Remembering the quake
Remembering the quake
Wednesday, August 17, 2011
It was my sister’s eighth birthday and the first time I had ever felt an earthquake. We were quite a ways from the epicenter - nearly 100 miles. We had all gone to bed, so I had a sense that it was the middle of the night, but it was still before midnight when the earth shook enough to wake at least some of us. What we felt was the strongest and deadliest earthquake to strike our area since the 1935 Helena earthquake. The Yellowstone Quake was 7.5 in magnitude. It was big enough to be felt as far away as Utah. In Eastern Idaho a landslide triggered by the quake killed eight people. Another 28 died in the Madison canyon area, mostly campers who were buried under the landslide. According to the U.S. Weather Bureau the quake lasted 30 to 40 seconds. It was probably an even shorter amount of shaking at our home, which suffered no damage. There were some buildings in Bozeman, sixty miles from our home, which were damaged.
The real damage was in the Madison Canyon. 80 million tons of rock, mud and debris slid into the valley with sufficient force to cause hurricane force winds strong enough to toss cars into the air. The water in Hebgen Lake started to slosh back and forth with enough intensity to flow over the dam. The dam held but it took until nearly noon the next day for the sloshing to subside. Initially the waves were over eight feet tall.
The landslide completely blocked the Madison River and a new lake, quake lake, started to rise behind the blockage. Roads were destroyed. There was enough damage to close the road between Norris and Mammoth. Phone service between West Yellowstone and Bozeman was lost, so it was hard to tell what happened.
At first light our father took off in a Super Cub to see what had happened. Later that day he flew our twin-engine airplane over the area with government photographers to assess the damage. Over the next few days he made several flights, including flying U.S. Senator Lee Metcalf over the area.
There were fears that the lake backing up in the canyon would release suddenly, causing a catastrophic flood downstream. The Army Corps of Engineers cut a channel into the slide about 14 feet deep and by early September water was flowing through the channel. That channel began to erode, so a second channel was cut and completed in late October. A survey of Hebgen Dam concluded that there was damage to the dam, so the lake was completely drained to make repairs of the dam. Crews had to use heavy equipment to remove the dead fish from the lake bed.
There are all kinds of details of the quake that I do not remember. I was a child and life went on mostly the same for me. I’ve always remembered the date, but I had the occasion of my sister’s birthday to anchor it in my mind. My parents were in the aviation business and had a fire patrol contract with Yellowstone National Park, so I also remember a lot of activity at the airport, which was exciting.
There were lots of changes in the park. New geysers and cracks in the ground sprouted up all over the park. Some geysers quit spouting. Others became more or less regular than before. After the quake, tourists weren’t allowed into the Crow’s Nest at Old Faithful Inn, a favorite high spot for watching the geyser spout.
There are some who believe that even more dramatic events are coming for the Yellowstone area. Yellowstone Lake is the caldera of a supervolcano and there has been a lot of seismic area centered around the northern end of the lake. There is an area beneath the lake that has been rising at the rate of about three inches per year since 2004, indicating a buildup of magma beneath the surface. There have been thousands of small quakes in the park, mostly under 3.0 magnitude, with a few as intense as 3.5. A bit to the northwest, the Norris Geyser basin has raised about 5 inches and the temperature of the Norris Geyser has increased.
All of this, however, happens in geological time. There is no known way of predicting earthquakes or volcanic eruptions. The nature of the next geological event in the Yellowstone area is not known. There are many who believe the area is capable of an eruption that is many times larger than the 1980 Mt. St. Helens eruption. It is not possible with the information that is currently known to place any kind of timing on such an event or to know for sure what will occur.
So on August 17 each year, in addition to wishing my sister a happy birthday, I remember the Yellowstone earthquake. Yellowstone is an amazing place and offers many opportunities to see wonders and to learn about the forces of nature. It is also a good place to ponder all of the things we do not understand about this wondrous planet we call home.
There is yet much that we do not know.
Copyright © 2011 by Ted Huffman. I wrote this. If you want to copy it, please ask for permission. thuffman53@mac.com. If you want to share it with a friend, please direct your friend to my web site.