ShakeAlert puts Southern California train safety on track

Southern California’s commuter rail system pilots a new technology to reduce train speed in advance of earthquake shaking.

By Lauren Koenig (@Lauren_A_Koenig)

Citation: Koenig, L., 2021, ShakeAlert puts Southern California train safety on track, Temblor,

On an average weekday, commuter trains carry 40,000 travelers to destinations throughout Southern California — a region rife with earthquake hazard. Now, earthquake early warning technology will help keep these passengers safer during an earthquake.

Starting on September 10, Metrolink — Southern California’s regional passenger rail system — and the California Department of Transportation are piloting earthquake early warning technology to stop or slow trains when an earthquake occurs. The first phase of the program is being evaluated along Metrolink’s 91/Perris Valley Line between Perris and Riverside.

Metrolink train at Riverside Downtown station. Credit: Juan Enrique Gilardi CC BY-SA 2.0
Metrolink train at Riverside Downtown station. Credit: Juan Enrique Gilardi CC BY-SA 2.0


“This line has the least amount of freight traffic on it, so it’s an ideal laboratory for us to test this new program,” said Paul Gonzales, a spokesperson for Metrolink.

The project relies on ShakeAlert, the West Coast’s earthquake early warning system, developed through a collaboration between the U.S. Geological Survey (USGS) and a coalition of state and university partners. During Phase I of the pilot program, data from ShakeAlert will be processed by the Commuter Seismic Railway Interface (CSRI), which will send instructions to train crews during an earthquake. Depending on the severity of shaking, crews can either stop or slow a train.

In the second phase of the program, Metrolink’s Positive Train Control (PTC) system will use ShakeAlert data to automatically slow and safely stop trains as needed. When human error and confusion can otherwise waste precious seconds during an emergency, this technology can prevent train collisions, derailments and other damage from strong ground shaking.

Metrolink’s Positive Train Control system showing an automatic speed reduction alert. Credit: Paul Gonzales
Metrolink’s Positive Train Control system showing an automatic speed reduction alert. Credit: Paul Gonzales


Data delivery before damaging waves strike

Metrolink’s new program relies on three products from the USGS’ Advanced National Seismic System: ShakeAlert, ShakeMap and ShakeCast. As such, the early warning system will be the first to incorporate real-time information from multiple USGS products during an earthquake.

ShakeAlert detects earthquakes so quickly that electronic alerts can reach people tens of seconds before shaking arrives, depending on the location of the quake. When sensors on the ground detect an earthquake’s fast-moving primary waves, they transmit information to the USGS processing center, which then estimates the quake’s magnitude and location and the likely severity of shaking throughout the region. USGS then alerts its partners to issue a message that lets people know to “Drop, Cover and Hold On” or take other proactive measures.

Besides slowing a train, ShakeAlert data can be used to trigger automated actions such as opening firehouse doors and parking gates, shutting off gas and water valves or stopping elevators at the nearest floor. A quick reaction to emergency alerts before an earthquake’s more destructive secondary waves roll in can prevent injuries or damage.

After an earthquake, ShakeMaps depicting ground motion and shaking intensity are calculated. ShakeCast automatically delivers that information, triggering earthquake response protocols. This post-earthquake review can help repair teams pinpoint where damage might have occurred on a rail line, says Robert de Groot, the technical engagement coordinator for ShakeAlert. These data will help repair crews find and fix infrastructure damage.

“I see this as a complement to Metrolink’s existing system,” de Groot said. “One of our goals is not for ShakeAlert to be a panacea or standalone solution. It’s part of a larger ecosystem of products that can be integrated so it can maximize the ability to reduce earthquake risk.”

USGS ShakeMap from the 2019 magnitude-7.1 Ridgecrest earthquake. Credit: USGS
USGS ShakeMap from the 2019 magnitude-7.1 Ridgecrest earthquake. Credit: USGS


Earthquake warning systems from Japan to the West Coast

The San Francisco Bay Area Rapid Transit System (BART) pioneered using ShakeAlert for trains nearly a decade ago. With its new integrated system, though, Metrolink’s new system marks the most comprehensive earthquake safety system for trains in the U.S., according to de Groot. Other parts of the world, like Japan and Mexico, have had warning systems in place since 2007 and 1995, respectively.

Japan’s system pumped the brakes on 33 trains only seconds before the Tohoku earthquake hit in 2011, saving lives and preventing critical damage. Both the Japanese and U.S. systems have robust technical backbones, but building the ShakeAlert system in the U.S. was a greater technological challenge, de Groot said.

In Japan, the primary earthquake hazard comes from faults that are offshore. The major active fault zones in the U.S. are on land, meaning they are much closer to populated areas. The U.S. system therefore must calculate and trigger an alert much quicker because the earthquake waves don’t have to travel as far before reaching people.

Human reaction times an important factor in safety

ShakeAlert notifications currently reach more than 50 million people in California, Oregon and Washington through cell phone apps such as MyShake and QuakeAlert USA, as well as FEMA’s Wireless Emergency Alert System.

But alerts are only as useful as the responses they trigger. People need training and experience to develop quick reaction times, according to de Groot.

“We want to understand human interaction with ShakeAlert because it’s asking people to do things very quickly,” said de Groot. “We’re committing a lot of resources to understand protective action and how to best implement ShakeAlert in schools and other places where there are people who are potentially untrained. … Ultimately it’s about keeping people safe.”


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