsunami is a series of waves, called surges, that travel outward from the epicenter of underwater earthquakes, or ones close to the ocean.
“These things are incredibly difficult to predict,” Taylor said. “Basically, they have to wait for (this tsunami) to hit an array of buoys that are along the equator between Chile and Hawaii.”
That’s how tsunamis are tracked — by looking at satellite data reports from buoys in the open ocean that measure the change in water level.
“In the open ocean, the water level could go up just an inch, but when it moves into shallow water it slows down and the water piles up,” Taylor said.
So one inch of elevated waves out in the open ocean could become a wall of water once it reaches shore.
“Considering the history of tsunamis, I would take a watch seriously,” Taylor said. “I wouldn’t be going down to the beach to check it out.”
Tsunami evacuation zones on Kauai are the coastal areas around the island and maps are available in the local phone book.
Again, in case a tsunami heads toward Kauai, people should head for high ground.
“Often the first sign of an approaching tsunami is the ocean receding from beaches and harbors,” the phone book’s tsunami disaster guide says. “If you are at the shoreline and see this, move inland to higher ground immediately.”
The last tsunami watch issued for Kauai was in August 2012, according to the Mayor’s Office. A warning was issued in October 2012, and an advisory was issued the following April.
“The 2011 earthquake in Japan caused a tsunami that did cause problems for Hawaii,” Taylor said. “I know the last couple of years, there were strong currents and it was a good thing that a watch was put on Kauai.”
In the case of this tsunami, and others generated from places like Japan, the Hawaiian Islands usually have several hours of warning before impact, but locally generated tsunamis may only offer minutes of preparation time.
“It’s extremely unlikely, but the big island is a giant volcanic mountain and some of that land could settle,” Taylor said. “That could cause a tsunami and our warning time would be minutes, definitely less than an hour.”