OT: Seismographs

Tradition

On Jul 29, 9:00=EF=BF=BDpm, "Paul Hovnanian P.E." wrot= e:

They are paper ballots leftover from the 2000 presidential election....

Yeah. No need for paper ballots, since the Demonicrats insisted on computers.

--
Keith

I felt the earthquake, that was rated a 5.4, in Chino Hills:

Interestingly, the first "shock" felt like someone had bumped into my RV. But there was no corresponding noise. I was pondering that, and the shaking increased until it felt like a couple of vandals shaking the RV. By the time I got outside to check for vandals, or feel the ground if it was a quake, it was over, but the TeeVee was all "BREAKING NEWS!!!!"

There were no injuries, no significant reportable damage, but the networks were loaded with "BREAKING NEWS!!!!" for as much as two hours after it was over!

One really weird thing is that even though the epicenter was near Chino Hills, which is about 15 mi. east of me, all of the Hollywood news was about how intense it was. They almost evacuated Disneyland! I don't understand how it could be more intense to my west than it was here, when I'm half the distance from the epicenter.

I wonder if it's because:

1. The fault was 7-8 miles deep
2. I'm on rock; LA proper is on sediment, which they say "magnifies" or maybe "amplifies" the shaking, like a bowl of jello
3. Could the topography have actually focused the waves?

Another thing, it didn't feel like either P (pressure) waves or T (transverse) waves; it felt more like ocean waves.

But TWO HOURS of "BREAKING NEWS!!!!" after a 15-second event that didn't even do any reportable damage? The hilite of the coverage was the security film from some liquor store, where the guy feels the first nudge in his feet, exits the store, and a whole shelf of liquor bottles falls down sploosh.

So, essentially, ho hum. ;-)

Cheers! Rich

"Breaking News", and nothing actually broke. Go figure.

-mpm

Looks like digital data to me. This data gets posted minutes after an event. The poor USGS servers were instantly bogged down right after the quake.

They probably have drum data as backup or a show & tell for the news dweebs.

This was a nice slow shaker where I am, about 120 miles (190 km) away.

-- Mark

5.4? BFD, we got one of those around here (relatively speaking) and all it got was a front page spot. 'Course, we're a couple hundred miles away from the epicenter, and having anything around here is very rare!

My story is, it was around 3 a.m., I was sitting here typing away on the computer and felt a low frequency oscillation, as if my leg were shaking, except I know it wasn't. I think it was magnitude 3 something by the time it got here.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

It can be a big deal. The magnitude = total energy released. If concentrated in a small spot, the ground motion can be intense.

I once had my chair literally jump right out from under me, as if kicked. Turned out the quake was 2 or 3-something, but nearby.

Cheers, James Arthur

Ever notice that the background noise under the news commentator is usually a teletype machine? When TV shows a time bomb, it always has an LED display, never LCD. When TV shows a computer, there are NEVER any exposed tangle of wired, battery chargers, USB dongles, etc. Argh.

Methinks the high tech seismographs are fiber optic loop/ring accelerometers. Basically, they're an interferometer. I've only seem one at the local multiversity, but was not allowed to even exhale next to the device.

Don Lancaster on seismography (1998) with lots of good references and broken links:

"Experiments in laser seismography"

I also found some articles on solid state MEMS low-g accelerometers for seismography.

My guess(tm) is that this is the high fashion current technolgy as the laser interferometer is probably too sensisitve to be generally useful. Just a guess(tm).

Here's a complete wireless kit with 3 axis accelerometer for $250:

I like the idea of taking a roller coaster ride to calibrate and test it.

--
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

s%22+e...

RV.

V.

it

) and all it

es away from

e

g,

by the time

=EF=BF=BDIf

My brother went throught the Loma Prieta quake back in '89. He claims practically everything in the apartment was fine, except the refrigerator jumped out the bay window. I don't think he was kidding, but then, he does have a slight penchant for exaggeration. I've heard similar tales from others. Almost like any heavy object in just the wrong spot can really lead to trouble.

-mpm

Chart recorders make *way* better theatre. That pen wiggling back and forth looks like a frustrated child scribbling on a drawing that didn't come out. Perfect.

Part of the problem is that definitions of earthquake magnitude depend on the frequency passband, which depends on the design of seismographs and probably on pen recorders too. One way to keep the numbers comparable is to keep the hardware the same.

The 'Richter' scale quoted by reporters is not the original Richter scale, but a modified one with a wider passband (and some low-frequency boost, iirc).

Cheers,

Phil Hobbs

The labor to maintain and operate pen recorders could be put to better use elsewhere. Backup? Wouldn't the money be spent more wisely on RAID storage? Same for show and tell. Even more, people are used to PC displays, computers, etc. Seeing the USGS using out of date technology makes me wonder if they really know what they're doing anymore.

--
Paul Hovnanian     mailto:Paul@Hovnanian.com
------------------------------------------------------------------
Life is like a buffet. Its not very good but there\'s plenty of it.

[after seeing drum recorder on the California quake, and accelerometer readings in old Indonesian quake footage]

Seismometers come in short-period and long-period variants, and resonance is an important part of the signal/noise equation: accelerometers pick up lots of out-of-band noise. A simple accelerometer with millisecond output has to be a short-period seismometer, suitable for local monitoring only.

The drum recorder is just a visual aid and is maintained as a photo-opportunity model or as a teaching/display model. The real recordings, nowadays, are digital for the central office units, and FM encoded onto analog tape for field units (battery power for an analog tape drive is ... favorable).

Agreed, but there is something to be said for "low-tech". Especially if you consider these chart recorders may be installed out in the boonies, off-grid, etc... I for one could not in good conscience recommend Vista for such applications. :)

-mpm

Doubtful that these would be installed "in the boonies". Most of the ones shown on TV are at some sort of USGS HQ (or university lab). The pen and paper requires a conditioned environment and frequent pen/ink/paper replacement. Not conducive to remote installation. I'd venture a guess that solid state event recorders are quite a bit more robust (and cheaper).

--
Paul Hovnanian     mailto:Paul@Hovnanian.com
------------------------------------------------------------------
Opinions stated herein are the sole property of the author. Standard
disclaimers apply. All rights reserved. For external use only. If
irritation, rash or swelling occurs, discontinue use immediately
and consult a physician. Void where prohibited.

Probably true. But on the other hand, think about the ability to 'play back' digital data for the news crew.

I'm sure that the response of a pen recorder could be modeled in a digital data acquisition system.

--
Paul Hovnanian     mailto:Paul@Hovnanian.com
------------------------------------------------------------------
When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.
                               -- Etaoin Shrdlu

It depends on the characteristics of the ground as well.

I went through the Nisqually 'quake in 2001. A couple of buildings (including the one I worked in) were nearly destroyed. When I finally made it back home, nothing had moved, in spite of the fact that my workshop, shelves, book cases, etc. are an avalanche of junk waiting to happen. My house is built on rock strata, not very deep, whereas the Boeing Renton plant is built on river bottom.

They tore down a couple of the damaged buildings, but the one I worked in was the office of a couple of geezers that they didn't want to move (think about the stress caused by changing the schedule at the old folks home). So we had to put up the dilapidated wreck until they retired.

--
Paul Hovnanian     mailto:Paul@Hovnanian.com
------------------------------------------------------------------
Bloody typical, they\'ve gone back to metric without telling us.

You will be old before you know it.

Most of the world except the illiterate use metric.

John G.