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Great Nevada Shake Out Hits Campus

Students prep to stop, drop, and hold on in an earthquake

Map of the history of earthquakes;
red dots indicate earthquakes
of magnitude 6 or larger.

Map of the history of earthquakes; red dots indicate earthquakes of magnitude 6 or larger.

Photo courtesy: Annie Kell

Photo courtesy: Annie Kell

Map of the history of earthquakes; red dots indicate earthquakes of magnitude 6 or larger.

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Brace yourself. This won’t last long, if you’re prepared.

Sierra Nevada College participated in the eigth annual Nevada Shake Out earthquake drill Oct. 19 at 10:19 a.m. with more than 590,000 other participants throughout Nevada. Students were notified of the campus-wide drill, via the e2Campus alert system.

According to the website shakeout.org, the chance of a damaging and destructive magnitude 6 earthquake within a 30-mile range of the Reno-Carson City-Tahoe urban area ranges between 60-70 percent in the next 50 years.

Dr. Annie Kell, a geophysicist, seismologist and coordinator for the annual Nevada Shake Out from the University of Nevada, Reno, is confident Nevada’s emergency management officials are well prepared in the event of an earthquake. But she is more concerned about individuals and communities.

“We’re not nearly as prepared as we should be. That’s due to lack of education on what the actual hazards are, and this sort of amnesia that we have as a society about the fact that big earthquakes and devastating earthquakes do happen in our region,” said Kell.

The necessary preparation for an earthquake involves seven safety steps, according to the Shake Out website. Steps include: secure your space, plan to be safe, organize disaster supplies, minimize financial hardship, drop, cover and hold on, improve safety, and reconnect and restore.

The Lake Tahoe Basin is formed by a series of three main faults, the West Tahoe fault, the North Tahoe Stateline fault, and the Incline Village fault. This series of faults is part of the Walker Lane, an approximately 100-kilometer-wide and more than 600-kilometer-long northwest-southeast trending zone of active faulting, according to the California Geological Survey Fault Evaluation Report.

“We say Tahoe is a tectonic lake, so it’s a lake basin that formed by fault activity,” said Kell.

The kind of earthquakes that we see in the Tahoe Basin are caused by “normal faults,” or the extension that is pulling Nevada apart, followed by the wrenching effect of the Sierra Nevada Mountains called “strike-slip faults” as they are caught in the Pacific-North American plate motion. “When a normal fault ruptures, one part drops down with respect to the other part, and they end up forming lake basins and then mountains, ranges and valleys,” said Kell.

The West Tahoe fault is the longest of the three faults, at 45 kilometers, running from south of Emerald Bay to Dollar Point on the North Shore. This fault has the capability of creating an earthquake of up to magnitude 7.5. Studies of this fault have shown the recurrence interval of earthquakes every 3,000 to 3,500 years in history. It’s been more than 3,500 years since the last event.

In a document shared by SNC’s geology class, scientists estimated about 40,000 years ago the West Tahoe fault had a massive earthquake, creating a landslide “which delivered material from the shores to the lake, creating a giant tsunami with waves 50 meters high, inundating all shore lines within 5 to 7 minutes.”

Kell notes that people often confuse earthquake forecasting and earthquake prediction.

“We cannot predict earthquakes. We can know where a fault is and look at what that fault’s behavior has been in the past, and from that we can make some sort of assumptions about what will happen in the future,” said Kell.

“So in a sense, we sort of assume that the West Tahoe fault is locked and loaded, that it’s accumulated the strain that it needs to have ruptures in the way that it has historically.” Kell adds that this doesn’t mean that other faults aren’t going to rupture too, like the Mount Rose fault, with a likelihood of a magnitude of 6.5 or larger.

The length of the fault as well as the thickness of the Earth’s crust assumes the magnitude of a fault. And the magnitude of an earthquake determines how long the shaking will last and the intensity. For example, a magnitude 6 will shake for about 20 seconds and a magnitude 7 will shake for 40 or 45 seconds, according to Kell.

Kell explains that the hazard of an earthquake in the Reno or Tahoe Basin area goes beyond areas close to or directly on a fault. The ‘amplitude and high shaking’ can be felt 50 miles away due to the composition of the soil. “We are on a certain type of soil that acts like Jell-O when an earthquake happens,” said Kell.

This also means that it may not take a large earthquake to cause destruction or loss of life, or to interrupt basic operations on the economic level.

Unlike other natural disasters, earthquakes give no warning. “I feel like disasters are on our brains lately,” said Kell. “It’s a really good opportunity to make sure that you have what you need in terms of emergency preparedness.”

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The student news site of Sierra Nevada College
Great Nevada Shake Out Hits Campus