1. ERIC ANGAT Environmental Science
Earthquakes
ERIC ANGAT Environmental Science

2. How do we protect ourselves from earthquakes?
Essential Question
How do we protect ourselves from earthquakes?

3. 1. In what area of our planet are earthquakes most common?
Transform boundary
San Andreas fault
Convergent boundary
volcanoes
Earthquakes happen because of too much stress in fault lines or a result of volcanic eruption. They are most common in the Pacific Ring of Fire.
Pacific Ring of Fire
Earthquake prone

4. 2. How is Earth affected by plate boundaries?
Divergent –Tensional stress
Convergent -Compressional stress
Transform-Shear stress

5. 3. Which is the hanging wall and which is the foot wall in a fault?
A is the _______wall while
B is the _____ wall.
hanging
foot

6. 4. Describe the motion of the foot wall and the hanging wall in a normal fault.

7. 5. Describe the motion of the foot wall and the hanging wall in a reverse fault.

8. Hanging wall goes down and foot wall goes up. Movement of the crust
Reverse Fault
Normal Fault
Hanging wall goes down and foot wall goes up.
Movement of the crust
Hanging wall goes up and foot wall goes down.

9. Rocks break in the focus because of too much stress!
6. What is the location within Earth where earthquake begin?
Epicenter
Seismic waves
Earthquake Facts
The largest recorded earthquake in the United States was a magnitude 9.2 that struck Prince William Sound, Alaska on Good Friday, March 28, 1964 UTC.
The largest recorded earthquake in the world was a magnitude 9.5 (Mw) in Chile on May 22, 1960.
The earliest reported earthquake in California was felt in 1769 by the exploring expedition of Gaspar de Portola while the group was camping about 48 kilometers (30 miles) southeast of Los Angeles.
Before electronics allowed recordings of large earthquakes, scientists built large spring-pendulum seismometers in an attempt to record the long-period motion produced by such quakes. The largest one weighed about 15 tons. There is a medium-sized one three stories high in Mexico City that is still in operation.
The average rate of motion across the San Andreas Fault Zone during the past 3 million years is 56 mm/yr (2 in/yr). This is about the same rate at which your fingernails grow. Assuming this rate continues, scientists project that Los Angeles and San Francisco will be adjacent to one another in approximately 15 million years.
The East African Rift System is a km (31-37 miles) wide zone of active volcanics and faulting that extends north-south in eastern Africa for more than 3000 km (1864 miles) from Ethiopia in the north to Zambezi in the south. It is a rare example of an active continental rift zone, where a continental plate is attempting to split into two plates which are moving away from one another.
The first “pendulum seismoscope” to measure the shaking of the ground during an earthquake was developed in 1751, and it wasn’t until 1855 that faults were recognized as the source of earthquakes.
Moonquakes (“earthquakes” on the moon) do occur, but they happen less frequently and have smaller magnitudes than earthquakes on the Earth. It appears they are related to the tidal stresses associated with the varying distance between the Earth and Moon. They also occur at great depth, about halfway between the surface and the center of the moon.
Although both are sea waves, a tsunami and a tidal wave are two different unrelated phenomenona. A tidal wave is a shallow water wave caused by the gravitational interactions between the Sun, Moon, and Earth. A tsunami is a sea wave caused by an underwater earthquake or landslide (usually triggered by an earthquake) displacing the ocean water.
The hypocenter of an earthquake is the location beneath the earth’s surface where the rupture of the fault begins. The epicenter of an earthquake is the location directly above the hypocenter on the surface of the earth.
The world’s greatest land mountain range is the Himalaya-Karakoram. It countains 96 of the world’s 109 peaks of over 7,317m (24,000 ft). The longest range is the Andes of South America which is 7,564km (4700 mi) in length. Both were created bythe movement of tectonic plates.
It is estimated that there are 500,000 detectable earthquakes in the world each year. 100,000 of those can be felt, and 100 of them cause damage.
It is thought that more damage was done by the resulting fire after the 1906 San Francisco earthquake than by the earthquake itself.
A seiche (pronounced SAYSH) is what happens in the swimming pools of Californians during and after an earthquake. It is “an internal wave oscillating in a body of water” or, in other words, it is the sloshing of the water in your swimming pool, or any body of water, caused by the ground shaking in an earthquake. It may continue for a few moments or hours, long after the generating force is gone. A seiche can also be caused by wind or tides.
Each year the southern California area has about 10,000 earthquakes. Most of them are so small that they are not felt. Only several hundred are greater than magnitude 3.0, and only about are greater than magnitude 4.0. If there is a large earthquake, however, the aftershock sequence will produce many more earthquakes of all magnitudes for many months.
The magnitude of an earthquake is a measured value of the earthquake size. The magnitude is the same no matter where you are, or how strong or weak the shaking was in various locations. The intensity of an earthquake is a measure of the shaking created by the earthquake, and this value does vary with location.
The Wasatch Range, with its outstanding ski areas, runs North-South through Utah, and like all mountain ranges it was produced by a series of earthquakes. The 386 km (240-mile)-long Wasatch Fault is made up of several segments, each capable of producing up to a M7.5 earthquake. During the past 6,000 years, there has been a M6.5+ about once every 350 years, and it has been about 350 years since the last powerful earthquake, which was on the Nephi segment.
There is no such thing as “earthquake weather”. Statistically, there is an equal distribution of earthquakes in cold weather, hot weather, rainy weather, etc. Furthermore, there is no physical way that the weather could affect the forces several miles beneath the surface of the earth. The changes in barometric pressure in the atmosphere are very small compared to the forces in the crust, and the effect of the barometric pressure does not reach beneath the soil.
From there were only four states that did not have any earthquakes. They were: Florida, Iowa, North Dakota, and Wisconsin.
The core of the earth was the first internal structural element to be identified. In 1906 R.D. Oldham discovered it from his studies of earthquake records. The inner core is solid, and the outer core is liquid and so does not transmit the shear wave energy released during an earthquake.
The swimming pool at the University of Arizona in Tucson lost water from sloshing (seiche) caused by the 1985 M8.1 Michoacan, Mexico earthquake 2000 km (1240 miles) away.
Earthquakes occur in the central portion of the United States too! Some very powerful earthquakes occurred along the New Madrid fault in the Mississippi Valley in Because of the crustal structure in the Central US which efficiently propagates seismic energy, shaking from earthquakes in this part of the country are felt at a much greater distance from the epicenters than similar size quakes in the Western US.
Most earthquakes occur at depths of less than 80 km (50 miles) from the Earth’s surface.
The San Andreas fault is NOT a single, continuous fault, but rather is actually a fault zone made up of many segments. Movement may occur along any of the many fault segments along the zone at any time. The San Andreas fault system is more that 1300 km (800 miles) long, and in some spots is as much as 16 km (10 miles) deep.
The world’s deadliest recorded earthquake occurred in 1556 in central China. It struck a region where most people lived in caves carved from soft rock. These dwellings collapsed during the earthquake, killing an estimated 830,000 people. In 1976 another deadly earthquake struck in Tangshan, China, where more than 250,000 people were killed.
Florida and North Dakota have the smallest number of earthquakes in the United States.
The deepest earthquakes typically occur at plate boundaries where the Earth”s crust is being subducted into the Earth’s mantle. These occur as deep as 750 km (400 miles) below the surface.
Alaska is the most earthquake-prone state and one of the most seismically active regions in the world. Alaska experiences a magnitude 7 earthquake almost every year, and a magnitude 8 or greater earthquake on average every 14 years.
The majority of the earthquakes and volcanic eruptions occur along plate boundaries such as the boundary between the Pacific Plate and the North American plate. One of the most active plate boundaries where earthquakes and eruptions are frequent, for example, is around the massive Pacific Plate commonly referred to as the Pacific Ring of Fire.
The earliest recorded evidence of an earthquake has been traced back to 1831 BC in the Shandong province of China, but there is a fairly complete record starting in 780 BC during the Zhou Dynasty in China.
It was recognized as early as 350 BC by the Greek scientist Aristotle that soft ground shakes more than hard rock in an earthquake.
The cause of earthquakes was stated correctly in 1760 by British engineer John Michell, one of the first fathers of seismology, in a memoir where he wrote that earthquakes and the waves of energy that they make are caused by “shifting masses of rock miles below the surface”.
In 1663 the European settlers experienced their first earthquake in America.
Human beings can detect sounds in the frequency range 20-20,000 Hertz. If a P wave refracts out of the rock surface into the air, and it has a frequency in the audible range, it will be heard as a rumble. Most earthquake waves have a frequency of less than 20 Hz, so the waves themselves are usually not heard. Most of the rumbling noise heard during an earthquake is the building and its contents moving.
When the Chilean earthquake occurred in 1960, seismographs recorded seismic waves that traveled all around the Earth. These seismic waves shook the entire earth for many days! This phenomenon is called the free oscillation of the Earth.
The interior of Antarctica has icequakes which, although they are much smaller, are perhaps more frequent than earthquakes in Antarctica. The icequakes are similar to earthquakes, but occur within the ice sheet itself instead of the land underneath the ice. Some of our polar observers have told us they can hear the icequakes and see them on the South Pole seismograph station, but they are much too small to be seen on enough stations to obtain a location.
Rocks break in the focus because of too much stress!
Deep focus-weak earthquake
Shallow focus- strong earthquake

10. 7. Which state has the most frequent earthquakes? Why?
Alaska registers the most earthquakes in a given year, with California placing second. California, however, has the most damaging earthquakes because of its greater population and extensive infrastructure.

11. http://www. washingtonstatesearch

12. Nuclear power plants in the United States
8. Describe the locations of nuclear power plants in the United States? Any relation with the earthquake map?
Nuclear power plants in the United States
There are 104 nuclear power plants currently in operation in the United States. For a link to the U.S. government NRC  Click Here
In addition there are 23 new nuclear plant locations planned in the United States. Of this total;  2 have been suspended, 2 suspended indefinitely, 1 delayed, 2 temporarily suspended, leaving 16 in progress with opposition.
The U.S. Chamber of Commerce has a website Project No Project  I put together a summary table from that source. But if you go to the Project No Project link you can find out the current status by state of new nuclear power plants.

13. 9. How do seismologists determine the location of the EPICENTER?
They calculate the distance and arrival time of seismic waves to determine the epicenter.

14. Deformed-does not return to original form.
10. Stress causes Strain. What are the three types of strain?
Breaks.
Brittle strain
Ductile strain
Deformed-does not return to original form.
Elastic strain
Returns to original form or shape.

15. 11. Seismic waves are produced by earthquakes
11. Seismic waves are produced by earthquakes. What are the three types of seismic waves?
P-wave
S-wave
Surface wave

16. Primary Wave (fastest)
12. Describe the movements of the three types of seismic waves?
Primary Wave (fastest)
expands and contracts
Surface Wave
Rolling motion
Secondary Wave
right angle

17. 13. What is the difference between intensity and magnitude?
Magnitude measures the energy released at the source of the earthquake. It is measured with a seismograph based on the amplitude.
Intensity is determined from effects on people, human structures, and the natural environment.

18. Intensity= I, II, III, IV, V, VI, VIII, IX…
Magnitude = 1,2,3,4,5,6,7,8,9…
Intensity= I, II, III, IV, V, VI, VIII, IX…

19. Magnitude 7 in California
14. Which will have a higher intensity of
earthquake given the same magnitude?
Magnitude 7 in Alaska
California will have a higher intensity because of higher population density and massive infrastructures.
Magnitude 7 in California
Magnitude does not change wherever you are.

20. 15. How is the intensity affected by the distance from the epicenter?
Richter Magnitude 9 in California ( Epicenter)
Intensity III
(Nevada)
Intensity II
(Utah)
Intensity VIII
(California)
Intensity I
(Colorado)

21. Transform boundary Shear Stress
Seismic waves
Epicenter
Transform boundary Shear Stress

22. 16.Why are seismic waves of an earthquake more strongly felt at the epicenter of an earthquake?
because the epicenter is directly the focus, the place inside the earth where the earthquake starts
because crustal plates rise and fall with the ocean tides
because most faults converge at the epicenter
because millions of small movements of the crust occur here

23. Landslide, mudslide, and avalanche all happen on a slope.
17. How are we affected by earthquakes?
Liquefaction - soil turns to mud due to severe shaking of the ground.
Soil and rocks
Mud
Snow
Avalanche
Mudslide
Landslide
Landslide, mudslide, and avalanche all happen on a slope.

24. 17. How are we affected by earthquakes?
Tsunami
earthquake
Japan 2011
Seismic wave
Water receded
The 2004 Indian Ocean earthquake was an undersea megathrust earthquake that occurred at 00:58:53 UTC on Sunday, 26 December 2004,
The earthquake was caused when the Indian Plate was subducted by the Burma Plate and triggered a series of devastating tsunamis along the coasts of most landmasses bordering the Indian Ocean, killing over 230,000 people in fourteen countries, and inundating coastal communities with waves up to 30 meters (100 ft) high.[8] It was one of the deadliest natural disasters in recorded history. Indonesia was the hardest-hit country, followed by Sri Lanka, India, and Thailand.
Indonesia, Sumatra 2004

25. Know where to go. Be aware!
17. What can we do protect ourselves against the dangers of earthquakes?
Know where to go.
Be aware!

26. 18. What can we do protect ourselves against the dangers of earthquakes?
Secure appliances, cabinets, and furniture.
Know what to do and where to go.
Be aware!

27. http://thelegallyinclined. blogspot

28. http://thelegallyinclined. blogspot

29. 19. Why are aftershocks so dangerous?
Aftershocks are small tremors that happen after the strong earthquake.
They are dangerous because they have the power to crumble buildings, roads, and bridges already weakened by the initial
earthquake
While foreshocks comes before a major earthquake.

30. Earthquakes Hazards and Safety

31. Define the following terms:
Epicenter ( p. 499 )
Fault ( p. 497 )
Focus ( p. 499 )
Primary wave ( p. 498 )
Secondary wave ( p. 498 )
Strain ( p. 496 )
Stress ( p. 495 )
Surface wave ( p. 498 )
Magnitude ( p. 505 )
Intensity (p. 506)

32. Open your textbook to page 507 to learn about earthquake intensity.