It is possible that those are not "earthquakes", but just "tremors" as the the relaxing of the rock. I worked in the Santa Susanna area and at Edwards AFB where our company tested rocket engines (150,000# thrust to 1.500,000# thrust). We had sensors at our "block-houses" where we had the recording of the thrust relative to the ground shock waves to air and other effects.

Some of the firing duration times were up to 6 minutes. - very impressive light shows from 10 miles away at night.

We also wired the beams and columns of the test stands and the joints to determine the effects and distortions of the gimballing engines under dynamic loads.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

There is also a discussion going on at the "Pat's Pub" site. I've experienced a number of earthquakes and underground test events including the Rulison Project near Parachute, Colorado. (That was a "fracking" test on a grand scale and politically e) With the continuous intermittent ground shaking (578 in this daily period at this instance), I am concerned about damage to the brittle and degradadated insulation inside the nearby electric transformers.

CONCRETE MASONRY: Interesting comments about your company testing rocket engines. I was involved in the seismic upgrading of the nuclear rocket test stand at Jackass Flats when the shaking events were going on. At this instance, the USGS site shows 581 events in the last day - which is different than what they said on my previous post. 7 shakes over 2.5 in that last 20 minutes. The USGS site shows a definite pattern of where the main slip is at this point. The shallowest one is about 1300 feet on my screen.

The USGS site is done so badly, I really hate it. I think it's a lame 'consumer' presentation offering little research ability. As an example why can't I select what magnitude quakes to display instead of their insipid idiotic selection. While I'm at it I hate their time handling too. You spend great gobs of effort trying to piece together what time events actually happen. They tell you "local time" and "standard time". Why can't we enter what time-base we want displayed and show everything in that. Blech!

Keith Cress
kcress - http://www.flaminsystems.com

Keith Cress: Did you go through the Loma Preita seismic event? We and another engineer did the Seagate Bldgs at Scotts Valley. No damage. Also did the "Temporary" Seawall at Rio Del Mar - had a fault under near or under the wall and it came down.
I think it's Coordinated Universal (UTC) time on the USGS site. I'm only keeping track of the intervals between ground motion and also realize that there must be tremendous amount of ground motion below 2.5.

Keith,

You can download all 5278 quakes from the last 7 days in a CSV, or several other formats for your own perusal.

TTFN (ta ta for now)
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Yes Oldrunner. It was centered about 5 miles from Santa Cruz. We got hammered. Buildings collapsed, people smushed, cliffs gave way dumping people. I jumped in my truck and blazed home from Scotts Valley. The freeway had a 1 foot curb across it -lucky I had a truck with tall tires. Lots of water-heaters fell over and torched the houses. There were columns of black smoke rising all over town. HWY 17 between Santa Cruz and San Jose had over a hundred ruptures across it. It was completely closed for two weeks then for about 2 months commuters could only pass over it in CHP lead groups. What a mess.

Keith Cress
kcress - http://www.flaminsystems.com

What happened to that aerospace facility up in the Santa Cruz Mountains during that quake? Why was their damage not reported?

For the M6.4 quake on the 4th, I was at home in Fresno sitting in the chair in my home office. I estimate about 20 seconds of strong rolling. It made our nearly 50-year-old house creak a little, but that was about it. The pool was quivering, but hadn't sloshed any water out.

For the M7.1 quake on the 6th, I was at Big Stump in Kings Canyon National Park for a night of observing with my 11" telescope. Before the sky got dark enough for good deep sky observing I entertained several groups of tourists with the Moon, Jupiter, some bright double stars, a couple bright star clusters, and the Ring Nebula. At 8:19 p.m., when the quake struck, I was looking at the Moon at 215x. My first thought was, "Why is the scope shaking when there is no wind?" Then I realized the ground under my feet was moving. I usually sit to observe, and I would have noticed the quake immediately. But this time I was standing and my own natural body sway covered up the quake at first. This shaking was longer than the quake on the 4th, maybe 30 to 40 seconds. BTW, this was the first quake I have experienced that was strong enough to also shake the Moon.

My wife told me the next day that the quake caused the water to slosh out both ends of our pool. I also noticed that the quake had opened one of the file drawers in my desk about two inches. We have a friend who lives in Ridgecrest. She let my wife know that she and her house were fine, but that the power was out and if it stayed out too long, she was going to go stay with her son in Bakersfield.

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"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

Buggar; The Lockheed facility is actually about 15 miles farther up the road away from the epicenter so it got less of a thrashing though it still got some. It's a lab facility so it also has lots of stout concrete structures. I doubt high-G test stands are very susceptible to quakes.

I suspect they had a few toppled items but nothing major. They have larger problems with the occasional major snow storm as they're located waaaaaaAAAaay up a problematic road in the middle of a forest clearing.

Keith Cress
kcress - http://www.flaminsystems.com

fel3; Surprised you got a sloshed pool that far away. I guess it being the right length and position could pump things up. My brother, way farther north (Sonora) in a large house, on stilts, on the side of a hill, said his house went in circles for about 40 seconds with the 7.1.


My office in the Loma Prieta quake. Note the red arrow pointing at my desk chair. You can see my Boy Scout heritage; I was prepared with a fire egress ladder for out that third story window. (Too bad the ladder was only 2 stories..)

Keith Cress
kcress - http://www.flaminsystems.com

itsmoked…

That's a real mess. BTW, my uncle and my cousin's husband were at Candlestick when Loma Prieta hit. It took them about 8 hours to get home to Mountain View. Both their houses were fine, but some books and knick-knacks tumbled from shelves, cabinet doors opened, etc.

Earlier on the 6th, after cleaning the filter elements, I had filled to pool to within 3" of the lip, so that helped the water escape. Our pool is a standard kidney shaped pool (about 32'x16'x8' deep max) and is oriented east-west. My distance to the epicenter is about 150 miles and my azimuth is about 120°.

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"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill