Physical Geology Exam 3
Synclines
(fold down)- looks like a smile
shield volcano
-Broad, domed structure -Fluid (basaltic) lava
Japan (2011)-Oceanic- oceanic crust ( a line of volcanoes) -japan is NOT A HOTSPOT
-Built largest sea wall in the world to prevent tsunami damage -Magnitude 9.0 -#4 largest earthquake -Large tsunami -Meltdowns at nuclear power plants -Over 10,000 deaths
Volcanic Hazards-Pyroclastic Flows
-Burns and goes right through you= Nuee ardente "glowing cloud" (French Origin) -NO WAY TO ESCAPE
Cinder cones
-Cylindrical volcano built by ejected lava fragments "Lava cones" or "tephra cones" -Tend to have basaltic lava
Dip- slip faults (normal and reverse, thrust)
-Define two parts: Hanging wall and footwall ex. Miner standing on the fault his feet touch the FOOT WALL and hand his lantern from the HANGING WALL -How do you determine if it is going up a dip (compressional- push elbows together) or down the dip(ex. Push one elbow to the left and one to the right) ...? Which way the force is coming -Find dip slip fault go up or down the dip we can tell which forces there were
Thrust Faults
-Dip slip faults two types: normal and reverse (down or up) -Low-angle reverse faults
joints
-Fractures with no displacement -Rocks break (crack) why? Under so much stress that you fold and you bend...than break -Pressure has been relieved (why does this happen?) ex. Six people are sitting on a couch and one person gets up. The other five feel relieve and can expand *fractures if they move= fault*
What is Orgeny?
-Greek for "Mountain generation" or mountain building event
hot spots- Yellowstone
-Hotpsot like Hawaii and Iceland BUT it is underneath a continent -Evidence of talldares going into Eastern Orgeon -The plate on top of the hotspot moved NOT YELLOWSTONE -Difference: Hawaii's hotspot goes through oceanic crust (mafic) and Yellowstone goes through continental crust (felsic).... When it erupts it is big
The Parkfield (spot on San Andreas Fault) Experiment
-In 1985, researchers predicted there was a 95% chance of a magnitude-6 between 1985 and 1993 -build up stress and release in a magnitude earthquake every several years (average of 20 (12 and 32) -September 28th, 2004 earthquake finally happened (6.0 magntidue)
Earthquake Prediction
-Long-range forecasts -Location and probability of a certain magnitude earthquake occurring over a given time period Ex. look in Alaska sections in the faults and when they had the last major movements
Virginia Earthquake (August 23,2011)
-Magnitude 5.8 -Felt in Asheville
Northridge (1994)
-Magnitude 6.7 -$44 billion in damage (about $15B covered by insurance -Most expensive earthquake in recent US history -Killed 60 and injured 7000+
Loma Prieta (1989)
-Magnitude 6.9 -Disrupted World Series
Haiti (2010)
-Magnitude 7.0 (possibly the strongest to ever hit this region) -About 220,000 killed -#5 most deadly in recorded history Tragic because the epicenter was right near port au prince the capitol and concrete walls so a lot of buildings collapsed -lack of clean water lead to Cholera outbreak -Microplates between the North American and Caribbean plates. Earthquakes occur here often
Chile (2010)
-Magnitude 8.8 (largest than a nuclear bomb) -#6 largest earthquake -900 times more powerful than Haiti's - at least 350 deaths -earth opened up
Alaska (1964)
-Magnitude 9.2 -#2 largest EQ recorded in world -Largest in US history Ex. did not feel earthquake because he was on a boat... magnitude 5 earthquake and made the water choppy
Chile (1960)
-Magnitude 9.5 -Largest recorded Earthquake
San Francisco (1960)
-Magnitude at least 8 -Most of city destroyed
San Francisco 1989
-On hayward fault and left lateral -San Andreas Fault (right lateral)
Hot spots-Hawaii
-Right in the middle of a plate boundary
Sumatra (2004)
-Same subduction zone as krakatoa -#3 largest recorded Earthquake -most deaths related to Tsunami -#4 most deadly recorded history
Mt. Mazama
-Volcanic eruption estimated to be 40 times more powerful than Mt. St. Helens -Collapsed Caldera is now Crater Lake
The amplitude of a magnitude of 4 earthquake is ______ times larger than a magnitude 2 (on the Richter scale).
100
domes
A circular or elliptical anticlinal structure in which the rocks dip gently away in all directions
Reverse fault
A fault in which the hanging wall moves up relative to the footwall. -can get fault scraps
faults
A fracture along which the adjacent rock surfaces are displaced parallel to the fracture
A seismic gap is?
A segment of an active fault where earthquakes have not occurred for a long time
Subduction-zone volcanoes
A subduction zone forms when continental crust and oceanic crust collide. ... Subduction zones produce volcanic arcs.
What are normal faults caused by?
Are caused by crustal extension (tension)
Mountains are?
Associated with crustal deformation (folding and faulting) caused by compressional and sometimes forces.
Which of following best describes an overturned fold?
Both limbs dip in the same direction
Mt. Adams, Mt. Hood, Mt. Mazama, Mt. St. Helens, and Mt. Rainer are apart of volcanic chain known as the?
Cascades
Which of these was the largest recorded earthquake in the world?
Chile (1960)
Basin-and-range topography formed as a result of?
Contiental extension
Which of the following is NOT a type of stress?
Divergent
Earthquake hazards
Earthquakes don't kill people; buildings do
Formation of a tsunami
Energy released where the fault moves. The energy moves through the water and the water stacks up on itself.
About how frequently has Yellowstone erupted in the past?
Every 600,000 years
Where the earthquake originates
Focus
Which of the following best describes how well geologists were able to predict the eruption of Mt. St. Helens?
Geologists detected signs of volcanic activity, but over 50 people died when the volcano erupted laterally (sideways) a couple months later.
signs of active volcanic activity
Ground deformation, increased earthquake activity, and New or changes in volcanic gas release
A syncline
Has limbs that dip toward the middle of the fold
Which of the following mountain chains were formed by continental collision?
Himalayas (India and Asia)
The San Andreas fault near San Francisco
Is locked and accumulating stress
Why do geologists refer to Yellowstone as a "Supervolcano?"
It's BIG
The resulting tsunami causes a nuclear meltdown
Japan (2011)
example of oceanic-oceanic subduction zone
Japan and Indonesia
Stratovolcano
Large, nearly symmetrical volcano composed of interbedded lava and pyroclastic deposits -Mainly from a central -Felsic magma and high viscosity (builds up gases and violent eruptions)
When water-saturated soil behaves like a fluid during an earthquake, it is called?
Liquefaction
Crater Lake (Oregon) occupies the collapsed caldera of
Mt. Mazama
Where in the U.S. could you go to see some tremendous horsts and grabens?
Nevada (basically all basin and range. Also, extends to other ranges)
The Andes and the Cascade Range (including Mt. St. Helens and Mt. Rainer) formed as a result of ?
Oceanic-continental convergence
Body waves
P wave: earthquake first or primary wave you feel S Wave: slower and you feel this wave second
The San Andreas fault is an example of a _______, _______ fault
Right-lateral, strike-slip
Elastic rebound
Rocks bend and then break Ex. rubber band bend a certain amount and reverts back to the original shape and if you pulled more it would snap.....rebound to original length) How does this relate to earthquakes? This is what happens along fault lines San Andreas Fault IS NOT ACTIVELY MOVING TODAY BECAUSE WHEN IT MOVES IT CREATES AN EARTHQUAKE (SAN ANDREAS FAULT IS ALWAYS UNDER STRESS) -stress is consist and continuously adds stress then it ruptures and then releases all at once (the release is when the earthquake occurs)
Which of these led to the earliest scientific research into the cause of earthquake?
San Francisco (1906)
What is an example of continental collision?
The Himalayas were formed by continental collision between India and Asia
The modified-Mercalli scale for earthquake magnitude is determined by?
The amount of damage
Richter magnitude is determined by?
The amplitude of the largest wave
Geologists studying the San Andreas fault near Parkland,CA failed to predict which of the following?
Timing
Volcanic hazards-lahars
Volcanic Mudflows-Lahars Lahara= mixture of ashe and water -Lot of have glaciers at top..., melts snow and ice and creates a flood... the flood is not made of just water it contains ashe and is like a thick soup
What are the mountain building processes?
Volcanoes Subduction Mountain Ranges (ex. Cascades and Andes)
Mt. St. Helen (1980)
Washington State -initial signs of activity in march; eruption on May 18 -3 main things that can be used to predict a volcanic eruption: Gases being released,earthquakes, ground can be deformed (volcano starts to change shape like burping) -People were evacuated and park was closed -Only 57 deaths (positive side of this) -evacuation zone basically a circle around the volcano
plunging anticlines
When there are three directions of push -Just fold with two sides is ridge with two layers and headbutted in looks like a "U" -limbs dip away from the limbs it must be anticline -oldest outside and youngest on the inside
basin
a low-laying area or area in which sediments accumulate with no surface outlet. -youngest near the middle oldest layers on the outside)
strike-slip fault
a type of fault where rocks on either side move past each other sideways with little up or down motion -Right- lateral -left lateral
This structure shown here is a (n)
anticline
If the rock layers on the outside of the circle (on a geologic map) are older than the rock layers on the inside of the circle, the structure is a(n)?
basin
terranes
block or crystal fragments that come from the same source and from the same continent. Different pieces that get added on.
Overturned fold
both limbs are now pointing to the left
Compressional
caused by convergent boundaries (dip-slip faults=reverse fault)
Tensional
caused by divergent boundaries (dip-slip faults=normal faults)
Shear
caused by transform boundaries (strike slip faults)
Recumbent fold
completely turned side ways
The angle at which a sedimentary layer is inclined from horizontal is called its ____
dip
On a geologic map, the rock layers form a circle.
either a dome or basin
plunging synclines
if the limbs dip toward the middle then its syncline
Seismometers
instrument that produces seismographs and How to measure movement of the earth
A fracture with no displacement is called a(n)?
joint
symmetrical fold
limbs have equal dip
Anticline
look like "A" and fold up): Ground surface looks flat
Surface waves
much more complex (up-and down and side to side motion)
Volcanoes occur?
occur because plate tectonics,subduction zones, rift valleys and beneath hot spots
Fault scraps
one blocks move down exposes the surface Ex. Salt Lake City, Utah live on an active Fault scraps -DON'T LIVE ON FAULT SCRAPS
asymmetrical fold
one side is steeper than the other (slopes are different there is still one point in each way)
Normal Faults
pulled apart (when moves you get an earthquake)
The intersection of a horizontal plane with a rock layer defines the rock layer's
strike
Seismographs
used to measure location and magnitude *Time between body waves tells you how far away the earthquake happened*
