July 5, 2014 – 40 Years of United States Earthquakes and a Prediction for the Future: The U.S. has experienced 21 major earthquakes, greater than 6.9 Magnitude, over the last 40 years. The State of Alaska topped the list with 12, followed by California with 7 and one each for Idaho and Hawaii. These 21 quakes ranged in Magnitude (M) from 7.0M to 7.9M.
On June 10, 1996; Alaska experienced two powerful earthquakes on the same day (7.9M & 7.3M), only 11 hours and 9 minutes apart. Further, In 1987 Alaska saw two tremors that were only 13 days apart – 7.2M on Nov. 17th and 7.6M on Nov. 30th. Additionally, three months and seven days after the Nov. 30th event, there was a 7.6 quake on March 6, 1988. Lastly, in 2002 Alaska experienced two large earthquakes that were one year and seven days apart – 7.9M on Nov. 3, 2002 (Fairbanks) and 7.8M on Nov. 17, 2003 (Rat Island in the Aleutian Island Chain).
California had seven quakes, between 7.1M and 7.6M, including the “World Series” Loma Prieta 7.1M tremor on Oct. 18, 1989. The infamous San Andreas Fault runs from the Gulf of California (the Sea of Cortez) through the Salton Sea, just east of Los Angeles, directly through San Francisco and off the northern California Coast. This Transform Fault (“Strike/Slip”) does not produce the super earthquakes that subduction zone faults do in terms of power, however they can do plenty of damage as seen in the renowned San Francisco quake and fire of 1906. With 38 million people in the most populous state in America, a shallow large earthquake next to a big city would be catastrophic. The Christchurch, New Zealand quake was less than 6.0M, however major damage was seen in the city because the tremor was directly under the town, at a very shallow depth.
Hawaii had a 7.1 quake on Nov. 29, 1975 and Idaho experienced a 7.3 tremor on Oct. 28, 1983.
What is noticeably missing from this graph? The states of Oregon and Washington, and the Canadian Province of British Columbia. This area is extremely dangerous, in terms of a potentially huge future earthquake and tsunami. That is because the 680 miles Juan de Fuca subduction Tectonic Plate, runs from Mount Lassen in California to Mount Garibaldi in British Columbia. Subduction Zones produce the largest earthquakes in the world. Both the Dec. 26, 2004 Sumatra quake and tsunami and the Mar. 11, 2011 Honshu Japan quake and tsunami, were generated from sudden releases of subduction zone faults. The Juan de Fuca fault is only 50 miles off shore, leaving only six minutes warning time for a tsunami. The odds of a major event along this fault are extremely high, since their has not been a major earthquake here in over 300 years. All other subduction zone faults, around the “Ring of Fire,” have experienced major events except this one. Portland, Oregon; Seattle, Washington and Vancouver, British Columbia are in severe danger.
Extensive earthquake cycle work points to the follow date as particularly troublesome, and will probably see a major release along the Juan de Fuca subduction zone. This date is July 16, 2014 +/- 15 days.
What would happen to Seattle in the event of a major earthquake taking place off shore? Since the subduction zone fault is so close to Seattle, a major seismic event would do considerable damage to the city; with extensive loss of life. Within six minutes of the quake, a huge tsunami would continue the devastation. Mount Reiner would erupt sending Lahars tearing what’s left of the city apart; not to mention the destruction raining from the sky in terms of molten rock, ash and fire. Lahars are like pyroclastic flows (super heated clouds of dust and debris) but are produced when the heat of the eruption melts vast quantities of snow and ice and send giant rivers of water, sand, mud, rock and other debris gushing down the flanks of the mountain. Lahars are the consistency of wet cement and virtually nothing is left standing in its wake. Lahars were present in the May, 1980 Mount St. Helens earthquake; which is small in terms of a major event occurring along the Juan de Fuca subduction Plate. Property damage would be in the billions and major corporations, e.g., Microsoft and Boeing; would be wiped out. Stocks would plummet.
The Master of Disaster