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It did significant damage also in Imperial County, CA, as well as being felt in multiple
counties. Dr. Lucy Jones, Chief Scientist of the the USGS Pasadena office said "It ... was felt by at least 20
million people". It swayed buildings from Los Angeles, to Phoenix.
At least one person was killed
in Baja, and there were a number of entrapments. South of the border, about 300 patients had to be evacuated from the
Mexicali General Hospital because the building had no electricity or water. There was structural damage north of the
border, electicity and communications were down, gas lines leaking, and damage to the water delivery systems.
According to Susan Hough of the USGS it involved six differing faults, not all of which were adjacent to each other.
She said: "This quake supports and aids plate motion." This is a statement that should be considered
concerning.
Initially, the robust aftershock sequence lined up with the Elsinore Fault, traveling in roughly a
southeast to northwest trend line. However, shortly after crossing the border into the U.S. those stresses migrated
toward the San Jacinto Fault, maintaining the same general trend line. They continue to drift toward the main arm of
the San Andreas Fault, the master fault for all of Southern California.
Hough said the El Mayor quake indicates
"bad news for buildings here in the future, because of the duration" of these larger magnitude quakes. This
quake was 40 seconds in duration, on 4/4/10. It has contributed to a significant increase in overall seismicity, and
there's been an observable increase in activity in all three major faults. Hough concluded: "We are not
done." Read that statement again!
A couple of weeks prior to the El Mayor quake, there was a 4.4 quake
at 4:40 in the morning centered in Pico Rivera. Within 48 hours of that event, our CEO, April Kelcy, announced to selected
individuals that there would be a quake that would be widely felt in Southern California on Easter Sunday. "I don't
know where exactly, what time, or what magnitude, only that a lot of people will feel a quake that day." Kelcy
knows that without those specifics, this cannot qualify as a prediction. In fact it was so vague it was not even a "forecast".
Readers may want to learn more about those relative terms later on. But it was Dr. Lucy Jones who referenced 20 million
felt the quake, which most people would concede coincides with Kelcy's "a lot of people".
Damage
to the water delivery systems in Imperial County were quite a bit more extensive than many members of the public initially
realized. In relation to what can happen to water delivery systems following larger quakes, this experience essentially
demonstrated that even one county, and that at a distance from the epicenter, can quickly tap out the available back-ups and parts,
and temporary resource assistance available throughout the entire United States.
Breezeways at schools
came down, with one firefighter testifying that some of those debris piles were about 10,000 pounds. We were very fortunate
that this quake happened on a Sunday when children were not in school.
A first responder, at home with a large
family for an Easter Sunday gathering, had guests throughout the house and in both front and back yards when the quake hit.
An item came off a coffee table with enough force to blast through a picture window, showering glass on and injuring a number
of the guests. But first responders often cannot always stay at home to deal with injuries and damage, because thousands
of people can also need assistance, and most public safety personnel have to report for duty according to their assignments
and emergency plans to serve the public. This small story highlights the dedication and heroism, and sacrifices, of
many of our public safety officials, who are just as human as anyone else.
Since the El Mayor quake there
has been at least one quake on the plate boundaries every month, and a swarm at Brawley, near the "sensitive spot"
on the San Andreas in December, 2010. Contact us for futher information at any time.
(Information gathered from multiple sources, including USGS presentations
at a SCESA conference, and a front page article in the Pasadena Star News on Monday, April 5, 2010.)
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