Post: Sunday August 23, 2015
It is not only earthquakes that you may need to keep in your mind as risks of natural disasters in Japan. Because of sea temperature level rise due to global warming in recent years, typhoons originate closer to Japan and are becoming more powerful.
Tropic storms which arise from tropic depressions are called "typhoons" in Japan and Eastern Asia. They are also called as "hurricanes" in North and Central America and "cyclones" in other regions. In Japan, a tropic depression with the maximum wind speed (MWS) faster than 33kt is called "Taifu". Internationally, any tropic depressions with MWS 64kt or faster are called as "Typhoon."
Scale of Typhoon
|Scale||The radius of the area where Wind Speed is faster than 15m/s|
|N/A||Smaller than 500km|
|Large||Larger than 500km but smaller than 800km|
|Huge||800km or larger|
|Max wind speed||Categorization in Japan||International Categorization|
|～17 m/s (33 kt)||Tropical Depression||Tropical Depression|
|17 m/s (34 kt) – 25 m/s (48 kt)||Taifu||Tropical Storm|
|25 m/s (48 kt) – 33 m/s (64 kt)||Taifu||Serve Tropical Storm|
|33 m/s (64 kt) – 44 m/s (85 kt)||Taifu (strong Tsuyoi)||Typhoon|
|44 m/s (85 kt) – 54 m/s (105 kt)||Taifu (very strong Hijoni tsuyoi)||Typhoon|
|54 m/s (105 kt)～||Taifu (violent Mo-retsuna)||Typhoon|
From Japan Meteoroidal Agency website Wind speed: m/s (meter/second) fu-soku, kt (knots) notto
On the news and weather forecast, a typhoon is normally described as "a large and very strong typhoon," etc.
When the Meteoroidal Agency announces the warning ("Keiho") or the advisory ("Chuiho"), please pay attention and be cautions.
Major warnings expected at the time of typhoon
|Type of alarms|
|Heavy rain warning
|It is announced when there is a risk of severe disasters due to heavy rain.Such disasters include severe inundation and severe sliding.|
|It is announced when there is a risk of severe disasters because river water levels rising due to heavy rain, continual rain, snow melting, etc.Such disasters include the rise or overflow of the river, damages or breakages of the dike, etc.|
|It is announced when there is a risk of severe disasters due to violent wind.|
|High surf warning
|It is announced when there is a risk of severe disasters due to high surf.
The "high surf" totally differs from "tsunami" appears after earthquakes.
|High tide warning
|It is announced when there is a risk of severe disasters due to the sea level rise caused by a typhoon or low atmospheric pressure.|
From Japan Meteoroidal Agency website
A gauge for the strength of wind speed
- 20m/s wind speed: People cannot stand straight easily, and driving a car can be dangerous.
- 25m/s wind speed: Trees can be torn down from the roots.
Weather warnings and alarms for the Kanto district
>> http://www.jma.go.jp/en/warn/206.html (English)
When an warning or advisory is announced
These are five rules of thumb to remember to take the appropriate action in the event of a storm or flood at home.
1. Prepare outside the house
Shut windows and shutters, secure things which can fall or be blown away, and clean places with poor drainage.
2. Prepare inside the house
Check emergency supplies (See appendix), and affix tape over glass to prevent glass from scattering causing shards.
3. Pay attention to storm/flood information
Listen to the latest weather warnings, alarms and evacuation information from the television and radio.
4. Evacuate at an early stage
Do not delay in evacuating when an evacuation advisory is issued or you feel in danger.
Please check the evacuation method and the location of an evacuation site in advance as they vary depending on local administrative offices.
5. Do not approach dangerous places
Do not approach places where the riverbed is high, or where a flood or landslide may occur.
Examples of dangerous places
[In case of high tide]
Shallow beach or harbor area, river mouth areas;
Around shallow beaches where water can deepen quickly and areas around harbors are vulnerable to high water conditions.
Coastal areas below sea level;
Stay away from areas that are below average sea level at full tide. Levee breaks may cause serious disaster.
[In case of flooding]
Exercise extreme caution because deltas (made of sediment carried by the river and deposited at the mouth of a river) and floodplains (area made of deposited sand carried by consistent floods) can flood easily.
River basins and dry riverbeds can have a danger of flooding during downpours.
[In case of sliding]
Developed land that was made by breaking up hillsides may contain unstable soil and terrain. These areas may slide when downpours loosen the ground.
Torrential downpours may cause mountain landslides, and alluvial cones at the foot of a mountain may receive a direct hit.
Steep sloping lands of greater than 30° angles and taller than 5m may landslide when there is rain. There is danger of mudslides at treeless mountains.
From Tokyo Metropolitan Government website
This entry was posted in Living Information