Joshua Bloom's homemade earthquake early warning alarm, in a Gregoire box. Photo: Joshua Bloom
Joshua Bloom’s homemade earthquake early warning alarm, in a box from East Bay restaurant Grégoire. Photo: Joshua Bloom

When the Napa earthquake struck on Aug. 24, Joshua Bloom had a 5-second warning.

That’s because the UC Berkeley astronomy professor likes to tinker.

It was when Bloom was a beta tester in the prototype ShakeAlert system being developed by a consortium of seismological researchers (including UC Berkeley), that he came up with an idea.

“I thought it was silly that every time I closed my laptop, I couldn’t get a warning,” he said.

So Bloom cobbled together his own earthquake alarm for just over $100, using a Raspberry Pi single-board computer ($36.39), a wired speaker ($14.99), a mini-WiFi adapter ($6.71), and SD card.

To house it, he uses a box from Grégoire, the local restaurant group known for its crispy potato puffs. And he keeps the device in the living room of his North Berkeley home, next to the fireplace.

ShakeAlert triggered a 10-second early warning alert for the Magnitude 6 Napa quake last month. Bloom’s device provided a five-second warning. (Bloom details how it worked on his blog.)

Meet Joshua Bloom at Uncharted on Oct. 24-25. Get your early-bird tickets now!

For Bloom, this is tinkering with a definite purpose. He sees his demonstration project as validation that Californians could have an earthquake alarm in every home for about the same price as smoke detectors and carbon monoxide alarms. And he hopes it adds pressure to the legislature to fund the $80 million it will take to roll out the ShakeAlert network beyond its few privileged early testers.

Joshua Bloom: His kids think the alarm is “super cool.” Photo: courtesy Joshua Bloom

“There’s a huge safety component to it,” Bloom said. “Knowing it’s cheap to make will get the public excited and hopefully get the legislature to fund it.”

Users can set the sensitivity of the alarm. Bloom has his set for something that could cause major damage, like the Napa quake.

With a network in place, he said, users could use the devices as early warning for a wide range of threats, including tsunamis, radiation leaks and chemical spills.

Bloom points out that Japan already has a comprehensive earthquake early alert network. Even with as little as five or 10 seconds warning, trains can be stopped, elevators can be halted at a floor, and residents can shelter under a table. Many lives can potentially be saved with such systems.

Bloom said he plans to finesse his prototype and make more of them so they can be placed in his kids’ classrooms and the homes of friends. He has added a tweetbot feature that listens for new seismic events and spreads the word over social media.

In Bloom’s house, the alarm is certainly proving popular with his children, who are in first and third grade.

“They think it’s super cool and we’ve been practicing,” he said.

Sunday’s quake: UC Berkeley scientists gave 10-second warning (08.25.14)
Magnitude 6 earthquake rattles Berkeley in early hours (08.24.14) 
Are you prepared to help kids, pets when disaster strikes?
Berkeley targets underserved for disaster preparedness (10.04.12)
Gear up for the Big One with help from friends (06.17.10)

Joshua Bloom will be one of the many exciting speakers at Uncharted: The Berkeley Festival of Ideas, Oct. 24-25, in downtown Berkeley. For information and tickets visit

Lance Knobel (Berkeleyside co-founder) has been a journalist for nearly 40 years. Much of his career was in business journalism. He was editor-in-chief of both Management Today, the leading business magazine...