The document discusses various aspects of volcanoes and volcanic eruptions. It defines key terms like volcano, lava, magma, pyroclastics, crater, and describes different types of volcanic eruptions and the landforms they produce. Specifically, it distinguishes between shield volcanoes, cinder cones, and composite cones; and explains how factors like magma composition, temperature, and gas content determine eruption styles.

1. Volcanos world

2. VolcanoVolcano
lavalava
Pyroclastic FlowPyroclastic Flow
MagmaMagma
PyroclasticsPyroclastics
CraterCrater

3. a cone-shaped mountain formed from lava
and /or pyroclastic

4. A body of molten rocks found at depth,
including any dissolved
gases & crystals.

5. A body of molten rocks found at depth,
including any dissolved gases & crystals

6. the volcanic rocks ejected during an eruption.
Pyroclastics include ash, bombs and blocks.

7. a highly heated mixture, largely of ash and
pumice fragments, traveling down the flanks of
a volcano or a long the surface of the ground

8. The depression at the summit of a volcano.

9. The Nature of Volcanic EruptionsThe Nature of Volcanic Eruptions
What determines, whether a volcano extrudes magma violently or gently?What determines, whether a volcano extrudes magma violently or gently?
1. Magma’s composition.( SiO2 content).
2. Magma's temperature.
3. The amount of dissolved gasses it
contains.
The moreThe more
viscous theviscous the
magma,magma,
the greaterthe greater
itsits
resistanceresistance
to flowto flow ..
 All of above points affect magma viscosity
table

10. Factor effecting viscosityFactor effecting viscosity
•Temperature.
•SiO2 content; The more the SiO2 content,
the greater viscosity .
Materials Extruded During An EruptionMaterials Extruded During An Eruption
1. Lava flow.
2. Gases.
3. Pyroclastic materials.

11. Lava FlowLava Flow
Basaltic: example: as in Hawaii Islands
(Mauna Loa,
the largest on the Earth and Kilauea)
- Flow rapidly 10-300 m/hr  may reaches
30 km/hr.
- Travel about 150 km before congeal
(consolidate).

12. Basaltic flows in Hawaii formBasaltic flows in Hawaii form
1. pahoehoe flows: A lava flow with smooth-
to- ropy surface. It resembles the twisting
braids in ropes.
2.aa flows: A lava flow that has a jagged
blocky surface.

13. Lava tubesLava tubes
conduit that the molten lava continued to
move through it.
Pillow lavaPillow lava
basaltic lava that congeals under water
environment and develops a structure that
resembles a pile of pillows.
1. Andesitic: intermediate viscosity.
2.Rhyolitic: This is too slowing, thicker and
more viscous than andesitic or basaltic

14. GasesGases
Magma contains variable amount of dissolved gases
held in the molten rock by confining pressure.
These gases are:
70 % = water vapour.
15% CO2.
5% = N2.
5% = S.
and amount of Cl2,H2,Ar.
The gas content is important in widening the volcanic
vent and the cracks by the expansion of the gases to
hundred or thousand times.

15. Pyroclastic materialsPyroclastic materials
Pyroclastic material is any ejected lava fragments of ash, dust, glass
fragments, ….. that range in size from microns to large pieces of metric size.
ExamplesExamples
Ash: rise in the atmosphere that cause darkness and the drop of
temperature in the atmosphere.
Tuff: A rock formed from fine-grained pyroclastic particles
)ash and dust(.
Pumice: light, glassy, highly vesicular, it is as forth like lava.
Lapilli: size of walnut = little stone.
Cinder: pea-size= contain voids resulting from escaped gases.
Blocks: large grain
Bomb: A streamlined Pyroclastic fragment ejected from a volcano
while molten.
table

16. Volcanoes And Volcanic EruptionVolcanoes And Volcanic Eruption
Based On Their Eruptive Patterns & Characteristic
Form, Three Groups of Volcanoes Are Recognize:
1. Shield volcanoes.
2. Cinder cones.
3. Composite cones )stratovolcano(.

17. Shield volcanoesShield volcanoes
1. Broad, gently sloping volcano built from fluid basaltic flow .
2. Have small percentage of pyroclastic material.
3. Ex: Mauna Loa, the largest volcano on the earth surface, is one of the
five shield volcanoes that together make up the island of Hawaii. Its
elevation reaches 9170 m )5000 m above ocean floor and 4170 m above
water surface(.

18. Cinder conesCinder cones
1.Build from ejected pyroclastic materials.
2.It has a high angle )30-40 degree(. Cinder
cones are small, usually less than 300 m
in height.
ExEx: Paricutin )west Mexico city( Cinder cones .

19. Composite coneComposite cone
Composed of alternatives of lava flows and
pyroclastics.
- Steep near the crater & more gentle a way.
- Andesitic lava )intermediate(.
- Encircle the Pacific Ocean )Ring Of FireRing Of Fire(.
Ex: Mt. Fujiyama )Japan(, Vesuvius )Italy,
extruded violently in A.D 79(, Mount Mayon
)Philippines(, Cascade Range in the northwestern
part of USA. It includes )Mt. St. Helens, Mt. Rainier
and Mt. Shasta(.

20. nuee ardentenuee ardente =glowing avalanche: it is deadly
pyroclastic flow that occur when hot gases infused
with incandescent ash are ejected, this fiery cloud
race down the volcano flank and travel a bout
200km/hr, and reach a bout 100 km away from the
source. )in Pompeii )Italy( during 3 days, 2000
person were killed(
LaharLahar: Ash + rain, which moves rapidly )about 30
km/hr( and carries the materials in its way.
Composite coneComposite cone

23. VolcanicVolcanic LandformsLandforms
The most obvious volcanic landform is aa conecone ,
but there are other landforms:
1.Crater and caldera:
Caldera is a large crater
(must be >1 km in diameter)
caused by collapse or ejection of the summit
of a volcano.

24. VolcanicVolcanic LandformsLandforms
2.Volcanic Neck:
An isolated, steep-sided, erosional remnant
consisting of lava that once occupied the vent of
the volcano.
3- Vent & Pipes :
Vent: conduit connects the magma chauper to a
volcanic crater.
Pipe: a vertical conduit reaches a bout 200-km or
more throw which magmatic materials have passed.
So it is consider as a window on the upper mantle
(Asthenosphere), mostly the magma of ultramafic
type.
- Ex: diamond-bearing pipes of South Africa.

25. VolcanicVolcanic LandformsLandforms
4- Fissure Eruptions and Lava Plateaus:
Fissure eruption: eruption where basaltic
lava is extruded via fractures or crack in the earth
crust.
The eruvative material cover an extensive area to
thickness of hundreds of meters,
form Flood Basalt.
Plateaus: flat topography result from
repeated eruptive phases of lava, it may reach 2-3
km in thickness and composed from flood basalt.

26. 5- Pyroclastic flow:
Rich in SiO2, mainly of ash and pumice
fragments, when rest on the earth
surface, it resembles lava flow.
Ex: Yellowstone plateau, Wyoming,
USA.
VolcanicVolcanic LandformsLandforms