short course on eew - reaktproject.eu · short course on eew part i. concepts, ... nuclear power...

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


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


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


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


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


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

short course on eew - reaktproject.eu · short course on eew part i. concepts, ... nuclear power...

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