Citizen science brings seismology to smartphones

December 21st, 2016, Published in Articles: PositionIT

 

UC Berkeley’s worldwide network of smartphone earthquake detectors has recorded nearly 400 earthquakes since the MyShake app was made available for download in February 2016.

The Android app harnesses a smartphone’s motion detectors to measure earthquake ground motion, then sends that data back to the Berkeley Seismological Laboratory for analysis. The eventual goal is to send early-warning alerts to users a bit farther from ground zero, giving them seconds to a minute of warning that the ground will start shaking. That is enough time to take cover or switch off equipment that might be damaged in a quake.

To date, nearly 220 000 people have downloaded the app, and at any one time, between 8000 and 10 000 phones are active — turned on, lying on a horizontal surface and connected to a WiFi network — and thus primed to respond.

From 12 February 2016 until 1 December 2016, 395 earthquakes with confirmed waveforms were detected by MyShake users around the world.

The recently updated version of the MyShake app provides an option for push notifications of recent quakes within a distance determined by the user, and the option of turning the app off until the phone is plugged in, which could extend the life of a single charge in older phones.

Ten months of operation clearly shows that the sensitivity of the smartphone accelerometers and the density of phones in many places are sufficient to provide data quickly enough for early warning. The phones readily detect the first seismic waves to arrive — the less destructive P waves — and send the information to Berkeley in time to issue an alert that the stronger S wave will soon arrive.

The app can detect quakes as small as magnitude 2,5, with the best sensitivity in areas with a greater density of phones. The largest number of phones to record a quake was 103, after the 5,2 magnitude quake that occurred on the San Jacinto fault near Borrego Springs in San Diego County on 10 June 2016. Phones 200 km from the epicentre detected that temblor. The largest quake detected occurred on 16 April in Ecuador: a 7,8 magnitude quake that triggered two phones, 170 and 200 km from the epicentre.

The 10 June 2016 earthquake near Borrego Springs in San Diego County, a 5.2-magnitude temblor, triggered 103 smartphones with the app installed (green dots). (Blue star is the epicentre; Red dots are phones that were not ready to trigger; Yellow-orange dots are phones that were primed but did not trigger.)

The app’s performance shows it can complement traditional seismic networks, such as that operated nationally by the US Geological Survey, and that it can also serve as a stand-alone system in places with few seismic stations, helping to reduce injuries and damage from earthquakes.

While the app has detected quakes in seismically active areas such as Chile, Mexico, New Zealand, Taiwan, Japan and the West Coast of the US, one surprising hot spot has been the traditionally quiet state of Oklahoma. The practice of injecting oil well wastewater deep underground has activated faults in the area to the extent that the state is rattled hundreds of times a year.

Contact Berkeley Seismological Laboratory, info@seismo.berkeley.edu

  • omshhaol

    Fascinating article….

    The article states: “….. Phones 200 km from the epicentre detected…. the 5,2 magnitude quake that occurred on the San Jacinto fault near Borrego Springs in San Diego County on 10 June 2016…. Yet the image that shows the epicenter (blue dot) is approximately 30 or so miles NNW of Borrero Springs, in San Diego county. And it also shows that phones that were triggered (green dots) were as far as Santa Maria which is in Santa Barbara county, a good 280-300 miles away… That is 2 to 2 1/2 times the 200km distance quoted.

    Am I misreading something?

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