The Need for Speed

Speed is important in an earthquake warning system both to eliminate Blind Zones and to provide maximum warning times for applications.
Map showing locations of red tagged buildings from South Napa Ea
CC-Attribution-NonCommercial-ShareAlike 4.0/SWS

The damaging S-wavesSecondary, or S, waves are the first waves to arrive from an earthquake that are large enough to cause damage. They are slower than P-waves but cause much greater shaking. of an earthquake travel more than 10 times faster than sound waves, around 8000 miles per hour. At those speeds, seconds and even fractions of seconds count.

If an earthquake warning system is slow to produce a warning, those near the epicenter left unprotected. A 5 second delay results in a area 11 miles in diameter. The map shows the epicenter for the 2014 South Napa Earthquake and the red circle shows the area unprotected. The red squares are red-taggedBuildings that are damaged too severely to be re-occupied are "red-tagged". Many of these are ultimately demolished. buildings.

Damage from South Napa earthquake
TBD-lic/Rick Loomis/Los Angeles Times/MCT

Damage, like that in Napa shown here, occurs commonly near the epicenterThe location on the surface directly above the point deep in the earth, called the Hypocenter, where the earthquake starts.. These areas need to be warned along with those farther away.

Seismic Warning Systems set out to develop an earthquake warning system that can warn everyone, even people right at the epicenterThe location on the surface directly above the point deep in the earth, called the Hypocenter, where the earthquake starts. of a major earthquake.

Graphic depicting how to Beat the S-wave to the surface
CC-Attribution-NonCommercial-ShareAlike 4.0/SWS
The Time Budget

Earthquakes in California typically begin about 5 miles underground. The fast-moving P-wavePrimary, or P, waves are the fastest moving waves produced by an earthquake and are first to arrive. They do not carry much energy and cause only slight shaking. hits the surface at the epicenterThe location on the surface directly above the point deep in the earth, called the Hypocenter, where the earthquake starts. a little over one second after the earthquake begins. About one second later, the damaging S-waveSecondary, or S, waves are the first waves to arrive from an earthquake that are large enough to cause damage. They are slower than P-waves but cause much greater shaking. reaches the surface at the epicenterThe location on the surface directly above the point deep in the earth, called the Hypocenter, where the earthquake starts.. So the QuakeGuardOur earthquake warning product capable of initiating alerts and protective actions for every earthquake, even at the epicenter. system has to do all the work of detecting, confirming, and evaluating the earthquake, as well as sending out the warning, within one second.

The SWS California Earthquake Warning System plan
CC-Attribution-NonCommercial-ShareAlike 4.0/SWS
The Hardware

Seismic Warning Systems is deploying a network with stations spaced every 5 miles along all known faults in urban areas, so that any earthquake is never more than 2 ½ miles from the nearest station.

QuakeGuard Network sensors
CC-Attribution-NonCommercial-ShareAlike 4.0/SWS

The QuakeGuardOur earthquake warning product capable of initiating alerts and protective actions for every earthquake, even at the epicenter. system uses a custom-built sensor, capable of detecting earthquakes that are too weak to be felt by humans. These cost a tiny fraction of the cost of a top-of-the-line $100,000 research seismometer. Not only can we put down more stations, but we can put two of these sensors at every station. Why? Trucks.

A truck with trailer
CC-Attribution-Share Alike 3.0 via Wikimedia Commons/End dump 2005-11-28.km

A single sensor can be fooled by a passing truck, electrical glitches, or even malicious interference. By comparing the data from both sensors, the QuakeGuardOur earthquake warning product capable of initiating alerts and protective actions for every earthquake, even at the epicenter. system rejects all non-earthquake noise sources instantly. With the confidence that the earthquake is real the system can then issue a warning to everyone, even if only one station is reporting it.

South Napa USGS shakemap
Public Domain/USGS
The Software

The proprietary QuakeGuardOur earthquake warning product capable of initiating alerts and protective actions for every earthquake, even at the epicenter. earthquake warning algorithms can determine the intensity of the S-waveSecondary, or S, waves are the first waves to arrive from an earthquake that are large enough to cause damage. They are slower than P-waves but cause much greater shaking. and the location of the earthquake based on only half a second of P-wavePrimary, or P, waves are the fastest moving waves produced by an earthquake and are first to arrive. They do not carry much energy and cause only slight shaking. data. The system is designed to focus on what matters: the amount of shaking, not the magnitude of the earthquake.

A data center
CC/dreamservers

The QuakeGuardOur earthquake warning product capable of initiating alerts and protective actions for every earthquake, even at the epicenter. system is designed with high-speed communication protocols that take full advantage of the capabilities of the Internet to deliver data to everyone near the epicenterThe location on the surface directly above the point deep in the earth, called the Hypocenter, where the earthquake starts. within a tenth of a second. Dedicated, always-on devices at the receiving end ensure that the warning is received, authenticated and acted upon in the shortest possible time.

Map showing warning contours for the future QuakeGuard network
CC-Attribution-NonCommercial-ShareAlike 4.0/SWS
The Result

A single QuakeGuardOur earthquake warning product capable of initiating alerts and protective actions for every earthquake, even at the epicenter. station at the Napa airport can provide up to four seconds of warning in Napa, Vallejo and Sonoma for the Napa Earthquake. A network of just over 100 QuakeGuardOur earthquake warning product capable of initiating alerts and protective actions for every earthquake, even at the epicenter. stations can protect the entire Bay Area, and a network of 500 stations can protect all of California. Because the QuakeGuardOur earthquake warning product capable of initiating alerts and protective actions for every earthquake, even at the epicenter. system is the fastest in the world, we can protect everyone, for any earthquake.