"We learn geology the morning after an earthquake."
~ Ralph Waldo Emerson
~ Seismology ~
All About Earthquakes
Earthquakes / More Quakes
Recent Equakes / Latest Equakes
The Science of Earthquakes / Fun Facts
This Week's Quakes / Earthquakes in History
What Causes Earthquakes: An Interactive World Map
FYI: Earthquakes commonly occur at plate boundaries along the Pacific "Ring of Fire."
FACT: Over 90% of EARTHQUAKES occur at PLATE BOUNDARIES.
What about the other 10%? (Answer: Faults)
Above: Map of U.S. Earthquake Hazard Zones
~ Earthquakes of New England ~
Our New England Earthquakes / Map
The Weston Earthquake Observatory
Mass Earthquake Resource Guide / History
The Clinton-Newbury Fault
The Lake Char-Bloody Bluff Fault
Above: Exposed Fault at the Bloody Bluff, Concord, MA
Above: Earthquake Proof Home on Virginia Road in Concord, MA
Earthquake-Proof Geodesic Dome Homes in California
"You fish on your side; we fish on our side; nobody fishes in the middle"
The 1755 Cape Ann, Massachusetts Earthquake
on the Lake Char-Bloody Bluff Fault
Cape Ann Earthquake of 1755 / More Info / Verses
Richter Magnitude Estimate: 6.5 - 7.0
How do scientists rate the severity of an Earthquake?
Click here: The Richter, Mercalli, and Moment Magnitude Scales
~ Earthquake Faults ~
Fault: A crack in the crust along which movement occurs.
Hanging Wall: The Rock Block ABOVE the Fault
Foot Wall: The Rock Block BELOW the Fault
Earthquake Fault Animations
Test your knowledge:
Identify the Hanging Wall and Foot Wall.
What kind of faults are shown above and below?
Transform (Lateral) Fault
( Stress: Shearing )
( Stress: Tension )
Reverse (Thrust) Fault
( Stress: Compression )
Left: Normal Fault ..............................Right: Reverse Fault
~ Focus and Epicenter ~
Focus and Epicenter
EPICENTER: Point on the surface directly above the focus (greatest shaking occurs here).
FOCUS: Underground location along a fault where displacement (movement) occurs.
TRIANGULATION: Locating the Epicenter
~ The Three Types of Stress ~
Types of stress that cause rock to fold and fracture:
Tension & Compression & Shearing
~ Folding ~
Folding is due to the force of compression acting upon rock.
Anticline and Syncline:
Faulting and Folding
~ Seismic Waves ~
Primary Waves: arrive first / travel the fastest / can go through both solids and liquids / are gentle
Secondary Waves: arrive second / travel through solids (not liquids) / cause much damage
Surface Waves: travel the slowest / make the ground roll like ocean waves / are the most destructive
P-waves compress and expand like an accordian or like slinky coils that are held and then released.
S-waves travel up and down & side to side like a rope that is flicked.
Left: P-waves / Right: S-waves
Click here: Green Dot Demo / P and S Demos / Slinky Slo Mo Style
Primary (P) / Secondary (S) / Surface (L/R)
Below: Surface Waves (Love Waves and Rayleigh Waves)
Below: Surface Wave Damage to an Athletic Track (Japan)
~ Earthquake Safety ~
Earthquake Safety Regulations / Damage Photos
Disaster Plan / Hazards
Drop, Cover, Hold On Song: Caribbean Style
Earthquake Rumble Song / Earthquake Safety Turtle Song
DROP, COVER and HOLD during an earthquake!
Rather than: PANIC, CRY and DIE!
What to Do After the Quake
Above: Rescue Dog
Post-Earthquake Danger: Bridge/Bridge/Bridge / Freeway / Building Collapse / Photos
Post-Earthquake Danger: Seismic Sea Wave-Tsunami (See Below)
Post-Earthquake Danger: Gas Pipe Breakage and Fire
Post-Earthquake Danger: (Fore) & Aftershocks
Post-Earthquake Danger: Liquefaction
Earthquake-Proof Your Home / Easy Steps / Build / Prepare
Above: Epic Fail
~ Liquifaction ~
Mexico City, Mexico, 1985
Above: Damage to structural foundations due to Liquefaction
Liquifaction (Quicksand Soil) = Water-Saturated Loose Sediment that Flows like a Liquid.
Mini "Sand Blow Craters" form as a result of Liquefaction:
Water from the "saturated zone" perculates up to the surface:
Above: Aquifer and Water Table
Above: Note the tighter packing of sediment grains after an earthquake
(Less pore space = Less room for groundwater)
Learn About Liquefaction / Video Clips
Above: Liquefaction Zone after the Sendai, Japan earthquake of 2011
~ Tsunami ~
Click here: Tsunami Information Page