Tsunami Risk Zones
Am I in danger?
Tsunami Risk Zones
Risk is often defined as a combination
of the danger posted by an event (tsunami hazard), the vulnerability of
people to an event (exposure, e.g., coastal communities), and the
likelihood of the event occurring (probability of destructive tsunami).
If you live along the coast in a tsunami hazard zone, you are at risk
from tsunamis.
All oceanic regions of the world can experience tsunamis, but in the Pacific Ocean and its marginal seas, there is a much more frequent occurrence of large, destructive tsunamis because of the many large earthquakes along the margins of the Pacific Ocean.
All oceanic regions of the world can experience tsunamis, but in the Pacific Ocean and its marginal seas, there is a much more frequent occurrence of large, destructive tsunamis because of the many large earthquakes along the margins of the Pacific Ocean.
All low lying coastal areas can be
struck by tsunamis, some of them can be very large; their height can be
as great as 10 meters or more (30 meters in extreme cases), and they can
move inland several hundreds meters, depending on the slope of the
ground.
A tsunami consists of a series of waves
with crests arriving every 5 to 60 minutes. Often the first wave may not
be the largest. The danger from a tsunami flooding and strong wave
currents can last for several hours after the arrival of the first wave.
Sometimes a tsunami initially causes the water near shore to recede,
exposing the ocean floor.
The force of some tsunamis is enormous.
Large rocks weighing several tons, along with boats and other debris,
can be moved inland hundreds of meters by tsunami wave activity, and
homes and buildings destroyed. All this material and water move with
great force, and can kill or injure people.
Tsunamis can occur at any time, day or
night, and they can travel up rivers and streams from the ocean. They
also can easily wrap around islands and be just as dangerous on coasts
not facing the source of the tsunami.
For more information on historical tsunamis, click here
Global tsunami source zones.
Tsunami hazard exist in all oceans and basins, but occur most frequently
in the Pacific Ocean. Tsunamis can occur anywhere and at any time
because earthquakes cannot be accurately predicted. Courtesy of
LDG-France.
Understanding Risk Behavior: The Fundamental Challenges
(NOAA Coastal Service Center)Human exposure to risk from coastal hazards is increasing because vulnerable coastal areas are becoming more densely populated. Coastal hazards such as hurricanes and floods are predicted to become more intense as a result of climate change. Better risk communication can save lives, protect property, lessen damage to coastal economies, and create more resilient coastal communities that recover more quickly after a disaster.
(NOAA Coastal Service Center)Human exposure to risk from coastal hazards is increasing because vulnerable coastal areas are becoming more densely populated. Coastal hazards such as hurricanes and floods are predicted to become more intense as a result of climate change. Better risk communication can save lives, protect property, lessen damage to coastal economies, and create more resilient coastal communities that recover more quickly after a disaster.
What Is Risk? Risk
is often defined as a combination of the danger posed by an event
(hazard), the vulnerability of people to an event (exposure), and the
likelihood of the event occurring (probability). But why do two people
exposed to the same level of risk behave differently? Why does one
family evacuate for an oncoming storm while other neighbors stay?
Because peoples’ behavior is also determined by their own perceptions
and their own decision- making processes.
Risk perception There
are many models and frameworks that attempt to explain how people
perceive and interpret risk. A common idea in the models is that people
perceive risk from two dimensions: what they know about the risk, and
how they feel about the risk. Feelings about risk are shaped by peoples’
past experiences, the opinions of their social networks, their level of
control over the risk, and many other factors. Risk managers tend to
pay too little attention to how people feel about the risk, focusing
instead on increasing their knowledge. Conversely, the public tends to
put a lot of emphasis on how they feel about the risk, sometimes
ignoring important messages or information.
Making decisions in the face of risk Perception
can be seen as the first step in making a decision, followed by
considering options, calculating which option is in your best interest,
and then taking action. As with risk perception, psychological and
social factors such as the decisions of friends and family, as well as
physical circumstances such as mobility and access to transportation,
impact how a person weighs the costs and benefits of different options.
Many people use intuition or “rules of thumb” to make decisions, which
can be helpful or harmful. Decision-making is rarely limited to two
mutually exclusive options; there are often many alternate paths.
Risk Communication Risk
communication is a critical component of risk management. The ultimate
goal of risk communication is generally to change peoples’ behavior in a
given situation. And because research has repeatedly shown that
behavior change is rarely achieved without highly tailored and carefully
crafted messages, a keen understanding of audiences and their
situations is essential to success:http://itic.ioc-unesco.org/index.php?option=com_content&view=category&id=1166&Itemid=1166
Gefahren
Die primäre Gefahr bei einem Beben besteht in den Auswirkungen der Bodenbewegungen. Neben der direkten Beschädigung der Gebäude durch die Erschütterungen selbst kann der Baugrund, auf dem die Gebäude stehen, in Mitleidenschaft gezogen werden. Gebäude können sogar in den Boden einsinken, wenn eine Bodenverflüssigung eintritt, bei der lockere Sande und Grundwasser durcheinandergeschüttelt werden, so daß der Boden ähnlich wie Treibsand reagiert. Nach dem Beben verfestigt sich dieser Boden dann wieder. Besonders gefährdet sind hier meist Flußtäler und Uferbereiche. Starke Oberflächenwellen können durch ihre großen Bewegungsamplituden Gebäude beschädigen. Als Folge der Bodenerschütterungen können auch Erdrutsche und Schlammlawinen ausgelöst werden, wodurch es dann zu weiteren Folgeschäden kommen kann..
Die zweite Gefahr ist die bleibende Bodenverschiebung bei sehr starken Beben. Gebäude, die in unmittelbarer Nähe von Verwerfungen stehen, können hierdurch starke Schäden erleiden.
Die dritte Gefahr besteht in Flutwellen. Erdbeben können Staudämme zerstören oder Deiche beschädigen, was zerstörerische Überflutungen zur Folge haben kann. Bei Seebeben können Tsunamis entstehen. Tsunamis sind Flutwellen, hervorgerufen meist durch Vertikalbewegungen des Meeresbodens. Sie können sich über ganze Ozeane ausbreiten und in Küstenregionen zu Flutwellen von mehreren zehnermetern Höhe führen.
Die vierte Gefahrenquelle liegt in Bränden. Beben können Ver- und Entsorgungslinien zerstören. Insbesondere beim Bruch von Gasleitungen können Brände entstehen. Diese Brände werden dann verstärkt zu einem Problem, wenn auf Grund geborstener Wasserleitungen kein Löschwasser zur Verfügung steht.
Die wesentlichen Gefahren eines Erdbebens gehen von den Strukturen aus, die von Menschenhand geschaffen wurden. Die eigentliche Gefahr für Menschen ist es, von Gebäudeteilen erschlagen zu werden, in Flutwellen von zerbrochenen Staudämmen zu ertrinken, unter Erdrutschen verschüttet zu werden oder von begleitenden Bränden eingeschlossen zu werden.
http://www.seismo.uni-koeln.de/edu/gefahr.htm
Here the GEAR1 forecast is for years 2014 and after,
representing the magnitude forecast rate of 1% per year within a local circle
of radius 100 km about each point.
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