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…there is a range of volcanic cones that attract the eye, not only on account of their height and the symmetry of their curving slopes of light gray lapilli, but also because they form so striking an exception to the prevailing mountain forms in view. These are the Mono Craters. So perfect are their shapes and so fresh is their appearance that the eye lingers about their summits in half expectation of seeing wreaths of vapor or the lurid light of molten lava ascending from their throats. Israel C. Russell
VOLCANOVILLE
THE MONO CRATERS
A RARE EVENT Imagine a volcanic eruption 2,500 times greater than
the Mt. St. Helens blast of 1980! Twenty miles south of
present-day Mono lies the northern edge of Long Valley
Caldera. Seven hundred sixty thousand years ago the Long
Valley eruption blasted more than 150 cubic miles of
earth and ash skyward, burying much of the region in
hundreds of feet of volcanic debris. Ash fell as far east
as Nebraska. The earth’s surface collapsed more than
one mile deep following the eruption, forming a 200
square mile depression, called Long Valley Caldera.
Today, Long Valley Caldera is part of a large volcanic
complex that stretches from Mammoth Mountain to Mono
Lake.
AN ANCIENT LAKE Geologists have determined the age of Mono Lake from the Long Valley eruption. In 1908, oil prospectors, drilling for oil on Paoha Island, discovered an ash layer from the Long Valley eruption beneath hundreds of feet of lake sediment. Beyond the ash layer was more lake sediment. The unlucky prospectors did not find oil, but they did inadvertently discover the secret to Mono Lake’s age. Geologists determined that Mono Lake has held water since the Long Valley eruption 760,000 years ago, and lake sediments below the ash layer hint that Mono Lake could be much older, among the oldest lakes in North America.
See these additional geology sources: Long Valley Caldera Information (USGS)
RECENT REGIONAL EARTHQUAKE MAP (Courtesy USGS)
Click here to see a list of the most recent earthquakes.
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Except
for the Sierra Nevada immediately to the west, Mono Lake
is surrounded by a volcanic landscape. The Bodie Hills to
the north and the Cowtrack Mountains to the East of the
lake do not look much like volcanoes today, but they are
remnants of an earlier volcanic era that predated the
existence of Mono Lake hundreds of thousands to millions
of years ago. The Mono Craters, stretching to the south
of Mono erupted recently in geologic time and are the
some of the more obvious volcanic features at Mono Lake
along with Black Point and the Negit Island volcanoes. 
This volcanic
chain stretching ten miles north to south and topping
9,000 ft. may be the youngest volcanic mountain range in
North America. The last eruption in the Mono Craters
chain occurred less than 700 years ago at Panum Crater.
Panum Crater, located just above the south shore of Mono
Lake, is not a true crater. It is more accurately a plug-dome
volcano, where cooled lava has created a massive
dome-like structure that now "plugs" the
volcanic vent at the bottom of the crater. The entire
Mono Craters chain is actually a series of plug dome
volcanoes that erupted into existence within the last
40,000 years. Odds are the Mono Craters will erupt again.
