© NASA
The fault appears to have been recently active, and could be an earthquake threat today, reported the Portland Oregonian. Scientists said the last time the fault ruptured, possibly as a magnitude 6 or 7 earthquake, the ground ripped six feet (1.8 meters) apart.
The fault was discovered by scientists flying over Mt. Hood using lasers to scan the terrain. The fault is about 20 miles (32.2 kilometers) long and stretches from the northern flank of Mount Hood to the Columbia River.
Earthquakes are not a foreign concept to Oregonians. The nearby Cascadia Subduction Zone could unleash a magnitude 9 earthquake, similar to the size of the deadly earthquake that ruptured in Japan. Scientists aren't sure how big of an earthquake could rupture from the new Mount Hood fault. The research team, from the Oregon Department of Geology and Mineral Industries, are now working to estimate the threat that the fault poses to nearby communities.
"We don't know where all the seismic faults exist in Oregon. We don't know how often they cause earthquakes," Oregon State University engineer Michael Olsen, told the Oregonian. "That leads to a lot of uncertainty when we try to design buildings," he says, that are sufficiently resistant to earthquake damage.
In the coming weeks, scientists will dig a trench above the fault line so they can examine the soil for clues about past earthquakes. Looking at how the gravel and dirt has settled after past quakes could tell scientists about the size of previous quakes along the fault.
I live about 50 miles from Mt Hood. It's been out there, out my eastern windows all the time I've lived in Portland, Oregon. It is a dormant pile of eroding rock dikes, tuff and gravel cemented together with mud, and covered with a few small glaciers and lots of snow in the mild winters.
It's a stratovolcano with its peak at 11,249 feet (3,429 meters). I have climbed it five times, I think, and led two of those parties up the gently sloping ski runs above Timberline Lodge to the steeper slopes of the hogsback and the short scramble up the ice and snow summit couloir.
It's not to be trifled with, however. A number of people have died on the mountain, due to falls, falling rock and ice, caught in bad weather and simply getting lost and walking down into its wilderness canyons.
Read "Mountaineering, The Freedom of the Hills". [Link]
My first wife stole my copy of that, but I'd already taken it all to heart.
But I'm not about to believe that Mt Hood or any geological fault that stretches only 20 miles from it is a serious danger to this local area.
If Mt Hood suddenly wakes up and erupts, then Timberline Lodge and Government Camp and all of the vacation communities below it will have to evacuate, and some folks along the Sandy river might have to clear out too, and they might lose their homes. No big deal.
A 9.0 earthquake 100 miles or so off the west coast of Oregon is a much more serious concern. But even that is not too worrying here.