Data Processing for National Tsunami Warning Center in JAPAN

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Data Processing for National Tsunami Warning
Center in JAPAN

• Yuji NISHIMAE
• Japan Meteorological Agency

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What should TWC do ?

• Watching seismic activities
• Determination of hypocenter and magnitude
• Evaluation of potential of tsunami generation
• Estimation of amplitude of arrival time of the
  tsunami
• Issuance of tsunami warning and earthquake
  information
• Monitoring sea level

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Historical review of earthquake observation and
tsunami warning
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Major Tsunami Disasters In Japan
Mostly by Earthquake
Mostly by Tsunami
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Development of Tsunami warning system in JMA
1952-1979 Within 15-20 minuets after the
occurrence of the earthquake
1980-1986 Within 12-13 minuets
1987-1993 Within 7-8 minuets
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1960s---1970s
Telegram
Warning Center
Observatory
Compass
Displacement seismograph
Strong motion seismograph
Empirical method
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1980s---1990s
Displacement seismograph
High sensitivity seismograph
Telegram
JMA communication network
Location and magnitude
Automatic Processing System
Empirical method
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1994New Seismological Network
1998 Introduction of Quantitative Tsunami
Forecast System
Empirical method
Quantitative Tsunami Forecast
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Issue time for Tsunami Warning after occurrence
of an earthquake
Seismic data processing by computer
Manual procedure
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Earthquake Observation
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Seismic activities around Japan
Hypocenter Determined by JMA in 2005 About
128,000
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Seismic Data Transmission Network in Japan
Japan Meteorological Agency 2005/3/9
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Seismometers used in JMAs Network

• Velocity type seismometer with 3 components
• Strong motion accelerometer

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Accelerometer sensor
JMA Seismic Station
Velocity type Sensor - Short period - Three
component
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Determination of Magnitude and Hypocenter
2. Read P/S Arrival Time and Maximum Amplitude
1. Real-time Data Collection
3. Determination of the Hypocenter
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Calculation of magnitude
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Estimation of magnitude for local events (1)

• Displacement Magnitude MD
• MD1/2log(AN2AE2)BetaD(Delta, H)CD
• Maximum horizontal DISPLACEMENT amplitude (AN ,
  AE)
• Using displacement obtained by double integration
  of acceleration
• Delta epicentral distance (km), H Focal depth
  (km)
• BetaD attenuation function depending on Delta
  and H
• CD Constant

Contour representation of BetaD
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Estimation of magnitude for local events (2)

• Velocity Magnitude MV
• MVAlpha log(AZ)BetaV(Delta, H)CV
• Maximum vertical VELOCITY amplitude (Az)
• Delta epicentral distance (km), H focal depth
  (km)
• BetaV attenuation function depending on Delta
  and H
• Alpha, CV Constant

Contour representation of BetaV
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The Tokachi-oki Earthquake in 2003
Integrated displacement from acceleration
Vertical Component of Velocity Seismometer
Seismic wave
Determination of the Hypocenter
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Seismic Intensity
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Measurement of Seismic Intensity
Index of of damage
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Seismic Intensity Meter
Processor
Sensor (Accelerometer)
Printer
Display
Seismic Intensity is calculated on the basis of
amplitude and frequency of acceleration
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Seismic Intensity Measurement Stations
Total about 4,000
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JMA Seismic Intensity Scale
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Emergency Operation by Seismic Intensity
Information
EQ.
Prime Ministers Official Residence Cabinet
Office Defense Agency Japan Coast
Guard Metropolitan Police Department Fire and
Disaster Management Agency NHK, a broadcast
organization
6lower(5upper for Tokyo)
Emergency Assembly team Conference
Estimation of damages
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Investigation of damages
5lower
Investigation of damages
5lower
Investigation of damages
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Announcement with TV or Radio
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Quantitative Tsunami Forecast System
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Empirical Method (1952 --- 1999)
Tsunami Forecast Chart
Possibility of tsunami generation and its grade
are estimated from the magnitude and hypocenter
using the tsunami forecast chart.
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Inverse Tsunami Travel Chart
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Overall Description of Quantitative Tsunami
Forecast System of JMA
Hypoceneter Magnitude
Numerical Simulation
3 minutes
??????
Database
Even a most-advanced computer needs much time to
simulate tsunami propagation!
Tsunami Height Arrival Time
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Setting Earthquake Parameters to be simulated
Assumed epicenter
Simulation Points about 100,000 Magnitude
5.8,6.2,6.8,7.4,8.0 Depth 0,20,40,60,80,100km
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Initial Value Setting of Numerical Simulation
Initial shift of sea surface is assumed to be
same as crustal deformation of sea floor
crustal deformation of sea floor
Movement of fault ? Crustal deformation of sea
floor (OKADA 1985) Crustal deformation of sea
floor Initial shift of sea surface
Assigned to numerical simulation as an initial
value
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Introduction of numerical simulation for
prediction of tsunami

• Deformation of sea surface
• Deformation of sea surface deformation of sea
  floor by an earthquake
• Propagation of tsunami
• Height at coasts

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Setting of Fault Parameters

• Fault Parameters (dependent on Magnitude)
• Length (L)
• log L(km)0.5M-1.9
• Width (W)
• log W(km)0.5M-2.2
• Strike (f)
• along trench or coastline
• Dip (d)
• 45 degree ? worst case
• Slip angle(?)
• 90 degree ? worst case
• Slip amount (D)
• log D(cm)0.5M-3.2

d Depth of fault top edge L Fault Length W
Fault Width D Slip amount f Strike angle
(clockwise from North) d Dip angle ( from
horizontal plane) ? Slip angle (
counterclockwise from horizontal line on the
fault plane )
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Example of Tsunami Simulation
The Tokachi-oki Earthquake (2003.9.26)
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Numerical Simulation of Tsunami Propagation
Tsunami Forecast point
Long Wave Theory
Greens law
Taniokas model Consideration of Coriolis force
( Effect of Coriolis force on simulation of
distant tsunami is large enough to be
considered) Simplification of equation of
tsunami propagation wave length gtgt sea depth
gtgt tsunami height ? this relation is not
correct near coast the equation becomes
too complicate to be simulated
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Estimation of tsunami amplitude at coast
Greens Law
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Greens Law Derivation of Tsunami Height at
Coast

Tsunami's height is in proportion to a
biquadratic root of water depth's change and in
inverse proportion to a square root of expanse
of wave front. When tsunami get close to coast as
in the left figure, the latter contribution can
be neglected. We assume h equals 1 meter and get
an equation below.
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Quantitative Tsunami Forecast (1)
Computer simulation of tsunami generation and
propagation
Tsunami Database
Scenarios of tsunami arrival time and height
according to 100,000 different tsunamigenic
earthquakes
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Quantitative Tsunami Forecast (2)
JMA Seismic Network
Tidal Network
Tsunami Warning
Evaluation of Tsunami
Tsunami Database
?Quantitative Tsunami forecast (arrival time and
Tsunami height) ?Tsunami warning for 66 regions
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Categories of Tsunami Forecast
66 Tsunami Forecast Regions
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Tsunami Warning/Advisory issued in 2005
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Monitoring Room
Operation and maintenance 24 hours a day 7 days
a week
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Preparation for troubles

• Duplex System

• Trouble of power supply (power failure)
• Uninterruptible power supply system
• Private power generator

Stand-by
Active
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Tsunami Observation
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Tsunami Monitoring Network in Japan
Tide Gauge (Float Type)
Tide Gauge (Acoustic Type)
Huge Tsunami Gauge
Pressure Sensor on Sea Floor
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2003.9.26 Tokachi-oki earthquake
2003/09/26/ 0450 41? 46.5' N 144? 04.9' E
45km M8.0
M8.0
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Tsunami heights observed by tide gauge
NEMURO
KUSHIRO
HAKODATE
MUTSU
HACHINOHE
MIYAKO
KAMAISHI
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Removal of Tide Signal
Removal of Tide Signal
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Elements to be observed
(1) Arrival Time of Tsunami (2) Amplitude of
Initial Wave (3) Maximum Amplitude
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Screen image of JMA system for tsunami
observation
Initial wave amplitude
Station Name
Observed Value
Arrival Time
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Tsunami monitoring (Tsunami Arrival)
Arrival time
Time of maximum tsunami amplitude
Initial Max. amplitude
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Tsunami monitoring (Maximum amplitude)
Arrival time
Time of maximum Tsunami amplitude
Initial amplitude
Initial Max. amplitude
Max. height
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Tsunami monitoring (Cancellation)
Cancellation of warnings and advisory at all
coasts
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(No Transcript)
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Earthquake Information and Tsunami Warning
Service in Japan
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Thank you very much.