Earthquakes
and
Volcanoes
Bell Work 12/9/10
Turn on computers
Notes today
Rest of this week and next
• Wednesday (12-8-10)- Slides 1-6 and handout
science fair packets and talk about it
• Thursday (12-9-10) - Complete slides 7-12 and start
B/F/F scenario
• Friday (12-10-10)- Complete B/F/F Scenario
• Monday (12-13-10)- B/F/F Scenario is due and
complete study guide
• Tuesday (12-14-10)- Go to library for science fair
• Wednesday- 15 mins: just over study guide answers
• Thursday - opportunity to work on their science fair
project and/or study for upcoming exams.
• Friday: Final exam 1:18-3:05
Earthquakes
Earthquake – is the shaking and
trembling that results from the
sudden movement of part of the
Earth’s crust.
Tsunamis – A giant sea wave
produced by an earthquake.
Seismic Waves
Focus – The point beneath the
Earth’s surface where the rocks
break and move, the underground
origin of the earthquake.
Epicenter – The point directly
above the focus, on the earth’s
surface where the origin of an
earthquake is above ground.
Faults- Once the elastic limit of rocks is
passed, they break and move along
surfaces.
• 3 types of faults are:
• Normal Fault- These form at divergent
boundaries.
• Reverse Fault- These form at convergent
boundaries.
• Strike-Slip Fault- These form at transform
boundaries.
Seismic waves – earthquake waves.
*Three types.
1. Primary waves (P-waves) –
arrive at a given point before any
other type of seismic wave. Will pass
through solid, liquid and gas.(fastest of the
three)
2. Secondary Waves (S-waves) –
arrive at a given point after the P wave.
(second fastest) Will only travel thru solids.
Will NOT pass through liquids and gases
thus creating a shadow zone.
3. Surface waves (L-waves) –
slowest moving seismic
waves.
Arrives last.
Seismograph – is an instrument that
detects and measures seismic waves.
Seismogram – is the record of waves.
(paper record)
Seismologists – scientists who study
earthquakes.
Richter scale – calculation of the strength
or magnitude of an
earthquake.
For every 1 point rise 30 times the
energy is released.
Magnitude - Height of a line traced on a
Liquefaction – Shaking up of wet soil making it
unstable. This causes surface object to sink.
Earthquake preparedness – Tie down heavy
objects, take objects off of high shelves. Build
on an earthquake proof foundation. Have a plan
and emergency items.
Volcanoes
Volcano – the place in the Earth’s
surface through which magma and
other materials reach the surface.
Magma – rock that exists as a hot
liquid deep within the earth.
Lava – is magma that reaches the
Earth’s surface.
Vent – an opening from which lava
erupts.
Crater
– Steep walled depression
around a volcano’s vent.
Hot Spot – Hot rock that is a result of
unusually hot areas in the mantle and
core where volcanoes form on the
Earth’s surface. Hawaii is the result of a
hot spot.
Lava flows
• Basaltic – Is lava that contains a lot
of water and rich in iron and
magnesium. Thin and quiet eruptions.
• Granitic - this lava contains very little
water and is rich in silicon and
aluminum. Thick heavy lava causing
gases to trap underneath producing
large violent eruptions.
Composite Volcanoes – are made of alternating
layers of rock particles and lava. Violent eruptions
followed by quiet lava flows are the reasoning for
the alternating layers.
Caldera – A roughly circular, steep-sided pit at
the top of a volcanic cone whose diameter is at
least three times its depth.
Andesitic - is a combination of both
granitic and basaltic lava flows (quieter than
granitic but more violent than basaltic).
Gas filled lava – This lava cools to form
hole filled rock that has the appearance of a
sponge or loaf of bread. This rock type is
typically light in weight. Pumice and scoria
are examples of this type of igneous rock.
Tephra – bits of rock or solidified lava dropped
from the air.
Volcanic Dust – Is fragments of rock that are
blown into the air during a volcanic eruption. (very
small particles)
Volcanic Ash – Is particles blown into the air
from a volcano that are bigger than volcanic dust
yet smaller than anything else.
• Volcanic Bombs – Are large rock particles that
are blown out during a volcanic eruption.
• Volcanic cinders – are smaller volcanic
bombs.
• Cinder cone volcano – Volcanoes made
mostly of cinders and other rock particles that
have been blown into the air. Narrow bases with
steep sides due to loosely arranged cinder type
eruptions.
Shield volcano – Volcanoes composed of quiet
lava flows. Gently sloping sides with very wide
base.
Dike –
Batholith –
Sill -
Dormant – (sleeping) has erupted but not in
modern time.
Extinct – Not known to have erupted in recorded
time. Usually weathered down to base.
Active – well, it is active in modern time.
ZONES
Ring of fire – is the zone of active earthquakes
and volcanoes due to very active tectonic plate
movement.
Mid-Atlantic ridge – chain of ridges caused by
sea floor spreading.