Q : What Are Some Significant Earthquakes In The Past

New Madrid Quakes

December 16, 1811 through February 1812, early settlers of the Central Mississippi Valley must have thought the world was coming to an end when three of the most powerful earthquakes ever to happen in the Continental USA hit the New Madrid Missouri, and Marked Tree, Arkansas area.

There are accounts of the Mississippi and Arkansas rivers heaving upward, rolling backwards for a few seconds then rerouting their banks before settling down. A series of finger lakes disappeared and new ones were created. Reelfoot Lake in TN is said to have been created by the quakes.

Damage reports were as far away as Washington, DC, Philadelphia, PA and Charleston, SC. Each of the three quakes would have measured 8.0 plus on the Richter Scale, if a seismograph would have been in place.

San Francisco April 18, 1906 Quakes

At 5:12 am Pacific time, San Francisco was devastated with a a series of violent shocks starting with a 7.7 on the Richter scale. It took the lives of 700 to 800 people (some 3,000 total following a consortium of aftershocks) and left 225,000 homeless, with 28,000 buildings destroyed. The largest problem in San Francisco was fire, gas mains and lights ruptured creating a fire which burned for many days.

It ranks as one of the most significant earthquakes of all time. The great earthquake broke loose some 20 to 25 seconds later, with an epicenter near San Francisco. Violent shocks punctuated the strong shaking which lasted some 45 to 60 seconds. The earthquake was felt from southern Oregon to south of Los Angeles and inland as far as central Nevada. The highest Modified Mercalli Intensities (MMI's) of VII to IX paralleled the length of the rupture, extending as far as 80 kilometers inland from the fault trace

Anchorage, Alaska 1964 Quake

It was March 27, around 5:30 p.m., on a Good Friday when cars filled chasms were sidewalks once stood after the 9.2 shock hit Anchorage, A Tsunami ripped into Prince William Sound killing 115 people and 15 more inland. A 30 block Area of dwellings and commercial buildings were damaged or destroyed in the downtown area. The tsunami devastated many towns along the Gulf of Alaska, and left damage at Alberni and Port Alberni, Canada, along the West Coast of the United States (15 killed), and waves hit in Hawaii. The Uplifted sea floor at Cape Cleare, Montague Island, Prince William Sound, in the area of greatest recorded tectonic uplift on land (33 feet).

San Francisco 1989 (Loma Prieta Quake)

At 5:04 P.M., Tuesday, October 17, 1989, as over 62,000 fans filled Candlestick Park for the third game of the World Series and the San Francisco Bay Area commute moved into its heaviest flow, a Richter magnitude 7.1 earthquake struck. It was an emergency planner's worst-case scenario. The 20-second earthquake was centered about 60 miles south of San Francisco, and was felt as far away as San Diego and western Nevada. Scientists had predicted an earthquake would hit on this section of the San Andreas Fault and considered it one of the Bay Area's most dangerous stretches of the fault.

Northridge California January 17, 1994 Quake

The 6.7 Magnitude Northridge Earthquake struck early in the early morning of January 17, 1994 at 4:31 AM. The Epicenter was in Northridge, California, a suburb of Los Angeles in the San Fernando Valley. This same general area had been hit by a 6.6 Magnitude quake in 1971. It was one of the most expensive natural disasters in US history, with total damage estimated at $15 billion. The death toll of 57 and 1500 serious injuries is considered low for a quake of this size in a heavily populated area. This was one of the best prepared areas in the world. Most people were safe in their beds at the time of the quake, reducing the casualties. Earthquake awareness in California was high following the 1971 San Fernando quake in this same area and the 1989 Loma Prieta quake in northern California. Building codes required earthquake resistant designs that prevented outright collapse in almost all cases.