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It quakes, it shakes. It’s the Seismic Seat!

Ride this new attraction at the upcoming "Explosion Detectives" exhibit.
August 28, 2020
graphic image of a blue chair shaking

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The idea of the Seismic Seat is that you will be able to sit on a stool that will shake and replicate different kinds of seismic events.—Mel Strong

 

Under construction now, the Seismic Seat is a riveting focal point for the upcoming “Explosion Detectives” exhibit about ground-based nuclear explosion monitoring. In the Defense Gallery, the 200-pound-plus seat will be anchored at the foot of a panel that reveals how scientists distinguish between an earthquake and an underground explosion.

You might imagine something like a mechanical bucking bull ride. While it’s true the Seismic Seat reproduces signals from real-live quakes, you won’t have to hang on for dear life (or duck under a table).

“The idea of the Seismic Seat is that you will be able to sit on a stool that will shake and replicate different kinds of seismic events,” says Bradbury educator Mel Strong, who designed and tested it.

As a young child, Mel lived along the coast of Northern California, where earthquakes associated with the Mendocino Triple Junction out in the Pacific Ocean were common.

“Although I was never in a strong catastrophic earthquake, I do remember earthquakes occasionally waking us up at night. The Seismic Seat reminds me strongly of the real thing,” he says.

What do explosion detectives do? 

The Global Security Nuclear Nonproliferation and Security program office at Los Alamos National Laboratory, which sponsored this upcoming exhibit, works with all kinds of scientists across the Lab such as seismologists, mathematicians, geologists, computer modelers, and more to detect nuclear explosions around the world.

The Seismic Seat is just one part of the Museum’s newest Nuclear Explosion Monitoring (NEM) exhibit. 

To be able to distinguish between seismic waves created by a nuclear explosion or something else, this group analyzes seismic signals that come from both natural and human sources. Differences between the two can sometimes be detected on a seismogram (a graph of seismic waves).  

Typically, a seismic station records shaking in three directions (front-back, left-right, up-down). To help create the Seismic Seat, Michael Begnaud of the Lab’s Geophysics group mined data from six actual seismic events, capturing all three directions and converting the data into files for Mel to use. 

That’s how the Seismic Seat reproduces the shaking intensity of events exactly as they were felt at the seismic station. 

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WATCH: In this YouTube video, see Mel Strong designing the Seismic Seat at home during the coronavirus pandemic, with six feline co-workers.

Ride the seismic waves!

Drawing from real events in Japan, Indonesia, North Korea, Washington State and Nevada, the Seismic Seat pumps out signals from both explosions and earthquakes. Each seismic wave ride lasts less than 30 seconds, although the actual event may have carried on for many minutes, Mel says. 

Given six red buttons to choose from, you might first ride the 2017 North Korea underground nuclear explosion (magnitude 6.3), then try the 2018 Japan earthquake (magnitude 6.0) — both of which are moderate events on the Richter scale.

The last button is a “mystery” event, where you must guess earthquake or explosion.

graphic image of seismic exhibit panel
Real seismic waves from real events.
Electrician Mark Hartman reaches for the 2019 Japan earthquake button.
Electrician Mark Hartman reaches for the 2019 Japan earthquake button. “This is fast becoming my favorite exhibit. It is the most elaborate because of the number of videos and push buttons and the amount of wiring,” he says.

When you push a red button, three seismograms display on a computer screen. “Each one of these seismograms is a record of the shaking in a different direction: vertical, front and back, left and right,” Mel says. “As you watch the marker go by on the computer screen, the Seismic Seat is going to shake accordingly as if you were there feeling the seismic event at the time.” 

For younger kids, the Seismic Seat will simply be a way to feel a simulation of an event. Adults, on the other hand, will be more able to feel subtle differences.  

“You can experience the different seismic events over and over until you understand (and feel) how the waves are behaving differently,” Mel says. “You should be able to feel the difference between an underground chemical explosion (conventional explosion), an underground nuclear explosion, and a natural earthquake caused by fault movement.” 

Nuts and bolts

In August, Bradbury exhibit fabricator Mike Martinez was putting the final touches on the Seismic Seat. Bringing a realistic (and safe) shaking sensation to the Seismic Seat is indeed a mechanical undertaking, he attests. Take a peek at the innerworkings.

The Seismic Seat in the fabrication shop on Aug. 17
The Seismic Seat in the fabrication shop on Aug. 17. In October, it will be unveiled for the virtual 2020 annual conference of the Association of Science and Technology Centers (ASTC). The public can hop on when it’s safe for the Bradbury to re-open.

Wiring for the seismic seat.
Mike Martinez attaches a subsonic transducer to the interior of the Seismic Seat. Inside each transducer is a 1.5 kg mass that will move back and forth to reproduce seismic signals, causing the seat to shake.


Buttkicker low frequency sound equipment
The secret kick behind the Seismic Seat.

 

 

 

WATCH: Earthquake or nuclear explosion?