By Scott Miller EAGLE COUNTY — A pair of small earthquakes just north of Glenwood Springs were recorded in the early-morning hours of Tuesday, Dec. 11.
According to the Glenwood Post Independent, the first quake, about 1 mile north of Glenwood Springs, was recorded at 3:02 a.m. and had a magnitude of 3.4 The second, which was recorded at 4:13 a.m., was located about 3.7 miles north of town. That quake registered at 3.6 on the Richter scale. Both are considered mild quakes, but the rumblings were felt as far east as Edwards.
Small earthquakes are fairly common throughout the Rocky Mountains.
In an email, Colorado Geographic Survey Assistant Director Matt Morgan wrote that earthquakes occur along fault lines in the earth. When those fault lines move against each other in a big way, you can get mountains. Colorado’s mountains were formed by that massive movement of plates against each other. But smaller movements happen all the time.
“The earth is in a constant state of flux,” Morgan wrote.
While geologists and seismologists have mapped many fault lines in Colorado, “we do not know where all of them are,” Morgan wrote.
But, he added, there are mapped fault lines around Glenwood Springs, so small earthquakes can be expected from time to time. Morgan wrote that small quakes aren’t necessarily harbingers of bigger tremors to come.
“Making these types of predictions with limited data is difficult, if not impossible,” he wrote.
And earthquake activity, even substantial quakes like the one that recently hit Alaska — which was many times stronger than those recorded near Glenwood — usually are just earthquakes.
Nearby Volcano
There’s a dormant volcano just north of Dotsero — the remains of the lava flow can be seen on either side of Interstate 70 in the area. Scientists believe the Dotsero volcano last erupted roughly 4,150 years ago. Morgan wrote that long-ago eruption was “pretty small” compared to most volcanos. And, he added, the magma chamber beneath the volcano is no longer active.
With all that in mind, Morgan wrote that even large earthquakes rarely trigger volcanic events. Small quakes can occur around volcanoes. In an active zone such as Yellowstone National Park, fluids can migrate through the earth’s crust and change pressure in the surrounding rocks, causing small earthquakes.
But, Morgan wrote, earthquakes and volcanoes are largely separate phenomena.
According to information on the U.S. Geological Survey, a large earthquake in Hawaii in 1975 triggered a relatively small eruption from the nearby Kilauea volcano. But that earthquake was a robust 7.2 magnitude quake.
Compared to the tremors that hit north of Glenwood, that 1975 quake was roughly 40 times stronger, and released more than 120 times the energy.
Officials are able to closely track earthquakes all over the globe. Morgan wrote that the Colorado Geological Survey operates eight seismometers around the state. Data from those devices is sent to the U.S. Geological Survey’s office in Golden. Officials plan to install three more seismometers over the next two years.
The data and research — including placing trenches along …read more
Via:: Vail Daily