Tsunami warning systems continue to improve

'Tsunami' is a Japanese word meaning "large waves in harbors." This description is a particularly apt one, especially after seeing the tremendous amount of damage this past March 11 from the killer tsunami that occurred some 30 minutes after the record 9.0 earthquake in the bays and harbors of northeastern Japan that killed at least 10,000 people.

Most tsunamis have occurred following strong earthquakes along the so-called 'Ring of Fire' in the Pacific Ocean regions. A section of the ocean floor shifts radically, either up or down, just prior to a catastrophic tsunami. Submarine landslides also occasionally cause tsunamis, but these are rare.

When the ocean floor suddenly drops as an earthquake shifts the sea vertically, it has an effect similar to when a plug is pulled from a bathtub drain. The downward movement of the sea floor into the 'hole' before it rises sharply back to the surface creates the deadly tsunami wave.

This displacement of a vast quantity of water sends huge waves of great force radiating from the epicenter of the strong earthquake in all directions. However, in most cases, it's almost impossible to see these waves until they crash upon the shores causing enormous amounts of damage like they did in Japan.

At the same time, knowing the depth of the ocean through which the tsunami is moving makes it possible to predict just when it will arrive at a given point.

The speed of the tsunami is well known. It travels at between 500 and 600 miles per hour, near the speed of a jet aircraft.

There are actually two main facts that scientists must determine after a strong earthquake in order to predict the exact cause of the tsunami.

First, these scientists must know the precise epicenter of the quake and the depth of the ocean over which the tsunami is traveling. Recent extensive soundings in the Pacific have shown an average ocean depth of about 14,000 feet.

Second, by multiplying the average water depth by the acceleration of gravity, thirty-two feet per second, and taking the square root of the sum, the specific speed and the direction of its path can be determined.

For example, a huge undersea earthquake in the Gulf of Alaska could be expected to produce a tsunami that would reach San Francisco in about 5 hours. An earthquake centered offshore from Los Angeles would reach Cape Horn in the southern tip of South America in approximately 17 hours.

Since the late 1940s, this knowledge has led to an advanced tsunami warning system throughout the Pacific. Following the deadly May 1960 tsunami in Hawaii, which killed 61 people in Hilo on the eastern side of the Big Island, scientists have been issuing wave-size predictions for particular regions. This helped save many lives following the huge earthquake in Alaska on Good Friday in 1964. Even the recent tsunami in Japan would have seen a much higher death toll without the much improved warning systems. Some people had only minutes to reach higher ground.

In our current cycle of increased earthquake activity in the Pacific 'Ring of Fire' regions, we could see at least a couple of more disastrous tsunamis in the next decade, possibly even along the western U.S. coastlines. Stay tuned.

NORTH IDAHO WEATHER REVIEW AND LONG-RANGE OUTLOOKS

Even though areas to the east of us from Montana to the Great Lakes region are still seeing heavy snows, up to 20 inches in parts of the Dakotas and Minnesota where severe flooding is likely later this spring, we are experiencing mostly rain across the Inland Empire at the lower elevations thanks to a bit milder temperatures.

We did see one to three inches of the white stuff on Saturday, March 19, the last day of the winter season, but the past week has been snowless in the lowlands. We may still see some light flurries during the colder overnight hours in places into early April, but these snows will quickly melt in the driveway. My snow shovel has been put away along with the snow-blower for the season. My lawnmower has been tuned up. Bring on the warmer weather.

The 'La Nina' is weakening in the waters of the Pacific Ocean, but still tenaciously holding on to life. April and May still appear as if they will be wetter and somewhat cooler than normal until high pressure finally builds in by late May or early June. We will see brief periods of warmer weather and sunshine, however, even during the next six weeks, but there will be plenty of showers for those May flowers and early planted gardens.

Longer-term, Randy Mann and I are still hopeful that we'll see a warm and dry summer season in 2011 as 'La Nina' finally dies off in the tepid waters of the Pacific.

A very strong stationary ridge of high pressure could begin in June lasting through July, August and at least early September. This should mean lots of 'Sholeh Days' this summer with afternoon highs near or above 90 degrees. At least three or four days may see afternoon maximum readings near or above the century mark in the Inland Empire.

But, if we do see unusually hot, dry and windy weather this summer, it could spell BIG TROUBLE for this region's parched grasslands and forests. Fires could rage over wide areas of the Far West later in the season. Stay tuned.

SPECIAL ANNOUNCEMENT

Fifty years ago this past week, two teenage lovers, high school sweethearts, hopped a Greyhound bus in Pittsburg, Calif., and eloped to Caldwell, Idaho, where they were married in a small Baptist ceremony on March 23, 1961.

Exactly a year later, on their first anniversary, these teenage parents had their first son, Brian. The hospital staff baked a cake for the happy couple. Another year later, in May of 1963, their second son, Brent, was born.

Three adult grandchildren and five toy poodles later, we're still teenagers at heart. Sharon is still my "sweet little sixteen."

Thank you, honey, for putting up with this "weather nut" for more than five decades. You're truly a gift from God.

Love forever,

Cliff Harris is a climatologist who writes a weekly column for The Press. His opinions are his own. E-mail sfharris@roadrunner.com