Volcanic blasts and tsunami history

On Jan. 15, one of the world’s largest volcanic eruptions was seen by satellite in the South Pacific near an island called Tonga. An underwater volcano called Hunga-Tonga-Hunga-Ha’apai exploded — the biggest since Mount Pinatubo erupted in June of 1991.

The volcanic eruption triggered a large sonic boom that was heard over 1,000 miles away in New Zealand. There was a report that the sonic boom was heard as far away as Minnesota. The shockwave that was produced by the volcanic eruption traveled close to 700 mph, nearly the speed of sound. Scientists say that the soundwave circled the planet twice within a day.

There was also a tremendous ash cloud sent from the volcano that reached over 24 miles above the Earth’s surface. According to Oxford University, it was the first time that volcanic ash had been detected that high into the atmosphere by modern instruments.

Because the eruption was underwater, the amount of ash and sulfur dioxide within the cloud was much smaller when compared to other major volcanic events like Mount Pinatubo, Krakatoa and Mount Tambora. According to an article on Space.com, the amount of sulfur dioxide emitted from the recent blast was only a fraction of what Mount Pinatubo emitted back in 1991. Therefore, very little cooling to the planet, if any, is expected. However, had this volcano erupted on land, then conditions may have been different in terms of a “global temperature response.” Despite less ash, the plume traveled to Australia, which is more than 2,500 miles from Tonga.

One of the largest effects from the recent eruption was the tsunami that was generated. Tsunami is the Japanese word meaning “harbor wave.” Many people envision a tsunami as a large breaking tidal wave, but they often resemble a rising tide in a series of large waves. Since tsunamis have longer lengths of waves, they would not be felt in the middle of the ocean.

Unlike normal ocean waves that are generated by winds, tides or the gravitational pull of the moon and the sun, these tsunamis are born through the large displacements of water from earthquakes, volcanic eruptions or other types of underwater explosions. Near Tonga’s capital, one of the islands close to the eruption, there were reports of waves that were 4 feet high in addition to ash falling from the sky.

Waves from 1 to 3 feet high were reported along some of the coastal areas of Oregon and Washington. According to the National Oceanic and Atmospheric Administration, there were waves higher than 4 feet at Port San Luis Harbor, which is between San Jose and Los Angeles. The tsunami resulted in damage in Hawaii as Hawaii News Now reported that a Sea Quest retail store had a 300-gallon propane tank moved across the yard from the floodwaters.

The most devastating tsunami in recent history occurred on Dec. 26, 2004. It was generated by a “megathrust” underwater earthquake along a major fault zone that was estimated to be as high as 9.3 in magnitude. The tsunami waves were as high as 100 feet as it hit the surrounding countries of Indonesia, India and Thailand. Over 240,000 people were killed from the massive event.

On March 27, 1964, the Great Alaskan earthquake, with a magnitude of 9.2, produced numerous tsunamis that were reported in over 20 countries including New Zealand, Japan, Mexico and as far away as Antarctica. The largest wave had a height of 220 feet at Shoup Bay, Alaska.

Back in 1700, on Jan. 26, an estimated 9.0 magnitude megathrust earthquake along the Pacific coast, a 700-mile stretch from British Columbia to California, led to a tsunami that hit the western coastlines of North America and the eastern coast of Japan. Tree rings and written records were some of the evidence used to determine the strength of the tsunami as it likely traveled an estimated 500 miles per hour from the Pacific coast to Japan.

Scientists believe that the volcanic event in the South Pacific could lead to further eruptions, but not likely to be as severe as the one last Saturday. Located along the active “Ring of Fire” that stretches from New Zealand northward to Alaska and then down the Pacific coastline, more earthquakes and volcanic eruptions are expected. Currently, scientists say there is a 37% chance of another big quake in the Northwest within the next 50 years.

SNOW SET FOR COMEBACK

In terms of our local weather, since Jan. 8, very little snow has fallen across the Inland Northwest. According to Cliff’s records, it’s been the most snowless period at this time of year and conditions are looking dry for most of the week. However, it’s looking colder with an increasing chance of snow by early February, so winter will be making a comeback.

And, with indications of storms returning from the Gulf of Alaska and other areas, our chances for at least an 80-inch seasonal snow season are going up in Coeur d’Alene. Stay tuned.

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Contact Randy Mann at randy@longrangeweather.com