1. Post-Earthquake Response
Art McGarr

2. Contents Earthquake Early Warning Systems
Shakemap for Emergency Response
Post-Earthquake Probability Estimates

3. Earthquake Early Warning Systems
Automated system
Detect earthquakes real-time
Assess threat to urban areas
Issue warning to relevant parties
Warning time enough to stop transportation, evacuate dangerous structures (bridges), and cut off utilities.
This would minimize damage to assets, and considerably reduce risk of fires
Remember that radio-communications travel MUCH faster than seismic waves (~5000m/s vs m/s)

4. ElarmS – Earthquake Alarm System
Under development at UC Berkeley for events in California
Earthquakes located using P-wave arrival times
Designed to generate a map of predicted ground shaking.
Output continually updated as P-wave arrive at more distant stations and EQ location refined
Allen, 2004

5. Warning Times using ElarmS method
Warning time probability density functions using the ElarmS methodology have been calculated for northern California. These are based on the current distribution of broadband velocity and accelerometer stations across the region and the 35 earthquake rupture scenarios identified by the Working Group on California Earthquake Probabilities [2003]. Figure shows the probability that there will be an earthquake in the next 30 years for which there would be a given warning time for the city of San Francisco. The warning times for different events range between -4 sec (i.e. the warning would only be available 4 sec after peak ground shaking had started) and 80 sec. The color scale indicates the predicted intensity of ground shaking for the city for each event using the Scenario ShakeMaps. The inset figure shows the probability there will be greater than 0, 5, 10, 20 and 30 sec of warning along with the cumulative probability of one of the 35 rupture scenarios occurring (labeled QUAKE). These calculations show that it would be possible to provide warning for the vast majority of these damaging earthquakes. It also shows that for the most damaging events that cause ground shaking with MMI > X in the city, it is more likely than not that there will be more than 20 sec warning.
Allen, 2004

6. ElarmS Magnitude Error
The error in the magnitude estimate after testing ElarmS offline using a set of 32 earthquakes in southern California.
Errors shown as a function of time with respect to the S-wave arrival at the epicenter.
Offline testing of ElarmS using a dataset of 32 earthquakes in southern California shows that the first predictions of ground shaking are available before the S-arrival at the epicenter for 56% of earthquakes (Fig. 1a). The majority of these predictions are based on trigger times and magnitude estimates from more than one seismic station. The offline algorithms gather all available information and update hazard estimates once per second. The density of seismic stations (typically 20 km spacing in the populated regions) means that within a 1 sec time interval usually two, and often three, stations trigger. The first event location, hazard and warning time estimates are therefore based on information from multiply stations providing a more accurate location and magnitude estimate that using a single station (see next section).
Allen, 2004

7. Usefulness of Early Warnings
Warnings approaching one minute would be available only for a major earthquake in which the population to be warned was at considerable distance from the earthquake source.
Shorter warnings (such as 10 seconds) will prevail where the earthquake source and population are geographically more proximate.
Given a 10 second warning, the population can adopt actions that they ordinarily implement when they feel ground shaking, only sooner.
Given a 50 second warning, a broader array of measures could be implemented including damage reduction, preventing data loss, reducing secondary hazards (such as spillages and fire) and more effective emergency response activities.

8. Communicating Early Warnings
Broadcast a signal over the Internet to user organizations
Organizations would convert the signal to an alarm to alert employees and automatically initiate shutdown procedures
Alerts could be disseminated within organizations using public address systems, 2-way radios, telephones and computers.
Broadcasts on public radio stations in addition to highway signage could be used to alert people on the road

9. Commercial Products for Individuals
Products are available commercially for individuals to buy.
‘QuakeAlert’ is a cheap ($120) alarm system which detects the first P-wave arrival.
Operates on principal of P-S wave time interval
The vertical displacement is measured, and alarm triggered if threshold displacement is reached
© Innovative Technologies, 2006

10. Mexico uses the Seismic Alert System (SAS)
Mexico uses the Seismic Alert System (SAS). It is thought that future large earthquake will occur near the Guerrero Coast where a ‘seismic gap’ exists. This is 280km from Mexico City, but as witnessed previously (the 1985 earthquake was disastrous) this earthquake is still likely to cause widespread damage because of the lake fill sediments the city is built on. Therefore the SAS is highly advantageous. This figure illustrates the advance warning of an earthquake in 1995, because of which 4.3 million people in Mexico City were given 72 seconds warning of the impending shaking.

11. Shakemap
Produced by first making a contour map of the distribution of peak ground motion, acceleration or velocity.
This is then converted into shaking intensity.
Shakemaps can be produced within minutes of an earthquake.
This information helps to optimize the emergency response.

12. 1994 Northridge Earthquake M6.7
(over 40 minutes for epicenter and location)

13. ShakeMaps
ShakeMaps show the distribution of earthquake shaking within 4 minutes after an earthquake.
This ShakeMap, however, was made many years after the earthquake.

14. Magnitude Intensity
Represents the size of the earthquake but not necessar-ily the damage or shaking level.
Only one number (e.g., 6.7) is used represent magnitude.
Described as “Richter scale”, though “energy” magnitude is now generally used.
Represents the effects of an earthquake: the shaking and damage at different locations.
The number (Roman Numeral from I to X) varies depending on location.
Modified Mercalli Intensity Scale is used in U.S. Intensity is also used worldwide.
Just a reminder that magnitude measures the size of an earthquake, whereas intensity is a qualitative measure of the peak ground motion.

15. 1906
These ShakeMaps were also made long after the earthquakes. The map for 1989 Loma Prieta was based on recorded ground motion and that for 1906 was based on intensity reports. Maximum intensities are nearly the same for these two earthquakes but they are much more localized for Loma Prieta.

16.  Newhall: Intensity IX Collapse of Overpass
ShakeMaps are quite useful to guide emergency response. 
Newhall: Intensity IX
Collapse of Overpass

17. 
Northridge: Intensity IX
Parking Garage Collapse

18. Granada Hills: IX
Gas/Water Line Rupture 

19. Did You Feel It? If you felt it, we want to know about it!
Intensity maps can also be produced soon after an earthquake using input from the community over the internet.
pasadena.wr.usgs.gov/shake/

20. The First CyberQuake - Los Angeles Times, 10/17/99
Chris Walls, Ea
rth Consultants Interna
tional
Katherine Kendri
ck, USGS
The M7.1 Hector Mine, California, earthquake in 1999 provided the first demonstration of ShakeMap in real time.
Scientists, emergency officials, and citizens alike were almost instantly wired together through inter-active Internet Web sites and online data networks to exchange damage reports and to assess ground-shaking intensities and shock wave readings

21. How A
ShakeMap
Is Made

23. Aftershock Hazard Forecasts (AHF)
After a major earthquake, the occurrence of strong aftershocks, or possibly a larger mainshock, is increased
This continuing hazard threatens the resumption of critical services, and re-occupation of essential, but partially damaged structures
An aftershock which is stronger than the original mainshock will become known as the mainshock, and the original mainshock re-termed as a strong foreshock.

24. Aftershock Hazard Forecasts (AHF)
Stochastic Parametric models allow determination of probabilities during intervals after the mainshock.
In general, the rate of earthquakes increases abruptly after a mainshock, and decreases with time according to a power decay law.
However, magnitudes have an exponential relationship that is stationary in time.

25. Aftershock activity after 2 Californian EQs
The ratio of large magnitude to small magnitude earthquakes is observed to be constant during an aftershock sequence (e.g., 10 M4’s for each M5).
Reasenberg and Jones, Science, 1989

26. Aftershock Hazard Maps
May be plotted from model parameters:
Observation time period (e.g. 4 days after)
Forecast period (e.g. 30 days)
Probability level (e.g. 33%)
Number of source zones
Preferred selections depend on user
Some users may be interested in worst case scenarios (use 10% probability level)
Others may be interested in an accurate forecast/high probability of exceedance (use 90%)

27. Probabilistic Aftershock Hazard Maps
1999 Mw 7.1 Hector Mine Earthquake, CA
Horizontal Peak Ground Acceleration (g)
33% Probability of exceedance
Probabilistic aftershock hazard maps for the same probability of exceedance (33%) at varying times after the mainshock of the of the 1999 Mw 7.1 Hector Mine Earthquake. Shaded contours indicate the forecasted horizontal peak ground acceleration, computed 4 days, 14 days, 30 days, and 60 days after the mainshock, each forecasting the next 30 days. Gray lines mark the faults that ruptured in the Hector Mine mainshock; a star marks the hypocenter. Larger aftershocks are marked with a white circle (4.0 M < 5) or white triangle (M 5.0) in the appropriate forecast period.
Wiemer et. al. BSSA, 2002

28. Real-time Forecasts
AHFs are not tailored to the particular EQ sequence (generic model)
AHFs do not contain information on the location of aftershocks
Real-time forecasts build upon AHFs by:
Re-casting the forecast in terms of the probability of strong ground shaking
Combines an existing time independent earthquake occurrence model based on faults and historical seismicity

29. Real-time Forecasts Time independent Time dependent
Combination of both contributions
Maps of California, showing the probability of exceeding MMI VI over the next 24-h period. The period starts at 14:07 Pacific Daylight Time on 28 July a, The time-independent hazard based on the 1996 USGS hazard maps for California. SF and LA are the locations of San Francisco and Los Angeles, respectively. b, The time-dependent hazard which exceeds the background including contributions from several events: 22 December 2003, San Simeon (SS, Mw = 6.5), a Ml = 4.3 earthquake 4 days earlier near Ventura (VB), a Ml = 3.8 event 30 min before the map was made near San Bernardino (FN), the 1999 Hector Mine Mw = 7.1 earthquake in the Mojave desert (LHM), and the 1989 Mw = 6.9 Loma Prieta (LP) earthquake. c, The combination of these two contributions, representing the total forecast of the likelihood of ground shaking in the next 24-hour period.
Gerstenberger et. al. Nature, 2005

30. Post-Earthquake Response Summary
Early warning systems based on automated analysis of seismic data can be used to improve public safety by automatically turning off critical systems in advance of the strong ground motion.
Shakemaps produced within minutes of a major earthquake can guide the emergency response.
It is feasible to develop time-dependent earthquake hazard maps based on the long-term hazard together with the change in hazard due to recent large earthquakes.