"We learn geology the morning after an earthquake."

~ Ralph Waldo Emerson

~ Seismology ~

PBS Quakes

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."


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"

Lake Chargogogga...whatever...

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?

Charles Richter
Guiseppe Mercalli

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


Normal Fault
Reverse Fault
Strike-Slip 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 )



Normal Fault

( 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

Triangulation Technique

~ 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

Remember to:

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