Hilo -
Stars glimmer overhead in a black velvet sky as tradewinds gently rattle the graceful fronds of coconut palms. The dark sea rises and falls gently, like some giant being deep in restful sleep, belying the warning sirens which shriek and wail into the tropical night. An earthquake off Honshu, Japan, has shoved the sea. Waves of energy are racing through the largest body of water on Earth, and Hawai`i is in the middle.
But Hawai`i has been through this before.
Sailboats cast off and motor out to sea, seeking the safety of deep water.
In Downtown Hilo, at 11:00 pm store lights blaze as families and friends empty their stores into trucks, SUVs, vans, and sedans. They will take their livelihoods to higher ground. As storefronts are boarded over, the homeless who sleep in the doorways slip, by ones, twos, threes, to higher ground where they cluster, cigarettes glowing in their hands.
Hawai`i County Civil Defense workers prepare the barricades at the perimeter of the innundation zone, calm and cheerful despite being called from vacation, or sleep.
Unusual for Hilo, rudeness takes hold of a few drivers fighting for position in gas lines at the stations. As a pedestrian steps without looking into a protected crosswalk, a car runs the red light, almost hitting him. Haili Street suffers a brief traffic jam as drivers block it, a panicked urge to buy gas and groceries blocking common sense, as well as a road out of the innundation zone.
The one road out of the shoreline community of Keaukaha lies almost at sea level, so the residents cross the tarmac of Hilo International Airport, their official escape route. A runway becomes a huge parking lot, offering refuge form potential waves.
Hilo, usually known for its rain, prepares for innundation of another kind.
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The 8.9 magnitude earthquake that hit the east coast of Japan on March 11, 2011 caused a devastating tsunami that swallowed up entire communities. The US is making emergency delivery of coolant to help prevent a nuclear disaster as a consequence of the state of emergency declared at the failed Fukushima Daiichi nuclear power plant.
This Sendai earthquake was due to thrust faulting at a subduction zone where two tectonic plates move towards each other with the lower plate of rock being pushed up and over the other. This earthquake was located at the fault where the Pacific and North America plates meet. The Pacific plate thrusts beneath Japan and west beneath Eurasia. The seismic activity occurred at a depth of 20 miles. The energy that is released by the sudden shifting of the plates results in the shaking that is felt above ground.
When this type of seismic activity is centered beneath an ocean, a massive tidal wave or tsunami can ensue. As in the current nightmare that is unfolding in Japan, the tsunami is often more destructive in terms of physical damage and lives lost than the actual earthquake itself.
A tsunami is much different than the repeated crashing of waves that occurs during a storm. The wavelength or distance from crest to crest is about 120 miles instead if about 330 feet. However, because of the enormous distance between waves, the amplitude or height of each wave is only a few feet and may go unnoticed. An unfortunate onlooker, prior to being swept away by the tidal wave, may first see water retreating into the ocean, exposing the sea bed below. This is called a drawback. The returning surge is of such enormous volume of water displaced from the sea that it sweeps away most everything in its path of destruction.
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The National Weather Service(NWS) has issued a tsunami or tidal wave warning for Hawaii and the entire west coast of the United States. The warning comes in response to a magnitude 8.9 earthquake that jolted Japan early this morning.
The tsunami, say the National Oceanic and Atmospheric Administration (NOAA)is expected to begin arriving on the west coast at approximately 7:10 am PST, in Washington and Oregon. Within minutes the wave, moving from west to east, will begin impacting California. Hawaii is expected to see the leading edge of the tsunami just before 3:00 am local time.
The peak height of the water is measured in terms of height above normal sea level, not peak to trough level. The popular notion that the initial wave strike is the most dangerous part of the tsunami is not true according to the NWS. The NWS says tsunamis strike as a series of waves with the strongest often coming later in the series.
Each wave can force more water inland, much like an extraordinary tide or storm surge rushing in. The exact height of the wave is difficult to predict because it is highly dependent upon the topography of the coasts in its path.
The wave has already started to impact Alaska with an amplitude or height of 3.5 feet above normal sea level recorded at Shemya, Alaska. At present, the highest tsunami amplitude was recorded at Ofunato, Japan shortly after the earthquake that triggered the massive waves. In Ofunato, says the NWS, the wave measured as much as 10.7 feet above the normal sea level.
Boats along the coast of Japan were capsized and cars were swept from the roads by the inrushing tsunami waters. Casualties, including deaths have been reported from Japan, although it may be some time before accurate numbers can be given. Aftershocks continue to shake Tokyo and are expected to continue throughout the day.
The earthquake’s magnitude of 8.9 on the Richter Scale makes it one of the top 5 most powerful earthquakes of the last 100 years. It was centered at a depth of 12 miles off the coast of Honshu, Japan says the NWS. At this point, the west coast is under a tsunami warning, meaning that “a tsunami with significant widespread inundation is imminent or expected. Warnings indicate that widespread dangerous coastal flooding accompanied by powerful currents is possible and may continue for several hours after the initial wave arrival.”
Persons in coastal or low-lying areas within a tsunami warning zone should move immediately inland to higher ground away from all harbors and inlets including those sheltered directly fromt he sea, says the NWS. The imminient arrival of the tsunami may be preceded by the ground shaking or rapidly rising or falling water levels. The NWS further warns that small buildings do not represent protection from a tsunami as they are not designed to wiithstand such an event. Residents in an affected area should seek specific direction from local civil authorities.
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A massive earthquake measuring 8.9 on the U.S. geological survey Richter scale occurred off the east coast of northern Japan at ~ 2:45 PM local time, i.e. 5:46:23 UTC, March 11, 2011.
This 2011 Sendai earthquake is the largest earthquake ever to hit Japan. The resulting tsunami in Japan has washed away vehicles and houses. The tidal wave reached 10 meters high at Sendai airport. Some buildings are on fire. Death toll is yet to be determined.
A weather radio awakened me at ~ midnight PST, announcing a tsunami warning for the United States’ Pacific coast, with the first surges expected between 8:30 and 9:00 AM PST. The tsunami waves are expected to hit Hawaii at 2:59 AM local time.
It takes ~ 11.5 hours to fly non-stop from Los Angeles, CA to Tokyo, Japan. So it takes approximately the same amount of time for an earthquake-induced tidal wave to travel from Japan to LA.
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