Eric Sandman,age 13, of Cleveland Heights, Ohio, for his question:
Is it true that Mount Lassen is still an active volcano?
Certain volcanos are continuously active for centuries. Every night, sparks from Stromboli Lighthouse of the Mediterranean shoot up into the sky. But most volcanos become active and then rest. A period of quiet may continue for ages or it may last till the end of time.
It is not easy to decide whether an eruption is the final gasp of an aged volcano. These fiery mountains have been known to burst into violent activity after centuries of quiet serenity. Mount Lassen looks as calm and serene as the eastern Appalachians. Its rounded, snow capped peak stands 10,452 feet high in a National Park, dozing amid the scenic slopes and woodlands of California. But in 1914 and again in 1915, a smoky aloud of steamy volcanic fumes hung above its peak. Both times there were underground rumblings and small streams of hot lava flowed down its sides.
These small eruptions may have been the last gasps of a dying volcano, the final small spurts of activity before Mount Lassen sinks quietly to its eternal sleep. But no one is sure. A century is a short time in the life of a volcano and a dormant period may last 1,000 years. Mount Lassen has had two mild attacks of volcanic hiccups within living memory. It looks quiet now, but nobody can tell whether its dormancy will continue or for how long. Only after centuries of serenity can we be certain that Mount Lassen is an extinct volcano.
At present, we can say that it is sleeping in a state of dormancy and that it may or may not have puffed out its last gasp of activity. The serene Appalachians were seething volcanos millions of years ago. Mount Lassen stands in a chain of more recent volcanos, created during the formation of our far western mountains. Their lofty peaks, most of them crowned with snow, add to the scenic beauty of Oregon, Washington and California.
Once in a while, some of them show signs of half hearted activity. Like weary giants, they puff a slight volcanic hiccup before settling down to sleep. Two of the old giants growled and muttered in the last century. Mt. St. Helens puffed up a plume of fumes and erupted a little lava in 1841 and again in 1842.
The 1980 eruption of Mount St. Helens was a major volcanic eruption. The eruption was the most significant to occur in the contiguous 48 U.S. states in recorded history exceeding the destructive power and volume of material released by the 1915 eruption of California's Lassen Peak. The eruption was preceded by a two-month series of earthquakes and steam-venting episodes, caused by an injection of magma at shallow depth below the mountain that created a huge bulge and a fracture system on Mount St. Helens' north slope. An earthquake at 8:32 a.m. on May 18, 1980, caused the entire weakened north face to slide away, suddenly exposing the partly molten, gas- and steam-rich rock in the volcano to lower pressure. The rock responded by exploding into a very hot mix of pulverized lava and older rock that sped toward Spirit Lake so fast that it quickly passed the avalanching north face.
A volcanic ash column rose high into the atmosphere and deposited ash in 11 U.S. states. At the same time, snow, ice, and several entire glaciers on the mountain melted, forming a series of large lahars (volcanic mudslides) that reached as far as the Columbia River. Less severe outbursts continued into the next day only to be followed by other large but not as destructive eruptions later in 1980. By the time the ash settled, 57 people (including innkeeper Harry Truman and geologist David A. Johnston) and thousands of animals were dead, hundreds of square miles reduced to wasteland, over a billion U.S. dollars in damage had occurred ($2.74 billion in 2007 dollars, and the face of Mount St. Helens was scarred with a huge crater on its north side. At the time of the eruption, the summit of Mount St. Helens was owned by the Burlington Northern Railroad, but afterward the land passed to the United States Forest Service. The area was later preserved, as it was, in the Mount St. Helens National Volcanic Monument. Today, this snow capped peak in Washington looks like a frosty ice cream cone. Today, the serene white peak of Mt. Hood looks calmly down on the city of Portland, Oregon. Yet this sleeping giant erupted a little lava in 1859 and again in 1864. And sometimes climbers find a smoky plume of fumes issuing from holes in its sides.
Tapering Mt. Hood is the most handsome, but massive Mt. Rainier is the most majestic of these sleeping giants. Seeing it from afar, no one would suspect that the serene mountain was built by fiery volcanic activity. But climbers have leached the crater at its peak, a round hollow half a mile wide, walled with cliffs 30 to 40 feet high. And several observers have seen jets of steam and plumes of smoke issuing from vents in the crater floor.
The range of mountains in which these old volcanos belong is young. There are still earthquakes and other activity in the region, but most of the mountain growing seems to be finished. The volcanos that helped to build them are old and tired. Maybe in a few centuries all of them may become totally extinct. At present, they appear to be gasping their last. However, we cannot class them as extinct as long as they have enough energy for a faint puff or a quiet hiccup. And for a few centuries, Mt. Lassen must remain on the list of active volcanos, even though it may have breathed its last.