Folds, Faults, Earthqquakes and Volcanoes

When rock responds to stress by becoming permanently deformed without breaking, the result is

Folding

Tsunami

Giant ocean waves caused by earthquake. Also called siesmic sea waves

Tephra

bits of rock or solidified lava dropped from the air during an EXPLOSIVE volcanic eruption. Ranges in size from volcanic ash to volcanic bombs and blocks. Can come from CINDER CONE Volcanoes

Tension - what is it?

tension is the force that pulls rocks apart.

What are the 3 types of forces that act on rocks?

tension, compression and shear

isostatic adjustment

the land slowly bounces back from the compression caused by a glacier

What happens to rocks once the elastic limit is passed?

the rocks may break.

What causes an earthquake?

the vibrations produced by the breaking of rock. rocks moving over, under or past each other along the fault surfaces.

Richter Scale

used to describe the strength of an earthquake based on the height of the lines. THe Magnitude. 9.5 usually heighest.

Pyroclastic Flow

volcanic ash and debri ruch down the side of the volcano.

VOLCANOES FORM HOW?

volcanoes form 3 ways: #1 where one plate sinks beneath another plate, #2 where 2 plates are moving apart and # 3 at hot spots.

Siesmograph

how seismic waves from earthquakes are measured. Allows scientists to record primary, secondary and surface waves from earthquakes.

Cinder Cone Volcano

is a steep-sided, loosely packed volcano formed from tephra..EXPLOSIVE

What are some hazards of volcanos?

lava causes destruction, acid rain, lahar which is mudslides. Pyroclastic Flows

Explain how and where most earthquakes occur?

p.304

Stresses on rock are created by what?

plate movements

Why do earthquajes occur in MAssachusetts

plates are always moving, we may not feel them.

Folds that face downwards are called __________ Occur due to COMPRESSION STRESS

synclines

What controls ERUPTIONS?

The amount of water vapor and other gases control the type of eruption and the amount of silica in the magma.

Lava

molten rock that flows from volcanoes onto earth's surface.

Divergent Plate Boundary

...As 2 plates move apart because the stress is TENSION, the hanging wall falls down. NORMAL FAULT is caused by a DIVERGENT PLATE BOUNDARY.

What is the limit to how far a wooden craft stick can bend?

It's elastic limit

elastic rebound theory

earthquake occurring at a plate boundary.

Compression - What is it?

Compression is the force that squeezes rocks together.

What is the difference between continental and oceanic volcanic eruptions

Continental can be explosive while ocean is quiet.

What kinds of of cones will CONTINENTAL and OCEANIC volcanic will they form?

Continental will form either Cinder Cone or Composite Cone and Oceanic will form Shield Cone

Thrust faults and reverse faults can occur at what type of boundaries

Convergent Plate Boundaries

3 kinds of Plate Boundaries

Convergent Plate Boundary, Divergent Plate Boundary and a Transform Fault Plate Boundary.

Foot Wall and Hanging Wall

Rocks usually break along angles that create "walls"

Transform Fault Plate Boundary

Rockspushing in opposite horizontal directions. Type of Stress is SHEARING. This causes a STRIKE SLIP FAULT

3 TYPES OF VOLCANOES

SHIELD CONE, CINDER CONE, and COMPOSITE VOLCANO

How do scientists measure and locate earthquakes.

Scientists measure the earthquakes with Seismograph. They locate the earthquakes and the epicenter with the use of the waves. If seismic waves reach 3 or more seismic stations, a radius is drawn around each seismic station and the point where all 3 circles intersect is the location of the epicenter.

Thrust Fault and Reverse Fault are the same...Tor F

True but a thrust fault is much more gentle angle.

Shearing pushes rocks in opposite horizontal directions. T or F

True.

Faults form when streesed rocks break along surfaces T or F

True. Faults do form when stressed rocks break along surfaces.

What hazards are associated with earthquakes?

Tsunamis, destruction, death, liquefication (when the soil is shaken so much it acts like liquid...

Large synclines create

Valleys

Faults

When the rocks break, they move along surfaces called faults.

What determines whether an eruption will be violent or quiet?

2 factors control whether it will be quiet or violent. #1 the amount of water vapor and other gases that are trapped in the magma. #2 how much silica is in the magma.

Major earthquakes have what number on the Richter Scale?

6 and up Ex. Magnitude could be a 6 on the Richter Scale (but the Intensity *damage, destruction) may be a 9

Shield Cones Volcano

A broad, gently sloping volcano formed by QUIET eruptions by balsatic lava.

What is a Normal Fault?

A normal fault is when TENSION forces inside the Earth cause rocks to be pulled apart. When rocks are stretched by these forces a normal fault can occur. Along a normal fault, rock above the fault line moves downward in relation to rock below the fault surface.

Types of Stress-Shearing

A strike-slip fault is when the rock on either side of the fault slides horizontally. This occurs at transform boundaries Ex, San Andres Fault

transform fault

A transform fault plate boundary...when 2 plates try to slide past each other horizontally. they build up stress (SHEARING) along their bounderies. Eventually the plates slip and move past easch other. A transform fault plate boundary causes a Strike-Slip Fault.

"Folding Song" by Ms. Hebda

Angry, angry anticlines frowning in dismay Smiling, smiling synclines happy all day And disharmonic folding goes its own way

Folds that curve upwards are called _________. They occur due to COMPRESSION STRESS

Anticlines

Convergent Plate Boundary

As 2 plates COLLIDE because the stress is compression, the hanging wall is pushed up. REVERSE FAULTS/THRUST FAULT result from COMPRESSION

How do most volcanos form?

Deep inside the earth, heat and pressure changes cuasing rock to melt forming liquid rock or magma. Magma is less dense than the rock around it and it is forced slowly toward the earth's surface. Volcanoes form in places where plates are moving together *convergent), apart *divergent) and hot spots.

How and where do most earthquakes occur?

Earthquakes are vibrations produced when rocks break along a fault. They occur at plate boundaries.

How did Hawaii form?

Hawaii was formed as a result of volcanic activity. They are not at a plate boundary. They are on a hot spot. The volcanoes that rise above the water form the islands.

Where is the safest place to be during an earthquake?

Indoors, move away from windows, get in doorway. Outside: stay in the open away from buildings.

HOt Spots

It is thought that some areas at the boundary between the Earth's mantle and core are unusually hot. HOT rock at these areas is forced toward the crust where it melts partially to form a hot spot. The Hawaiian Islands sit on top of a hot spot under the Pacific Plate.

Large anticlines create

Mountains

What is a Reverse Fault?

Reverse Faults results from COMPRESSION forces that squeeze rock. If rock breaks from forces pushing from opposite directions, the rock above a reverse fault surface is movedup and over the rock below the fault surface.

Shear - What is it?

Shear is the force that causes rocks on either side of a fault to slide past each other.

What is a Strike-Slip Fault?

Strike-Slip Faults results from SHEARING force pushing rocks past each other...When rocks on either side of the fault are moving past each other (HORIZONTALLY)without much upward or downward movement.

Where is the Ring of Fire located and what happens there?

The Ring of Fire is a belt of active volcanoes that circles the Pacific Ocean.

Epicenter

The point on Earth's SURFACE directly above an earthquake's focus.

Focus

The point where the energy first occurs in the earth

When rock does not fold, sometimes it breaks. If rocks are bent too far, or if they are cool when pressure is exerted, they

They will break or what is called FAULT

If the rocks are of different strengths, you may get a wavy line of folds called

disharmonic folding.

What are some signals that a volcano might erupt?

earthquakes change in gasses (sulfur) emitted by a volcano. a bulge in the side of a volcano. giving off smoke.

Composite Volcano

formed by alternating EXPLOSIVE and QUIET ERUPTIONS that produce layers of TEPHRA AND LAVA.