The quake intensity as per the Mercalli scale that was used at that time was between 8 and 9, which seismologists today equate to a value of 7.9 on the Richter scale. [Dr. Frank J. Collazo] the quake created a rupture of 296 miles, which rates it as one of the biggest quakes ever. Geologist John M. Clarke said, " the heavy waves travelled at the rate of about 11,000 ft a second and the lighter preliminary and subsequent waves much more rapidly, at about 40,000 feet a second." [New York Times] With San Francisco as its epicentre, the quake took a toll of 3000 human lives and absolutely wrecked the city destroying most structures while what was left was consumed by the conflagration that ensued. The predominantly wooden structures of San Francisco was the reason for such a rapid spread of fire. [New York Times] in an attempt to stop the spreading fire firelighters were forced to destroy buildings on its path by dynamiting. Water shortage made things worse for the fire fighters who tried their best to douse off the fury of the flames. The quake triggered a new interest in the study of earthquakes, particularly in the study of the San Andreas fault line and contributed immensely to the scientific research on earthquakes. Mr. Henry Fielding Reid, a Geology professor at the Johns Hopkins University and one of the researchers involved in the study of the 1906 quake, proposed the 'elastic rebound theory' which even today constitutes the base of our understanding of earthquakes. [USGS]

New Brunswick (1982)

Compared to the two previously discussed earthquakes, the 1982 New Brunswick quake can be termed to be of moderate intensity with a Richter scale reading of 5.9. The quake, which jolted the New Brunswick region with Woodstock as its epicentre, started at 7:52 A.M and lasted for 30 seconds. Reports indicate no human casualty or severe injuries. A mild aftershock followed three hours after the main quake and was measured at an intensity of 4.9 on the Richter scale. [the Associated Press]

Imminent warning for major earthquakes would be critical...

However, it transpires that though scientists are able to predict quakes based on fault lines they are still unable to issue short-term predictions with any certainty. It is saddening that in spite of the warning Tangshan country did not take enough action (compared to Quinglong). Anticipation and preparedness and timely response as was done by residents of Qinglong would have saved millions of lives in Tangshan. Despite our efforts, our scientific knowledge is still a long way from a successful prediction of earthquakes leaving us with a large amount of unpredictability.
Bibliography

SANDRA BLAKESLEE, 'Mercilessly Unpredictable, Quakes Defy Seismologists',

Accessed April 23rd 2007, available at http://www.nytimes.com/2004/12/28/science/28pred.html?ex=1261890000&en=3a888aa1e18b1a35&ei=5090&partner=rssuserland

New York Times, "Tangshan Quake Area in China is Toured by Premier," Aug 5, 1976

Andrew H. Malcolm, "Chinese Disclose that 1976 Earthquake was Deadliest in Four Centuries," New York Times Jan 2, 1977

Reuters, "Quake Struck Chinese City is a Vast Plain of Rubble," Jun 11, 1977, New York Times

Dr. Frank J. Collazo, "History of Earthquakes in the United States," Accessed 23rd April 2007, available at http://www.fjcollazo.com/fjc_publishings/documents/SFErthquakes.htm

USGS, '1906 Marked the Dawn of Scientific Revolution', Accessed on April 23rd 2007, available at http://earthquake.usgs.gov/regional/nca/1906/18april/revolution.php

The Associated Press, 'New England is Shaken by a Sharp Earthquake', Jan 10, 1982

GlobalWatch, 'Integration of Public Administration and Earthquake Science: The Best Practice Case of Qinglong County', Accessed April 23rd 2007, available at http://www.globalwatch.org/ungp/qinglong.htm

New York Times, "Disasters Suffered by San Francisco', Apr 19, 1906

New York Times, "Albany Gets a Record of the Pacific Shocks," April 19, 1906