Topic: Earthquakes

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Topic Earthquakes
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Sub-project 1 Earthquake Risk International
experience, including tragic lessons from recent
large earthquakes, shows that the growth of
earthquake prone communities, following the
global processes of development and urbanization,
commonly gives rise to seismic risk unless proper
countermeasures are taken to prepare for future
earthquakes and manage the risk. This is true as
well for the countries of low and moderate
seismicity taking into account that the risk
value depends not only on the hazard level, but
also on the aggregate elements at risk and their
vulnerability to probable seismic influence.
Thus, the proper approach to the problem of risk
assessment and risk management should include
consideration of all the contributing
factors HazardLiving in seismic prone areas
means that seismic risk is unavoidable. It is
impossible to manage the risk through prevention
of future earthquakes. But improvement of seismic
hazard assessment and providing reliable
seismological and engineering-seismological
information for planning and design purposes is
an important factor contributing to efficiency of
risk management programs. Exposure (elements at
risk)When earthquakes occur in uninhabited
areas they are not considered as disasters.
Sometimes civilization and urbanization make
human beings more vulnerable to the natural
phenomena. It happens, in particular, when there
is high concentration of population and
complicated infrastructure in earthquake prone
zones. So, the processes of land use and urban
planning as well as development of new
technologies should take into account the
existing seismic threat. VulnerabilityThe
bitter engineering truth is that earthquakes do
not kill people, vulnerable buildings do. Though
future earthquakes cannot be avoided, the
community can improve seismic performance of
buildings and lifelines, reconstruct or retrofit
old structures and build new earthquake-resistant
constructions, in particular, for residential and
critical buildings. AwarenessLack of awareness
(as a psychological component of vulnerability)
contributes to seismic risk considerably. It
concerns people from every sector of the
community, all members of which are to realize
how to prepare for possible disasters, how to
behave if an earthquake strikes and what to do
after.
 

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Earthquake

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Fault

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3 Major Types of Faults
Normal
Reverse
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One Famous Fault in the USA

• The San Andreas Fault in California

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Focus

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Epicenter

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Seismic Waves (earthquake waves)

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• Three Types
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1) P-waves (Primary waves)

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2) S-waves (Secondary waves)

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3) L-waves (Long or Surface Waves)

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Seismograph

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Waves refract (bend) in different densities
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Earthquake Magnitude
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• Richter Scale (Magnitude)
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Mercalli Scale -
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Time to Review
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What type of wave?
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What type of wave?
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What is this point called?
Earths surface
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What is this point called?
Earths surface
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Focus
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Final Question

• Which seismic wave type travels the slowest?