ShakeAlert Phase 1: West Coast Earthquake Early Warning Doug Given, USGS EEW Coordinator Education Symposium, Dec. 4, 2018
Population WA 7M OR 4M Annualized Earthquake Losses, $6.1B 61% in California, 73% on West Coast ($4.5B) CA 39M Total 50M FEMA 366, April 2008 FEMA, P-366, 2017
Earthquake Physics: Three Types of Earthquakes on the West Coast
Earthquake Physics: Earthquake waves P-wave Faster Less destructive S-wave Slower More destructive P-wave S-wave
Earthquake Physics: Magnitude is NOT Intensity Magnitude describes the relative size of earthquakes. The scale is arbitrary, has no physical units, and uses a logarithmic scale (10x). Intensity describes the severity of shaking at a place. It depends on magnitude, distance to the fault, and the local soil/rock type.
Earthquake Physics: Big Earthquakes Rupture Long Faults Big earthquakes are not points (epicenter) Fault rupture & magnitude grow with time We can t predict how far the rupture will go Shaking intensity depends on distance to the rupture NOT the epicenter distance to rupture Epicenter M7.8 - Shakeout Scenario Simulation - Rupture length = 180 miles - Rupture duration = ~1:40 min. 12x realtime
shakealert.org PacNW Alert Area Sensor Networks Field telemetry Processing Alert Service Alert Delivery User Actions ShakeAlert Network & Alert Centers No. CA Road To EEW à 2006-2012 R & D à 2012 Demo System à 2016 CA Production Prototype à 2017 Full West Coast Prototype à 2018 Phase 1: Initial uses à???? Future phases to Full Operation USGS National Seismic Hazard Map So. CA 7
Seismic Station Build-Out Progress ShakeAlert Station Inventory TARGET Contributing Percent completed CISN 1,115 608 55% West Coast 560 1,675 297 905 53% 54% PNSN
Overview of the architecture of the ShakeAlert v2.0 system. Data processing flows upward from the Data Layer, up through the Production Layer, then to the Alert Layer, which publishes alerts for subscribers.
Earthquake Detection Tradeoff of Speed vs. Accuracy System can be tricked by Noise Regionals Teleseisms Background noise Distant Earthquake (teleseism) Calibration Pulses
Is it an Earthquake?
South Napa Earthquake, M6.0
Is it an Earthquake?
Bolivia Teleseism (distant event)
ShakeAlert Products: 3 Primary Messages 1) Event Message Earthquake Source Point: location, magnitude & uncertainty Finite fault (If M6.0+) Hayward M7.0 Simulation 2) Ground Motion Contour Message Event Message + MMI contours nested 8-pt polygons enclosing areas by MMI, PGA, PGV 1) Event Source 3) Ground Motion Grid Message Event Message + MMI grid grid map of MMI, PGA, PGV ~20km spacing 2) Contour Map An alert updates as event grows Also specialized formats like CAP & QuakeML 3) Grid Map
Earthquake Physics: Big Earthquakes Are Not Simple Warning time depends on your threshold for action Time after start Magnitude MMI = II Estimate Polygon Lower threshold = more alert time but more false alerts Higher threshold = less alert time but fewer false alerts Hayward M7.0 Simulation T = MMI II ~25sec to S-wave
Earthquake Physics: Big Earthquakes Are Not Simple Warning time depends on your threshold for action Time after start Magnitude MMI = III Estimate Polygon Lower threshold = more alert time but more false alerts Higher threshold = less alert time but fewer false alerts Hayward M7.0 Simulation T = MMI III ~22sec to S-wave
Earthquake Physics: Big Earthquakes Are Not Simple Warning time depends on your threshold for action Time after start Magnitude MMI = IV Estimate Polygon Lower threshold = more alert time but more false alerts Higher threshold = less alert time but fewer false alerts Hayward M7.0 Simulation T = MMI IV ~17sec to S-wave
Earthquake Physics: Big Earthquakes Are Not Simple Warning time depends on your threshold for action Time after start Magnitude MMI = V Estimate Polygon Lower threshold = more alert time but more false alerts Higher threshold = less alert time but fewer false alerts Hayward M7.0 Simulation T = MMI V late alert
Ground Motion Predictions Ground motions predicts are approximate Intensity is subjective: individual perceptions vary MMI = 4 Estimate Polygon What people reported South Napa, M6.0 Aug. 24, 2014
Two Main User Categories People (personnel, public) Drop, cover, and hold on Move away from hazardous areas Secure delicate medical procedures Things (automated systems) Slow/stop trains, traffic, aircraft, vulnerable actions Close valves, stop pumps, blowers, other processes Park delicate machinery in safe mode Others?
Alerts will be sent when Magnitude Threshold Intensity Area Alerted (MMI) Alert Delivery Mechanism 5.0+ 4+ WEA (Future: DataCasting, EAS, etc.) 4.5+ 2+ Phone Apps user determined 4.0+ user determined 2+ user determined Various human interfaces: PA, lights, sirens, in-house apps, VoIP, etc. Various automatic interfaces Recipients General Public (many untrained) Initially: test groups. Eventually: those who download the app Institutional users: to students, employees and non-employees on premises Institutional users: to automated systems
Recommended Cell Alert Signals Alert sound (TBD) Alert text (voice on some phones) Earthquake! Earthquake! Expect shaking. Drop, Cover, Hold on. Protect yourself now. Follow up message later
Public Mass Alerting Technologies Cell-broadcast, IPAWS/WEA Speed uncertain (test next year) No EEW-specific sound Cell apps, push notifications Scalability & speed unknown (Tests by City of L.A. and others) Someone must provide the service DataCasting, alert encoded in TV broadcast signal Crude geotargetting Requires special receiver (not displayed on TV)
Key Points ShakeAlert is not earthquake prediction is not perfect, there will be false and missed alerts Warning time depends on your distance from the fault. You may get an alert before, during, or after you feel shaking. There will be updates ShakeAlert is not complete General public alerting is not yet available but it s coming ShakeAlert is looking for earlier adopters
ShakeAlert Phase 1: West Coast Earthquake Early Warning Doug Given, USGS EEW Coordinator Education Symposium, Dec. 4, 2018
Earthquake Physics: West Coast Plate Tectonics
Earthquake Physics: Three Types of Earthquakes on the West Coast