Subject: Honduras meteor, quake sonics,opticals? (Was: Re: Earthquake in New Brighton
From: bsandle@southern.co.nz (Brian Sandle)
Date: 20 Dec 1996 19:28:52 GMT
Brian Sandle (bsandle@southern.co.nz) wrote:
: Here is an attempt at portraying the museum seismometer seismographs for
: Hanmer and New Brighton, if that is where it was.
:
: New Brighton
: x
: x
: Hanmer x
: xx
: x xx xxxxx x
: xx xx xx xx x xx xxxxxxxxxx
: xxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxx
: xx x xx xx x xx xxxxxxxxxx
: x xx xxxxx x
: xx
: x
: x
: x
:
: The New Brighton quake seemed to be about half way to full scale. There
: has been one quake which went to full scale in not too distant times.
:
: So it seems that the part of the quake which we felt was the part that
: was greater than the Hanmer level - just one pulse up and two down which
: I couldn't show.
:
: Can anyone talk about amplification of ground motion on alluvial planes?
: What was the significance of the blast effect?
:
: Brian Sandle
Perhaps the sci.geo.earthquakes people might talk about why the MM scale
figures are not given more often. The local scientists have not replied
why they do not, so I allow myself a little luxury of some fantasy, too.
The second depicted quake was said to be magnitude 3 or less, presumably
as registered in a recorder in rock but quite a jolt on the alluvial
plane, indicated by the diagram (for which intensity figures have not been
provided).
The Hanmer quake was about 130 km from Christchurch - I left the diagram
to ask more about the sound of quakes, and to give other data happening
within the given window of the Honduras meteor.
Some months back someone plsted that light effects can accompany quakes.
Is that anything to do with piezo-electric fields from crushed rocks?
Nuclear blasts can be heard hundreds of km away. For faintest connection
I ask whether the Honduras meteor sound could have been focused here
causing our blast effect? What does cause a blast effect from a quake?
I repeat two articles which may be of interest.
From: ln10e@ldcsp34.london.waii.com (Stephen Traylen)
Newsgroups: sci.geo.earthquakes
Subject: Re: meteorite impact - Honduras
Date: 18 Dec 1996 11:42:24 GMT
Organization: Western Geophysical, Div. of Western Atlas Int'l, Houston, TX
Message-ID: <598lb0$d5e@mail1.wg.waii.com>
References: <32B6F049.7C0@psnw.com> <32B75E89.3F27@ix.netcom.com>
Bill Oertell (woertell@ix.netcom.com) wrote the following:
> Tom Whiteway wrote:
> >
> > I saw sketchy information on a meteorite impact in Honduras probably
> > late week ending 15 December, causing 165 foot crater and ancillary fire
> > damage (no kidding)...Have seen no other reports and I can't imagine it
> > has gone unnoticed excpet by popular press. Has anybody in this seismic
> > group seen anything relative to this event? Any info is greatly
> > appreciated!
> I can't imagine something of this magnitude not being reported by the
> media, not to mention affecting conditions on pretty much a global
> level.
> --
There was a report on it in 'The Times' (London) yesterday. Supposedly it
happened up to 2 weeks ago, but took a while to get out due to the
remoteness of the locale.
The impactor was speculated to be around a foot in size.
I'm expecting to see more about this in tomorrow's 'New Scientist'
--
Steve Traylen Seismic Analyst
Home: 0181-568-2065 Western Atlas
Work: 0181-585-4224 London
ln10e@london.waii.com stephen.traylen@waii.com
These Views Do Not Represent Those of Western Atlas.
From: Mark Boslough
Newsgroups: sci.astro,sci.astro.amateur,sci.space.science,sci.geo.meteorology
Subject: Oct. 3/4 bolide swarm?
Date: Mon, 16 Dec 1996 20:37:58 -0700
Organization: Sandia National Laboratories
Lines: 119
Approved: sci-space-tech@isu.isunet.edu
Message-ID: <32B61596.53F1@sandia.gov>
October 3/4 Bolide Swarm?
Mark Boslough, SNL
There is some evidence for a swarm of particularly bright bolides on
the evening of Oct. 3 over North America, several of which generated
infrasound signals (see ReVelle report, below). One (in California)
exploded at an altitude of about 40 km and generated a sonic boom that
was detected by Caltech's seismic array, allowing its time (8:45 pm
PDT) and location (near Little Lake) to be precisely determined.
Eyewitness reports are consistent with a ENE near-grazing trajectory.
An earlier fireball (at 8:01 pm MDT) was observed over New Mexico and
the Texas Panhandle, also on an ENE near-grazing trajectory, and
videotaped from El Paso, TX. Infrasound instruments detected an event
20 minutes before that over Utah (see below), which may not have been
observed from the ground due to cloudcover. Eyewitnesses reported
bright fireballs that same evening over Nevada, Indiana, Ohio, and
later events in California. Finally, there were unusual high-altitude
haze streaks observed earlier in the day near Boston (see Volz report,
below). These observations may or may not all be related; the purpose
of this summary is simply to report what was seen and detected.
=====================================================================
October 4th Infrasound Summary
Doug ReVelle, LANL
During the period from 0000 Z to 0600 Z on October 4, (the
evening of Oct. 3 in the western U.S.) 1996, infrasound arrays operated
by Los Alamos National Laboratory detected a number signals whose
characteristics were relatively unusual. This behavior included
unusually large trace velocity (indicating either a source at large
heights or waveguide propagation with returns from the Earth's
Thermosphere) and in some cases a source azimuth which was shifting
significantly during the detection. Taken together these
characteristics indicate a source that is also quite close, i.e.,
near-field type propagation. In addition to detecting a number of
events with these unusual characteristics, we also detected two of the
largest of the many fireball sightings that were reported on that
night. We detected the entry of the New Mexico fireball at the Los
Alamos array with the correct directions, but with no physical time
delay between the fireball appearance and the detection of the
infrasound (detection at 02:00 Z, or 8:00 pm MDT, Oct. 3). This by
itself is very puzzling. We also detected the California fireball of
03:45 Z (or 8:45 pm, PDT) at three arrays (operating in Nevada, Utah
and in Wyoming). The azimuth intersections of these three detections
converge very near to Little Lake, California, which is also the ground
projection of the seismic detections from 31 sensors operating in the
Los Angeles area. Prior to the New Mexico fireball, there was an
infrasound detection of a moving elevated source at 0140 Z (or 7:40
MDT, Oct. 3) from St. George Utah and also at the array at Pinedale,
Wyoming later that night. The bearing and elevation angles are changing
rapidly at St. George, but not at Pinedale so the suspicion is that the
source is closer to St. George.
=====================================================================
Unusual Haze Streamers Above Cirrus Level Seen
Near Boston On October 3, 1996.
FREDERIC E. VOLZ
24 Tyler Road, Lexington MA 02173
During a period of clear, cold weather, thin haze streaks already
visible by noon had developed by 1500 LT to become very long and
strange, especially near the northern horizon. Having worked formerly
in atmospheric optics, I am always looking for such events.
Observations happened to be made at a playfield in in western Lexington
and access to a high roof provided a mostly free horizon. The rather
broad streamers converged to the WSW to a knotty, fibrous structure of
considerable density, but lacked horizontal layering usually associated
with tropospheric and stratospheric (volcanic) haze. Isolated patches
could be seen between the sun and the horizon, but I missed the
opportunity to determine their drift direction. The upper edge of
cirrus in the far North was banded, too, but structure and direction of
the bands was clearly different from those of the streamers. The
cirrus also was at a lower altitude, as were a few short contrails and
small patches of lenticular clouds in other parts of the sky. Photos
by automatic exposure show the broad streamers farther from the sun,
but the more interesting regions near the sun were overexposed. The
haze streamers faded in the eastern direction, but the lower horizon
was hidden by trees.
By about 1630 LT, the last traces seemed to disappear in the WSW.
However, these must have been the last patches arriving from that
direction. According to the evening sounding at Brookhaven on Long
Island, the wind, about 20 km/hour from about 250 deg, was steady up to
the top of the sounding at 16 km. There was a strong inversion at
about 7 km, probably related to the lenticular clouds. In mostly clear
skies, no haze streaks were seen in the days following the event.
The streamers seemed to have had no relation to condensation or icing
processes but rather looked like sheets of poorly dispersed dust, which
possibly was still in the process of turbulent mixing as indicated by
the contorted fibers.
There has been some recent volcanic activity. At Soufriere Hills,
Montserrat, West Indies, some moderate ash eruptions occurred from 11
to 22 August, but only those on the 12th reached 10 km. On Iceland, an
eruption in the morning hours of October 3 also went to about 10 km,
but that haze could not have arrived within a few hours. Also, meteor
events over Texas and California in the evening of the same day, widely
reported in the media occurred several hours after my sighting.
However, more meteor sightings in the same night have been reported.
In view of these events, and the possibility that meteors also arrived
at earlier times, I should like to add that my streamers could well
have been much higher than the tropopause. However, the smoke trail at
about 60 km of the daytime meteor of August 10, 1972, starting as a
very bright narrow line, only lasted about 90 minutes when it looked
like a "diffused single-jet contrail", but apparently was not much
distorted (Sky and Telescope, Oct.1972, 269-272). On this basis, and
the probably bigger size of the 1972 meteor, my streamers are expected
to have had 1.) several sources (as from a split meteor); 2.)
probably much more total smoke mass, and 3.) been in a much more
turbulent environment. Trails of micrometeorites, or shooting stars,
usually become strongly distorted within their liftime of about 60
seconds.
FREDERIC E. VOLZ Telephone 617 861 8849, daytime 617 377 3666.
====================================================================
Subject: Re: Sacramento is Low!
From: ted.smith@cdmg.uucp.netcom.com (Ted Smith)
Date: Fri, 20 Dec 1996 23:14:00 GMT
cjones@mantle.colorado.edu (Craig Jones) wrote:
Subject: Re: Sacramento is Low!
C>In Article <32B95B83.1BC3@nts.ohn.hydro.on.ca>, Harold Asmis
> wrote:
>>Another tiny snip (hopefully below the gaze of those Internet-destroying
>>copyright lobbyists in Europe :)
>>***
>>Included in the least risky areas are most of the Central Valley.
>>Sacramento has the least risk of destructive earthquakes of any big
>>city in the state, and San Diego is well below the norm.
>>--
>The problem with the maps are frequently in the underlying assumptions.
>Earlier versions of these sorts of maps for the US has a bullseye of low
>risk in central Idaho that was shortly thereafter filled by the Borah Peak
>EQ in 1983. Generally speaking, areas of high risk are not going to go down
>with increasing research (with the possible exception of areas of very
>infrequent EQs that have had an historic event, e.g., New Madrid,
>Charleston), while areas of low risk *might* increase.
C>Many of these maps are based on a probabilistic approach using historic
>seismicity. Areas lacking historic seismicity are underrated. Other maps
>try to include geologic information to counter this problem (which was the
>cause of the Borah Peak boo-boo), but then you run into problems with things
>like blind thrusts that might not be recognized (and there *are* blind
>thrusts in the western San Joaquin/Sacramento Valley, and I have no idea if
>they have
>been incorporated into the maps you are looking at).
The maps don't reflect surface geology (a uniform geologic condition is
assumed); we're working on those added factors for a future product. The
maps do include a factor for earthquakes on unanticipated sources and
along faults that haven't produced an earthquake during historic time.
The fault parameter data are summarized in a table at
http://www.consrv.ca.gov/dmg (link to the probabilistic map). We should
have the entire report available via the web in a couple of weeks.
One item to note... The map displays the probabilities/accelerations
for a specific period. If/when a map for a longer period is developed,
it will appear different. What this all means is that the current map
portrays accelerations for a period that is likely to affect houses and
low structures, but not accelerations likely to affect tall buildings
like those found in metropolitan areas. In our own Sacramento building,
for example, the intensity of shaking felt by 24th floor occupants from
a M 7+ Cape Mendocino earthquake (some 300-400 miles away) was
equivalent to that experienced at ground level in Ferndale, the town
closest to the epicenter. Most people on the ground level in Sacramento
didn't feel the quake at all.
-- Ted
================================================================
California | Ted Smith
Division | or
of Mines & | -------------------------------------------------
Geology | Sysop, CDMG ONLINE (BBS modem line: 916-327-1208)
| GeoInfo * MLPnet * SurveyNet * & Selected USENET
Visit CDMG's WWW site at http://www.consrv.ca.gov/dmg/
---
* QMPro 1.52 * What can you do at 3 AM? PSSSTTT - got a modem?
Subject: Distance calc, MM scale, Brighton quake (Was: Re: Honduras meteor, quake sonics,opticals? (Was: Re: Earthquake in New Brighton))
From: bsandle@southern.co.nz (Brian Sandle)
Date: 21 Dec 1996 15:30:12 GMT
Brian Sandle (bsandle@southern.co.nz) wrote:
:
: Brian Sandle (bsandle@southern.co.nz) wrote:
:
: : Here is an attempt at portraying the museum seismometer seismographs for
: : Hanmer and New Brighton, if that is where it was.
: :
: : New Brighton
: : x
: : x
: : Hanmer x
: : xx
: : x xx xxxxx x
: : xx xx xx xx x xx xxxxxxxxxx
: : xxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxx
: : xx x xx xx x xx xxxxxxxxxx
: : x xx xxxxx x
: : xx
: : x
: : x
: : x
: :
: : The New Brighton quake seemed to be about half way to full scale. There
: : has been one quake which went to full scale in not too distant times.
: :
: : So it seems that the part of the quake which we felt was the part that
: : was greater than the Hanmer level - just one pulse up and two down which
: : I couldn't show.
: The Hanmer quake was about 130 km from Christchurch
For reference the Hanmer quake was a shallow mag 4.5. (9.32 pm UCT 11 Dec).
The Chch quake was at 11.53 am UCT 14 Dec.
Is the large pulse an S wave? It is about 5 seconds later than the start
of the trace.
How much faster are primary waves than secondary on an alluvial plain?
The museum where the Christchurch seismometer is is about 9 or 10 km from
New Brigton where the quake was felt strongly.
If the P wave travels at 7 km/s and the S wave at 4 km/s then I calculate
that where t is the time from quake to arrival at seismometer and d is
distance from it then roughly
d/7=t and d/4=5+t or d is approximately 45 km, maybe 35km out to sea.
: :
: : Can anyone talk about amplification of ground motion on alluvial planes?
: : What was the significance of the blast effect?
: :
: : Brian Sandle
:
: Perhaps the sci.geo.earthquakes people might talk about why the MM scale
: figures are not given more often. The local scientists have not replied
: why they do not, so I allow myself a little luxury of some fantasy, too.
: The second depicted quake was said to be magnitude 3 or less, presumably
: as registered in a recorder in rock but quite a jolt on the alluvial
: plane, indicated by the diagram (for which intensity figures have not been
: provided).
:
The book "More Eartquakes Explained" by Aitken and Lowry gives the twelve
steps of the surface intensity Modified Mercalli scale.
I Not felt in general
II Felt by a few on tops of buildings
III Hanging objects may swing slightly
IV Felt indoors by many, dishes rattle walls creak.
V People run outside, crockery dislodged from shelves, hanging pictures
move.
VI Felt by everyone, heavy furniture moved, plaster cracks
VII Frightens everyone, damage to weak buildings, difficult to stand up.
VIII General fright and some panic, unreinforced chimneys fall, but only
superficial damage to ordinary buildings.
IX Panic is general, some damage to strong buildings, ground cracks,
some houses shifted off their foundations.
X General panic, wooden buildings seriously damaged, landslides, rivers
slop over banks.
XI General panic, broad ground cracks, soil slumps, great damage to
underground pipes, few buildings remain standing.
XII General panic, total destruction, objects thrown up in air.
I would have put the New Brighton quake at a good IV. How did you class it?
Note that this is different from the Richter _Magnitude_ which is the
energy released at the hypocentre and has a greater _intensity_ closer.
- I left the diagram
: to ask more about the sound of quakes, and to give other data happening
: within the given window of the Honduras meteor.
:
: Some months back someone plsted that light effects can accompany quakes.
: Is that anything to do with piezo-electric fields from crushed rocks?
:
: Nuclear blasts can be heard hundreds of km away. For faintest connection
: I ask whether the Honduras meteor sound could have been focused here
: causing our blast effect? What does cause a blast effect from a quake?
Or could a fragment have landed here? Someone emailed me and said there
_was_ an explosion in a park in the New Brighton area about the time of the
quake.
:
: I repeat two articles which may be of interest.
The blast effect might have been just coincidental with the quake. When I
phoned the New Brighton police later they said I was describing unrelated
events. They had not known of a quake at that time.
Brian Sandle
