Heavy Rain / Strong Wind
Earthquakes are not the only disasters
that can strike Tokyo. Many various
risks can be assumed, from natural
disasters such as heavy rain, storms
and torrential rain, to human threats
such as terrorist and armed attacks.
In this chapter, we have compiled
knowledge on the various risks that
lurk in Tokyo and measures to deal with
them. Learn about them now so you can
Terrorist and Armed Attacks
Heavy Rain and Storms
Pay attention to the latest weather information
The Meteorological Agency will issue advisories when
there is the possibility of disasters occurring from
heavy rainfall or strong winds, etc. Pay attention to
evacuation preparation information announced by the
municipalities. And, in districts that are easily affected
by rain and wind, people who need special support in
evacuating should be ready to move early.
Details → p. 246
Warnings are issued when there is the possibility of a
major disaster occurring, with the relevant areas called
upon to exercise caution. Pay attention to evacuation
information issued by municipalities, and evacuate
quickly if necessary.
Details → p. 246
An emergency warning is issued when there is a
heightening danger of a serious disaster of a scale that
Importance of preparing in advance for floods and
occurs only once every few decades, which will far
exceed the criteria for issuing a warning. You should
Stationary rain fronts in early summer and fall often cause heavy
immediately move to a safe place.
rainfall. In addition, over the past
30 years (1981-2010), there has
Details → p. 247
been an average of 26 typhoons a year. If these typhoons approach or
land on Tokyo, extremely strong winds and heavy rainfall could result
in inundation and river flooding. You should always check the latest
weather information and protect yourself from disasters. Confirm in
advance what places are at high risk by checking the hazard map, etc.
Weather conditions that require special caution
Places requiring special caution
Spring - mid Summer (stationary front)
During the seasonal transition from spring to mid-summer,
The lowlands have the risk of flooding from heavy
the stationary front (Baiu front) appears from Japan to near
rainfall. Caution is necessary because it could become
the Chinese continent. When the ground is weakened by
difficult to see the location of gutters, etc.
the long rains brought by this front, heavy rainfall could
easily trigger sediment disasters.
Summer - Fall (stationary front)
Basements and semi-basements
In the seasonal transition from summer to fall, pressure
Buildings that have basements or semi-basements, or are
patterns become similar to the Baiu front, with the stationary
located on land that is lower than the road, are inclined to
front appearing near Japan bringing about long or heavy
have more flooding damage due to torrential rainfall. Prepare
rainfall that can result in road flooding and other incidents.
sandbags, water stops and other items to prevent flooding, and
evacuate before you feel endangered.
July - October (typhoon)
The number of typhoons approaching or landing in
Tokyo increases in the period from July to October,
Do not approach rivers as they have the risk of
making it necessary to be cautious of heavy rainfall and
overflowing from heavy rainfall. If you live along a
strong winds. For example, Typhoon No. 15 in 2011
river, listen to local disaster information, etc., and be
caused roadside trees in Shibuya and Ginza to fall over,
prepared to evacuate immediately.
and affected commuters by stopping train operations.
Storm surge (coastal areas)
Tokyo is located at the innermost part of Tokyo
In areas near cliffs and mountainous areas, beware of
Bay. Because the mouth of the bay is located on the
sediment disasters. Even if no warning has been issued,
southwestern side, and because the water is relatively
if you see the signs of a sediment disaster, secure your
shallow, Tokyo is very susceptible to storm surge
safety and evacuate.
damage. Other than storm surge due to typhoons,
Details → p. 152
you should also beware of tsunamis generated by
Protect yourself from wind and flood damages
Listen to information issued by the authorities
Wait until the typhoon passes
The Meteorological Agency and local governments issue
If you are outside when a typhoon is approaching, wait
disaster information over the TV, radio, and other media,
inside a nearby facility until it passes. If you are at
and the municipalities use the wireless emergency
home, refrain from going out. It will also be dangerous
alert system to issue evacuation advisories and orders.
to go out to repair roofs or windows.
When your local government has issued evacuation
information, secure your safety and evacuate.
Know the location of places at risk of flooding
t use the elevator
The Tokyo Metropolitan Government has released a
If strong winds cut power lines, the resulting power
map showing districts at risk of flooding to let everyone
failure could trap you in the elevator. Use the stairs to
know the risk of flood from typhoons, etc., so they can
all possible extent in the event of a typhoon or heavy
prepare for floods and quickly evacuate. Make it a habit
to confirm what places are susceptible to flooding.
Evacuate before water comes up to your knees
Check and clean drainage facilities
Water up to your knees can be considered a yardstick for
Trash, etc., accumulating in catch basins and gutters
how high water can come before it becomes difficult to
prevent rainwater from flowing and increase the risk
walk in a flood. And even though the water may not be
of flooding. In basements and semi-basements, there is
that deep, as there is also the danger of being unable to
also the risk of flooding if drainage pumps malfunction.
move due to a strong flow of water, when you see water
Make it a point to routinely check and clean the drainage
flowing in, evacuate immediately to a high place.
Evacuate from underground to a higher place
Simple ways to prevent flooding
Evacuation could become difficult if water flows into
Use sandbags, water bags, and water stops to prepare for
levels underground due to flooding above ground. Go to
flooding. You can also align simple water bags, in which
a designated evacuation area or go to the ground level
garbage bags are half filled with water, or use a long
and evacuate to a sturdy building nearby that is at least
plank as a water stop, to prevent flooding.
two stories high. In this way, evacuate to a safer place.
Protect yourself from torrential rain
Stay away from rivers and canals
Never approach rivers or canals when a torrential
downpour occurs as there is the potential for waters to
rise and a powerful flow to be generated.
t use roads below the ground level
When torrential rain occurs, do not use an underground
walkway or an underpass—the road below ground
level at a grade separated crossing—because they could
Evacuate basements and semi-basements
Houses with a basement or semi-basement—housing
with a floor completely or partially below ground
level—are prone to becoming submerged. Doors to a
basement could also become difficult to open due to
pressure from the water, trapping you, so evacuate to a
safer place such as the second floor.
Torrential rain occurs suddenly
In general, river facilities and sewerage systems in urban areas are created to withstand
Submerged roads are dangerous
rainfall of 50 mm per hour. Rainfall exceeding this level could cause urban flooding. It
Submerged roads and paths are dangerous because you
is said that urban flooding occurs because of a river basin’s lowered capacity to contain
could fall into a manhole or gutter whose cover has been
and retain water as a result of the ground being covered by asphalt pavement and the
displaced. If you have to go through a submerged zone,
increased use of underground space. Following signs such as a growing cumulonimbus
walk carefully while feeling your way with an object
cloud, approaching black clouds, and roaring thunder, torrential rain can strike a city
like an umbrella.
in an instant.
Signs of an impending sediment disaster
Protect yourself from a sediment disaster
Confirm your evacuation area
Signs are cracks on cliffs, small stones falling down,
Regularly talk with your family about your designated
water welling up on cliffs, spring water stopping or
evacuation area and how to contact each other, and confirm
becoming cloudy or muddy, being able to hear the earth
your evacuation routes. When you evacuate, keep your
baggage to a minimum so that you can keep your hands free.
Prepare an emergency bag
Signs are cracks and sinkholes in the earth, the ground
Prepare a hazard map, a map of your evacuation area,
developing clefts and becoming uneven, water spurting
and an emergency bag. If you feel in danger, change into
from cliffs and slopes, water in wells and streams
clothes that are easy to move around in, and be ready to
becoming cloudy or muddy, sounds of rumbling from
evacuate any time.
the earth or mountain, trees leaning, etc.
Check for sediment disaster hazard areas
Signs are sounds of rumbling from the mountain,
The Tokyo Metropolitan Government’s Bureau of
river water suddenly becoming cloudy or muddy and
Construction’s website provides a map of sediment
containing driftwood, an unpleasant earthy smell, river
disaster hazard areas with which you can search for
level becoming lower despite continuous rainfall, sound
hazard areas by region. Confirm in advance hazard areas
of trees being torn and stones bumping into each other,
in your neighborhood.
(in Japanese only)
Areas where you must be cautious
Open areas such as a playing field, golf course, outdoor swimming pool, riverbank,
beach, and on the sea can be dangerous. You also need to be on alert when you are in a
high place, such as at the top of a mountain or ridge.
Stay away from tall objects like trees
Lightning often strikes tall objects like trees and tall,
protruding objects. Therefore, when you are close to a
tree, especially, keep at least 2 meters away from the
tree (trunk, branches and leaves).
In an open space
It is dangerous to be in an open space like a playing
field, because lightning could directly strike you.
Quickly move to a safe place, such as a reinforced
concrete building, car, bus, or train.
s no safe place nearby
Lightning can be life-threatening
If you cannot find a safe place nearby, take shelter at
Lightning can be life-threatening. Although high places and tall, protruding objects
least 4 meters away from any tall object such as a utility
attract lightning, more than half of those killed by lightning were actually in open
pole. Maintain a low posture and make sure that nothing
areas such as a golf course, or under a tree taking shelter from the rain. If you hear
in your possession protrudes into the air.
thunder or see thunderclouds approaching, quickly move to a safe place, such as a
reinforced concrete building, car, bus, or train.
Protect yourself when a tornado strikes
If you are inside
In a detached home, move to a room on the first floor
that has few windows in order to avoid broken window
glass and projectiles. Close the storm shutters and
curtains, move away from windows, and remain under a
sturdy table until the tornado passes.
If you are outside
Move inside a sturdy building or underground facility to
avoid wind gusts and objects flying through the air. In
the event you are not near any of these structures, take
cover or hide in a ditch, and wait for the tornado to pass.
Check the areas where tornadoes are forecast
You can check areas where there is the probability of
strong wind gusts, including tornadoes, ahead of time
by viewing the Radar and Nowcasts weather map on the
Japan Meteorological Agency’s homepage and clicking
Tornadoes can occur anywhere in Japan
Even in Japan, damage inflicted by tornadoes is occurring frequently in recent
years. Although tornadoes occur at any time of year, more tornadoes are seen
particularly during the typhoon season months of September and October.
When a tornado forms, violent winds swirling at the center of the storm, pick
up debris from the ground, including materials from buildings and signs, and
turn these objects into dangerous projectiles, causing serious damage at times.
To avoid danger, enter a sturdy building such as a reinforced concrete building
or an underground facility and wait for the storm to pass.
Protect yourself from heavy snow
Avoid going out
If heavy snow is forecast, stockpile enough food so that
you will not need to leave home, and make preparations
to stay warm without electricity in case of a power
Be careful not to slip
When it snows and afterwards, roads become extremely
slippery. If you go outside, put on slip resistant footwear
such as snow boots, and be very careful as you walk. Do
not ride bicycles or use cars.
When using a car
Refrain from using a car as much as possible. If you
must drive, change your tires to winter tires for use
on snowy and icy roads, and prepare a shovel, boots,
blanket, and emergency food. Be sure to maintain at
least double the distance between vehicles that you
normally would, as sudden braking and abrupt steering
is extremely dangerous.
Heavy snow can paralyze a city
Points to be aware of when shoveling or
The Japan Meteorological Agency predicts that although snowfall frequency
and amounts are decreasing, if snow does fall, there is the possibility that it will
When shoveling snow or removing it from your roof,
become heavy snow. When snowfall is heavy, public transportation may shut down,
use equipment such as safety lines and helmets, put on
expressways may close, and there is even the possibility that ordinary roads will
slip resistant footwear, and always work in a groups of
become impassable. When heavy snow is forecast, you should return home as soon as
two or more. Since snow that has accumulated on the
possible and avoid going out again. Heavy snowfall in February 2014 not only caused
roof loosens as it melts on sunny days, take care to avoid
chaos for the transportation system, but also made roads in the Tama area impassable,
snow that slides off the roof.
resulting in some outlying villages becoming cut off.
Protect yourself from a volcanic eruption
Confirm the dangerous areas on the disaster
In order to protect yourself from a volcanic disaster,
it is important that you confirm the dangerous areas
and evacuation centers beforehand using disaster
prevention maps (shows dangerous spots, evacuation
routes, evacuation centers, etc.) made public by the
municipality or others.
Prepare food and items for a disaster
When a volcano erupts, the ashes may affect logistics
and lifelines. Prepare drinking water, food, flashlights,
extra fuel, and other necessities. It would also be better
if you prepare helmets, masks and goggles as protection
Confirm the designated evacuation center
When an evacuation order or advisory is issued due to
a volcanic eruption, quickly evacuate to the municipal
government’s designated evacuation center. Confirm in
advance the location of the designated evacuation center
Tokyo has 21 active volcanoes
nearest to you.
Tokyo has 21 active volcanoes on its islands such as Izu Oshima and Miyakejima, and
people are living on eight of those volcanic islands (Izu Oshima, Toshima, Niijima,
Kozushima, Miyakejima, Mikurajima, Hachijojima, Aogashima). In recent years,
eruptions on Izu Oshima in 1986 and Miyakejima in 2000, led to the evacuation of
all the residents from the islands. In November 2013, a phreatomagmatic eruption
was observed on Nishinoshima island of the Ogasawara islands, and the lava flow
increased the island’s area.
Details → p. 251
Be careful of volcanic ash
t overlook volcanic warnings
When the volcano erupts, volcanic ash will fall along
with large and small cinders. Breathing in ash will affect
When the Meteorological Agency announces a volcanic
the respiratory system causing coughing or breathing
warning, restrictions on mountain entry, evacuation
difficulties, and will also cause eyes to become itchy,
orders and evacuation advisories will be issued. Follow
painful or bloodshot. Protect yourself with dust masks
the instructions. If you feel even slightly endangered,
and goggles. Since volcanic ash could also cause
malfunctioning of the sewage system, do not flush ashes
down the sewer.
If an eruption occurs
Put on protective headwear such as a helmet, and while
taking steps to prevent yourself from inhaling volcanic
ash and gases such as holding a towel to your mouth,
quickly move away from the mouth of the volcano.
Volcanic alert level
The volcanic alert levels in volcanic forecasts/warnings
are classified from 1 to 5 according to the degree of
danger. Take actions suitable to the level.
Evacuate from the residential area
Prepare to evacuate from the residential
Do not enter the danger zone near the
Risk of Mt. Fuji erupting and expected damage
Do not enter the area around the crater
If Mt. Fuji erupts as it did in 1707, volcanic ash will fall on a wide area of the Kanto
No special response is necessary but
caution is required
region, and it is estimated that a few centimeters to 10 centimeters of ash will fall
on Tokyo. Ashes will not only affect the transportation system, lifelines, and the
agriculture, forestry, and fisheries industries, but could also affect health. If Mt. Fuji
erupts, confirm the ash fallout forecasts on the Meteorological Agency website and
others, and make preparations in advance if you are in an area that will have a large
volume of ash fallout.
Terrorist and Armed Attacks
Attack by insurgents or special forces
Such an attack can result in sudden, unpredictable damages.
If the target of an attack is a nuclear facility, the damages
could be huge.
It would be extremely difficult to identify the target of
the attack, and it is estimated that the time to impact will
Landing invasion and air attacks
In an invasion, landing operations are likely to target the
coastal areas, and air attacks are also assumed to target
major facilities in urban areas.
Danger of terrorist and armed attacks
As Tokyo is the center of government and economy, it could become the target of
Attacks using chemical agents, etc.
terrorist and armed attacks. The Act Concerning the Measures for Protection of the
Attacks using chemical or biological agents, or nuclear
People in Armed Attack Situations, etc. (“Civil Protection Act,” Act No. 112 of 2004)
materials will have health effects, requiring special
was enacted with the aim of protecting the lives and assets of the citizens of Japan.
Based on this act, in the event of an attack, the public will be warned through the
municipalities’ wireless emergency alert systems. Make a note to listen to information
broadcast over the TV, radio, and from publicity cars as well, and follow the
Protect yourself from a terrorist or armed attack
If an explosion occurs
Evacuation from an attack by insurgents
If an explosion occurs, quickly get low and hide under
Damages from an attack by insurgents will generally
something like a sturdy table. Explosions could continue,
be limited to a relatively small area, but the damages
so evacuate to a safe place.
may spread. First evacuate indoors and then follow the
instructions of the authorities.
Evacuation from a missile attack
If a fire breaks out
Since it will be difficult to identify the area where the
If a fire breaks out due to a terrorist or armed attack,
missiles will hit, if you are outdoors, evacuate into a
cover your mouth and nose with a handkerchief, etc., to
strong building, underground shopping area, or other
keep from inhaling smoke, and quickly evacuate while
indoor areas nearby. Afterwards, follow the instructions
keeping yourself as low as possible.
of the authorities.
Evacuation from chemical or biological attacks
Cover your mouth and nose with a handkerchief, and
leave the area immediately. Evacuate to a safe place that
Tap on pipes or other things nearby to let others
is unlikely to become contaminated such as a closed-off
know where you are. Calling out loudly for help
place indoors or high ground upwind.
should be the last resort since this could cause dust
to be breathed in.
Evacuation from a nuclear explosion or
If there is a nuclear explosion, hide behind cover
and evacuate to an underground facility or strong
building. An explosive called a “dirty bomb” will
cause radioactive contamination of the area. Follow the
instructions of the authorities and consult a physician.
Protect yourself from infection
Wash your hands and gargle
Washing your hands and gargling are fundamental to
prevent infection. Wash your hands thoroughly with
soap, including your fingertips and under your nails.
Use gloves to protect yourself when you might come in
contact with a patient’s blood, body fluids, secretions,
Use a mask
Wear a mask when you are coughing or sneezing so that
you do not infect others.
If an epidemic is forecasted
Infections occur when pathogens such as viruses or bacteria enter your body and
multiply, resulting in symptoms such as fever, diarrhea, and cough. Infectious diseases
from influenza to Ebola virus disease, from those with relatively mild symptoms
to those with a high risk of death, are designated under the Act on Prevention of
Infectious Diseases and Medical Care for Patients Suffering Infectious Diseases
(Act No. 114 of 1998). If proper response is not taken, these diseases can spread
rapidly in Tokyo with its high population density. If you think you might be infected,
immediately get proper treatment at a medical institution.
Some 10 to 20 days after infection, a fever of about 38 degrees
Celsius or common cold symptoms continue for about 2 to
3 days, followed by a high fever of over 39 degrees Celsius
and the appearance of a rash. This could become serious if the
patient develops encephalitis. Since the body’s immune system
is weakened, the patient could also develop pneumonia or an
Pay attention to your health after returning
ear infection. As there is no specific treatment for this disease,
treatment is given to lighten the symptoms.
If you feel unwell after returning from abroad, there is the risk
that you have contracted an infectious disease. Be careful if
The main symptoms are nausea, vomiting, diarrhea, stomach pain,
you have symptoms such as diarrhea or fever after your return.
and a slight fever. After these symptoms continue for about one
Go to a medical institution as soon as possible. Inform the
to two days, the disease is cured with no aftereffects. However,
in children or the elderly, the symptoms could become serious,
doctor of details such as the travel destination, itinerary, and
activity during the trip, and follow the doctor’s instructions.
with the possibility of death resulting from accidentally choking
on vomit. As there is no specific treatment for this disease,
symptomatic treatment such as intravenous fluids is given.
Know the danger of a pandemic
Even now, over 20,000 people contract this disease each year.
Go to a medical institution as soon as possible if coughing or
A pandemic is a global epidemic of an infectious
phlegm continues for over two weeks or, in the case of senior
disease. The WHO (World Health Organization)
citizens, if ailments such as fatigue or loss of appetite continue.
classifies pandemics into six phases according to its
If you are diagnosed to have tuberculosis, in most cases this can
spread. If you hear about a pandemic on TV or other
be cured if medicine is properly taken every day for six months.
sources, avoid going out unless it is essential or going
to places that attract crowds. Schools and other facilities
may be closed.
Details → p. 265
You could become infected if you have close contact with a bird
with avian flu. Symptoms such as high fever and cough will
appear if you are infected. This could rapidly cause multiple
organ dysfunctions, and result in death. If you have had contact
with a bird with avian flu and have symptoms that could be
influenza, see a doctor and inform him/her of the situation.
Symptoms of major infectious diseases and response
General symptoms (e.g. headache, joint and muscle pains) and
Ebola virus disease
Symptoms such as sudden fever, headache, fatigue, muscle pain,
specific local symptoms (e.g. sore throat, runny nose, sneezing,
sore throat, vomiting, diarrhea, chest pain, and bleeding (blood
cough) suddenly appear, and it can be fatal. If influenza anti-
in vomit, blood in stool) appear. As there is no specific treatment
viral drugs are first taken within 48 hours of the onset of
for this disease, treatment for the symptoms will be given. If you
symptoms, a reduction of the symptoms can be expected. Go to
come down with a fever within about a month after returning
a medical institution as soon as possible.
from a country where this disease was spreading, do not go to a
local medical institution, but contact the public health center and
follow its instructions.
s active volcanoes with magma activity
Nothing to fear if you can grasp
Disaster Preparedness Quiz
the warning signs
Magma is active
What is the difference between an advisory, warning, and emergency warning for heavy rain
or strong wind issued by the Japan Meteorological Agency?
Answer → p. 145
on a volcanic island
Tokyo has 21 active volcanoes. Eight of
What types of places are easily affected by heavy rain or typhoons and
these volcanic islands (Oshima, Toshima,
require special caution?
Answer → p. 147
Niijima, Kozushima, Miyakejima,
Mikurajima, Hachijojima, and
What areas should you not approach during torrential rain?
Aogashima) are inhabited by a total of
Answer → p. 151
30,000 residents and many tourists visit
Name three warning signs of a sediment disaster.
High levels of volcanic activity can be
Answer → p. 152
observed on Oshima and Miyakejima (see
When you are in an open space such as a playing field, how can you protect
p. 251), and the volcano on Hachijojima
yourself from lightning?
Answer → p. 155
almost erupted in 2002. And earthquake
and tectonic movements are still
What time of the year should you be cautious of tornadoes, and what
observed on Niijima and Kozushima.
should you do to protect yourself from them?
Answer → p. 156
Even if movements cannot be felt on the
surface, magma is steadily building up
What should you do when a heavy snow forecast is issued?
Answer → p. 159
1986 Izu Oshima ©T. Miyazaki (top);
2000 Miyakejima (bottom)
How many active volcanoes are there in Tokyo?
Answer → p. 160
Become conscious of warning signs of an eruption
But there is no need to always live in fear. Unlike earthquakes, warning signs of an eruption
What is the name of the law to protect the public from terrorist and armed
can be seen in almost all cases. When volcanic activity builds up, phenomenon that cannot be
Answer → p. 164
captured by a seismograph occur. Noticing such signs will allow safe evacuation.
What is the word used when an infectious disease spreads over a wide
For instance, residents living near a volcano might notice smoke, sounds, smells and other
Answer → p. 170
conditions that are different from usual. If they contact the municipal office right away when
they notice such things that are out of the ordinary, the authorities can bolster their observations
and prepare for an eruption. Moreover, it would be desirable for people to gain “literacy” on
volcanoes such as using a disaster protection map to decide where to evacuate if it becomes
(talk by Hidefumi Watanabe, Professor Emeritus, University of Tokyo)