Predicting Earthquakes - Scientists Explore Methods and Challenges
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3. • Earthquakes have occurred since the planet
came into being and yet we are still unable to
predict with even half decent accuracy their
magnitude, timing or location. Government
and academic departments around the world
have continued their hard work and in recent
years scientific evidence has emerged which
one day could save thousands of lives.
4. • Earthquake prediction– It is usually defined as
the specification of the time, location, and
magnitude of a future earthquake within stated
limits and particularly of "the next strong
earthquake to occur in a region.
6. •Can we predict earthquakes ?• Scientists have tried lots of different ways of
predicting earthquakes, but none have been
successful. They have a pretty good idea of where
an earthquake is most likely to hit, but they still
can't tell exactly when it will happen.
• However, the probability of a future earthquake
can be calculated, based on scientific data.
Scientists at the US Geological Society (USGS)
estimate that the probability of a major
earthquake occurring in the San Francisco Bay area
over the next 30 years is 67%.
7. •Why can’t we predict earthquakes?
• So far, scientists haven't been able to find a signal
for earthquakes - there is no obvious sign to say
that an earthquake is coming very soon. Vibrations
can be detected just before an earthquake occurs,
but this doesn't give enough time for people to
escape.
• The processes that cause earthquakes mostly
occur far below the Earth's surface. There are
many tectonic plates - sections of the Earth's crust
that rub together and cause earthquakes - and
their interactions are complex. This makes
earthquakes very hard to study.
8. •Will we ever be able to predict
earthquakes?• Scientists at USGS and other organisations
are working hard to developing methods
which will predict earthquakes. Hopefully,
scientists has progressed significantly in
recent years and may soon help save
thousands of lives.
10. •What constitutes a valid prediction?
• Date and time
• Place of occurrence
• Magnitude
• Recorded in written form
• Confidence estimate (probability)
• Enough of the scientific basis for the
prediction that its validity can be evaluated
11. • A prediction can be made, or not, and an earthquake may occur, or not;
these basic possibilities are shown in the contingency table at right. Once
the various outcomes are tabulated various performance measures can be
calculated.E.g., the success rate is the proportion of all predictions which
were successful [SR = a/(a+b)], while the Hit rate (or alarm rate) is the
proportion of all events which were successfully predicted [H = a/(a+c)].
The false alarm ratio is the proportion of predictions which are false [FAR
= b/(a+b)]. This is not to be confused with the false alarm rate, which is
the proportion of all non-events incorrectly "alarmed" [F = b/(b+d)].
12. •Consequences of an false
prediction
• Predictions must also be reliable, as false alarms and cancelled
alarms are not only economically costly, but seriously
undermine confidence in, and thereby the effectiveness of, any
kind of warning.
13. •Possible signals of an earthquake
about to come
• Laptops could be also used for the prediction of
earthquakes