Wednesday, May 23, 2018

America Has Other Volcanoes: Airliner Chronicles Visits Mt. Hood

The tragic and yet fascinating activity on the Big Island of Hawai'i has focused attention on volcanism in the United States, and has served to remind us that Hawai'i isn't the only place in the country that has to face up to the hazards of living in the shadow of dangerous mountains. I traveled to Washington by plane last week and was lucky enough to capture images of several of the volcanoes of the Cascades. We looked at Mt. Rainier first, and then at California's largest yet little-known volcano, Medicine Lake Highland. I really wanted to show some shots of St. Helens but we flew right over it, so I cheated and used some shots from 2006. But I wasn't disappointed by Oregon. The face of Mt. Hood was still illuminated by the rapidly setting sun.
Mt. Hood is the headache for emergency planners in Portland and the small villages south of the Columbia River. It is the highest mountain in Oregon at 11,249 feet (3,429 meters). The upper slopes are extremely rugged and steep and as such present a serious threat of debris avalanches similar in nature to that which destroyed the summit of Mt. St. Helens in 1980. The scar of the most recent avalanche can be seen on the right side of the summit in the picture below. The slide took place about 1,500 years ago. The prominent spike of rock in the alcove is called Crater Rock, and it is the remains of a lava dome that erupted around 1781. An earlier avalanche around 100,000 years ago removed the north flank of the mountain and flowed down Hood River Valley and across the Columbia River.

The thick mantle of snow presents the other serious hazard, that of lahars, or volcanic mudflows. The fluid masses have reached the outskirts of Portland in the past, and some lahars have occurred in recent years even though no eruption took place.

Living near volcanoes doesn't and shouldn't mean living in constant fear, but it is important to be aware of the potential threats where you live, and an understanding of what you will need to do in the event of an eruption. And because of all the crap roiling around on the internet, get your information from the geologists who work for the U.S. Geological Survey or state surveys in your area. Always be aware of the potential of exaggeration in the media, because even if they present good information, it will be cloaked in clickbait-style headlines that they utilize to get attention these days.

Meanwhile, the plane continued southward, and another volcano or two could still be discerned in the fog and mist. My mention of the Airline Chronicles refers to my first blog series that started way back in 2008. Some more information on Mt. Hood is available at  https://pubs.usgs.gov/fs/2000/fs060-00/.