Newsgroup sci.geo.earthquakes 6008

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EDWARD ZWOLAN wrote:
> 
> Hello everyone,
> 
> My question is:  Is it possible for a properly working seismograph not to
> record a small event occuring directly under the measuring equipment?
> 
> Example: Very shallow quake whose epicentre is right underneath a
> seismograph.
> 
> This Wednesday many Las Vegans reported an event of extremely short
> duration.  Something like a sudden boom from underneath the ground.
> Absolutely no waving sensation, no prolonged shaking- nothing of the usual
> signs of an earhtquake.  The University of Nevada, Las Vegas seismograph
> registered nothing!
> 
> As I was sitting in front of my computer at the time, the monitor sudenly
> jerked like if someone kicked the desk from underneath.  That was it!
> Nothing else, whatsoever!  I am not superstitious, but for a moment I
> thought this to be a devilish manifestation, of some sort.
> 
> I have a 50 inch long string hanging from the ceiling nearby (there is a
> weight attached to its end, and it serves as a crude, but reliable earth
> motion detector) -it didn't swing a bit.
> 
> What was this event???  Please comment.
> 
> Thanx,
> S.Zwolan
I live on a small island in the East China Sea, and have been through my
share of quakes. I had one earlier this year, though, that sounds
similar to yours, only it was registered.
It was on October 4th, in the evening and -- like yours -- it felt as if
someone underneath just kicked directly upward, one thump and everything
jerked. I was sure it was a gas explosion, but minutes later NHK went on
the air with the report of an extremely small quake centered near my
location (mag. 2).
Interesting, though -- I never quite felt one like that before.
Edward A. Mazza II

We've gone through a bit of this before.  Body waves remain the most
damaging overall, because most damage is right up close where body waves
dominate.  On those wonderful California Jello basins, we have the
complex moving-standing waves, but you can't call them surface waves.
In Eastern North America and California, there is the 100km anomaly
where lots of damage seems to be at this point.  We used to think that
the surface waves were just getting organized there, but now it looks
fairly conclusive that these zones are due to reflected body waves off
the Moho, or other reflectors.
From an engineering perspective, most of the surface waves are at too
low a frequency to cause damage.  An exception in the east, are high
rises, where damage to fish tanks and waterbeds is almost exclusively
due to surface waves. :)
Bill Oertell wrote:
> 
> Donald J. Stierman wrote:
> >
> > Many Physical Geology texts assert that surface waves are responsible for  <>
> > How can fundamental contradictions persist for decades in those books used
> > to teach introductory courses?
>    I've seen seismographs supposedly showing the different P, S, and L
> waves, and by far the L waves are both the strongest and longest
> wavelength.
>    In the Loma Preita earthquake I am fairly certain that I felt the
> separate arrival of the P, S, and L waves.
<>
Harold Asmis (at home)

Geo-Monitor newsletter, a monthly publication on earthquake
prediction, is going out of business.
In publication for 6 years it has covered
the scientific developments in quake 
prediction, with a focus on the ultra-low
frequency (ULF) precursors discussed by
A. Fraser-Smith, etc.  Focus is 
amateur science.
If any individual, group, school, club, etc.
is interested in taking over publication, I would
be glad to turn over the journal, and submit
my sources.  I read about 40 scientific and
popular journals, newsletters, etc. for 
info, however I no longer have the time or
availability to continue this worthwhile effort.
Fraser-Smith has in operation only 4 sensing units.
Here is an opportunity for amateur scientists to
build ULF monitors and report on results - - 
a possibility to make a major contribution to 
an evolving science.
If interested write to Geo-Monitor, #400
65 Washington St.  Santa Clara, CA 95050.
Message (408) 749-6770.
Admittedly this is a nail looking for a 
hammer, but a very important quake prediction 
science.
Vince T. Migliore, Editor
See Web page at:  http://home.earthlink.net/~geomonitor/

I've run into this too, with our seismic array.  If you look at the
daily output of a single seismometer, you'll see dozens of 'events' that
look like small earthquakes.  These are wind bursts, thunderstorms, or
cows kicking the seismometers. The way to handle this is to have an
array and plot all the traces on a big sheet of paper.  Then a trained
eye can look for correlations that indicate an earthquake.  On our
array, this gets you down to about M1, but I think they have to be at
least a kilometre or more deep.
It's conceivable to have a very shallow earthquake that is felt by
people, but not declared by the array.  We had something recently where
a local farmer swore he felt something, but we didn't declare an event.
Only if he knew the very exact time, could we look for a 'burst'. 
Things might get better, when we start putting on live traces, then
people could feel something, and look it up right away.
Harold Asmis (at home)

In article ,
Donald J. Stierman  wrote:
(on whether more eqk damage is due to S or surface waves):
>It is obvious that both points of view can not be correct.
Why is it obvious? Why shouldn't S waves cause more damage at some
places from some eqks, but surface waves cause more damage at other
places from other (or even the same) eqks.  
John Harper Mathematics Dept. Victoria University Wellington New Zealand

can anyone assist us in finding info regarding the 1906 quake in San 
Francisco. The main need here is the rebuilding efforts. Pictures are the 
most desired for a before and after report.

 Essay Research  about Earthquake.
Acknowledgment 
                                  page                 
Introduction     ???????????????????.???.    3
Causes            ??????????????????????..    4
Effects             ??????????????????????..    6
Conclusion      ??????????????????????..    8
References     ??????????????????????..     9
Photos            ??????????????????????..     10
           Stamatopoulos 3                 
Introduction
	An earthquake, one of the most destructive natural phenomena, consist of
rapid vibrations of rock near the earth surface.  It is the most terrifying
of all natural phenomena and brings fear since ancient times because of its
sudden unpredictable occurrence and enormous capacity of destruction.  A
single shock usually last no more than a few seconds , although several
quakes may last for as much as couple of minutes.  The quake as felt on the
surface is always the result never the cause of some geologic process. 
There are  many causes of earthquake and the damage done may be immence.
								Stamatopoulos 4
Causes
The Greek word for "shaking", and (when it applies to the earth)
"earthquake", is seismos.  The science of earthquakes, therefore, is called
seismology (Oxford Advanced learner's Dictionary).  The scientific study of
earthquakes is comparatively new. Until the 18th century, few accurate
descriptions of earthquakes was recorded, and the natural cause of
earthquakes was little understood.  The great majority of earthquakes are
caused by sudden movement of the large blocks of the Earth's crust less
than 70 Km from the surface along lines called faults.  When the stress
that develop in the crust become too big for the rock to support, one side
of the fault slips on the other side.  This movement causes vibrations that
transmit waves which travel for long distances through Earth interior or
along surface.  The energy released by an earthquake moves in the form of
waves through the rock which act as an elastic body.  These Waves make the
ground to vibrate, and are what we call earthquake.  The two main types of
earthquake waves are P waves and S waves (photo 4).  P waves or primary
waves are the fastest and can travel through solid and liquid matirials. 
"The rate of propagation through granite mountains for P waves is approx.
5.5km/sec; The rate is much reduced through liquid materials.   (water: 1,5
km/sec)"  (Environmental Geology, Edward A. Kellier, Macmillan, 6th
Edition, 145-146).  In other words, P wave is a fast body wave that travel
through the intrerior of Earth and arrives first at the seismograph.  On
the other hand, S waves (secondary or shear waves) are slower body waves
than P waves and have approximately velocity 3km/sec.  Due to slow speed
that S waves can travel, they can not pass through the liquid metirials. 
Earthquake magnitudes are expressed on the Richter scale, and measure the
amount of energy released.  Seismograph, an important geological
instrument, record earthquake waves.  According to this, scientists can
predict what kind of waves will come up to surface and for how long.  Of
the million or so earthquakes per year, strong enough to be noticed, only
few release enough energy to do serious damage.  
Stamatopoulos 5
About 10 really violent earthquakes occur each year on the average but only
one of them happens to be involved in a populated urban area.  " The most
destructive earthquake or record occurred in 1556 in Shensi Province in
China, where an estimated 830,000 people died.  Those people lived in Cave
dwellings excavated in loess which collapsed as a result of the quake. (
Physical Geology, 2nd  edition, Brian J. Skinner,395)
								Stamatopoulos 6
Effects  
	The catastrophic effects of earthquakes are generated in four main
principal kinds:
Ground motion which damage or sometimes completely destroy buildings. 
Although, today, modern Engineering in order to prevent such damage has
given many solutions to the problem, in very strong earthquakes there is no
possible structure of safety.       
The ground motion,  causes fires not only because it breaks the gas lines
but also because it displaces the electrical wires and stoves.  More than
90% of San Francisco building damage was caused by fire.
"In regions of hills and steep slopes, earthquakes vibrations may cause
regolith to slip and start rapid mass  wasting movements."(Physical Geology
2nd Edition, Richard Foster Flint,394). As a result of these, almost all
structures are destroyed by rapidly moving regolith.  
Finally the seismic sea waves causes movement of the sea floor.  These
waves are called tsunami.  These huge waves struck  Hawaii and destroyed
1500 houses and killed more than 150 people.   	
The Destructivenness  of quake is determined by such factors as velocity,
accelaration period and duration of the earthquake waves.  The size, shape,
metirial and quality of construction of building is the most important
factors to determine the range of destruction and consequently the number
of deaths.  " About 75% of fatalities attributed to earthquake are caused
by the collapse of buildings." (Earthquake Protection,Robin Spence,6-7 ) 
At the beginning of this century less than one out of three earthquakes
with large magnitude causes at least one death.  Unfortunately today,  two
out of three earthquakes have fatal results.  The San Francisco Earthquake
of 1906 was one of the most destructive in the history of America.  The
Earthquake and the fire that followed killed nearly 700 people and left the
city with smashed ruins.  It was one of the most significant earthquakes of
the early years.  That great earthquake that struck San Francisco a little
after  5:00am on the 
							Stamatopoulos 7
morning of the 19, April, 1906 is in special interest because its study
gave us the opportunity to formulate the "elastic rebound theory" of
earthquake source. " This theory remains today as the principal model of
the earthquake cycle"  (http://quake.wr.usgs.gov/more/1906, San Francisco
Earthquake 1906, Internet Source ). Many buildings collapsed especially
those on marshy or filled ground. Others buildings with solid rock was
little damage by the shock. (photo 2).  On the other hand big fire burned
an area of 4.7 sq. miles, and destroyed many of building that left
standing(photo 1).  As a result of this more than  225000 people out of
400000 became homeless (photo 3).  Although the loss of life could only be
estimate, it probable exceed 700 direct deaths and more than 3000 indirect
deaths.  On the other hand, material loss was more that $400 million. The
strong shaking with magnitude 7.7~7.9 R last 45 to 60 seconds.  " The
frequently quoted value of 700 deaths caused by the earthquake and fire is
now believed to underestimate the total loss of life by a factor of 3 or 4"
(http://quake.wr.usgs.gov/more/1906, San Francisco Earthquake 1906,
Internet Source.)
							Stamatopoulos 8
Conclusion
An earthquake is a natural phenomenon like rain. Earthquakes have occurred
for billions of years. Descriptions as old as recorded history show the
significant effects they have had on people's lives. Long before there were
scientific theories for the cause of earthquakes, people around the world
created folklore to explain them. In simple terms, earthquakes are caused
by the constant motion of Earth's surface. This motion creates buildup and
release of energy stored in rocks at and near the Earth's surface.
Earthquakes are the sudden, rapid shaking of the Earth as this energy is
released.  However, the science and practice of how to protect ourselves,
our buildings and our cities from earthquakes has also been developing
during the second half of the twentieth century. The approach to protection
is necessarily and requires a wide range of measures including public
education programs, better building design and increasing  quality of
construction in the areas most likely to suffer an earthquake.
Stamatopoulos 8
References
Edward A. Keller, Environmental Geology,  Macmillan: 2nd edition
Robin Spence and Andrew Coburn, Earthquake Protection, New York: 
Wiley, 1992
Oxford Advanced Learner's Dictionary , Oxford Univ. Press: 1992
Earthquake," Microsoft ? Encarta ? 96 Encyclopedia. © 1993-1995 Microsoft
Corporation. All rights reserved. © Funk & Wagnalls Corporation. All rights
Internet site: http://Quake.wr.usgs.gov/?/gifts/photo
Skinner Brian and Richard Flint, Physical Geology, 2nd edition 1983

In article <4258660350.23003675@fuhsd.k12.ca.us>,
Martin N. Ross  wrote:
>Perhaps the government is playing with its new electronic toy THE HARRP. 
>Don't laugh, it is real and can do some interesting things.
>
>Marty
What's that?  I imagine that there are some interesting aircraft under 
development in that area.  I wonder what they are?  The Stealth 
technology had been in the works for 15 or so years before the military 
went public with it.  They had tested it secretly out of Nellis, I think, 
for years - night flights so no one would see it.  Is THE HARRP some kind 
of weird stealth aircraft technology?  There were a lot of rumors about 
some sort of stealth aircraft years before the Stealth was made public.
Andrew

Our planet last week is a weekly journal about natural disasters,
global pollution, and natural and environmental topics.
You can subscribe for free to receive a weekly email copy. If you are
interested just sent an email message to:
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   You can also visit the State of the Earths Website at url:
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State of the Earth Magazine --- The Creators of Awareness!!
----------------------------------------------------------------------
--Earthquakes--
No major Earthquakes last week. However the Earth moves
plenty of times each day. Most of the time we don't notice
it. When you want to see weekly reports of all quakes, every
week then try our Seismology Link Page at:
      http://www1.tip.nl/users/t000208/more.htm
The Earth also moved in the eastern and northeastern part of
Japan (4,7 & 4,0), Kuril Islands (4,9) and the Pyrenees (3,5)
--Tropical Storms--
The storm that was left from the Hurricane Lili caused some
problems in parts of Northern Europe. Especially Great
Britain had to suffer from the bad weather. 6 people were killed,
and thousands of people had to do it without electricity.
+++
In Bangladesh 4 people were killed and at least 100 people
were injured by the tropical cyclone 34W. Also much cattle
was killed due to floods that were caused by the cyclone.
--Volcanoes--
The Popocatepetl in Mexico is active again. A lot of volcanic
ash came down on the suburbs of Mexico City. Also the
western part of Mexico had to suffer from the volcanic ash.
Residents who live around the volcano are yet prepared to be
evacuated.
+++
The Merapi on the Indonesian Island of Java was also active
again. Scientists measured a lot of tremor within the volcano
wich can be a signal for a nearby eruption.
--Wildlife  This Month a Spotlight On:--
THE TIGER ....LARGEST CAT ON EARTH
At the turn of the century, there were 100,000 tigers in their native
Asia, including about 40,000 in India. But by 1973 the world
population of these magnificent creatures had been reduced to under
4,000, mainly as a result of hunting. The tiger, the largest cat on
earth, came to be threatened with extinction by man. But is the tiger
a threat to humans? What is this cat really like? Have efforts to save
it from extinction been successful?
Now you can read all about it at: 
http://www1.tip.nl/users/t000208/news.htm
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Without the support of its readers, 'Our Planet Last Week' would not
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                    email: dennis.van.paassen@tip.nl
    STATE OF THE EARTH ---- CREATORS OF AWARENESS
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Those who think that Toronto is as boring seismically as Canada in
general, should get hold of the new Nov/Dec issue of Canadian
Geographic, and look at the article by Elizabeth Shilts "Toronto's
Seismic Secrets".
-- 
Harold W. Asmis        harold.w.asmis@hydro.on.ca
tel 416.592.7379  fax 416.592.5322
Standard Disclaimers Apply

> I am looking for any information on earthquake prediction methods.  Any 
> help would be greatly appreciated.
My method of prediction works rather well.  I put my ear down to the
ground and sauy, "Ayup, there's an earthquake coming."
Cho-Cho San!
/

In article <847052952.11927.0@cisft64.demon.co.uk>, Martin Hogbin  writes:
>Does anyone have any information on the so called earthlights that
>may be connected with earthquakes?
Earthquake lights are bright luminescences at ground level, as much as
a quarter-mile across, which may last for as long as two minutes. They
are seen during an earthquake or immediately before. They are pretty
obviously some sort of electromagnetic effect, though quite what has
yet to be explained. The most popular explanation invokes
piezoelectricity (voltage induced by squeezing rock) or
triboluminescence (photon discharge on breaking atomic bonds).
Earthquake lights are pretty well documented and have been
photographed in Japan. Several of the photographs are reproduced in
"Earthquake lights: a review of observations and present theories," by
J.S. Derr, Bulletin of the Seismological Society of America, v. 63, p.
2177-2187, 1973. Derr also includes this old haiku:
         The Earth speaks softly
            To the mountain
         Which trembles
            And lights the sky
Here in Hawaii the phenomenon is sometimes called "Pele's Dog" (I guess
because a big earthquake may be a precursor to volcanic eruption and
Pele is the Volcano Goddess). The last reliable report I heard of
Pele's Dog was from Honuapo on the Big Island of Hawaii right after the
magnitude 7.2 Kalapana earthquake of 1975: lights started flickering in
the sky in an area with no roads or power lines, followed within a few
seconds by the shaking. Bloke says to his wife "We have to get out of
here!" They run out the front door of the house as the first wave of
the tsunami pushes in the back door.
Dunno if you have wintergreen LifeSavers(tm) in the Old Sod, but if
you can find some, take them into a dark room and smash them with a
hammer. Triboluminescence. Sure is weird.
-- 
Gerard Fryer      
gerard@hawaii.edu        http://www.soest.hawaii.edu/~gerard/
Personal views only.

I have new method for eartquake prediction.It based on the material I 
collected during last 10 years.If you still interested in it please 
contact me.
Armen Kazarian.