With Big Island earthquake activity ramping up since 2018, Monday’s 4.9 magnitude quake was somewhat par for the course.
The epicenter was on the Hamakua coast area, but with the ever-present geological activity on Hawaii Island, the state lives with the constant threat of a locally generated tsunami.
If a tsunami is created by a local earthquake, much of the state will have a matter of minutes to reach higher ground.
“In Hawaii, if it’s on the Big Island, which is the most likely source for a tsunami, it’s going to come within minutes of the coastline nearest to the earthquake.” said Dr. Nathan Becker, and Oceanographer for the Pacific Tsunami Warning Center.
“Oahu has about 30-45 minutes before the first wave arrivals from the Big Island depending on where the earthquake is.” he added.
Sirens will sound and bulletins will go out, but in the open ocean, a tsunami can travel up to 500 miles per hour. If you feel an earthquake and are near the ocean, that can function as a tsunami warning.
“Right if you’re at the beach and the ground is shaking so strongly you can’t stand up, or if it lasts about 20 seconds or longer that’s a clue that this is a big enough earthquake to make a tsunami.” Dr. Becker said.
“They will feel the earthquake and be able to react to it faster than we can get a bulletin out for the people nearest to the earthquake.”
Your instinct might be to get into a vehicle and drive away, but Dr. Becker warns that might not be the quickest escape route.
“There’s an evacuation zone, they need to know how to get out of it quickly. You don’t necessarily want to drive out of your evacuation zone walking is perfectly fine, don’t try and grab stuff and run away that’s in the past this has been led to tragedy.”
These types of earthquakes are rare but are entirely possible to strike at any time without warning.
“We have earthquakes all of the time on the big island, most of them aren’t tsunami hazards.” Dr. Becker said.
“It’s not a warning until it’s a magnitude 6.9 which is pretty darn big. The earthquake that was last year wasn’t 6.9 it was right at the threshold. The last time we had a deadly tsunami was a magnitude 7.6 just to give you an idea.”
Tsunami evacuation zones are available on the NOAA website.