Like the much more well known Lassen and Shasta, Medicine Lake is a volcano that's always rumbling, and erupted perhaps as recently as 1910 with a little poof of ash from the Glass Mountain vent.
Harmonic tremor is what you see at the bottom of this chart, and represents the chatter of magma or lava moving underground.
A shallow, but wide (4.3x7.5 mile) caldera basin containing its namesake lake, which is located at the summit of the volcano. Intermittent, mostly effusive (non-explosive) eruptions over the last half-million years produced this large, shield-shaped volcano. In the last 13,000 years, effusive flank eruptions created expansive lava flows with single flows covering as much as 75 square miles.
Two-thirds of Lava Beds National Monument, on the north flank of the volcano, is covered by one such flow. Seven of the nine eruptions of the last 5,200 years, however, included an early explosive phase. The two youngest sent ash tens of miles downwind during their explosive phases before switching to slow effusion of thick, glassy-looking lava flows, forming Little Glass Mountain about 1,000 years ago, and Glass Mountain about 950 years ago. Exploratory drilling and geophysical studies reveal a high temperature geothermal system below Medicine Lake volcano fueled by a deeper zone of partially molten rock (magma). Ground surveys by USGS scientists show that the center of the volcano is slowly subsiding, due to motions on through-going regional faults and weakening of the rocks by high heat flow.
Below, the Glass Mountain lava flow, from the caldera rim, with Shasta in the background to the west.
Below, the Medicine Lake and Shasta
Satellite view of the region.
Mrs. CW has her bug-out bag packed and ready, and the car is fueled. Erupt away!
Okay, did anyone have volcanic disaster on their list of drama before the election?
ReplyDeleteCheck out Dutchsinse on youtube.
DeleteLots of small hotspots along plate boundaries lately, and a helluva lot of tremors from Seattle down to the Oregon border.