1. Earthquakes AICE Environmental Management
Unit 2: Lithosphere – Earthquakes & Volcanoes

2. Guided Reading Questions

3. BELLRINGER: Earthquake Probability
Use this map and bar graph inside to answer analysis questions in your comp. book.

4. GR #1

5. Why do earthquakes occur?
GR #1
Why do earthquakes occur?
focus
epicenter
Fractures, faults
Energy released
and propagates in all directions as seismic waves causing
earthquakes
Why do rock break?
Review three types of stress: tension, compression, shear
Three types of deformation resulting: elastic, plastic and brittle
We’re concerned with the brittle deformation – causes faults, fractures through which energy, created by the friction, is released
Define Focus, epicenter and seismic waves

7. Where do earthquakes occur:
Most earthquakes occur along the edge of the oceanic and continental plate (convergent)
Along faults: normal, reverse, transform
80% occur in circumference of Pacific plate

8. Types of Faults

9. VIDEO: Earthquakes 101

10. ACTIVITY: Types of Faults Foldable Booklet

11. BELLRINGER: Learning From the Past
Read the article and summarize the key points in your comp. book.

12. Seismic waves: forms P-waves: S-waves:
called compressional, or push-pull waves
Propagate parralel to the direction in which the wave is moving
Move through solids, liquids
S-waves:
Called shear waves
Propagate the movement perpendicular
to the direction in which the wave is
moving
Surface waves (L-waves or long waves).
Complex motion
Up-and-down and side-to-side
Slowest
Most damage to structures, buildings
P-waves: the bell analogy: waves felt by both sound

13. Seismic waves: Properties
Velocity: function of the physical properties of the rock the wave is traveling through
Velocity increases with rock density
Velocity changes when passing from one material to another (increases/decreases)
Liquids: S-waves do not get transmitted through liquid; P-waves slow down
Why is this important?
If we know the velocity of the wave, we can infer
the type of rock it traveled through- that’s how we map
the interior of the Earth!!!

14. Measuring earthquakes
Seismometers: instruments that detect seismic waves
Seismographs
Record intensity, height
and amplitude of seismic
waves
Earliest seismograph was invented in China ~ 2000 years ago (or 136 AD)
Easy to make; can make your own at home

16. Locating the Shaking
Measure time between P and S waves on a seismogram
Need at least 3 seismographs

18. LAB: Locating Epicenter

19. Ways to Measure Earthquakes
GR #2
Magnitude: Richter Scale
measures the energy released by fault movement
related to the maximum amplitude of the S wave measured from the seismogram
Logarithmic-scale; quantitative measure
each whole number there is a 31.5 times increase in energy
eg. an increase from 5 to 7 on the Richter scale = an increase in energy of 992 times!!
Write Table 11-1 on the board, to help relate to Richter scale

20. Intensity: Mercalli Scale
What did you feel?
Assigns an intensity or rating to measure an earthquake at a particular location (qualitative)
I (not felt) to XII (buildings nearly destroyed)
Measures the destructive effect
Intensity is a function of:
Energy released by fault
Geology of the location
Surface substrate: can magnify shock waves e.g. Mexico City (1985) and San Francisco (1989)

21. Frequency of Occurrence of Earthquakes
Descriptor
Magnitude
Average Annually
Great
8 and higher
1 ¹
Major
17 ²
Strong
134 ²
Moderate
1319 ²
Light
13,000 (estimated)
Minor
130,000 (estimated)
Very Minor
1,300,000 (estimated)
¹ Based on observations since ² Based on observations since 1990.
Magnitude 2 and smaller earthquakes occur several hundred times a day world wide. Major earthquakes, greater than magnitude 7, happen more than once per month. “Great earthquakes”, magnitude 8 and higher, occur about once a year.

22. Recent Earthquake Activity in the World
GR #3
Recent Earthquake Activity in the World

23. Largest Earthquake in the World
More than 2,000 killed, 3,000 injured, 2,000,000 homeless, and $550 million damage in southern Chile
tsunami caused 61 deaths
$75 million damage in Hawaii;
138 deaths and $50 million damage in Japan;
32 dead and missing in the Philippines;
$500,000 damage to the west coast of the United States.
Chile : 1960 May 22 19:11:14 UTC Magnitude 9.5

25. Earthquakes & Society
Earthquakes and tsunamis can affect human societies.
Homes, buildings, and bridges can be strengthened to decrease earthquake damage.

26. Earthquake Hazard
a measurement of how likely an area is to have damaging earthquakes in the future
level determined by past seismic activity
more frequently earthquakes happen, the higher the earthquake-hazard level
EX: California, for example, has a very high earthquake-hazard level because a lot of earthquakes happen there

27. Types of Earthquake Damage
Ground Failure - constructions collapse
Fires - from broken gas and electrical lines
Landslides - EQ's triggered; occur in hilly/mountainous areas.
Liquefaction - water-saturated, unconsolidated materials flow
Tsunami (seismic sea waves; "tidal" waves) - can grow up to 65 m

28. San Francisco – 1989 Earthquake
On October 17, the Bay Area was buzzing about baseball. The Oakland Athletics and San Francisco Giants, both local teams, had reached the World Series. The first game of the series was scheduled to begin at 5:30 p.m. at San Francisco’s Candlestick Park. Just prior to the game, with the cameras on the field, a 7.1-magnitude tremor centered near Loma Prieta Peak in the Santa Cruz Mountains rocked the region from Santa Cruz to Oakland. Though the stadium withstood the shaking, much of the rest of San Francisco was not so fortunate. The city’s marina district suffered great damage. Built before 1972, on an area of the city where there was no underlying bedrock, the liquefaction of the ground resulted in the collapse of many homes. Burst gas mains and pipes also sparked fires that burned out of control for nearly two days.

29. VIDEO: San Francisco EQ

30. Earthquakes - San Andreas Fault
Collapse of the Nimitz Expressway

31. San Francisco-Oakland Bay Bridge

32. India, Gujarat earthquake Jan 26, 2001

33. Landslides: May 30, 1970 Peru disaster
Magnitude: 7.9
A large mass of ice and rock slid from a vertical face on Nevado Huascaran, the highest peak in Peru
Debris reached a velocity of 280 km/hr
traveled 11 km horizontally in about 4 minutes at a mean velocity of 165 km/hr.
Buried the towns of Yungay and Ranrahirca, The death toll in both villages was 20,000.
A large mass of ice and rock separated from a vertical face on Nevado Huascaran, the highest peak in Peru
The slab fell 1000 m vertically, disintegrated, slid down the lateral slopes of the mountain, and then was launched off a 'ski jump'.
Debris reached a velocity as high as 280 km/hr
buried the towns of Yungay and Ranrahirca, having traveled 11 km horizontally in about 4 minutes at a mean velocity of 165 km/hr.
The death toll in both villages was 20,000.

34. The town of Huaraz flattened
The reason for the rather unattractive modern buildings is that the town was completely rebuilt following a catastrophic earthquake in 1970 which flattened all but one street of buildings and killed half of the city’s population.

35. Landslides & Mudflows Earthquakes triggers mass movements
cause destruction & loss of life
cause loose rock & soil on slopes to move (landslides)
Where water content of soil is high, can cause mudflows
Mixture of soil & water slides downhill burying everything beneath it

36. Liquefaction
where sediment layers & rock are saturated with water, earthquake can cause liquefaction
what had been stable soil suddenly turns into liquid
liquid cannot support buildings or other structures
buildings & bridges may settle & collapse
underground storage tanks or sewers lines may float to the surface

37. Foundation Weakening Due to Soil Liquefaction in Adapazari, Turkey - Source: USG

38. Tsunami
wave formed when the ocean floor shifts suddenly during an earthquake
form when an earthquake pushes up a slab of ocean floor along a fault.
an underwater landslide or volcanic eruption can also trigger a tsunami
once formed resembles the ripples created when you drop a stone in the water

40. Tsunami: December 26 , 2004 Sumatra–Andaman earthquake
Magnitude: 9.4 Earthquake West of Sumatra in Indian Ocean
killing 230,000 people in 14 countries
inundating coastal communities with waves up to 30 metres (100 ft) high
third-largest earthquake ever recorded on a seismograph
longest duration of faulting ever observed, between 8.3 and 10 minutes
Indonesia was the hardest-hit country, followed by Sri Lanka, India, and Thailand
triggered other earthquakes as far away as Alaska
A large mass of ice and rock separated from a vertical face on Nevado Huascaran, the highest peak in Peru
The slab fell 1000 m vertically, disintegrated, slid down the lateral slopes of the mountain, and then was launched off a 'ski jump'.
Debris reached a velocity as high as 280 km/hr
buried the towns of Yungay and Ranrahirca, having traveled 11 km horizontally in about 4 minutes at a mean velocity of 165 km/hr.
The death toll in both villages was 20,000.

41. VIDEO: Indian Ocean Tsunami

42. Earthquake risk and prediction
Long-term methods
Real-time 24 Hour
Forecast
seismic hazard maps
probability analysis based on: - historical EQ records - geologic EQ records - slip-rate on active faults - frequency and magnitude of recent EQ's

43. Short-term predictions
Precursor phenomena (<1 year to days)
Foreshocks: usually increase in magnitude
Ground deformation
Fluctuations in water well levels
Changes in local radio wave characteristics
Anomalous animal behavior???
Animals and earthquakes:
On February 4, 1975 the Chinese successfully evacuated the city of Haicheng several hours before a 7.3 magnitude earthquake-- based primarily on observations of unusual animal behavior.
Conventional science has never been able to adequately explain the phenomenon.
Although the majority of accounts pertain to dogs and cats, there are also many stories about other types of animals in the wild, on farms, and in zoos; including horses, cows, deer, goats, possums, rats, chickens, and other birds. The behavior has been reported in many other animal species as well, including fish, reptiles, and even insects. Deep sea fish, for example, have been caught close to the surface of the ocean on numerous occasions around Japan prior to earthquakes (Tributsch, 1982).
A number of theories have been proposed to explain this phenomenon, and what the precursory signals that the animals are picking up on might be. Because many animals possess auditory capacities beyond the human range, it has been suggested that some animals may be reacting to ultrasound emitted as microseisms from fracturing rock (Armstrong, 1969).
Another candidate is fluctuations in the earth's magnetic field. Because some animals have a sensitivity to variations in the earth's magnetic field (usually as a means of orientation), and since variations in the magnetic field occur near the epicenters of earthquakes (Chapman and Bartels, 1940), it has been suggested that this is what the animals are picking up on.

44. Impacts of Earthquake Prediction

45. GR #4