In April 2016, scientists at the Nevada Seismology Laboratory warned that a major earthquake along the Eastern Sierra is long overdue. The region averages a magnitude 7 event about every 30 years, and it’s been 60 years since the last one.
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“Lake Tahoe lies on the western rim of the Basin and Range province,
one of the most seismically active regions in the United States.”
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An active fault system runs from south of Yosemite National Park to north of Reno and Lake Tahoe. There were seven magnitude 6.5 or larger temblors from 1915 to 1954, but none since. (Scientists today use a moment magnitude scale to measure quakes – the familiar Richter scale has been largely abandoned.)
In the Far West, terra firma is an illusion. Alaska experiences the most earthquakes in the country, but California and Nevada rank second and third, respectively, and together account for about 80 percent of all quakes in the 48 contiguous states. The magnificent Sierra Nevada is roughly 400 miles long and 45 miles wide, sculpted by glacial ice into steep, deep canyons and elevated peaks exceeding 14,000 feet high.
To the casual hiker, climber or skier, the range may seem stable, but it is really in a constant state of uplift that helps offset the weathering process that would otherwise slowly wear it down. Mountains rise along faults and earthquakes result from this building process. Lake Tahoe lies on the western rim of the Basin and Range province, one of the most seismically active regions in the United States.
The Tahoe Basin was formed about 3.6 million years ago when a fault on the eastern margin created the Carson Range and a massive up thrust to the west forced the Sierra Nevada up out of a shallow sea. The landmass between these two ranges collapsed and over time filled with water. The Sierra is actually enormous blocks of granite tilted toward the Pacific Ocean, which produce a 35-mile gradual slope on the west, and a steep, 10-mile descent on the east.
The westward tilt of the large fault blocks in the Sierra uplift generated towering walls of granite along its eastern edge, which today represent the highest peaks in the Tahoe Basin, such as Freel Peak (10,881 feet), Pyramid Peak (9,983 feet in Desolation Wilderness) and Mount Tallac (9,735 feet).
Scientists studying the bottom of Lake Tahoe have found evidence of huge landslides they think were triggered by ancient earthquakes of magnitude 7.0 or larger. Chunks of rock and dirt the size of city blocks ripped from surrounding mountains and smashed into the lake during powerful temblors thousands of years ago. Geologists have also warned that several faults that lie directly beneath and west of Lake Tahoe are thought capable of generating quakes with a magnitude near 7.0 with enough movement to produce tsunami waves exceeding 30 feet high in the Tahoe Basin.
Few people ever see a mountain range grow, but on March 26, 1872, the 300 residents of Lone Pine did. The small hamlet is located on the Sierra east slope near the Owens Valley, about 350 miles south of Reno. This extraordinary seismic event occurred on a clear, calm night under a bright, full moon. At 2:30 a.m. sleeping residents in Lone Pine were awakened by a sound like rumbling thunder accompanied by the crash of falling dishes, mirrors and glassware. The heaving ground broke plaster from ceilings and tossed filled water pitchers into the air.
People grabbed what clothes they could and ran from their collapsing homes in stark terror. Timber is scarce in this region and all the dwellings were built of adobe brick. The brittle adobe construction offered no safety in the severe quake and the destruction in Lone Pine was nearly total. Out of the 62 buildings lining Main Street, 52 crashed to the ground in piles of rubble. Falling bricks and debris killed 27 people. Four miles south of Lone Pine a small lake disappeared and the Owens River decreased in volume. The cloud of dust that rose over the disaster could be seen from 20 miles away.
Witnesses reported that “every few minutes heavy shocks of a few seconds duration occurred” and from 2:30 a.m. until 6:30 a.m. there were not less than 50 distinct shocks and “the earth seemed to vibrate all the time.” The first tremor cracked and threw down many walls and buildings, but it was the succeeding aftershocks that leveled the town.
At Big Pine, 43 miles to the north, the tectonic violence injured many and tore the land apart. A large fissure opened from 50 to 200 feet wide and 20 feet deep, running close along the base of the Sierra Nevada. Along several sections of the road the earth was thrown up 5 to 10 feet, and in many places water was forced out of the barren ground. Springs failed that were never known to be dry before. Several people saw flashes of fire from the mountainsides at points between Bishop’s Creek and Independence. Rockslides blocked the road with boulders as big as a two-story house. When the stagecoach finally arrived, the exhausted driver gasped, “There was not a brick or adobe or chimney left standing between Bishop’s Creek and Independence.”
The great earthquake, estimated at a magnitude close to 8 on the moment magnitude scale, was felt from Winnemucca, Nev., to Oakland. The jolt was severe enough to stop clocks in Truckee, Blue Canyon and all along the Sierra west slope. In Sacramento, where the shaking lasted for a minute and a half, buildings rocked alarmingly and panicked residents poured into the streets in fear. At the Sacramento County Jail, prisoners begged and prayed with tears in their eyes to the jailer in charge to let them out. Their pleas were ignored.
Hard rock miners working the night shift far below in the dark shafts and drifts beneath Virginia City claimed that the “sensations in the bowels of the Earth were very disagreeable” and they would “infinitely prefer to being on the surface during earthquakes;” a typical Comstock understatement.
The dramatic 1872 Lone Pine earthquake represents powerful geologic forces that literally move mountains. Vertical displacement was measured at nearly 17 feet with a lateral movement near 40 feet. It left no doubt in the minds of local residents that their beloved mountain range can still grow in leaps and bounds.
Tahoe historian Mark McLaughlin is a nationally published author and professional speaker. His award-winning books are available at local stores or at thestormking.com. You may reach him at mark@thestormking.com. Check out his blog at tahoenuggets.com or read more at TheTahoeWeekly.com.
