3. Introduction of environmental
hazard
Environmental hazards is the state of events
which greatly effects the surrounding and
people’s health.
This situation cause pollution and natural such
as storm, earthquake and volcano.
4. What is Earthquake?
A sudden movement of the earth's crust caused
by the release of stress collected along faults or
by volcanic activity
5. How Earthquake Happens?
It caused by a sudden slip on a FAULT.
Stresses in the earth's
outer layer push sides of
fault together.
Stress builds up & rocks
slips suddenly, releasing
energy in waves that travel
through the earth's CRUST
& cause the shaking that we
Feel during an earthquake.
6. Fault- earthquake
A fault is a fracture along which the blocks of outermost
major layer of the earth, on either side have moved relative
to one another parallel to the fracture. Faults are classified
to Strike-slip and Dip-slip faults (normal, reverse and
thrust).
What is the crust?
The outermost major layer of the earth is called CRUST and
ranging from about 10 to 65 km in thickness worldwide.
The uppermost 25 km of crust is brittle enough to produce
earthquakes.
9. Types of Earthquake Waves
Body Waves
P-Waves (primary waves)
S-Waves (secondary waves)
Surface Waves
L – Love Waves
R – Raleigh Waves
10. Body Waves: P and S waves
Body waves
P or primary waves
fastest waves
travel through solids,
liquids, or gases
compression wave,
material movement in
the same direction as
wave movement
S or secondary waves
slower than P waves
travel through solids
only
shear waves - move
material perpendicular
to wave movement
11. Surface Waves: R and L waves
Surface Waves
Travel just length of the ground’s surface
Slower than body waves; rolling and side-to-side movement
Especially damaging to buildings
12. Tsunami
Tsunami is a series waves caused by earthquakes or
volcanic eruptions under the sea.
Out in the depths of the ocean, tsunami waves do not
dramatically increase in height. But as the waves travel
inland, they build up to higher and higher heights as the
depth of the ocean decreases. The speed of tsunami
waves depends on ocean depth rather than the distance
from the source of the wave. Tsunami waves may travel
as fast as jet planes over deep waters, only slowing down
when reaching shallow water
14. How Measure The Earthquake Strength?
1. Magnitude & 2. Intensity
1. Magnitude:
A measure of actual physical energy release at its source as
estimated from instrumental observations.
2. Intensity:
A measure of the felt effects of an earthquake rather than the
strength of the earthquake itself.
17. Volcanoes
A volcano is a vent that
connects molten rock
(magma) from in the
Earth’s crust to the Earth's
surface.
The volcano includes the
surrounding cone of
erupted material
Vent
Magma
Chamber
18. How and why do volcanoes erupt?
Hot, molten rock (magma) is floating and will rise up
through the crust to erupt on the surface.
When magma reaches the surface it depends on how easily
it flows and the amount of gas (H2, CO2, SO2) it has in it as
to how it erupts.
Large amounts of gas and a high viscosity (sticky) magma
will form an explosive eruption!
Small amounts of gas and low viscosity magma will form an
effusive eruption
21. Volcano Monitoring
Seismicity
Deformation
Gas Output
Remote sensing techniques
These three things are
the most important sign
to an eruption.
22. What is volcano monitoring?
As magma moves through the Earth’s crust it can alter it’s
environment producing sign’s on the surface, these signs
are called “precursors” to an eruption.
Precursors include
• Increased earthquakes in the area means increased
seismicity
• Swelling and cracking of the ground means deformation
• Change in the amount of chemistry of the gas coming out
of the volcano
• Change in the groundwater levels and chemistry.
23. Volcano Flow
However, the potential damage was reduced by
spraying seawater onto the advancing volcano flows.
This caused them to slow and stop away from the
undamaged part of the town.
24. Volcano Flow
It is not just explosive volcanic activity that can
be hazardous. Effusive activity is also
dangerous.
Notas del editor
Focus
Location in the earth where fault rupture actually occurs
Epicenter
Location on the surface above the focus