EAS 220 Lab 3: EARTHQUAKES

Travel Time Graph

Plate Boundaries

Types of BoundariesDivergent

Convergent

Transform

Divergent Boundaries: Spreading zones (ex. Mid Atlantic Ridge, Red Sea Rift)

Convergent: Subduction (ex. West coast of South America, Aleutian Islands)

Transform Boundaries: Plates slide past each other (ex. San Andreas in

California)

Richter Magnitudes Description Earthquake Effects Frequency of Occurrence

Less than 2.0 Micro Microearthquakes, not felt. About 8,000 per day

2.0-2.9 Minor Generally not felt, but recorded. About 1,000 per day

3.0-3.9 Minor Often felt, but rarely causes damage.

49,000 per year (est.)

4.0-4.9 Light Noticeable shaking of indoor

items, rattling noises. Significant damage unlikely.

6,200 per year (est.)

5.0-5.9 Moderate

Can cause major damage to poorly constructed buildings over small regions. At most

slight damage to well-designed buildings.

800 per year

6.0-6.9 Strong Can be destructive in areas up to about 100 miles across in

populated areas. 120 per year

7.0-7.9 Major Can cause serious damage over larger areas. 18 per year

8.0-8.9 Great Can cause serious damage in areas several hundred miles

across. 1 per year

9.0-9.9 Great Devastating in areas several thousand miles across. 1 per 20 years

10.0+ Great Never recorded; see below for

equivalent seismic energy yield.

Extremely rare (Unknown)

Earthquake FactsLargest ever recorded: 9.6 in Chile in 1960

2nd largest: (Largest US Earthquake): Alaska 1964 Good Friday Earthquake, Magnitude 9.4

3rd largest: Indian Ocean 2004. Indonesia/Sumatra. Generated tsunami (9.2-9.3)

*3 big earthquakes: 1811, 1812 (within two months!)

*made Mississippi flow backwards

*Rang church bells in Boston and felt widespread. Probably close to 7.8 magnitude.

New Madrid Fault Zone

Biggest NY EarthquakesUtica, Attica, Syracuse have had quakes.

Massena 1940’s: magnitude 6. Blue Mountains: active area, magnitude 5.5 a few years ago.

Historically, large earthquakes in NYC area. Frequent magnitude 2-3. Beneath city itself, historically 6’s. Magnitude 5.1, 2002.