Still the Rim of Fire

While California officials struggle with the state’s phenomenal human growth and development, it is well to consider that nature is not finished with the state yet. There are the almost-constant reminders such as fires, floods, mud slides and earthquakes. Then there are the volcanoes.

The U.S. Geological Survey has just published a 17-page bulletin by C. Dan Miller on the potential of damaging volcanic eruptions. The survey does not attempt to predict when the next eruption may occur in California, or the probability of such an eruption, but there is no question that it will happen, “sooner or later.” As with earthquakes, small eruptions tend to occur with greater frequency than large ones. Studies conducted at Mt. St. Helens in Washington state before its explosion in 1980 indicated that an eruption of a small volume of tephra--the ash and rock that falls after being blasted into the air--could be expected once every 100 years, one of moderate volume every 500 to 1,000 years and a significantly large eruption once every 2,000 to 3,000 years.

The greatest potential for eruptions in California are at Mt. Shasta, Lassen Peak and the Medicine Lake Highland in Northern California, and the Mono Lake-Long Valley region on the eastern side of the Sierra. The most recent eruptions were at Shasta in 1786 and Mt. Lassen during 1914-17. There was volcanic rumbling in the Mono Lake-Long Valley region about a decade ago.

As devastating as the Mt. St. Helens eruption was, far greater monetary losses are likely from even small future eruptions in California, the study says, because of the proximity of development. Further, the report says that the Mt. St. Helens blast was small in volume compared to possible future eruptions in California.

Since eruptions cannot be prevented or stopped, the study suggests careful monitoring of volcanic activity in suspect areas and evacuation when a major event seems possible. However, Miller says that precursors to eruptions can continue for weeks, months or years before an eruption occurs. Or, the rumbling may eventually stop without anything happening. Still, the report encourages local, state and federal authorities in areas of potential danger to develop contingency plans.

California can look to a prosperous future as a key trading outpost on the Pacific Rim. But the state must constantly remind itself that long before the Pacific Rim became a faddish socioeconomic term, it was known geologically as the Rim of Fire.