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Dr. Sibylle Steimen: The main cause of this earthquake
was the collision of the Arabian and the Eurasian tectonic plates.
In the zone where the actual event happened, crustal plates converge
and this lead to this strong earthquake.
Dr Sibylle Steimen: We distinguish between intraplate
and interplate earthquakes. The first happen on faults within a
plate of the Earth's crust and the latter at the boundary of two
separate plates.
We then further distinguish between three main types of earthquakes:
strike-slip, normal and thrust faults. The type depends on the direction
of movement of the two plates relative to each other. Most earthquakes
are a mixture of the different type described; thrust faults are
the most destructive earthquakes.
Dr Sibylle Steinmen: Earthquake prediction comparable
in accuracy to weather forecasting is currently not possible, nor
will it be possible in the future.
Compared to meteorological events, earthquakes are much harder
to understand and observe. Only indirect measuring methods like
the observation of plate movements with GPS signals and measurement
of seismic waves can be used.
Furthermore, our observation locations are limited to the Earth'
surface, apart from a new extremely deep boreholds used to calibrate
models on earthquake dynamics. Such models help us to undertand
what is going on during an earthquake.
What is possible, and an important contribution of earthquake scientists
to diaster mitigation, is an assessment of the regional probability
of an earthquake striking within a given time frame and with certain
strength (magnitude).
For example, the probability of a magnitude 6.8 or greater earthquake
in the San Fransisco Bay area is 63 percent for a time window of
30 years from 2007 to 2037.
Dr Sibylle Steinmen: There are a number of important
mitigation measures. First, authorities need to raise awareness
among the public that a region is prone to earthquakes.
Global and local hazard maps can give a good first indication of
where the 'hot spots' are. If you look at the region where this
most recent event in Turkey happened, you see that the epicentre
sits in an area of highest hazard.
Secondly, people need to know what to do in case of an earthquake
which means that a local disaster plan needs to be in place. In
Japan, for example, there are such plans in place and regular earthquake
drills take place. In California, millions of people simulated the
response after a magnitude 7.8 event in the greater San Francisco
area on October 20, including schoolchildren, fire fighters and
medical personnel. A disaster plan for Istanbul in Turkey exists
as well.
A third very important measure is the right construction codes
for buildings and controls which make sure that the codes are actually
applied. Modern construction codes allow buildings to swing and
dissipate seismic energy via elastic behaviour.
They might be damaged during this process but they do not collapse
and allow people to escape the buildings alive. In countries like
Turkey very modern and highly efficient construction codes are in
place as well but unfortunately history and this recent event teach
us that the codes are not enforced as they should be.
Dr Sibylle Steinmen: Japan and the United States.
Both countries do have leading institutions in earthquake science
and both of them have a very high contruction standards in place.
Both countries have a sad history of very large, destructive earthquakes
and they have learned bitter lessons. Furthermore, they are wealthy
enough to be able to put in place the required measures to prepare
their populations for such disastrous events.
As with all content published on this site, these statements are
subject to our Forward Looking Statement disclaimer, provided on
the right.
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