a)What is volcanicity? b)i.Apart from a sill, name three other intrusive volcanic features. Describe how the following features are formed -a sill -hot springs -A caldera. c)Explain four negative effects of...

      

a)What is volcanicity?

b)i.Apart from a sill, name three other intrusive volcanic features.
ii)Describe how the following features are formed
-a sill
-hot springs
-A caldera.

c)Explain four negative effects of earthquakes.

  

Answers


Davis
a)It is the process through which gaseous / liquid / molten rock / solid materials are
forced into the earth's crust and / ejected onto the surface.

b)i.Dykes/dikes
- Laccolith/laccolites
- Batholith/bathyliths
- Lopolith
- Phacolith/phacolite

ii)a sill;
- Below the earth's crust the rocks are at very high temperature and high
pressure. If the pressure becomes less, the hot, solid rock material may
become semi-fluid / Magma under high pressure enters crustal rocks.
- The semi-fluid rock / magma forces itself into horizontal cracks/
fissures.
- The magma cools and solidities in horizontal cracks or bedding plane.
- This horizontal sheet/layer of igneous rock is called a sill.

hot springs;
- Rainwater enters the crustal rocks through cracks / fissures.
- The water reaches a zone of hot igneous rocks.
- The water is (super) heated.
- The super heated water changes into water vapour
The vapour is under high pressure and so forces its way up heating the
ground water.
- The heated water under pressure flows out continuously/to form
hot springs.

A caldera.
- Lava pouring out of a central vent forms a volcanic cone.
- The vent may be sealed when lava solidifies in it.
The solidified plug block the gases and steam beneath from escaping.
- There is pilling up of pressure below the plug.
- The pressure leads to a violent eruption that blows off the top of the
cone forming a depression.
- The resulting large circular depression on the top of the (now lower)
volvano is called caldera.

c)Violent motions resulting from earthquakes damage structures from their foundations
leading to loss of life and property.
- When earthquakes occur faults may develop which damages infrastructure.
- During an earthquake on the sea floor vertical displacement occur leading to
development of tsunami leading to floods of coastal areas/disrupts human activities
loss of life/property.
- Earthquakes may lead to landslides which destroy agricultural land/loss of life/
damage of infrastructure..
- Strong vibrations from earthquakes may cause damage to nuclear plants which pollute
the environment and affect human health.
- Earthquakes may cause panic/emotional shock/fear
Githiari answered the question on September 15, 2017 at 04:08


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