Lake Mead has series of small earthquakes

The earth, for all its faults, adjusts to changing conditions. One of those changing conditions is more water entering Lake Mead. Over the past two months or so, there has been a series of small earthquakes, magnitude 2.1-2.5, in the Lake Mead area.

State geologist Lee Allison opines that these quakes are “due to the load on the rocks under the reservoir as the late, and large, snow pack runoff in the Rockies is filling the lake.” (See also)

According to the Las Vegas Review-Journal, meltwater from heavy snowfall last winter is filling the reservoirs:

The river system that fills Lake Mead and supplies 90 percent of Las Vegas’ drinking water is on track for its third wettest year since Lake Powell was filled for the first time in 1963.

The surface of Lake Powell has risen to its highest level in a decade…

The surface of Lake Mead is now 20 feet higher than it was a year ago, and current projections — ones now likely to be adjusted upward — call for it to rise another 33 feet by Aug. 1, 2012.

Last month’s inflow ranked as the second largest Lake Powell has ever seen in July. The 4.35 million acre-feet of water that poured into the reservoir on the Utah-Arizona border that month was almost three times the July average, and the flow in June was even greater — 5.4 million acre-feet, or almost 24 times the amount of water used in the Las Vegas Valley all of last year.

In other news:

The Arizona Geological Survey is currently featuring a video about the 7.4 magnitude Sonoran earthquake of 1887 which also shook southern Arizona.

For more information on earthquakes, see:

Where the Next Big American Earthquake and Tsunami Might Occur

Spanish Scientists Find Technique to Predict Earthquakes Claiming 80% Accuracy

The Measure of an Earthquake

Local atmospheric changes may foretell large earthquakes

Earth Fissures in Arizona

A home buyer’s guide to geologic hazards

For a brief history of Arizona geology, see my seven-part series:

Arizona Geologic History: Chapter 1, Precambrian Time When Arizona was at the South Pole

Arizona Geological History: Chapter 2, Cambrian and Ordovician Time