Asian Disaster Reduction Center
Visiting researcher program FY 2014B

Tsunami Early Warning System
in Japan

Fathmath Shaushan Moosa
Senior Administrative officer
National Disaster Management Centre, Rep of Maldives

Visiting Researcher Program FY2014B

Disclaimer
This report was compiled by an ADRC visiting researcher (VR) from ADRC member countries.
The views expressed in the report do not necessarily reflect the views of the ADRC. The boundaries
and names shown and the designations used on the maps in the report also do not imply official
endorsement or acceptance by the ADRC.

Cover photo
The lone-standing tree is acting as a symbol of hope for thousands of people left devastated by
Japan's tsunami in 2011.
Incredibly, it was the sole-surviving fern from a forest of 70,000 levelled in Rikuzentakata, in Iwate
prefecture, along Japan's north-east coast.
Now the so-called 'Miracle Pine', which stands at 88 feet (26.8 metres), has been reconstructed tocommemorate the second anniversary of the "Great East Japan Earthquake" (and tsunami).
The disaster killed nearly 19,000 people.
The tree survived the tsunami but later died in the Takata-Matsubara forest.
The "Miracle Pine" was reconstructed, with leaves and branches recreated out of plastic in a factory
and attached to the towering trunk.
A 3cm x 3cm stamp on the base reads: "Praying for recovery from disaster".

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Acknowledgement
I express my gratitude to Asian Disaster Reduction Center, Japan, Government of Maldives and my
Organization, National Disaster Management Centre (NDMC) for providing me this opportunity toparticipate in the Visiting Researcher Program. This program provided me an excellent opportunity to
study Disaster Management System of Japan and some other countries as well. Special thanks to theGovernment of Japan and many Japanese institutions which provided me this opportunity to visit
their facilities and offices and learn from their practices.
Secondly I would like to thank all the staffs of ADRC, Specially Ms. Yumi Shiomi for her exceptional
work in coordinating the program, the visits to facilitate my research studies and assistance during
my stay in Japan.
Special thanks to Deputy Minister of Defence and National Security Ms.Fathmath Thasneem, Project
Director Mr. Hisan Hasan and “team NDMC” for their support and assistance in my study here in
Japan.
Finally I wish to thank my parents, family and visiting researcher colleagues Ms. Ameerha P Ortega
from Philippines and Mr.Yeshi Lotey from Bhutan for their corporation during the program.

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Table of Contents
Japan ....................................................................................................................................................................... 6
General Information ........................................................................................................................................... 6
Physiography ................................................................................................................................................. 6
Climate........................................................................................................................................................... 7
Natural hazards in Japan ............................................................................................................................... 7
Earthquakes and Shaking ................................................................................................................................... 8
Earthquakes around Japan ............................................................................................................................ 8
Plate Subduction and Earthquake ................................................................................................................. 9
Seismic waves ................................................................................................................................................... 10
P-waves: ...................................................................................................................................................... 10
S-waves: ....................................................................................................................................................... 10
Measuring earthquakes ................................................................................................................................... 11
Japans scale ................................................................................................................................................. 11
Seismic Intensity and Magnitude ................................................................................................................ 12
Tsunami ............................................................................................................................................................ 13
The physics of a tsunami ............................................................................................................................. 14
Tsunami as it approaches land .................................................................................................................... 14
Measuring or observing a tsunami ................................................................................................................... 15
Tide Gauges ................................................................................................................................................. 15
Satellites ...................................................................................................................................................... 15
Open-ocean buoys ....................................................................................................................................... 16
Costal Tsunami monitoring system ............................................................................................................. 17
The Indian Ocean tsunami of 26th December 2004 ............................................................................................. 17
The cause ..................................................................................................................................................... 17
Early Warning .............................................................................................................................................. 18
Deaths.......................................................................................................................................................... 18
Worldwide effect ......................................................................................................................................... 18
Great East Japan Earthquake/ Tsunami (March 2011) ......................................................................................... 19
The cause ..................................................................................................................................................... 19
Early warning ............................................................................................................................................... 19
Deaths.......................................................................................................................................................... 20
Nuclear meltdown ....................................................................................................................................... 20
Worldwide effects ....................................................................................................................................... 20
A Data Collection and Processing System for Assured Communication .......................................................... 21
Earthquake and Tsunami Monitoring ............................................................................................................... 22
Seismometer Network ................................................................................................................................. 22
Seismic Intensity Network ........................................................................................................................... 23
Earthquake Information issued by Japan Meteorological Agency ................................................................... 23
Response to a Earthquake Early Warning System ....................................................................................... 25
Limitations of the Earthquake Early Warning .............................................................................................. 26
Tsunami Monitoring Network .......................................................................................................................... 26
Tsunami Observation ................................................................................................................................... 27
Tsunami Information issued by JMA ................................................................................................................ 28
Flow of information about Earthquake and Tsunami ...................................................................................... 29
Tsunami Warning/Advisory ......................................................................................................................... 30
Tsunami Information ................................................................................................................................... 31
Tsunami Forecast......................................................................................................................................... 33
Observation, Forecasting and Warning of Disaster Risks ............................................................................ 33
Information and communication system ......................................................................................................... 34
Issuing Evacuation Advisory and Order ....................................................................................................... 34
Central Disaster Prevention Radio Network ................................................................................................ 35
Dissemination of Forecast and EW .............................................................................................................. 36
J-Alert System .............................................................................................................................................. 37
Distant Earthquake Information and International Tsunami Advisories .......................................................... 38
Recommendations when Developing an Early Warning System...................................................................... 39

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Table of figures
Figure 1: Map of Japan ............................................................................................................................................ 6
Figure 2: Japan surrounded by sea ......................................................................................................................... 6
Figure 3: Topology of japan..................................................................................................................................... 6
Figure 4: Climate map of Japan ............................................................................................................................... 7
Figure 5: Loss of life due to natural disasters ......................................................................................................... 8
Figure 6: Types of plate boundary covering the earth ............................................................................................ 9
Figure 7: Plate Tectonics around Japan Source JMA .............................................................................................. 9
Figure 8: Types of earthquake Source JMA ........................................................................................................... 10
Figure 9: Two types of Waves P wave and S wave ................................................................................................ 10
Figure 10: Finding the hypocenter , Source JMA .................................................................................................. 11
Figure 11: Summary of JMA Seismic Intensity scale explained, Source JMA ........................................................ 12
Figure 12: Tsunami ................................................................................................................................................ 13
Figure 13: Tide Gauge source JMA ........................................................................................................................ 15
Figure 14: satellite image captured on 24 December 2004 – Tsunami - source NOAA..................................... 16
Figure 15: Open ocean buoy - Source JMA ........................................................................................................... 16
Figure 16: Costal tsunami monitoring system....................................................................................................... 17
Figure 17: Indian Ocean tsunami –Map of affected countries.............................................................................. 17
Figure 18: Great East Japan earthquake and Tsunami - Epicenter ....................................................................... 19
Figure 19: Houses, cars , ships were carried away by the tsunami wave, ............................................................ 19
Figure 20: Nuclear accident caused due to Tsunami ............................................................................................ 20
Figure 21: Data collection and Dissemination of information Source JMA .......................................................... 21
Figure 22: Seismic intensity network Source JMA ............................................................................................... 22
Figure 23: JMA Seismic station ............................................................................................................................. 22
Figure 24: Seismic intensity network Source JMA ............................................................................................... 23
Figure 25: earthquake early warning .................................................................................................................... 23
Figure 26: Response to an earthquake early warning........................................................................................... 25
Figure 27: Tsunami Observation Source Tohoku Regional Bureau of MLIT .......................................................... 27
Figure 28: Computer simulated tsunamis are stored on a data base Source JMA ............................................... 28
Figure 29: Issuing of Tsunami warning advisories Source JMA ............................................................................. 28
Figure 30: Flow of information, earthquake and tsunami Source JMA ................................................................ 29
Figure 31: Tsunami warning / Advisory categories and action to be taken Source JMA ...................................... 30
Figure 32: Early Warning System Source – Cabinet office, Government of Japan ................................................ 34
Figure 33: Disaster Pretension communication syste Source – Cabinet office, Government of Japan ................ 35
Figure 34: Flow of information from JMA to the public ........................................................................................ 36
Figure 35: J-Alert system ....................................................................................................................................... 37

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Japan
General Information
Japan is an island nation in East Asia. Located in the
Pacific Ocean, it lies to the east of the Sea of Japan,
People's Republic of China, North Korea, South Korea
and Russia, stretching from the Sea of Okhotsk in thenorth to the East China Sea and Taiwan in the south.
The characters that make up Japan's name mean "sunorigin", which is why Japan is sometimes referred to as
the "Land of the Rising Sun".
Japan is an archipelago of 6,852 islands. The fourlargest islands are Honshu, Hokkaido, Kyushu, andShikoku, which together comprise about ninety-sevenpercent of Japan's land area. With over 127 million Figure 1: Map of Japan
people Japan has the world's tenth-largest population.
Honshu's Greater Tokyo Area, which includes the de facto capital city of Tokyo and several
surrounding prefectures, is the largest metropolitan area in the world, with over 30 million residents.
About 73 percent of Japan is forested, mountainous, and unsuitable for agricultural, industrial, or
residential use. As a result, the habitable zones, mainly located in coastal areas, are highly populated.
Making Japan as one of the most populated countries in the world.

Physiography
The islands of Japan are located in a volcanic zone on
the Pacific Ring of Fire. They are primarily the result oflarge oceanic movements occurring over hundreds ofmillions of years from the mid-Silurian to the
Pleistocene as a result of the subduction of thePhilippine Sea Plate beneath the continental Amurian
Plate and Okinawa Plate to the south, and subductionof the Pacific Plate under the Okhotsk Plate to thenorth. Japan was originally attached to the eastern
coast of the Eurasian continent. The subducting plates Figure 2: Japan surrounded by sea
pulled Japan eastward, opening the Sea of Japanaround 15 million years ago.
Japan has 108 active volcanoes. Destructive
earthquakes, often resulting in tsunami, occur several
times each century. The 1923 Tokyo earthquake killedover 140,000 people. More recent major quakes are
the 1995 Great Hanshin earthquake and the 2011
Tōhoku earthquake, a 9.0-magnitude quake which hit
Japan on March 11, 2011, and triggered a large Figure 3: Topology of japan
tsunami. Due to its location in the Pacific Ring of Fire,
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Japan is substantially prone to earthquakes and tsunami, having the highest natural disaster risk inthe developed world.

ClimateA major feature of Japan’s climate is theclear-cut temperature changes between
the four seasons. In spite of its rather
small area, the climate differs in regions
from a subarctic climate to a subtropicalclimate. The side of the country whichfaces the Sea of Japan has a climate withmuch snow in winter by seasonal winds
from the Siberia. Most of the areas havedamp rainy season from May to July by
seasonal winds from the Pacific Ocean.
Japan is frequently visited by typhoons
from July to September.
The average winter temperature in
Japan is 5.1 °C (41.2 °F) and the averagesummer temperature is 25.2 °C (77.4 °F).
The highest temperature ever measured
Figure 4: Climate map of Japanin Japan—40.9 °C (105.6 °F) —wasrecorded on August 16, 2007.
The main rainy season begins in early May in Okinawa, and the rain front gradually moves north until
reaching Hokkaido in late July. In most of Honshu, the rainy season begins before the middle of Juneand lasts about six weeks. In late summer and early autumn, typhoons often bring heavy rain.

Natural hazards in Japan
Japan’s geographical and climatologically the country is vulnerable to frequent natural disasters suchas typhoons, torrential rains and heavy snow as well as earthquake, Tsunamis and volcanic eruptions.
Japan is located in the circum-Pacific mobile zone where seismic and volcanic activities occur
constantly.
Although the country covers only 0.25% of the land area on the planet, the number of earthquakes
and distribution of active volcanoes is quite high. Due to the geological formation with plateboundaries of the Pacific plate, the Philippine Sea plate, the Eurasian plate, and the North American
plate, Japan is substantially prone to earthquakes and tsunami, having the highest natural disasterrisk in the developed world.
Every year there is a great loss of people’s lives and properties due to natural disasters. As suchnatural disasters remain a menacing threat to safety and security of the country. However, with theprogress of society’s capacity to address disasters and mitigation of vulnerabilities to disasters bydeveloping disaster management systems, promoting national land conservation, improving weather
forecasting technologies and upgrading disaster information communication systems, disasterdamage has shown a declining tendency.

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Figure 5: Loss of life due to natural disasters

Earthquakes and Shaking
What is an earthquake? When people feel the ground shake, they exclaim, "It's an earthquake!"
Strictly speaking, what they are feeling is ground motion caused by an earthquake. As a technicalterm, ground motion is used to distinguish this movement from the earthquake itself. An earthquake
is a destructive slip movement inside a rock plate deep under the ground. We call the plane of thismovement a fault, and the point at which a destructive slip movement starts is called the
hypocenter.
Such destructive slip movements cause vibration that propagates in every direction. Since vibration
travels in a wave formation, its movement is called a seismic wave. When the vibration reaches theground surface, people become aware of earthquake motion. Thus, not all places on the surface ofthe ground shake at the same time. Locations closer to the hypocenter shake ﬁrst, while distantareas shake later.

Earthquakes around JapanThe boundaries of plates covering the surface of the Earth are classified into three types: convergent,
divergent, and transform types. Convergent boundaries occur where one plate subducts underneathanother plate with density lower than the subducting plate or collides with another plate in the casethat both plates are composed of continental material. Continental plates cannot dive into themantle because their densities are lower than that of the mantle.
Divergent boundaries occur where new lithosphere (plate) is produced and plates move away fromeach other at spreading ridges.
Transform boundaries occur where one plate laterally slides past another, displacing spreading ridge.
As an oceanic plate subducts underneath another plate at a convergent boundary, such area is calleda subduction zone. The Japanese Islands are situated in a subduction zone in the northwestern
margin of the Pacific Ocean where the Pacific Plate and Philippine Sea Plate subducting (the North
American Plate and the Eurasian Plate) several centimeters annually. These plate movements cause
forces to act in various directions around the country, which is the reason behind the extremely highseismic activity in the area. Around Japan, therefore, oceanic plates subduct beneath continental
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plates. These continental plates are dragged down as a result, andstrain energy is accumulated. When this strain exceeds a certain
level, it causes the continental plates to jump up, and tremors
known as interplate earthquakes occur. Conversely, tremors
generated by strain forces within a plate are called intraplate
earthquakes. They occur in subducting plates and shallow
underground areas of continental plates. Compared to interpolate
earthquakes, intraplate earthquake occurring in shallow
underground areas are relatively small, but can cause serious
damage if they occur directly below populous areas.
Convergent boundaries are characterized by volcanism,
earthquakes, and mountain building attributed to active crustal
movement.
The active crustal movement zone surrounding the Pacific Ocean iscalled the circum-Pacific orogenic belt, and also known as the Ringof Fire.

Figure 6: Types of plateboundary covering the earth

Plate Subduction and Earthquake
The Japanese Islands are in marginal areas of the
Pacific Plate, the Philippine Sea Plate, the North
American Plate, and the Eurasian Plate. A triple
junction at which the Pacific, the Philippine Sea,and the North American Plates meet one anotheris situated off the Boso Peninsula in central
Honshu (Kanto). Oceanic plates, the Pacific Plateand the Philippine Sea Plate, subduct at trenches
or troughs. The Pacific Plate descends underneaththe North American Plate at the Kuril Trench and
the Japan Trench and underneath the Philippine
Sea Plate at the Izu-Bonin Trench. The Philippine
Figure 7: Plate Tectonics around Japan
Sea Plate descends beneath the Eurasian Plate at
Source JMA
the Suruga and Nankai Troughs and the Ryukyu
Trench. The leading edge of the Pacific Plate reaches under the Eurasian Plate.
Earthquakes very often occur in borders between plates. In Japan, over 1300 felt earthquakes wereobserved in 2010, but more than 2000 earthquakes were felt in some years. The frequency of M ≥5aftershock of M 9 earthquake in eastern Japan in 2011 is over 400 two weeks after the main shock(M: magnitude).

In plate margins, the crust is stressed by plate movement. The rocks are broken and energy isreleased when the stress exceeds their strength. The rupture generally occurs along faults, which are
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considered seismic sources. Therefore, the rapid slip of rocks along a fault results in an earthquake.
Volcanic activity also causes earthquakes. There
are principally three types of fault motion: normal
dip-slip, reverse dip-slip, and strike-slip (left or
right). Fault movements may include a componentof strike-slip and dip-slip.

Figure 8: Types of earthquake
Source JMA

Seismic waves
For earthquake detection, it is important to understand the two types of seismic waves emitted byearthquakes: P-waves and S-waves. Although these waves are released at the same time, p-waves
are less powerful and travel relatively quickly, so early recognition of these waves is critical in orderto maximize warning time.

P-waves: P-waves propagate similarly to sound waves by alternating between compressing anddilating in the same direction that the wave is traveling. This longitudinal motion compresses the
Earth’s crust as it moves but causes very little or no destruction
These waves travel at a speed of 47km/second and can move through gas,liquid, and solids including the molten core of
the Earth (P-Waves and S-Waves, 2009). As aresult, p-waves move faster than s-waves andcan be used to detect the onset of anearthquake before the arrival of the

S-waves: S-waves, or shear waves,
oscillate sinusoidally and move perpendicular to their direction of travel. These waves cause most of
the earthquake-induced damage such as the
Figure 9: Two types of Waves P wave and S wave
destruction of buildings and landslides.
Unlike p-waves, s-waves cannot travel through gas or liquid and travel at a slower rate of 25km/second.
For an efficient earthquake warning system, it is critical that earthquake technology can quickly
detect the p-waves and issue a warning before the arrival of these s-waves.

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Measuring earthquakes
A seismogram is a record of theseismic waves from an earthquake.
A seismograph or seismometer isthe measuring instrument thatcreates the seismogram.
Almost all seismometers are basedon the principle of inertia: asuspended mass tends to remain
still when the ground moves.
The relative motion between thesuspended mass and the groundwill then be a measure of the
Figure 10: Finding the hypocenter , Source JMA
ground’s motion.
On a seismogram from anearthquake, the P-wave is the first signal to arrive, followed by the slower S-wave, then the surface
waves.
Given that we know the relative speed of P- and S-waves, the time difference between the arrivals of
the P- and S-waves determines the distance the earthquake is from the seismograph.
Vibration propagates as a wave, so the farther a point is from the hypocenter, the later the wave
arrives. As a result, if we can pinpoint where earthquake motion appears ﬁrst among many
monitoring sites (seismometers),the hypocenter can be assumed to near that site. In fact,
hypocenters are located by considering the subterranean structure (i.e., the structure of the earth scrust) and comparing diﬀerences in the appearance times of P-waves and S-waves.

Japans scale
The JMA scale describes the degree of shaking at a point on the Earth's surface, and is analogous to
the Mercalli intensity scale. The intensity of an earthquake is not totally determined by its
magnitude, and varies from place to place; for example, a quake may be described as "shindo 4 inTokyo, shindo 3 in Yokohama, shindo 2 in Shizuoka". It is measured in units of shindo (震度, seismic
intensity, lit. "Degree of shaking").
Japan experiences approximately 400 earthquakes every day, although the vast majority are shindo
scale "0" or less and detectable only using specialist apparatus.
The Japan Meteorological Agency (JMA) first assigned a four-stage Shindo in 1884, with the levels: 微(faint), 弱 (weak), 強 (strong), and 烈 (violent).
In 1898 this scale was changed to a numerical system, assigning earthquakes levels 0–7.
In 1908, the levels on this scale were given descriptions, and earthquakes were assigned levels basedon their perceived effect on people. This scale was widely used during the Meiji period, and revised
during the Shōwa period with the descriptions seeing an overhaul.
Following the Great Hanshin earthquake in 1995, levels 5 and 6 were divided in two, giving a total of
10 levels of earthquake: 0–4, weak / strong 5, weak / strong 6 and 7.
The Shindo scale has been used in Japan from 1996 without change.

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Seismic Intensity and Magnitude
Seismic intensity and magnitude are easily confused because both have similar values. Seismic
intensity describes the scale of the ground motion at a particular location. It varies with the distancefrom the epicenter and the surface geology at each point. JMA s seismic intensity scale has 10
degrees (0 (imperceptible), 1, 2, 3, 4, 5-lower, 5-upper, 6-lower, 6-upper, 7). Magnitude is anumerical value that represents the scale of a fault slip underground. Large earthquakes have highmagnitude.

Figure 11: Summary of JMA Seismic Intensity scale explained, Source JMA

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TsunamiTsunami is a Japanese word with the English translation: "harbour wave". In the past, tsunamis havebeen referred to as "tidal waves" or "seismic sea waves". The term "tidal wave" is misleading; eventhough a tsunami's impact upon a coastline is dependent upon the tidal level at the time a tsunami
strikes, tsunamis are unrelated to the tides. (Tides result from the gravitational influences of themoon, sun, and planets.) The term "seismic sea wave" is also misleading. "Seismic" implies anearthquake-related generation mechanism, but a tsunami can also be caused by a non-seismic event,such as a landslide or meteorite impact.
Tsunamis are also often confused with storm surges, even though they are quite different
phenomena. A storm surge is a rapid rise in coastal sea-level caused by a significant meteorologicalevent - these are often associated with tropical cyclones.
A tsunami is a series of very long waves generated by rapid, large-scale disturbances of the sea—thesudden displacement of a large volume of water, generally from the raising or lowering of theseafloor caused by:






earthquakes
landslidevolcanic eruptions
explosions
meteorites

Once a tsunami has been generated, its energy is distributed throughout the water column,
regardless of the water depth, and the waves travel outward on the surface of the ocean in all
directions away from the source, much like ripples caused by throwing a rock into a pond. The
wavelength of the tsunami waves and their period depend on the generating mechanism and thedimensions of the source event.
In the deep ocean, the height of atsunami from trough to crest can
range from a few centimeters to ameter or more depending on thegenerating source. Tsunami waves
in the deep ocean can travel at highspeeds for long periods of timeover distances of thousands ofkilometers and lose very little Figure 12: Tsunami
energy in the process. The deeper
the water, the greater the speed of tsunami waves is. A tsunami wave can travel more than 800
kilometers per hour (km/h) in the deep ocean, but slows to 30 to 60 km/h in shallow water near land.
But, amazingly, pass under a ship in the ocean with those aboard the vessel hardly noticing.
Tsunamis arrive at a coastline as a series of successive crests (high water levels) and troughs (lowwater levels) usually 10 to 45 minutes apart. As the tsunami waves become compressed near thecoast, their wavelengths are shortened, and the wave energy is directed upward—thus considerablyincreasing the height and force of the waves.
Tsunami waves may smash into the shore like a wall of water or move ashore as a fast moving floodor tide—carrying along everything in their path. The historic record shows that many tsunamis havestruck with devastating force, sometimes reaching heights of 30 to 50 meters. It should be
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remembered that a tsunami run-up of more than 1 meter is dangerous due to the strong force it has.
Flooding by individual waves typically lasts from 10 to 30 minutes, but the danger can last for hours.
Greater tsunamis tend to move inland with the derbies and sometimes with massive fire.
Generally, coasts and islands with steep fringes or surrounded by barrier reefs are safer than thosewith gradually rising fringes or those that are exposed to open ocean. This is because reefs canabsorb much of the oncoming waves’ impact and deep coastlines do not allow tsunamis to slow
down and grow into deadly towers of water.

The physics of a tsunami
Tsunamis can have wavelengths ranging from 10 to 500 km and wave periods of up to an hour. As aresult of their long wavelengths, tsunamis act as shallow-water waves. A wave becomes a shallowwater wave when the wavelength is very large compared to the water depth. Shallow-water waves
move at a speed, c, that is dependent upon the water depth and is given by the formula:

Where g is the acceleration due to gravity (= 9.8 m/s2) and H is the depth of water.
In the deep ocean, the typical water depth is around 4000 m, so a tsunami will therefore travel ataround 200 m/s, or more than 700 km/h.
For tsunamis that are generated by underwater earthquakes, the amplitude of the tsunami isdetermined by the amount by which the sea-floor is displaced. Similarly, the wavelength and periodof the tsunami are determined by the size and shape of the underwater disturbance.
As the tsunami propagates across the ocean, the wave crests can undergo refraction (bending),
which is caused by segments of the wave moving at different speeds as the water depth along thewave crest varies.

Tsunami as it approaches land
As a tsunami leaves the deep water of the open-ocean and travels into the shallower water near thecoast, it transforms, as the water depth decreases, the tsunami slows. The tsunami's energy flux,
which is dependent on both its wave speed and wave height, remains nearly constant. Consequently,
as the tsunami's speed diminishes, its height grows. This is called shoaling. Because of this shoaling
effect, a tsunami that is unnoticeable at sea, may grow to be several metres or more in height near
the coast.
The increase of the tsunami's wave height as it enters shallow water is given by:

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where hs and hd are wave heights in shallow and deep water and Hs and Hd are the depths of theshallow and deep water. So a tsunami with a height of 1 m in the open ocean where the water depth
is 4000m would have a wave height of 4 to 5 m in water of depth 10 m.
Just like other water waves, tsunamis begin to lose energy as they rush onshore - part of the wave
energy is reflected offshore, while the shoreward-propagating wave energy is dissipated throughbottom friction and turbulence. Despite these losses, tsunamis still reach the coast with tremendous
amounts of energy. Depending on whether the first part of the tsunami to reach the shore is a crest
or a trough, it may appear as a rapidly rising or falling tide. Tsunamis may reach a maximum verticalheight onshore above sea level, often called a run-up height, of tens of metres.

Measuring or observing a tsunami
In the deep ocean, a tsunami has small amplitude (less than 1 metre) but very long wavelength(hundreds of kilometres). This means that the slope, or steepness of the wave is very small, so it ispractically undetectable to the human eye. However, there are ocean observing instruments that areable to detect tsunamis.

Tide Gauges
Tide gauges measure the height of the sea-surface
and are primarily used for measuring tide levels.
These consist of an acoustic sensor connected to avertical tube open at the lower end which is in thewater. The acoustic sensor emits a sound pulse
which travels from the top of the tube down to thewater surface, and is then reflected back up thetube. The distance to the water level can then be
calculated using the travel time of the pulse. Thissystem filters out small-scale effects like windwaves and has the capacity to measure sea-levelchanges within 1mm accuracy.
The tide gauge at Cocos Island observed the Figure 13: Tide Gauge source JMA
tsunami on December 26th 2004 as it passed by theisland, as shown in these observations made during
December.

Satellites
Satellite altimeters measure the height of the ocean surface directly by the use of electro-magnetic
pulses. These are sent down to the ocean surface from the satellite and the height of the ocean
surface can be determined by knowing the speed of the pulse, the location of the satellite andmeasuring the time that the pulse takes to return to the satellite. One problem with this kind ofsatellite data is that it can be very sparse - some satellites only pass over a particular location about
once a month, so you would be lucky to spot a tsunami since they travel so quickly. However, during
the Indian Ocean tsunami of December 26th 2004, the Jason satellite altimeter happened to be in
the right place at the right time.

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The picture below shows the height ofthe sea surface (in blue) measured by
the Jason satellite two hours after the
initial earthquake hit the region
southeast of Sumatra (shown in red) on
December 26, 2004. The data weretaken by a radar altimeter on board thesatellite along a track traversing theIndian Ocean when the tsunami waves
had just filled the entire Bay of Bengal.
The data shown are the differences insea surface height from previous
observations made along the same
track 20-30 days before theearthquake, showing the signals of thetsunami.

Figure 14: satellite image captured on 24 December 2004 –Tsunami - source NOAA

Open-ocean buoys
An array of stations is deployed in the Ocean.
These stations give detailed information abouttsunamis while they are still far off shore. Eachstation consists of a sea-bed bottom pressurerecorder which detects the passage of a tsunami.
(The pressure of the water column is related tothe height of the sea-surface) . The data is thentransmitted to a surface buoy via sonar. The
surface buoy then radios the information to the
Tsunami Warning Center via satellite. The system
has considerably improved the forecasting andwarning of tsunamis.

Figure 15: Open ocean buoy - Source JMA

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Costal Tsunami monitoring system
This system can operate a wireless network with a PV system and astorage battery system even in the event of a disaster, whencommercial power and wired information networks areinaccessible.
With the coastal tsunami monitoring system, network cameras
were installed at different places to monitor the coasts. The plan isto transmit realtime video data to the City Hall Disaster Prevention
Headquarters via a wireless system, along with data from the wave
height gauge set up on the Coast. At the heart of this wirelesssystem is a multi-service access concentrator capable of handling
data transfer over three wireless networks—a 5G wireless link
capable of transmitting videos, a 920MHz band specified low-power
wireless system suitable for transmitting wave height data, andWiFi. The system is also powered by a self-sustaining power supply
system consisting of PV panels and a lithium ion storage battery
unit.
Figure 16: Costal tsunami
monitoring system

The Indian Ocean tsunami of 26th December
2004
An undersea earthquake in the Indian Ocean on
26th December 2004 produced a tsunami thatcaused one of the biggest natural disasters inmodern history.
The earthquake took place at about 1am UTC (8amlocal time) in the Indian Ocean off the western
coast of northern Sumatra. With a magnitude of 9.0
on the Richter scale, it was the largest since the1964 earthquake off Alaska and equal fourth largest
since 1900, when accurate global seismographic
record-keeping began.
Figure 17: Indian Ocean tsunami –Map of affected
countries

The cause
The epicentre of the earthquake was located about 250 km south-southeast of the Indonesian city ofBanda Aceh. It was a rare megathrust earthquake and occurred on the interface of the India andBurma tectonic plates. This was caused by the release of stresses that develop as the India plate
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subducts beneath the overriding Burma plate. A megathrust earthquake is where one tectonic plateslips beneath another, causing vertical motion of the plates. This large vertical displacement of thesea-floor generated the devastating tsunami, which caused damage over such a large area aroundthe Indian Ocean.
The earthquake was also unusually large in geographical extent. An estimated 1200 km of faultline
slipped about 15 m along the subduction zone over a period of several minutes. Because the 1,200
km of faultline affected by the quake was in a nearly north-south orientation, the greatest strengthof the waves was in an east-west direction.

Early Warning
The large tsunami which struck 11 of the nations that border the Indian Ocean was a complete
surprise for the people living on the area, but not for the scientists who are aware of the tectonic
interactions in the region. Many seismic networks recorded the massive earthquake, but there wasno tide gauges or other wave sensors to provide confirmation as to whether a tsunami had been
generated. There was no established communications network or organizational infrastructure topass a warning of any kind to the people on the coastlines. Non existence of an early warning system
is considered as the main cause of the huge number of casualties in the effected countries, in thisdisaster.

Deaths
The tsunami had its greatest impact and casualties in Indonesia, Thailand, India, Sri-Lanka, Malaysia,
Myanmar, Maldives and Somalia. Eleven (11) countries reported deaths, some in tens of thousands.
Over 226,000 people are known to have lost their lives including tourists from different parts of theworld that came to these countries on vacation. Thousands are missing and many more may havebeen killed in remote islands. More than 1.5 million people were left homeless around the region.

Worldwide effect
The tsunami waves caused considerable destruction and killed people more than 2,000 kilometers
away. Over 226,000 people are known to have lost their lives from different parts of the world.
Due to the distances involved, the tsunami took anywhere from fifteen minutes to seven hours (forSomalia) to reach the various coastlines. The northern regions of the Indonesian island of Sumatra
were hit very quickly, while Maldives, Sri Lanka and the east coast of India were hit roughly twohours later. Thailand was also struck about two hours later, despite being closer to the epicentre,
because the tsunami travelled more slowly in the shallow Andaman Sea off its western coast.
Waves of up to 10.5 meters in height struck Northern Sumatra, the Nicobar and Andaman Islands,
Thailand, Sri Lanka, India. Destructive waves also struck the Maldives, Somalia, Kenya and the islands
off the African coast, 4500 km west of the epicenter..

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Great East Japan Earthquake/ Tsunami (March
2011)
The 2011 earthquake off the Pacific coast of Tōhoku
often referred to in Japan as Higashi nihon daishinsai
and also known as the 2011 Tohoku earthquake, theGreat East Japan Earthquake, and the 3.11 Earthquake,
was a magnitude 9.03 (Mw) undersea mega thrustearthquake off the coast of Japan that occurred at 14:46
on 11 March 2011, with the epicentre approximately 70
kilometres (43 mi) east of the Oshika Peninsula ofTōhoku and the hypocenter at an underwater depth ofapproximately 30 km (19 mi). It was the most powerful
known earthquake ever to have hit Japan, and the fifth
most powerful earthquake in the world since modern
record-keeping began in 1900. The earthquake triggered
powerful tsunami waves that reached heights of up to
40.5 metres (133 ft) in Miyako in Tōhoku's Iwate Figure 18: Great East Japan earthquake andPrefecture, and which, in the Sendai area, travelled up to Tsunami - Epicenter
10 km (6 mi) inland. The earthquake moved Honshu (themain island of Japan) 2.4 m (8 ft) east and shifted the Earth on its axis by estimates of between 10 cm(4 in) and 25 cm (10 in).
Japan Meteorological Agency reported that the type of earthquake source fault was the reverse
fault, the size of fault was about 450 km long and 200 km wide, the fault slippage was 20 to 30
meters (maximum), and the duration of main failure was about three minutes.

The cause
The 2011 Tohoku earthquake struck offshore of Japan,
along a subduction zone where two of Earth's tectonic
plates collide. In a subduction zone, one plate slides
beneath another into the mantle, the hotter layer beneaththe crust. The great plates stick and slip, causing
earthquakes. East of Japan, the Pacific plate dives beneaththe overriding Eurasian plate. The temblor completely
released centuries of built up stress between the two
tectonic plates.

Figure 19: Houses, cars , ships were carriedaway by the tsunami wave,

Early warning
Residents of Tokyo received a minute of warning before the strong shaking hit the city, thanks toJapan's earthquake early warning system. The country's stringent seismic building codes and early
warning system prevented many deaths from the earthquake, by stopping high-speed trains andfactory assembly lines. People in Japan also received texted alerts of the earthquake warning on theircell phones.
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DeathsMore than 18,000 people were killed in the disaster. Most died by drowning.
Less than an hour after the earthquake, the first of many tsunami waves hit Japan's coastline. The
tsunami waves reached run-up heights (how far the wave surges inland above sea level) of up to 128
feet (39 meters) at Miyako city and traveled inland as far as 6 miles (10 km) in Sendai. The tsunami
flooded an estimated area of approximately 217 square miles (561 square kilometers) in Japan.
The waves overtopped and destroyed protective tsunami seawalls at several locations. The massive
surge destroyed many evacuation centers where people had gathered for safety. Near Oarai, thetsunami generated a huge whirlpool offshore, captured on video.

Nuclear meltdown
The tsunami caused nuclear accidents, primarily thelevel 7 meltdowns at three reactors in the Fukushima
Daiichi Nuclear Power Plant complex, and theassociated evacuation zones affecting hundreds ofthousands of residents. Many electrical generators
were taken down, and at least three nuclear reactors
suffered explosions due to hydrogen gas that had built
up within their outer containment buildings after
cooling system failure. Residents within a 20 km (12 mi)radius of the Fukushima Daiichi Nuclear Power Plant
and a 10 km (6.2 mi) radius of the Fukushima Daiichi Figure 20: Nuclear accident caused due to
TsunamiNuclear Power Plant were evacuated.
About 300 tons of radioactive water continues to leakfrom the plant every day into the Pacific Ocean, affecting fish and other marine life.

Worldwide effects
The tsunami waves also traveled across the Pacific, reaching Alaska, Hawaii and Chile. In Chile, some
11,000 miles (17,000 km) distant, the tsunami was 6.6 feet (2 meters) high when they reached theshore.
The surge of water carried tons of debris out to sea as it receded. Japanese docks and ships, andcountless household items, have arrived on U.S. and Canadian shores in the ensuing years.

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A Data Collection and Processing System for Assured
Communication
Japan is hyperaware of its shaky ground. The country withstands some thousand tremors a year, andthey’ve got 180 seismographs and 600 seismic intensity meters constantly tuned to what’s going onin the underworld. They also have around 30 sea level gauges operated by the coast guard andaround 80 operated by the JMA that work in chorus to provide feedback to a Data Processing andCommunication system. The sensors take a reading, upload it to a central processing system using
old-fashioned wires and/or satellite uplink, and that central system sends updates to thegovernment, police, coast guard, telephone companies, and the media. Sea level gauges also report
disturbances in real time and help organisations model trajectory and size of the oncoming waves.
And then there are more specialised tools. There are tsunami detection buoys that help rule out false
alarms and give monitoring agencies a better idea of what they’re in for – or what they’re not. Deep
Ocean Assessment and Reporting of Tsunami system, is made up of an anchored sea floor bottompressure recorder and accompanying fiberglass and foam buoy on the surface. The recorder on theocean floor, which takes a note of temperature and pressure every 15 seconds, sends data via an
acoustic link to the surface buoy. The buoy then sends information by satellite to Tsunami warning
centres.
JMA monitors seismic activity and issues Warnings/Advisories and information on a 24-hour basis. To
provide these resources urgently and precisely, JMA needs to collect various seismic data andanalyze them quickly. To this end, the Agency operates a comprehensive system called EPOS (theEarthquake Phenomena Observation System). This is responsible for issuing Earthquake Early
Warnings, Tsunami Warnings/Advisories, and Earthquake Information.

Figure 21: Data collection and Dissemination of information
Source JMA

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Warnings/Advisories and information issued by JMA are transmitted to disaster management
authorities, local governments and the broadcasting media over a nationwide computer network
immediately. Disaster management authorities and local governments take action to mitigate
disasters based on these resources. Such action is also announced to the public through the media
and the Internet.

Earthquake and Tsunami Monitoring
Located in one of the most active seismic andvolcanic zones in the world, Japan is frequently
affected by earthquakes and volcanic disasters. JMA
operationally monitors seismic and volcanic activity
throughout the country and issues relevant
warnings and information to mitigate damage
caused by disasters related to earthquakes,
tsunamis and volcanic eruptions.
To monitor earthquakes, JMA operates anearthquake observation network comprised ofabout 200 seismographs and 600 seismic intensity
meters. It also collects data from over 3,600 seismic
intensity meters managed by local governments andthe National Research Institute for Earth Scienceand Disaster Prevention (NIED). The data collected
are input to the Earthquake Phenomena
Observation System (EPOS) at the headquarters inTokyo and the Osaka District MeteorologicalFigure 22: Seismic intensity network
Observatory on a real-time basis.
Source JMA

Seismometer Network
When an earthquake occurs, it is important to know its locationand magnitude. To achieve this, JMA observe its waves and analyze
its hypocenter and magnitude; an instrument used to observe
earthquake waves is called a seismometer.
JMA operates a seismic network consisting of about 200
seismometers and collects seismic waveform data in real time aroundthe clock. The Agency also uses seismometers belonging to the
National Research Institute for Earth Science and Disaster Prevention(NIED), and issues Earthquake Early Warnings, Tsunami Warnings /Advisories and Earthquake Information.
JMA also collects and analyzes seismic data from NIED, universities Figure 23: JMA Seismic station
and related institutes in order to conduct comprehensive assessmentof seismic activity for the promotion of research activities in cooperation with the Ministry of
Education, Culture, Sports, Science and Technology (MEXT). The products of this analysis are sharedwith the relevant organizations.

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Seismic Intensity Network
A seismic intensity meter is an instrumentthat measures and records the seismic
intensity of ground motion. JMA has
installed about 600 seismic intensity meters
throughout the country, and also collects
seismic intensity data from another 3,600
stations (as of Apr. 1, 2009) operated by
local governments and the National
Research Institute for Earth Science andDisaster Prevention (NIED). These data areused for Earthquake Information issued by
JMA.
Figure 24: Seismic intensity network
Source JMA

Earthquake Information issued by Japan Meteorological
AgencyEarthquake Early Warnings (EEWs) are issued slightly after an earthquake occurs. There are noearthquake predictions which tell us occurrence of earthquake in advance.

Figure 25: earthquake early warning

As soon as an earthquake occurs, the EEW system uses seismometers located near the epicenter tocalculate the hypocenter, magnitude and P-wave data detected by the area that will be subjected tostrong shaking, and provides a ﬁrst announcement. EEWs are transmitted promptly. A sophisticatedobservation system to detect seismic waves quickly, technology that enables forecasting from very
weak shaking and communication technology for prompt dissemination are the elements that enable
JMA to issue EEWs.
The Earthquake Early Warning is aimed at mitigating earthquake-related damage by allowing
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countermeasures such as promptly slowing down trains, controlling elevators to avoid danger andenabling people to quickly protect themselves in various environments such as factories, offices, andhouses and near cliffs.
Title

Content and Timing to be issued

Seismic Intensity
Information

This information is issued within about two minutes from an earthquake toprovide information on the regions where seismic intensity of 3 or more wasobserved. Each prefecture is divided into 2 or more regions.

Earthquake
Information

The location and magnitude of an earthquake is determined within about
three minutes. In case of no tsunamigenic earthquake, the message of“Tsunami is not expected” is added.

Earthquake andSeismic Intensity
Information

This information indicates the location of the hypocenter, magnitude, andname of regions, cities, towns and villages in which intensity of 3 or more
was observed.

Information on seismic All stations which observed intensity of 1 or more, hypocenter location andintensity at each site magnitude of the earthquake are provided.
Shake Map

Just after an earthquake, the shaking-intensity map is prepared. This map is
produced taking into account local geological conditions and observed
seismic intensity

Information on thenumber ofearthquakes

When earthquakes occur frequently in a same place called earthquake
swarm, hourly/daily number of earthquakes is provided.

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Response to a Earthquake Early Warning System
The period between the Earthquake Early Warning and the arrival of strong tremors is very short, i.e.
a matter of seconds (or between several seconds and a few tens of seconds). As a result, areas thatare close to the focus of the earthquake may not receive the Earthquake Early Warning transmission
before strong tremors hit.
And there are limits to the accuracy of the Earthquake Early Warning, such as the estimated seismic
intensity. This is because the system is necessarily dependent on very short-term data. It is important
to be aware of these features and limitations when responding to Earthquake Early Warnings.

Figure 26: Response to an earthquake early warning

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Limitations of the Earthquake Early Warning
Timing
The window of time from the announcement of an Earthquake Early Warning until the arrival of themain tremors is very short, i.e. a matter of seconds (or between several seconds and a few tens ofseconds).
In areas that are close to the focus of the earthquake, the warning may not be transmitted before
strong tremors hit.
False alarms
When using data from only one seismograph, false Earthquake Early Warnings may occur as a resultof noise from accidents, lightning or device failure.
Magnitude estimation
There are limits to the accuracy of estimating magnitude, especially for large earthquakes.
It is difficult to separate earthquakes and provide accurate warnings when multiple earthquakes
occur almost simultaneously or in close proximity to each other.
Seismic intensity estimation
There are limits to the accuracy of estimating seismic intensity by statistical attenuation formula, as
well as limits to the prediction of land surface amplification.
The Japan Meteorological Agency plans to continue improving the accuracy and timing of the
Earthquake Early Warning through joint research with the National Research Institute for Earth
Science and Disaster Prevention, and also intends to make further efforts toward publicizing the
Earthquake Early Warning.

Tsunami Monitoring NetworkWhen
tsunamisareobserved, JMA issues
tsunamiobservation
information
includingobservation
points,tsunamiheights
andexpected times of arrival.
The Agency operates
about 70 tidal gauge
stations and also collects
real-time sea-level datafrom stations operated by
the Ports and Harbors
Bureau (Ministry of Land,
Infrastructure, Transport

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and Tourism), the Geographical Survey Institute and the Japan Coast Guard. Currently, JMA issues
tsunami information using data from about 170 stations.

Tsunami Observation
Tide gauges and tsunami meters are used to observe sea levels and tsunamis in coastal areas. Whena very large tsunami with heights exceeding the measurement range of these instruments isgenerated, huge-tsunami meters are used. GPS buoys are installed offshore to detect tsunamis
promptly, and offshore-water-pressure gauges are installed farther offshore to help clarify thesituation of tsunamis in their early stages.

Figure 27: Tsunami Observation
Source Tohoku Regional Bureau of MLIT

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Tsunami Information issued by JMA
When a large earthquake occurs in a sea area,
JMA issues a Tsunami Warning/Advisory. A
numerical simulation technique is used toestimate tsunami potential and propagation.
After an earthquake occurs, Tsunami
Warnings / Advisories must be issued
immediately to enable evacuation before thewave strikes coastal areas.
To enable immediate issuance of Tsunami
Warnings / Advisories, JMA has conductedcomputer simulation of tsunamis withearthquake scenarios involving various
locations and magnitudes, and the resulting
Figure 28: Computer simulated tsunamis are stored on a
information on tsunami arrival times anddata baseheights is stored on a database. If a large Source JMA
earthquake occurs, the operation systemquickly calculates its hypocenter and magnitude, searches the tsunami database referring to thesecalculations, and selects the closest-matching results from the database. Using the estimated heightof the tsunami for each coastal region, JMA issues a Tsunami Warning/Advisory.

Figure 29: Issuing of Tsunami warning advisories
Source JMA

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Flow of information about Earthquake and Tsunami
When an earthquake occurs, the Japan Meteorological Agency (JMA) estimates the possibility oftsunami generation from seismic observation data. If disastrous waves are expected in coastal
regions, JMA issues a Tsunami Warning/Advisory for each region expected to be affected based on
estimated tsunami heights. JMA also issues information on tsunami details such as estimated arrival
times and heights.

Figure 30: Flow of information, earthquake and tsunami
Source JMA

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Tsunami Warning/Advisory
When an earthquake occurs that could generate a disastrous tsunami in coastal regions of Japan,
JMA issues Major Tsunami Warnings, Tsunami Warnings and/or Tsunami Advisories for individual
regions based on estimated tsunami heights around three minutes after the quake (or as early as two
minutes in some cases).
Immediately after an earthquake occurs, JMA promptly establishes its location, magnitude and therelated tsunami risk. However, it takes time to determine the exact scale of earthquakes with amagnitude of 8 or more. In such cases, JMA issues an initial warning based on the predefined
maximum magnitude to avoid underestimation.
When such values are used, estimated maximum tsunami heights are expressed in qualitative terms
such as "Huge" and "High" in initial warnings rather than as quantitative expressions. Once the exact
magnitude is determined, JMA updates the warning with estimated maximum tsunami heights
expressed in quantitative terms.

Figure 31: Tsunami warning / Advisory categories and action to be taken
Source JMA

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Tsunami Information
When Tsunami Warnings and/or Advisories are issued, Tsunami Information bulletins on matterssuch as estimated tsunami heights and arrival times are subsequently issued.
Messages about tsunami

Indication

Tsunami Information(Estimated Tsunami Arrival
Time and Height)

Estimated arrival times and heights of the tsunami for relevant tsunami
forecast regions.
* The estimated tsunami arrival time for each tsunami forecast regionis the time at which it is expected to hit first in any part of that area.
Hence, in some coastal regions, tsunamis may hit after the estimatedtime.

Tsunami Information(High Tide Time andEstimated Tsunami Arrival
Time at each place)

The high tide times and estimated arrival times of the tsunami atselected points.

Tsunami Information (*1)
(Tsunami Observations)Arrival times and heights of the tsunami observed at tide gauges ortsunami meters.

Tsunami Information (*2)
(Tsunami Observations at
Offshore Gauges)

Tsunami arrival times and heights observed at offshore gauges, andrelated tsunami heights along the coast in the corresponding forecast
region estimated from offshore observations.

(*1)Issuance of Tsunami Information based on Tsunami Observations
JMA announces the arrival times and initial movement of the first observed waves in coastal areas,
and also provides information on the arrival times and scale of the highest waves observed as of thetime of issuance.
As tsunami waves can hit repeatedly and those arriving later may be higher, it is inadvisable toabandon evacuation if the initially observed waves are small. Accordingly, when a Major Tsunami
Warning and/or a Tsunami Warning is in effect and observed tsunamis appear much smaller thanestimated, JMA uses the phrase "Currently Observing" rather than actual values to keep people
aware that higher waves may still approach.
Expressions used for observed maximum heights in coastal areas
Warnings/advisories in
effectMajor Tsunami Warning
Tsunami Warning
Tsunami Advisory

Observed heights

Information bulletin expressions

Height ＞ 1 m
Height ≦ 1 m
Height ≧ 0.2 m

Actual values

Height ＜ 0.2 m"Currently Observing" announcements(all cases)"Currently Observing" announcements
Actual values
Actual values("Slight" for very small waves)

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Visiting Researcher Program FY2014B(*2)Issuance of Tsunami Information based on Tsunami Observations at Offshore
GaugesJMA announces the arrival times and initial movements of the first observed waves offshore, andalso provides information on the arrival times and scale of the highest waves observed as of the timeof issuance. JMA also announces estimated data for tsunami waves in coastal areas (arrival times of
initial waves and arrival times/heights of maximum waves) for each tsunami forecast region expected
to be affected.
JMA does not provide actual values for observed tsunami heights offshore or estimated maximum
tsunami heights for coastal areas until the thresholds for issuance are reached (in the same way as
those for coastal areas) in consideration of the related influence on people's evacuation. When a
Major Tsunami Warning and/or a Tsunami Warning is in effect and estimated tsunami heights forcoastal areas are small, JMA uses the phrase "Currently Observing" for observed heights offshore and"Currently Investigating" for estimated heights in coastal areas to keep people aware that higher
waves may still approach.

Expressions used for observed maximum heights at offshore gauges and estimated maximum heights
in coastal areas.
Warnings/advisories in
effectEstimated tsunami
heights for coastal
areas
Height ＞ 3 m

Major Tsunami Warning
Height ≦ 3 m
Height ＞ 1 m
Tsunami Warning
Height ≦ 1 m
Tsunami Advisory(all cases)

Information bulletin expressions
Actual values for observed heights at offshoregauges and estimated heights in coastal areas"Currently Observing" for offshore observations and"Currently Investigating" for estimated heights incoastal areas
Actual values for observed heights at offshoregauges and estimated heights in coastal areas"Currently Observing" for offshore observations and"Currently Investigating" for estimated heights incoastal areas
Actual values for observed heights at offshoregauges and estimated heights in coastal areas

For gauges more than 100 km offshore, JMA does not announce the relevant estimated tsunami
heights for coastal areas due to the difficulty of determining which tsunami forecast regions waves
will reach from offshore gauges. Announcement of tsunami heights observed at such gauges is begun
when JMA issues an information bulletin detailing actual values for observed and estimated heightsfrom other offshore gauges closer to the coast. Until this time, the phrase "Currently Observing" isused.

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Tsunami Forecast
After an earthquake occurs, if no damage is expected, JMA issues Tsunami Forecasts.
Forecasted sea level changes
Message
No tsunami is expected"No tsunami is expected." (To be included in Earthquake Information.)
Tsunami height less than 0.2 No damage is expected because sea level changes will be less than 0.2
meters is expected
m, and no special action is needed.
Slight sea level changes are
expected to continue
Particular attention is needed when fishing, swimming or engaging inafter Tsunami
other marine activities because tsunami-related sea level changes
Warnings/advisories are have been observed and may continue for a while.
clearedObservation, Forecasting and Warning of Disaster Risks
Observation systems that can accurately detect disaster risks in real-time have been progressively
improved for establishing early warning systems, supporting early evacuation and response activities,
and thereby reducing disaster damage. Organizations involved in disaster reduction, especially the
JMA, use 24-hour systems to carefully monitor various natural phenomena and weather conditions.
In addition to observed information the JMA issues a wide range of forecasts, warnings andadvisories. Furthermore, in August 2013, it started to issue “Emergency Warnings” in case that asevere disaster far exceeding the past level of issuing warnings is anticipated.

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Information and communication system

Issuing Evacuation Advisory and Order
When a disaster occurs or is imminent, residents may start evacuating on their own volition, and themayor of the municipality may also issue an evacuation advisory or order. It is effective formunicipalities to prepare a manual explaining the criteria regarding disaster situations that require
the issuance of evacuation advisories or orders, including under what situation and to what area,
thereby helping the mayor’s quick decision.
The Cabinet Office, with new disaster management information being released and lessons from pastdisasters, has revised the “Guidelines for Producing a Decision and Dissemination Manual for
Evacuation Advisories and Orders” entirely in April 2013, and has requested that each local
government review and revise its criteria for issuing advisories or orders for evacuation.
Also, it has requested relevant prefectural and national entities to proactively give advice in theefforts of municipalities making such revision.
The new guidelines place an emphasis on making it easy to understand the criteria for issuingadvisories or orders for evacuation, and urges municipalities to issue them early enough without fearof resulting in unnecessary action.
Efforts will be to support, in full cooperation with relevant entities, the municipalities to understandand recognize the purpose of this guideline and make progress in amending the criteria for issuing
evacuation advisories or orders.

Figure 32: Early Warning System
Source – Cabinet office, Government of Japan

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Central Disaster Prevention Radio Network
The development of a quick and accurate communications system is essential for the effective use ofdisaster early warning information.
For this purpose an online system has been built, linking the JMA with disaster management
organizations of the national and local governments and media organizations.
Disaster management organizations have also been developing radio communications networks
exclusively for disasters: the CAO's Disaster Prevention Radio Communication System, whichconnects national organizations; the Fire Disaster Management Radio Communication System, whichconnects firefighting organizations across the country; and prefectural and municipal disastermanagement radio communications systems, which connect local disaster management
organizations and residents.
The Cabinet Office has established the CAO's Disaster Prevention Radio Communication System tolink with designated government organizations, designated public corporations and prefectural
governments, providing communications by telephone, fax, data transmission, video conferencing
and video transmission of disaster situations from helicopters and other sources.
Simultaneous wireless communications systems using outdoor loudspeakers and indoor radio
receivers are used to disseminate disaster information to residents. Tsunami and severe weather
warnings are widely provided to citizens via TV and radio broadcasts.

Figure 33: Disaster Pretension communication syste
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Dissemination of Forecast and EW
In order to prevent and mitigate damage caused by natural disasters and support prompt disasterprevention activities, JMA disseminates weather information and warnings via various channels togovernment disaster prevention agencies, local governments, the mass media and the public. For thispurpose, the Agency maintains direct communication links with meteorological offices andcentral/local governments. Strong communication with municipal governments that play direct roles
in disaster management and mitigation in affected areas is essential. Such communication is ensured
via various channels for information dissemination, such as prefectural governments, NTT (Nippon
Telegraph and Telephone Corporation), J-ALERT (an instant information broadcasting system
introduced by the Fire and Disaster Management Agency (FDMA) and the Internet. To support
prompt disaster mitigation activities by local governments, the Agency has introduced a new
information provision system called the Information Network for Disaster Prevention (INDiP), whichenables effective and rapid dissemination of data in both text and graphic form. INDiP connects
disaster prevention agencies and local governments with JMA headquarters via the Internet andprovides detailed weather information and warnings tailored to individual municipalities.
Information for maritime users is transmitted via the JMH radio facsimile broadcast service operated
by JMA and fishery radio communications services. Such information is also disseminated within theframework of the Global Maritime Distress and Safety System (GMDSS), i.e. via the NAVTEX
broadcast service of the Japan Coast Guard for seas in the vicinity of Japan, and via the Safety-Net
broadcast service for ships in the high seas via the maritime satellite INMARSAT. Nowadays, theInternet plays a vital role for JMA in the public dissemination of a wide range of meteorologicalinformation not only on forecasts but also on historical and current observation data.

Figure 34: Flow of information from JMA to the public

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J-Alert System
J-Alert is the system to immediately transmit emergency information such as Emergency Earthquake
information, tsunami warning, information of ballistic missiles, which people have no enough time todeal with, is transmitted to the municipalities by using satellite (via the Fire and Disaster
Management Agency, the Cabinet Secretariat, and JMA). It became operational on 09 February 2007
and on 01 October 2007 started sending the emergency earthquake information. As of first March
2010, 344 municipalities have introduced this system. Among them, automatic activation system ofradio broadcasting and community FM has been introduced to 282 municipalities.

Figure 35: J-Alert system

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Distant Earthquake Information and International Tsunami
Advisories
JMA monitors seismic activity not only around Japan but also worldwide. If a tsunami generated by adistant earthquake is expected to hit the Japanese coast and possibly cause disastrous conditions,
JMA issues Tsunami Warnings/Advisories in the same way as for local tsunamis. When a major
earthquake occurs somewhere far from Japan, the Agency issues Distant Earthquake Information to
the public.
Tsunamis spread ocean-wide regardless of the borders of countries, and can cause serious damage in
multiple coastal areas. In order to protect human life and property against tsunami hazards, we must
work together with overseas related organizations. Within a worldwide framework for a tsunami
warning system, countries exchange observational data and information to enable
earthquake/tsunami detection and measures against expected tsunamis as early as possible. Japan
has a wealth of experience and knowledge on tsunamis, and JMA, in such an international
partnership role, plays a major part in contributing to tsunami disaster management measures inother countries. When a large earthquake occurs in the Sea of Japan, the northwestern Paciﬁc region
or the Indian Ocean, the Agency analyzes the related observation data and quickly provides
International Tsunami Advisories to the countries in each region. These advisories contain
information on the earthquake and the possibility of tsunamis, and are used in the recipient
countries for the implementation of emergency action such as nationwide tsunami warnings andoﬃcial evacuation.

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Visiting Researcher Program FY2014B

Recommendations when Developing an Early Warning
System
Early Warning Systems plays a major role in saving human lives and reduce economic losses caused
due to natural disasters such as earthquakes, floods, tsunamis, landslides, and other events. And it
gives time for people living on risk areas to escape to higher ground, protecting themselves fromfalling objects and stopping trains before they are overtaken by these events. But it’s important tostart early warning systems in sustainable way for them to have a positive effect on the community
on the long run.
Link with community-based activities: Warning systems and other measures organized bycommunities may be particularly relevant in developing countries where government capacity andresources are limited.
Start with low-cost systems: Start Warning systems with simple methods. Low-cost equipment, suchas fire bells and sirens can be used. And they can evolve by replacing equipment, such as automatic
monitoring equipment and telemeter systems, based on these basic systems.
Conduct Communication drills: Communities, governments, and experts should exchange
information and ideas about potential risks. Communities should be able to understand theinformation delivered in the warning, while also being aware of the system’s limitations. Also,
government staff must understand communities’ response to disasters to design warning systems.
Understand the limitations of technology: Although various technologies, such as flood prediction,
tsunami simulations, communication systems, and earthquake monitoring are all needed to develop
effective warning systems, their limitations must be taken into account.
Guidelines for quick decision making: disaster related organizations and government agencies
should have a user manual or SOP for quick decision making. explaining when to disseminate theevacuation orders.
Understand communities’ coping mechanisms: Since warning systems are meant to benefit
communities on the ground and to inform their actions, the responsible organizations should
understand how local people cope with and respond to disasters. Community members decide on
their own when, where, and how to escape. The organizations should tailor the contents of warning
messages to the users’ needs and points of view. Such messages need to be simple, timely, andencourage evacuation.
Establish uninterrupted systems: To ensure that warnings reach the communities at risk. Multiple
communication channels should be established so that information keeps flowing in case of powerand communication failures. (eg: SMS, loudspeakers, sirens.. etc)
Ensure services are available 24/7: Since natural events can happen at any time, the organizations
concerned are required to function around the clock—24 hours a day, 7 days a week. Staff duty
rotation should be arranged in the organizations.

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Reference
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Asia Watch:About Asia:Japan. (n.d.). Retrieved March 2, 2015, from http://asiawatch.info/eg/html/aboutasia/aboutasia_japan.html
brochure201203.pdf. (n.d.). Retrieved fromhttp://www.jma.go.jp/jma/en/Activities/brochure201203.pdf
corporateName=Bureau of Meteorology; address=GPO Box 1289, M. (n.d.). Joint Australian Tsunami
Warning Centre. Retrieved March 9, 2015, from http://www.bom.gov.au/tsunami/info/
Environmental Management and Disaster Preparedness: Lessons Learnt from the Tokage Typhoon(Typhoon 23 of 2004) in Japan. (2005). UNEP/Earthprint.
Giz Explains: How Earthquake And Tsunami Warning Systems Work. (n.d.). Retrieved March 30,
2015, from http://www.gizmodo.com.au/2011/03/giz-explains-how-earthquake-and-tsunamiwarning-systems-work/
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Japan in a subduction zone (1) -- GLGArcs. (n.d.). Retrieved April 3, 2015, fromhttp://www.glgarcs.net/intro/subduction.html
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PAPER FORMAT FOR THE INTERNATIONAL SYMPOSIUM on MANAGEMENTS SYSTEMSFOR DISASTER PREVENTION - IWPM_Kazusa.pdf. (n.d.). Retrieved fromhttp://management.kochi-tech.ac.jp/PDF/IWPM/IWPM_Kazusa.pdf
Rauhala, E. (2011, March 11). How Japan Became a Leader in Disaster Preparation. Time. Retrieved
from http://content.time.com/time/world/article/0,8599,2058390,00.html
Reviews, C. T. (2012). e-Study Guide for: Diversity Amid Globalization by Rowntree, ISBN
9780131330467. Cram101 Textbook Reviews.
Tsunami 101: How a Tsunami Forms. (n.d.). Retrieved March 9, 2015, fromhttp://www.canadiangeographic.ca/tsunami/tsunamis101.asp
TSUNAMI MALDIVES LAYOUT - TSUNAMI_MALDIVES_LAYOUT.pdf. (n.d.). Retrieved fromhttp://www.unep.org/tsunami/reports/TSUNAMI_MALDIVES_LAYOUT.pdf
What We Can Learn From Japan’s Early Earthquake Warning System - viewcontent.cgi. (n.d.).
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日本の災害対策_入稿.indd - saigaipanf_e.pdf. (n.d.). Retrieved fromhttp://www.bousai.go.jp/1info/pdf/saigaipanf_e.pdf

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