Suzy B Software 2/Suzy B Software CD-ROM 2 (1994).iso/nasa/flare_eq/flare_eq.rtc

Text File | 1995-05-02 | 15.8 KB | 349 lines

GEnie Space and Science Roundtable Science RTC         May 30, 1993

Guest: Lowell Whiteside
       NOAA/National Geophysical Data Center
       325 Broadway
       Boulder, CO  80303-3328
       Internet: [e-mail]
       Tel.: [phone]

Files of related interest in the Space and Science library:
No.  Name          Description                               Size
-------------------------------------------------------------------
3107 FLARE-EQ.ZIP  Lowell Whiteside's TIF-format graphs      246656
                   re: solar flare/earthquake connection
 967 FLARE.GIF     GIF pictures of a solar flare              20160
 968 FLARE2.GIF    GIF pics of a solar flare #2               31500
 1547 SOLAREXP.ZIP Explanation of solar reports in RT         85680
 2780 EBEL.RTC     New England Earthquakes?  You bet!         12160
 2255 EQ-1990.TXT  Significant Earthquakes, 1990              26752
 2256 EQ-1991.TXT  Significant earthquakes, 1991              29056
 2776 EQ-1992.TXT  Significant quakes, 1992                   29440
 3084 EQ-1992.ZIP  Earthquake Bulletins, 1992 (archive)      121216
 2254 EQ-STATS.TXT Earthquake statistics from the NEIC        12416
 2222 MERCALLI.TXT Desc. of Mercalli earthquake scale          5504
 2050 QUAKES.TXT   Two brief articles on earthquakes          10240

<FRANK.REDDY> Lowell Whiteside has worked in graduate programs in
geology, geochemistry, and geophysics at the University of
Nebraska, Georgia Institute of Technology, Oswego State University
of New York, and the University of Colorado.  He has worked for the
past five years with CIRES (Cooperative Institute for Research in
Earth Sciences) and NOAA at the National Geophysical Data Center,
where he's seismologist in charge of the World Data Center
Earthquake Database. Part of these duties include the analysis of
earthquake patterns in global catalogs.

<FRANK.REDDY> His interest in solar triggering of seismic events
stems from a natural curiosity of the relation between earthquakes
and other natural phenomena, and he's worked on this problem for
about 15 years.  He has written several papers on the subjects of
solar triggering of earthquake activity and/or electromagnetic
phenomena associated with earthquakes, and believes on the basis of
this research that a case can be made that solar flares do trigger
earthquakes under specific circumstances.

<FRANK.REDDY> First, thanks for coming!  Second, can you bring us
quickly up to speed on some of the history of the idea that solar
flares may influence geophysical events?

<[lowell] SPACE.GUEST> Sure.  When earthquake catalogs were first
produced, it became obvious that there were cycles in them.
Fourier analysis of these catalogs has shown a number of periodicities.
In many regional and global catalogs, there appeared 1-, 11-, 22-, 56-
and 88-year cycles which corresponded to cycles related to the Sun.
Many matched those of the Sun's magnetic variations.  The chief periods,
often 11 years (or multiples thereof) were immediately related to the
solar period. Explanations for the relation have been put forward
ranging from interaction with solar flares (through weather
patterns) to generation of electrical currents in the crust
(induced from the ring currents in the atmosphere).

<FRANK.REDDY> You've found evidence for connections where?

<[lowell] SPACE.GUEST> The most obvious relation I have found
between solar flares and subsequent earthquakes is in Ethiopia
and Baja, California. In Ethiopia there is a very predictable 4
day 12 hour lag time between large solar flares and subsequent
earthquakes.  In Baja California, the same lag time occurs,
leading to a mistaken impression that earthquake in Ethiopia leads
to quakes in Baja, or vice versa.

<[Al] A.CHOU1> In Ethiopia or Baja, is there often an earthquake
following a solar flare?

<[lowell] SPACE.GUEST> There is a sizable quake (M > 5) in Ethiopia
following major solar flares about 90 percent of the time.  This
relationship is especially obvious during the last solar maximum
(1987-1993). Here "major flare" is usually considered an X-type flare.
The catalog for Baja is very crowded with quakes, so a high-magnitude
cut must be made to see the relation.

<[Al] A.CHOU1> Wow, 90 percent?  Surprising.  I'm not familiar with
the classification of flares.  Also, at what magnitude must you cut
the Baja catalog in order to see the relation?

<[lowell] SPACE.GUEST> In terms of flare classification, X are
the most energetic, M and C are next. Flares are also classified
by importance on a scale from 1 to 4 (4 is the largest). A
magnitude cut at MB = 5 is appropriate for Baja.

<[Al] A.CHOU1> What is MB?

<[lowell] SPACE.GUEST> MB is what is usually referred to as the
Richter magnitude. It is actually the body-wave magnitude.

<[Al] A.CHOU1> Are there other places that show anywhere near as
strong a correlation of flares to quakes?

<[lowell] SPACE.GUEST> Al, yes, there are. I did a study
of locations which have a statistically significant relation with
flares and earthquakes. The highest correlations occur within
about 5 degrees of the magnetic equator and at the areas within
about 2000 miles of the magnetic poles.

<[Dave] SPACE> Is this suggestive of a mechanism?

<[lowell] SPACE.GUEST> Ethiopia runs directly below the magnetic
equator. This correlation suggests that currents set up by
induction in the earth may responsible for this behavior. Earth
currents are also powerful near the magnetic poles.

<[Al] A.CHOU1> Roughly how many events show this correlation?

<[lowell] SPACE.GUEST> The most obvious correlation in Ethiopia
has occurred since the beginning of the last solar maximum (in
1988). In this time period, 10 out of 12 major flares have
corresponded with earthquakes of magnitude > 5.6 in the African Rift
valley.

<[Al] A.CHOU1> OK, so what are the proposed mechanisms?

<[lowell] SPACE.GUEST> The most logical mechanism is that as the
flare interacts with the earth's magnetosphere, it produces ring
currents in the ionosphere (this is known).  These currents, in
turn, induce electrical currents in the earth.  The electrical
currents run up against faults.  Many faults mark the junction of a
change between low and high electrical resistance.  This means they
can act as capacitors.  Laboratory research shows that electricity
added to slipping systems can change the frictional coefficients
and promote sliding. Electrical heating at the fault due to the
differences in electrical properties on the two sides of the faults
is perhaps the main effect which could promote the generation of
earthquakes.

<[Al] A.CHOU1> Roughly how much current/charge (per unit
area/volume?) are we talking about?

<[lowell] SPACE.GUEST> In 1989 (October 19) a major solar flare
caused power outages in Canada by the induced currents generated
in underground cables.  This has happened on several occasions.
The size of these currents can reach about 9 volts.

<[Al] A.CHOU1> Ah, substantial, then.  This is typical of large
flares?

<[lowell] SPACE.GUEST> Yes.

<FRANK.REDDY> Yes, the electrical effects of flares in long
conductors is well established.

<[Al] A.CHOU1> Other, less logical mechanisms?

<[lowell] SPACE.GUEST> A second mechanism for the production of
earthquakes in the area of Ethiopia is heating of the interior due
to these currents.  The Ohmic heating due to one flare-induced
current may change the temperature of magmas in the upper level
(just below the surface) by about 1 - 2 degrees C depending on the
conductivity and resistivity of the rocks. This is sufficient to
cause doming, which has been observed by sensitive tiltmeters in
the area.  The doming itself will cause faults to open up and less
normal friction to exist, promoting the earthquakes through the
Coulomb failure criterion.  This may be why this effect is most
obvious in areas like Ethiopia (the Afar hotspot) and Baja (the
Baja hotspot).

<[Al] A.CHOU1> Are there data on the conductivity (vs.
frequency?) of these geologic areas (Baja and Ethiopia)?

<[lowell] SPACE.GUEST> There is data on the conductivity of these
areas. Unfortunately, it is not good, since it must be
extrapolated from depth. In general, in the westward side of
the San Andreas there is good conductivity, on the eastward side
poor conductivity.

<[Al] A.CHOU1> Is there a lot of quake activity in Ethiopia (as
there is on the west coast of the Americas)?

<[lowell] SPACE.GUEST> No, in fact Ethiopia shows a clear 11-year
cycle, with major quakes occurring at the peak of the solar maximum
every 11 years.  Larger quakes do not occur in the intervening time
(quakes of magnitude 4 and below are associated with the motion of
magmas). But tectonic quakes are not common in the region, certainly
not as common as in Baja.

<[Al] A.CHOU1> Is there anyone saying that your conclusions are
in error?

<[lowell] SPACE.GUEST> There is a great deal of controversy in
this subject. American scientists have long contended that quakes
cannot be triggered by something as small as is postulated here.

<FRANK.REDDY> You've mentioned to me that the Soviets were more
willing to look at this.

<[lowell] SPACE.GUEST> But after the Landers quake in southern
California last summer (M 7.5), which caused earthquakes to occur
throughout the United States, this opinion has rapidly changed.
The Soviets and Chinese are very interested in this subject.
They are more interested in how the weather is related to solar
flares, and how this in turn affects earthquakes.

<[Al] A.CHOU1> What are the Americans' proposed explanations of
the data (especially, in Ethiopia)?

<[lowell] SPACE.GUEST> The Americans, as I have said, have not
generally taken the solar-earthquake connection very seriously.
But recent explanations are a wind effect pushing against the
mountains or a relation between planetary positions, solar flares,
and gravitational influences on the Earth.  This was largely
discounted because several people have not backed up their theories
with good data. The data and conclusions on Ethiopia have
not yet been published, so little feedback is yet available here.

<FRANK.REDDY> In some of the material you sent me, you mentioned
some effects of flares on Earth's rotation rate. Could you
elaborate on those ideas?

<[lowell] SPACE.GUEST> Flares can affect the Earth's rotation rate
in two ways. First, by the influence between the ionospheric
currents and weather patterns.  The weather patterns (winds) are
changed at high levels immediately after solar flare interaction.
This can been seen in the radiosonde pattern above the Himalayas,
which shows stronger winds occurring about a day after large solar
flares. These winds push on continental masses and cause stresses
which can be relieved by earthquakes.

<[lowell] SPACE.GUEST> The second method is the generation of
eddy currents in the Earth due to the magnetic field variations.
These can speed the Earth up or down depending on their size and
direction.

<F.CONDON> Is the frequency of the currents around 3 Hertz?

<[lowell] SPACE.GUEST> The frequency is around 3 hertz but is
quite variable.

<F.CONDON> Would there be a decrease in amplitude prior to a
seismic event?  Could this signal decrease occur 5 to 24 hours
before an earthquake?

<[Al] A.CHOU1> What is important about 3 Hz?  A characteristic
frequency of something?

<[lowell] SPACE.GUEST> The frequency of 3 Hz is a frequency often
associated with magnetic changes which have been observed prior
to earthquakes in Taiwan, China, Japan, and the West Coast of the
United States. It is also a frequency common to the induced
currents.

<[lowell] SPACE.GUEST> Condon's questions: The signal would have
a temporal variation.  Immediately after the solar flare
interacts with the Earth, it would induce the current.  This
current would then interact with a fault.  There will be a time
during which the electrical energy interacts with the fault zone
to decrease the normal friction before the quake occurs -- 5 to
24 hours is reasonable.

<[Al] A.CHOU1> Are the winds generated by flare interaction
generally in some particular direction or are they just stronger
in whatever direction?

<[lowell] SPACE.GUEST> The winds generated by flares are
stronger in a particular direction (towards the West) in the
Himalayan data I have studied. For other areas this may not be the
case.

<FRANK.REDDY> What is needed to confirm if these things are
really important determiners of fault activity?

<F.CONDON> Would it be possible to see the signal decrease with a
increase in the water table level (ballast)?

<[lowell] SPACE.GUEST> The effects cited above are small compared
with the overall environmental noise. It is possible that flares
induce free earth oscillations which could be seen in water level
changes, but this would be a difficult thing to see. The electrical
effect of flares on faults can be studied in more detail by sensitive
instruments (measuring telluric currents) near the faults, and
measuring any increase in electrical current on the opposing sides
of the fault.  By the way, in Russia in the 1960's, there was a
power plant which grounded its electrical energy on a daily
basis. It was noticed that a fault about 100 miles distant always
had an earthquake immediately after the grounding. As for other
effects, theoretically they should behave as outlined here. Changes
in the Earth's magnetic field could not be monitored, however,
since these changes may have lag times of months to years after the
flare occurs.

<[Dave] SPACE> >Always<...as in...always?  Every time??

<[lowell] SPACE.GUEST> Dave, the poorly translated Russian article
I read suggested that the fault was a perfect indicator of
grounding at the power plant during the 6-month study period.

<[Dave] SPACE> Very interesting! Kind of a neat effect....

<FRANK.REDDY> The quakes were rather small, though, 3-4 MB?

<[lowell] SPACE.GUEST> Frank, yes, the magnitudes were small (M
3-4).

<[lowell] SPACE.GUEST> By the way, I should note, that any theory
should be backed up with predictive ability. In the case of the
Ethiopian quakes, I sent the material to Frank in February. Since I
was looking at it, I was able to give a 2-day warning of a series
of quakes between March 11 - 20 1993 (which occurred 4 days 12 hours
after the first major flare since September 1992).  Of the five largest
flares to occur in this series, all were followed by quakes in the Red
Sea with a time lag of 4 day 12 hr +/- 3 hours. The flares cited
were of importance II and III and occurred from March 6, to March 15
1993.

<FRANK.REDDY> And of course the Red Sea _is_ the northern part of
the East African Rift... :)

<[lowell] SPACE.GUEST> Yes.  In fact this was the first major
activity in the Red Sea since March 30, 1969, following another
large burst of solar activity.

<FRANK.REDDY> Any more questions for our guest?

<[Al] A.CHOU1> None here.  Sounds fairly convincing.

<FRANK.REDDY> Well, in that case, I'd like to thank you all for
coming, and thanks Lowell for wearing his fingers to the bone!

<[Al] A.CHOU1> Thanks very much, Lowell!

<[lowell] SPACE.GUEST> I really enjoyed answering your questions,
maybe we could do this again on another aspect of earthquake
triggering?

<F.CONDON> Yes, thanks Lowell...

<FRANK.REDDY> I'll send you a copy of the transcript, if you
like.

<[lowell] SPACE.GUEST> Yes, please, If you need anything more
from me, Frank, let me know.

<ODY> Nice to "meet" you, by the way, Lowell.

<[lowell] SPACE.GUEST> Good to meet you to, ODY.

<FRANK.REDDY> Will do. If there's any breaking predictions you
feel like sharing, please feel free to write me!

<[lowell] SPACE.GUEST> I sure will. Keep in touch.