Crowd-Sourced Global Earthquake Early Warning

Sarah E. MinsonCalifornia Institute of Technology

Benjamin A. Brooks, Jessica R. MurrayU.S. Geological Survey

Susan E. OwenJet Propulsion Laboratory

Robert A. IannucciCarnegie Mellon University – Silicon Valley

Global EEW

EEW and real-time GPS are expanding globallyMost high-risk areas still not covered

RT GPS

EEW

Global EEW

Requires dense networks of scientific instrumentsExpensive to build and maintain

Scientific GPS: $1,000-$7,500 per year, per stationMany high-risk areas cannot afford this investment

RT GPS

EEW

Global EEW

Consumer electronics contain geophysical sensorsSmartphones, laptops, tablets, cars

What if we could monitor earthquakes with just consumer-quality sensors?

RT GPS

EEW

Consumer GPS

This is not what you get from scientific instrumentsPseudorange only (no phase information)Single frequency (coarse acquisition) vs. dual frequencyBroadcast orbits

What do pseudorange GPS data for the Tohoku earthquake look like?

Tohoku earthquake

Post-processed scientific GPS

Pseudorange

Tohoku earthquake

North UpEast

Static

Pse

ud

ora

ng

e

Can we detect earthquakes?Count number of stations for which they and their 4 closest neighbors have offsets greater than threshold

Tohoku

Can we detect earthquakes?

5 excursion from background

Can we locate earthquakes?Displacement amplitude decays with distance

Power law fit to observed offsets

Can we locate earthquakes?

S-wave reaches population

center

5 exceeded

Can we model slip?

Consumer GPS vs. seismic EEW vs. global seismic monitoring

EEW

True Mw

NEIC/PTWC

Pseudorange

That was consumer electronics-style processing of permanent GPS sites…

…What about actual consumer electronics?

Permanent GPS stations vs. iPad

The FutureIf we wanted to replace GPS network with iPads:

500 stations @ $100 = $50,000About the cost of installing 1-2 permanent GPS stations

To replace GPS network with equal noise:2,000 stations @ $100 = $200,000

The FutureWe could build a workable early warning network for orders of magnitude less cost……But really we don’t want to be responsible for the network

The Future: Crowd-SourcingWe should be using the GPS receivers people already own and maintain

Significantly noisier (bad sky view, noisy environment)Potentially orders of magnitude more sensorsMarginal cost to build and maintainBuilt-in way to track location and customize warningsCitizen science

The Big PictureScientific GPS:

Mw 8.9Best Slip Model:

Mw 9.1Pseudorange:

Mw 8.9

The Big Picture

Seismic EEW

Scientific GPS

NEIC/PTWC

Pseudorange

True Mw

What we are doing

What we could do in western

U.S.

A way forward everywhere else