Notable Earthquake of the Week

Owens Valley M7.6 - M8.0 Earthquake, March 26, 1872  

According to John Muir, who was in a cabin in Yosemite Valley on March 26, 1872, it was a clear moon lit morning when the strong shaking began. Muir wrote the earthquake struck at about 2:30 a.m. and it was later estimated to have measured about M7.6 - M8.0. Muir ran from his cabin and had trouble standing as the Earth was violently thrown from side to side, and up and down.

Although from his isolated little hamlet of Yosemite Valley he could not have realized that the earthquake was actually centered along the eastern front of the Sierra Nevada in Owens Valley, some 110 miles away.

Reports from the epicentral area were not as inspiring as Muir's. Shaking from the event was intense, registering X-XI on the Modified Mercalli scale (a relative shaking intensity rating from 1-12 and shown in Roman numerals). The severe ground motion devastated the town of Lone Pine, where of a population of 300 people, 27 were killed, and 52 of 59 structures were destroyed.

The temblor knocked items from shelves, stopped clocks and awoke people from as far away as San Diego, Red Bluff and Elko, Nevada (Modified Mercalli Intensity (Isoseismal) Map ). Landslides and rock falls were common throughout the mountainous regions, and in some cases formed cascades that mowed down trees like they were twigs. Water spouts were formed around Owens Lake and liquefaction failures produced enormous settlements and cracks around the perimeter of the once pristine eastern Sierra lake. Dust filled the sky and clouds were still forming with each strong aftershock, and there were several.

The aftershock sequence was intense and included numerous events that were widely felt, including three in the M6 range, the largest of which registered M6.9 on April 11 - 17 days after the main jolt! Muir describe the shaking from many of these aftershocks as strong enough to topple rocks from the Yosemite valley walls for months.

Extensive and specular discontinuous surface fault ruptures occurred for over the course of 76 miles, from just south of Owens (Dry) Lake near Haiwee Reservoirs, to a little north of Big Pine (See Fault Rupture Map - 104k). The type of fault movement was normal-slip, the west (Sierra) side up, with a slight right-lateral strike-slip motion. Maximum off-sets measured 23 feet vertical and up to 22 feet horizontal and the scarps can still be seen today. Notice the height difference between the two men in the pictures above (click on the images to enlarge).

It is California's strongest historical earthquake away from the San Andreas fault, and until the San Francisco earthquake in 1906, the Owens Valley 1872 earthquake was considered California's "great" earthquake.

Photo Credits: Steinbrugge Collection, Earthquake Engineering Research Center (EERC), University of California, Berkeley.

Additional Links:

John Muir and the March 26, 1872, Owens Valley Earthquake, courtesy of UNR

Owens Valley and Mono Craters, photography of a geological journey, By Aron Meltzner



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