hey everyone got a geography project and worries what will u all use well u can go ahead and use mine ;p

1. Volcanoes
Made by simran-parashar
Md -7

2. Content
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What is a Volcano ?
How are volcanoes formed
Different Volcanoes X 3
thank you ;p

3. What is a volcano
• What is a volcano?
• 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. 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 rockfalls.

4. How are volcanoes formed
• Volcanoes are formed when magma from
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 bigger.

6. Why do volcanoes erupt?
• 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.

7. Different Volcanoes
• Active
• Dormant
• Extinct

8. Active Volcanos
An active volcano is a volcano that has had at
least one eruption during the past 10,000 years.
An active volcano might be erupting or dormant.
eg Mt. Nyiragongo

9. Mt. Nyiragongo

10. Mt. Nyiragongo
• This is one of the most active volcanoes in the African
region. Located in the Democratic Republic of Congo, it
has erupting since 1882. The crater inside the
mountain serves as the holder of magma fluid. When
this crater got ruptured in the year of 1977, the whole
magma fluid was drained within an hour and it paved
its way to the nearby villages. The average velocity of
the flowing lava would be 60 kilometer per hour.
Recent eruption happened in the year of 2002, making
nearly 120,000 people homeless. The seismologists of
Congo expect soon there would be an eruption.

11. dormant volcano
• A dormant volcano is an active volcano that is
not erupting, but supposed to erupt again.
• The Volcanoes of the Three Sisters
Area, Oregon

12. The Volcanoes of the Three Sisters
Area, Oregon

13. The Volcanoes of the Three Sisters
Area, Oregon
• Situated on the Cascade plateau, the region
known as the Tumalo Volcanic Center was active
in the Pleistocene epoch with explosive eruptions
between 700,000 and 170,000 years ago that left
extensive pyroclastic deposits on which basaltic
and basaltic andesitic lava flows formed a great
number of shields. One of these eruptions
resulted in tephra deposits as thick as 13 meters
(42 feet) composed largely of fist-sized and
smaller white pumice clasts which is exposed in
numerous pumice quarries.

14. An extinct volcanov
• An extinct volcano has not had an eruption
for at least 10,000 years and is not expected
to erupt again in a comparable time scale of
the future.
• Black Butten

15. Black Butten

16. Black Butten
• On Saturday we stopped to take a photo of Black Butte, an extinct
volcano near Mt. Shasta. It looms over I-5 as you pass Weed, CA.
Northern California is home to many volcano's in the Cascade
Mountain Range, most are extinct. The Cascades start in Canada
and wind their way through Washington, Oregon, and into
California.
• -- Geographic Setting, Geologic and Eruptive History - Two of the
main eruptive centers at Mount Shasta, the Shastina and Hotlum
cones were constructed during Holocene time, which includes
about the last 10,000 years. Holocene eruptions also occurred at
Black Butte, a group of overlapping dacite domes about 13
kilometers west of Mount Shasta. ... The extrusion of the domes
about 9,500 years ago was accompanied by the formation of
pyroclastic flows which extended more than 10 kilometers south
and 5 kilometers north of the domes. -- Excerpt from: Miller, 1980,
USGS Bulletin 1503