ShakeAlert Nears Completion,
But How Will It Affect Preparedness?

This is Pete. He’s connected to a network of seismic stations spanning the entire length of the U.S. West Coast. Photo credit Sam Ceisler.

By Sam Ceisler

May 1, 2020
When a major earthquake hits the Pacific Northwest, the first tremors will be felt by a seismic sensor named Pete. Buried in Springfield’s Bob Artz Memorial Park, Pete is one of 65 seismic stations operated by the University of Oregon as a part of the ShakeAlert earthquake early warning system. 

Scientists are working to connect stations like Pete throughout the U.S. Geological Survey’s ShakeAlert array to a public warning system that could become an important defense against earthquakes. An early alert about a seismic event could allow students to escape from old buildings, stoplights at bridges to turn red, and trains up and down the coast to slow down.

“I really hope that we get to build it out completely because it can totally save lives,” said Sue Graves, the safety coordinator for Oregon’s coastal Lincoln County school district. Graves is responsible for managing the district’s six disaster caches, as well as developing emergency response plans for students and staff.

Around $7.5 million of grant money for the University of Oregon to finish building seismic stations is moving through the state Legislature, but the coronavirus pandemic has left the legislation stalled in the Ways and Means committee.

ShakeAlert status:

Thousands of lives are at-risk in the event of an earthquake along the Cascadia Subduction Zone. In recorded history, the average time span between major earthquakes along this fault is 250 years; the longest span without one is 330 years. It has been 320 since the last one occurred.

The Cascadia subduction zone exists where the Juan De Fuca oceanic plate and the North American continental plate meet. It runs all the way from Victoria Island, BC, Canada, down to Cape Mendocino, California.

When the fault ruptures, the damage will be severe.

“Either four or five minutes of shaking would disrupt pretty much all of our local infrastructure and would destroy a number of bridges,” said Steve Robinson, president of Cascadia Prepared, a nonprofit organization that studies economic and infrastructure challenges related to earthquakes. “Life after the quake in Lane Country and through the entire region would basically be broken up into pretty small islands where each island was formed by, you know, downed bridges. We could be looking at six months of no economic activity.”

Still, in a devastating event such as an earthquake, every second counts.

Leland O’Driscoll is a former regional coordinator for ShakeAlert, and currently works as a research seismologist with the University of Oregon. “Bigger earthquakes have a really long slip and tear, and they go on and on and sort of unzip like a zipper,” O’Driscoll said. “That means the system could have detected that earthquake when it first started, but then there are many minutes of that event unfolding. So if you’re down the line of the fault like in Portland and it starts in Northern California, you’re looking at two and a half, three minutes of potential warning.”

Robert de Groot, ShakeAlert’s national coordinator for communication, education, and outreach said that these earthquake warning apps will use two different types of notifications. “There’s WEA- that’s federal wireless emergency alerts, like an Amber Alert,” de Groot said. There are also push notifications through the app, like a Facebook or Twitter alert.

The WEA system is operated by FEMA, and ShakeAlert partners are currently sharing data from experimental warning apps to improve communication and response times between this national alert system and the hundreds of ShakeAlert sensors.

ShakeAlert is projected to not only cover Cascadia, but the entire West Coast.

Southern California is currently experimenting with three different mobile applications that utilize ShakeAlert data, but Oregon and Washington will need to finish building out their sensor networks before they can take this step.

Although there are other earthquake prone regions in the United States, the USGS is dedicated to finishing ShakeAlert on the West Coast before jumping into anything else.

“Our director, Keith Riley, has spoken about potentially going to Alaska, but clearly has set out in our plans that we need to finish off what we started here first,” de Groot said. “We’re only about 63% of the way finished with the sensor network. The system is up and running and functioning fine, it’s just that we need that extra coverage.”

In the Pacific Northwest, adequate coverage will take about 250 new seismic stations.

A map of recent seismic events from at 4:30 p.m. on April 24, 2020. The Pacific Northwest Seismic Network has been monitoring earthquakes since installing their first five seismometers in 1969.

Earthquake alert systems worldwide:

Earthquake early warning systems have been around for close to 30 years now. The SASMEX system, or Seismic Alert System of Mexico, debuted in 1991 and is widely regarded as the world’s first public earthquake early warning system.

Mexico’s seismic network focuses on the country’s southern coast and a seismic fault called the Guerrero Gap, a subduction zone between the North American tectonic plate and the Cocos oceanic plate. With 97 operational seismic stations, the system originally provided radio alerts of incoming seismic events and now also includes TV warnings, and a mobile application.

Although SASMEX has provided more than 30 public alerts since its inception, its most significant use was during a series of seismic events in 2017. In September 2017 a magnitude 8.2 quake struck off the southern coast of Mexico, and SASMEX was able to provide around two minutes of forewarning to residents of Mexico City. However, a few weeks later Mexico was struck by a 7.1 magnitude earthquake whose epicenter was much closer to Mexico City. This affected the SASMEX response time, with residents only receiving a few seconds warning before shaking began. This event resulted in more than double the fatalities of the first event.

Japan launched its own seismic alert system in 2007, and the nation’s more than 1100 seismic stations faced their first major earthquake less than four years later during the 9.0 magnitude Tohoku earthquake–– the largest recorded earthquake in Japanese history.

The aftermath of a 9.0 magnitude earthquake in Oshima-Mura, Japan. Photo credits to Dylan McCord, U.S. Navy.

When an earthquake occurs it sends out both compressional waves, and shear waves. Compressional waves arrive first, and are also called primary waves or P-waves. Shear waves, also called S-waves or secondary waves, are the more dangerous and damaging of the two. The 2011 Tohoku quake was an undersea earthquake that occurred fewer than 50 miles off the coast of Sendai, but Japan’s earthquake alert system was able to send out warnings before those S-waves reached the coast.

Mexico and Japan aren’t the only two nations with effective earthquake alert systems. Turkey, Taiwan, South Korea, and Chile all have allocated funding to build out seismic networks and provide early warnings. By working with scientists at the Berkeley Seismology Lab, Israel and Peru are also developing their own systems. Costa Rica, El Salvador, and Italy are undertaking testing to build systems as well.

With the mobile applications currently being tested in California, the U.S. is getting closer to finishing the ShakeAlert system and establishing an effective earthquake alert network for the whole West Coast.

Seismic stations explained:

Rudimentary seismic stations require little more than a pendulum and a writing utensil, which make them a popular project in high school science classes. ShakeAlert seismic stations are a little more complex, and normally use an electromagnet inside of a case. When ground movement begins, the electromagnet can register relatively how much its case has moved, and then relay that information to one of ShakeAlert’s data hubs.

Seismic stations connected to the ShakeAlert array interpret earthquake information through tomography, the same way a CAT scan reads the human body. Different types of sites–– strong motion accelerometers and weak motion seismometers–– can feel the ground vibrations caused by waves of seismic energy, and triangulate the earthquake. Then, the system is programmed to initiate precautionary measures like slowing trains down to prevent derailments, and shutting valves in important pipelines.

The University of Oregon currently operates 65 seismic stations. This map from the Pacific Northwest Seismic Network, at, displays strong motion accelerometers in blue, and broadband sensors in orange.

Weak motion seismometers can detect the smallest amount of ground vibration.

“Weak motion sensors are expensive, highly calibrated sensors that can capture magnitude 0.1 earthquakes,” O’Driscoll said. “The absolute smallest earthquakes you can see, but also can capture a magnitude 5.0 that happens anywhere on earth.” These sensors are also called broadband sensors, and are essential for understanding how seismic waves travel. If scientists didn’t have these broadband sensors, they wouldn’t know the geological makeup of different areas of the earth’s crust, and therefore wouldn’t be able to identify the speed of seismic waves during earthquakes.

Earthquakes in Russia, Australia, and Africa can all be mapped in Oregon by a weak motion seismometer, but that seismic station has to be built effectively. These stations typically exist outdoors and draw their power from either a personal solar array, or a local power source. “It needs to be a quiet location and then we need usually to get away from buildings,” O’Driscoll said. “We punch down the earth with an auger a couple meters. Get the sensor down in the hole, and so it’s quiet, it’s protected from noise, thermally constant, and it does its thing down there.” However, these types of seismic stations are limited in their ability to map large or close-by seismic events. Much like a tape recorder when a noise becomes too loud, these seismic stations can clip and become unable to effectively measure the magnitude of an earthquake.

Strong motion accelerometers like Pete are helpful to discern the true magnitude of earthquakes. These seismic stations are less prone to interference so they can be used indoors or outdoors. An indoor strong motion accelerometer usually resides in the basement of a building. “It’s typically in an aluminum box, you know, two–foot–by–two–foot cube bolted to the ground, plugged into the internet,” O’Driscoll said. Outdoor strong motion accelerometers are bolted down to a concrete pad.

“You have to be kind of close to the earthquake so you can see the magnitude 3.0, 4.0, 5.0, 6.0s, 7.0s. That’s kind of the sweet spot for strong motion,” O’Driscoll said. “You can tell exactly how much the ground shook and fully, fully moved. It’s a forced situation. It’s good for understanding how much buildings or bridges and infrastructure can be damaged.”

COVID catastrophe underscores need:

The COVID-19 pandemic is giving Oregonians a look at what decreased economic activity in the state could look like, and is making clear just how important it is for individuals to take precautions against earthquakes where they can.

For earthquakes, the Department of Homeland Security suggests that all Americans keep at least three days worth of food and water in their homes. Depending on the number of residents in a household, the amount of food and water needed may vary, although officials suggest keeping one gallon of water per person, per day. Oregon’s Office of Emergency Management also suggests that residents keep toiletries, filter masks, a flashlight, and a battery–operated radio in their homes in case of extended power outages.

If an earthquake does occur, people should drop down onto their hands and knees, cover the back of their necks and heads, and hold on until the shaking stops. They should avoid heavy objects that may fall like picture frames, or refrigerators. They should also stay away from windows, and crawl under a sturdy table if possible.

If residents are outside or in a vehicle during an earthquake, they should stop moving and stay away from buildings. Even after the ground has stopped moving there may be aftershocks, so it is suggested that Oregonians quickly take stock of the situation, and move to high ground and a more secure location if possible. In all of these ways, even as the West Coast waits for ShakeAlert’s completion, residents can protect themselves and reduce the risk of being seriously injured in a seismic event.

Once state senate bill 1537 is passed through the Oregon state legislature, the University of Oregon will be able to build out the necessary remaining seismic stations, and bring ShakeAlert even closer to providing real-time earthquake alerts. As Sue Graves said, “ShakeAlert could be very, very valuable for us.”

Due to the coronavirus pandemic, many of Lane County’s parks are closed. Pete, however, is still hard at work. Photo credit Sam Ceisler.