Stress and Strain 

1) Stress: force per unit area
2) Strain: deformation of the earth
3) Material behavior

• plastic
• brittle
• elastic

Folding and Faulting

1) Folding - plastic deformation

• synclines
• anticlines

• normal faulting - extensional tectonics

• reverse or thrust faulting - compressional tectonics

• strike-slip - compressional tectonics

Elastic Rebound

 - stored energy of deformation

• exceeds strength of material or friction on fault
• energy "returns" rock to pre-deformation state
• vibrations generated: seismic waves

Seismic Waves

1) body waves 

• P-waves
• compressional
• longitudinal particle motion
• change in shape and volume

• S-waves
• perpendicular particle motion
• shear
• change in shape only

2) surface waves

• restricted to surface of the earth
• motion like an ocean wave
• retrograde and elliptical

p-wave > s-wave > surface wave

p-wave travel  through all medium

s-wave not through liguid or gas (no shear strength)

Earthquake Parameters

1) focus and epicenter 

2) location

• determine time interval between P- and S-wave from seismogram 

• determine distance from P- and S-wave travel time curves

• plot distances for at least three different seismic station...intersection represents epicentral location.

3) Magnitude & Energy

• magnitude = log (A/T) +D

 - a 10x increase in amplitude with each unit increase in the magnitude number
• energy:

 - energy increases 30x with each unit increase in the magnitude number

link to National Earthquake Information Center's description of the different magnitude calculations
at: http://wwwneic.cr.usgs.gov/neis/phase_data/mag_formulas.html

4) Intensity

• Mercalli Intensity map
• Example from the 1886 earthquake
Charleston, South Carolina 


Modified Mercalli Intensity Scale

       I. People do not feel any Earth movement.

       II. A few people might notice movement if they are at rest and/or on the upper floors of tall buildings.

       III. Many people indoors feel movement. Hanging objects swing back and forth. People outdoors might not realize that an earthquake is
       occurring.

       IV. Most people indoors feel movement. Hanging objects swing. Dishes, windows, and doors rattle. The earthquake feels like a heavy truck
       hitting the walls. A few people outdoors may feel movement. Parked cars rock.

       V. Almost everyone feels movement. Sleeping people are awakened. Doors swing open or close. Dishes are broken. Pictures on the wall move.
       Small objects move or are turned over. Trees might shake. Liquids might spill out of open containers.

       VI. Everyone feels movement. People have trouble walking. Objects fall from shelves. Pictures fall off walls. Furniture moves. Plaster in walls
       might crack. Trees and bushes shake. Damage is slight in poorly built buildings. No structural damage.

       VII. People have difficulty standing. Drivers feel their cars shaking. Some furniture breaks. Loose bricks fall from buildings. Damage is slight to
       moderate in well-built buildings; considerable in poorly built buildings.

       VIII. Drivers have trouble steering. Houses that are not bolted down might shift on their foundations. Tall structures such as towers and
       chimneys might twist and fall. Well-built buildings suffer slight damage. Poorly built structures suffer severe damage. Tree branches break.
       Hillsides might crack if the ground is wet. Water levels in wells might change.

       IX. Well-built buildings suffer considerable damage. Houses that are not bolted down move off their foundations. Some underground pipes are
       broken. The ground cracks. Reservoirs suffer serious damage.

       X. Most buildings and their foundations are destroyed. Some bridges are destroyed. Dams are seriously damaged. Large landslides occur.
       Water is thrown on the banks of canals, rivers, lakes. The ground cracks in large areas. Railroad tracks are bent slightly.

       XI. Most buildings collapse. Some bridges are destroyed. Large cracks appear in the ground. Underground pipelines are destroyed. Railroad
       tracks are badly bent.

       XII. Almost everything is destroyed. Objects are thrown into the air. The ground moves in waves or ripples. Large amounts of rock may move.

Earthquake Damage

• buildings: steel or wooden frame versus concrete or brick
• bridges, roads
• infrastructure: gas, water lines

Mitigation

1) zoning
2) building codes
3) predicted seismic intensity maps

Prediction

1) paleoseismicity and frequency
2) seismic gaps
3) seismic patterns
4) physical parameters of rocks

• magnetism
• electrical conductivity/resistivity
• radio waves
• well water levels
• radon
• animal behavior

• swelling or tilting
• foreshocks

1) Core

• S-wave shadow zone
• P-wave shadow zone

Notable World Earthquakes

Year	Location	Deaths	Magnitude
856	Corinth, Greece	45,000
1290	Chihli, China	100,000
1556	Shensi, China	830,000
1737	Calcutta, India	300,000
1828	Echigo, Japan	30,000
1868	Ecuador/Columbia	70,000
1886	Charleston, SC	60
1897	Assam India	1,500	8.7
1906	San Francisco, California	700	8.25
1908	Messina, Italy	120,000	7.5
1935	Quetta, India	60,000	7.5
1939	Erzincan, Turkey	23,000	8.0
1950	Assam, India	1,530	8.6
1960	southern Chile	5,700	8.5
1962	northern Iran	14,000	7.3
1964	Alaska	131	8.6
1970	Peru	66,000	7.8
1971	San Fernando, California	65	6.5
1972	Managua, Nicaragua	5,000	6.2
1975	Liaoning, China	few (predicted)	7.4
1976	Guatemala	22,000	7.9
1976	Tangshan, China	=250,000	7.6
1980	southern Italy	3,000	7.2
1982	Yeman	2,800	6.0
1985	Michoacan, Mexico	9,500	7.9
1988	Spitak, Armenia	25,000	7.0
1989	Santa Cruz, California	63	7.0
1990	Iran	>40,000	7.7
1990	Luzon, Philippines	1,700	7.8
1992	Landers, Califronia	1	7.5
1993	Latur, India	10,000	6.4
1994	Northridge, California	56	6.9
1995	Kobe, Japan	5400	6.9