Convener: Prof. Aldo Zollo Co-Convener: Dr. Matteo Picozzi Co-Convener: Dr. Simona Colombelli
Short Course On EEW
Part I. Concepts, approaches and future challenges
Part II. Parameters, methodologies and real-time strategies for EEW
Part III: Analysis of specific case studies & guidelines for design of EEWS
Part I. Concepts, approaches and future challenges
Convener: Prof. Aldo Zollo Co-Convener: Dr. Matteo Picozzi Co-Convener: Dr. Simona Colombelli
Short Course On Earthquake Early Warning
REAL-TIME SEISMOLOGY & EW
EGU 2014 EEW - Short Course 3
decades years days
Early Warning
Long-Term Forecasting
Short-Term Forecasting & Prediction
Long-term Hazard Mapping
ShakeMaps &Rapid Loss Assessment
0 minutes
Earthquake
seconds days/ months
Aftershock Hazard
The different time scales of the earthquake process
From an original figure of Tom Jordan redrawn by Stefan Wiemer
REAL-TIME SEISMOLOGY
• Based on the difference between the propagation velocity of the seismic waves in the undersoil and that of the analogue (digital) signals transmitted by radio (or cable)
• As a function of the distance from the source area of a strong earthquake, the information about its location and magnitude can reach a site that is “potentially at risk” from a few seconds to tens of seconds before the arrival of the largest amplitude seismic waves.
EPIC
Early Warning: the basic idea
TARGET
Information rate & quality vs. time for an Early Warning system
Quality of information
17 15 13 11 9 7 5 3 1
0 2 4 6 8 10 12 14 16 18 20 22 24
SECS AVAILABLE TO TARGET
NAPLES
TARGET
Early Warning Time-Line – PRESTo PLUS
SECS FROM ORIGIN TIME
Origin Time
P-Waves at 1st Station
On-Site Alerts
Probabilistic Location
Bayesian Magnitude
Regional Scale Peak Ground Motion
PDZ - Probable Damaged Zone
S-Waves At Target
EW WORLDWIDE
EGU 2014 EEW - Short Course 8
Worldwide Early Warning Systems
9
Current applications worldwide
Utilities
Power (fire prevention), gas
Industry
Hazardous chemicals, chip manufacturers,
eye surgeons
Construction
Site safety, (active control buildings)
Transportation
Airports, rail and subway, bridges
Response community
Fire departments, rescue teams,
government
Personal protection
Schools, housing complexes (evacuation),
hosing unit (preparation)
by RichardAllen, 2009
The Japan Meteorological Agency Early Warning System in Japan
JMA intensity
Early-Warning broadcast has started in Japan on October,2007
http://www.jma.go.jp/jma/en/Activities/eew.html
The Weather Service Law has been changed on December, 1, 2007 to include EEW:
1/ Legal responsabilities for EW issuance and transmission by JMA and other EW providers are clearly defined
2/ JMA technical standards are established that any warning service providers must satisfy to issue an EW
From October 2007 to March 2009: 11 earthquakes for which a public warning was issued and/or shaking intensity 5-lower or greater was observed. Two missed alarms, three false alarms. Nearly 80% of seismic intensity predictions were accurate within +-1 intensity unit on JMA scale.
The largest event is the offshore March, 11 2011 M 9.0 Tohoku earthquake. EEW was launched in the Tohoku region 8 sec after the first P-arrival. The warning received by cell phone, TV and radio. Final magnitude was underestimated (8.1)
REAKT WP7 EW Test sites in Europe EW
Application Where What
Nuclear Power Plant
Switzerland Implementation
Industrial Complex
SINES,Portugal Feasibility
Regional railway South Italy Feasibility
Schools South Italy Implementation
Natural gas network
Istanbul, Turkey Implementation
Harbour Tessaloniki, Greece Implementation
Hospital Tessaloniki, Greece Implementation
Nation-wide Iceland, Italy, Eastern Caribbean Islands
Feasibility
Bridges Rion Antirion, Patras and Fatih Sultan Mehmet
Implementation
APPROACHES TO EW &TECHNOLOGICAL REQUIREMENTS
EGU 2014 EEW - Short Course 14
Regional vs On-site: source, network and target geometry
Lead-time: (S-arrival time at the target)- (first-P at the network )
TARGET
EPIC
EPIC Lead-time (S-arrival time at the target)- (P-arrival at the target)
Reg
ion
al
TARGET
Warning and Lead-times for P-wave based regional and on-site systems
The expected lead-time of “Regional“system increases with distance and it is about twice than for “On-site” systems.
On-site systems can provide fast warning to targets close to the epicenter .
16
P-wave based Early Warning
Objective: To estimate in a fast and reliable way
the earthquake’s damage potential
17
Technological requirements for an Earthquake Early Warning system
• Speedness Fast data transmission & computing, small latency time
• Reliability
System capability to maintain its specific working characteristics stable in time, low probability of failures
• Robustness
System capability to work in “hard conditions”, automatic upgrade and re-start, face with anomalous conditions (data errors, component failures,…)
• Security
Protection against attack, data transmission redundancy
Main HW/SW System Components
Seismic equipment
Data transmission system
Control system Data base
(hardware and data management)
Data Information Flow at ISNET, southern Italy
OBSERVED PARAMETERS FOR EW
EGU 2014 EEW - Short Course 21
Observed Physical Quantities for EW
22
The parameters used for real-time earthquake size determination : period parameters (e.g. tp and tc , mainly measured on velocity and displacement records , respectively), peak measurements ( e.g. Pd, on displacement signals), integral quantities (e.g. CAV and IV2, measured on acceleration or velocity records) and peak levels (e.g. Va, measured on the acceleration).
Pd & 𝜏𝑐
23
An example of the vertical component of Acceleration, Velocity, Displacement and Integral of squared velocity (IV2) signals. The initial peak displacement (Pd) is measured as the absolute maximum of displacement waveform on the early portion of P-wave (typically 2-4 seconds) while the period parameter τc is measured from the ratio between initial displacement and velocity waveforms in the same time window.
Other parameters/approaches
• Cumulative Absolute Velocity (Erdik, 2006; Bose et al., 2008)
• Ground Motion Envelope - Virtual Seismologist (Cua et al., 2009)
• Seismic shaking intensity (Yamamoto et al, 2008)
• Integral of squared velocity (Festa et al., 2008)
OUTPUT OF A REGIONAL EWS
EGU 2014 EEW - Short Course 25
Output of a Regional Early Warning System
Location
• A conceptually simple problem, with techniques that are standard or are being developed; high precision
Magnitude
• A conceptually difficult problem; empirical regressions on complex observational measures; low accuracy
Peak ground motion at the target site
• Well established problem; critically dependent on accuracy of attenuation law; simplified assumptions about the source and propagation models
Alert notification
• Critically depends on uncertainties related to source parameter and peak motion estimation,.It must be designed according to the target application, probabilistic evaluation of missed/false alarms 26
Real time eqk location: Different approaches
E-larms (Allen et al.)
• Initial epicenter is fixed at the first triggered station
• As first-P is recorded at other stations the epicenter is fixed at the baricenter of the recording stations
• No depth information
Horiuchi (Horiuchi et al, 2005)
• Minimum two stations
• Trace the equal differential time surface between stations
• Intersect with the volume defined by not-yet recorded stations
RTLOC (Satriano et al.,2008)
• Use 1 station, evolutionary, probabilistic
• Define Voronoi volumes for location with 1 station
• As the time increases use information from not-yet –arrived data to constrain the voronoi volume shape
27
Location test for two synthetic event occurring at the center and outside the Irpinia Seismic Network (left and right panel respectively). The three orthogonal views show the marginal values of the relative location probability density function. The true hypocenter is identified by a star. The time from the first trigger is indicated as δt, while Δt is the time from event origin. For each snapshot, stations that have triggered are marked with a circle.
Real Time Earthquake Location (RTLOC)
28 Satriano et al., BSSA,2008
Magnitude estimate: an empirical approach
29
Pd = peak displacement τc = average period
log Pd = A + B * M + C log R log τc = A' + B' * M
Data from Japan,Taiwan,
and Italy
Data from European SM
data-base
Paradox of the real-time estimate of magnitude
How is it possible to have in
3 seconds of signal
information about the size
of an earthquake for which
the rupture lasts ten seconds
or more?
From Kanamori,Ann.Rev.Earth Pla.Sc2005
- Expand the P-wave time window evolutionary estimation of magnitude - Has the initial P-wave radiation a different «signature» for small and large eqks?
Small and large eqks: evidence for a different rupture initiation
EGU 2014 EEW - Short Course 31
A high-quality dataset of 43 moderate-to-strong Japanese events spanning wide magnitude (M) and distance (R) ranges (4≤M≤9; 0≤R≤500 km). more than 7000 3-component waveforms recorded at 1208 stations.
The evolution of P-wave peak displacement with time is informative about the early stage of the rupture process and can be used as a proxy for the final size of the rupture.
We found a rapid initial increase of the peak displacement for small events and a slower growth for large earthquakes differencies in the rupture nucleation processes
Small and large eqks: evidence for a different rupture initiation
EGU 2014 EEW - Short Course 32
A high-quality dataset of 43 moderate-to-strong Japanese events spanning wide magnitude (M) and distance (R) ranges (4≤M≤9; 0≤R≤500 km). more than 7000 3-component waveforms recorded at 1208 stations.
The evolution of P-wave peak displacement with time is informative about the early stage of the rupture process and can be used as a proxy for the final size of the rupture.
We found a rapid initial increase of the peak displacement for small events and a slower growth for large earthquakes differencies in the rupture nucleation processes
Real Time Magnitude
Basic Concepts
• Use of information carried out by early P- and S-waves recorded at a dense, high dynamics network deployed in the source area of earthquakes
• Determine empirical regression laws between real-time measured ground motion parameters (dominant period, peak displacement) and magnitude
• At each time step after first P, evaluate the magnitude using an evolutionary approach and combining P and S information at all recording stations
Offline application: The1995 Kobe Eqk (M=7.3)
Probability to exceed M 6.5 and M 7.0 thresholds as a function of time
M 6.5 M 7.0
Magnitude vs Time
Lancieri & Zollo, JGR, 2008
P(m|d) vs Time
Prediction of peak ground motion at the target site
Use of existing Ground Motion Prediction Equations (GMPE) for PGV,PGA, … At each time step, the instantaneous attenuation curve can be built given the estimated values of M. The map of predicted PGX is obtained by calculating the expected value of ground motion parameter, given the estimated Magnitude and Distance (from eqk location)
Increasing Magnitude
Log( Epicentral distance)
Log(
Pe
ak M
oti
on
am
plit
ud
e)
D1 D2
M1
M2
T0
PRESTo PLUS Playback of L’Aquila 2009, ML 5.9 Eqk
Epicenter
Vulnerable Site
S-Waves
Station Alert Level
Magnitude
Accelerograms P- and S-waves Windows
Depth
Issuing an EW alert: Can we by-pass the Magnitude estimation?
Observed correlation
between PD and PGV
(Wu & Kanamori, 2005)
For moderate to strong
eqks PGV is related to
seismic intensity
Using PD and Tau for
setting up an alert
decision table From Kanamori, 2005
A Threshold-Based Early Warning using P-waves
Initial P-peak displacement (Pd) correlates with whole-record Peak Ground Velocity. Pd>0.2 cm PGV > 16 cm/sec IMM> VII : DAMAGING EQK! Initial P-period parameter (tc) correlates with final
magnitude. tc > 0.6 sec M> 6 Japan Taiwan Central Italy
Alert levels Damages
nearby & far away from the station
Damages only
nearby the station
Damages only far
away from the station
No damages
3 2 1 0
Alert levels and threshold values for Pd and tc
Zollo et al., GJInt,2010
PGV IMM IJMA PDZ
Colombelli et al., 2011, Test of a threshold-based Earthquake Early Warning method using Japanese data, Bull.Seism.Soc.Am.
Test of the Threshold Method on Japanese Eqks
Qualitative comparison of the Threshold Early Warning method
with IMM maps of ten Mw>6 earthquakes in Japan occurred during the last decade
EARLY WARNING: FUTURE CHALLENGES
Early warning for large earthquakes
41
Lee et al., 2011
30s 65s
Hig
h F
req
uen
cy S
ou
rce
Low
Fre
qu
ency
So
urc
e
Moment rate function
Early Warning for Mega-Earthquakes (M>8)
Expanding time window for parameter measurements
Automatic detection /potential use of S wave phases
Regression laws recalibration
High-Frequency GPS for Early Warning
42
Real time GPS application
Automatic GPS data processing
Robust low frequency (down to static field) displacement
Real time robust magnitude estimation and finite fault models
Am
plitu
de
[m]
Time from the O.T. [s]
Seismic HF
GPS
Displacement
MYG011
0550
Colombelli, Allen & Zollo, JGR,2013
Designing an Early Warning Box
43
Compact low-cost seismometer+accelerometer for EW
P-wave based EW with MEMS technology
Lower quality but denser information
Stand-alone vs network integrated sensors
SOSEWIN ASTERISK
An integrated SW platform for Early warning
44
Standard data format
Integration in network monitoring softwares ?
Missing/false detection associated with network geometry.
Automatic Picking
RT Earthquake Location
RT Magnitude Estimation
PGx Prediction at Targets
Common platform for different kinds of seismic networks
Final Remarks
• The Earthquake Early Warning is feasible, despite of the limited alert times (seconds to tens of seconds), and usable for both automatic and individual actions for mitigation of earthquake effects
• Applications and Control systems: Targets and mitigation actions must be defined according to available lead-times. Need to develop control mechanisms able to take automatic decisions and interfaces, end-user oriented (civil protection, industrial plants security, transport networks,...)
• The legal issue of Early Warning: Need for specific laws regulating the experimentation and practice of Early Warning (the Japan example)
• Diffusion of knowledge and information about Early Warning: The system implementation must be accompanied by an adequate education and training of end-users
The Earthquake Early Warning is the next decade scientific and technological
challenge of real-time seismology and earthquake engineering
Thanks for your attention !
Suggested Reading • Hiroo Kanamori, “Real-Time seismology and earthquake damage
mitigation” 2005, Annu. Rev. Earth Planet. Sci. 33: 195–214, doi:10.1146/annurev.earth.33.092203.122626.
• Earthquake Early Warning Systems, Gasparini, Paolo; Manfredi, Gaetano; Zschau, Jochen (Eds.) 2007,Springer, XXIV, 350 p. 153
• R. Allen, P. Gasparini, O. Kamigaichi, and M. Bose, The Status of Earthquake Early Warning around the World: An Introductory Overview, Seismological Research Letters Volume 80, 2009
• C. Satriano, Y.-M.Wu, A. Zollo and H. Kanamori, Earthquake early warning: Concepts, methods and physical grounds, Soil Dyn. Earthq. Eng., 2010