Endogenous hazards such as earthquakes and volcanoes are caused by processes inside the Earth. Earthquakes occur along fault lines as tectonic plates shift and release built-up pressure. The magnitude is measured by the Richter scale. Volcanoes form at plate boundaries as magma works its way to the surface. There are different types of volcanoes classified by their shape that can have explosive or effusive eruptions. Plate tectonics theory explains how the movement of plates causes earthquakes and volcanic activity at plate boundaries.

1. ENDOGENOUS
HAZARDS

2. ENDOGENOUS HAZARDS
• Hazards which originate inside the surface of
the earth are termed as endogenic hazards.
• E.g. Volcanoes, Earthquake

4. EARTHQUAKE
• An earthquake (also known as
a quake, tremor or temblor) is is the shaking of the
surface of the Earth, resulting from the sudden
release of energy in the Earth's lithosphere that
creates seismic waves. Earthquakes can range in
size from those that are so weak that they cannot be
felt to those violent enough to the people around
and destroy whole cities.

5. EARTHQUAKE
• The seismicity or seismic activity of an area refers
to the frequency, type and size of earthquakes
experienced over a period of time.
• At the Earth's surface, earthquakes manifest
themselves by shaking and sometimes
displacement of the ground. When the epicenter of
a large earthquake is located offshore, the seabed
may be displaced sufficiently to cause a tsunami.

6. WHY DO EARTHQUAKES HAPPEN?
• Earthquakes are usually caused when rock
underground suddenly breaks along a fault. This
sudden release of energy causes the seismic waves
that make the ground shake. When two blocks of
rock or two plates are rubbing against each other,
they stick a little. They don't just slide smoothly;
the rocks catch on each other. The rocks are still
pushing against each other, but not moving.

7. (Cont..)
• After a while, the rocks break because of all the
pressure that's built up. When the rocks break, the
earthquake occurs. During the earthquake and
afterward, the plates or blocks of rock start
moving, and they continue to move until they get
stuck again. The spot underground where the rock
breaks is called the focus of the earthquake. The
place right above the focus (on top of the ground)
is called the epicenter of the earthquake.

9. (Cont..)
• Earthquake-like seismic waves can also be caused by
explosions underground. These explosions may be set off to
break rock while making tunnels for roads, railroads,
subways, or mines. These explosions, however, don't cause
very strong seismic waves. Sometimes seismic waves occur
when the roof or walls of a mine collapse. The largest
underground explosions, from tests of nuclear warheads
(bombs), can create seismic waves very much like large
earthquakes. This fact has been exploited as a means to
enforce the global nuclear test ban, because no nuclear
warhead can be detonated on earth without producing such
seismic waves.

10. WHERE DO EARTHQUAKES
HAPPEN?
• Most earthquakes occur along the edge of
the oceanic and continental plates. The
earth's crust is made up of several pieces,
called plates. The plates under the oceans are called
oceanic plates and the rest are continental plates.
The plates are moved around by the motion of a
deeper part of the earth (the mantle) that lies
underneath the crust.

11. (Cont..)
• These plates are always bumping into each
other, pulling away from each other, or past
each other. Earthquakes usually occur where
two plates are running into each other or
sliding past each other.

12. MEASUREMENT OF EARTHQUAKE
• The impact of an earthquake will be measured by
using a seismometer. A seismometer detects the
vibrations caused by an earthquake. It plots these
vibrations on a seismograph. The strength, or
magnitude, of an earthquake is measured using
the Richter scale. The Richter scale is numbered 0-
10.

15. • Earthquakes measuring just one or two on the scale
are very common and can happen everyday in
places like San Francisco. These earthquakes are so
small that people cannot feel them, they can only
be picked up by a seismometer.
• Earthquakes measuring around 7 or 8 on the
Richter scale can be devastating. The earthquake in
China's south-western Sichuan province in May
2008 measured 7.8 on the Richter scale.

16. EARTHQUAKE PREDICTION
• Earthquake prediction is a branch of the
science of seismology concerned with the
specification of the time, location,
and magnitude of future earthquakes within
stated limits, and particularly "the determination
of parameters for the next strong earthquake to
occur in a region.

17. (Cont..)
• Earthquake prediction is sometimes distinguished
from earthquake forecasting, which can be defined
as the probabilistic assessment of general
earthquake hazard, including the frequency and
magnitude of damaging earthquakes in a given area
over years or decades. Prediction can be further
distinguished from earthquake warning systems,
which upon detection of an earthquake, provide a
real-time warning of seconds to neighbouring
regions that might be affected.

18. TYPES OF EARTHQUAKES
• There are four different types of earthquakes:
• Tectonic
• Volcanic
• Collapse and
• Explosion.

19. (Cont..)
• A tectonic earthquake is one that occurs when the
earth's crust breaks due to geological forces on
rocks and adjoining plates that cause physical and
chemical changes.
• A volcanic earthquake is any earthquake that
results from tectonic forces which occur in
conjunction with volcanic activity.

20. (Cont..)
• A collapse earthquake are small earthquakes
in underground caverns and mines that are
caused by seismic waves produced from the
explosion of rock on the surface.
• An explosion earthquake is an earthquake
that is the result of the detonation of a
nuclear and/or chemical device.

21. VOLCANOES

22. VOLCANOES
• A volcano is a rupture in the crust of a planetary-
mass object, such as Earth, that allows
hot lava, volcanic ash, and gases to escape from
a magma chamber below the surface. A volcano is
a mountain that opens downward to a pool of
molten rock below the surface of the earth. When
pressure builds up, eruptions occur. Gases and rock
shoot up through the opening and spill over or fill
the air with lava fragments.

23. Eruptions can cause lateral blasts, lava flows,
hot ash flows, mudslides, avalanches, falling ash
and floods. Volcano eruptions have been known
to knock down entire forests. An erupting
volcano can trigger tsunamis, flash floods,
earthquakes, mudflows and rock falls.

24. How are volcanoes formed?
Volcanoes are formed, when magma form
within the Earth's upper mantle works its
way to the surface. At the surface, it erupts to
form lava flows and ash deposits. Over time
as the volcano continues to erupt, it will get
bigger and more bigger.

25. DIFFERENT STAGES OF VOLCANOES
Scientists have categorized volcanoes into three
main categories: active, dormant, and extinct. An
active volcano is one which has recently erupted
and there is a possibility that it may erupt soon. A
dormant volcano is one which has not erupted in a
long time but there is a possibility it can erupt in
the future. An extinct volcano is one which has
erupted thousands of years ago and there’s no
possibility of eruption.

26. VOLCANIC ERUPTION
• The Earth's crust is made up of huge slabs
called plates, which fit together like a jigsaw
puzzle. These plates sometimes move. The
friction causes earthquakes and volcanic
eruptions near the edges of the plates. The
theory that explains this process is called
plate tectonics.

29. PLATE TECTONICS
• The theory of plate tectonics is a interesting story
of continents drifting from place to place breaking
apart, colliding, and grinding against each other.
The plate tectonic theory is supported by a wide
range of evidence that considers the earth's crust
and upper mantle to be composed of several large,
thin, relatively rigid plates that move relative to
one another. Sometimes the plates crash together,
pull apart or sideswipe each other. When this
happens, it commonly results in earthquakes.

30. How many volcanoes are there?
• There are more than 1500 active volcanoes
on the Earth. We currently know of 80 or
more which are under the oceans. Active
volcanoes in INDIA are Barren
Island(Andaman Nicobar Islands), Deccan
Traps (West Central India),
Baratang(Andaman Nicobar Islands),
Dhinodhar Hills (Gujarat), Dhosi Hill
(Haryana), Tosham Hills (Aravalli mountain

31. DIFFERENT TYPES OF VOLCANOES
• Volcanoes are grouped into four types:
• Cinder cones
• Composite volcanoes
• Shield volcanoes and
• Lava volcanoes

32. CINDER CONES
• Cinder cones are circular or oval cones made
up of small fragments of lava from a single
vent that have been blown into the air, cooled
and fallen around the vent.

33. COMPOSITE VOLCANOES
• Composite volcanoes are steep-sided volcanoes
composed of many layers of volcanic rocks, usually
made from high-viscosity lava, ash and rock debris.
Mt. Rainier and Mount St. Helens are examples of
this type of volcano.

34. SHIELD VOLCANOES
• A shield volcano is a type of volcano usually built
almost entirely of fluid lava flows. Shield volcanoes
are volcanoes shaped like a bowl or shield in the
middle with long gentle slopes made by basaltic
lava flows. Basalt lava flows from these volcanoes
are called flood basalts.

35. LAVA DOMES
• Lava domes are formed when erupting lava is too
thick to flow and makes a steep-sided mound as the
lava piles up near the volcanic vent. The eruption of
Mount St. Helens in 1980 was caused in part by a
lava dome shifting to allow explosive gas and steam
to escape from inside the mountain.

36. PUMICE
• Pumice is a light, porous volcanic rock that forms
during explosive eruptions. It resembles a sponge
because it consists of a network of gas bubbles
frozen amidst fragile volcanic glass and minerals.
All types of magma will form pumice.

37. RING OF FIRE
• The Pacific Ring of Fire is an area of frequent
earthquakes and volcanic eruptions encircling the
basin of the Pacific Ocean. The Ring of Fire has
452 volcanoes and is home to over 50% of the
world's active and dormant volcanoes. Ninety
percent of the world's earthquakes and 81% of the
world's largest earthquakes occur along the Ring of
Fire.