Updated 14-Mrz-11 02:30h
A short note about
GEOL-120 and GEOL-110 LAB appeared in Kaiserslautern American,
the AvantiPro weekly, the May 28, 2009
issue. Thank you, Nicky (Editor):
This recent report is important for the following courses, currently scheduled at Kaiserslautern KAPAUN, summer term (June-July), MoWe:
Environmental Geology, GEOL-120
(3 credit hours), and
Physical Geology LAB, GEOL-110 (1 credit hour).
"Preparation through education is less costly than learning through tragedy."
- MAX MAYFIELD, DIRECTOR
NATIONAL HURRICANE CENTER
|1||1775||town Suchowola, NE Poland||Szymon Antoni Sobiekrajski, cartographer & astronomer||53°35′ N 23°06′ E|
|2||late 18th century||St. John's Church, village Krahule on the road to Kremnické Bane, near Kremnica, central Slovak Republic||Legend||48°45′ N 18°55′ E|
|3||1887||Dilove on the Tisza river, Rachiw, Galicia, SE Ukraine (near Romania)||Austrian geographers||47º 56' 3" N, 24º 11' 30" E|
|4||>1900||Frauenkirche church, Dresden, the Saxon capital, Germany||German geographers|
|5||1910||hill Dyleň, 939 m/m, W of Marienbad, W Czech Republic||Austrian geographers|
Hildweinsreuth near Flossenbürg, N Oberpfalz, Bavaria, Germany (south from the location above)
Geographic Institute, University München, Germany
|7||near the city Toruń, about 350 km east of the border with Germany, 150 km south of Gdańsk, 200 km NW of the Polish capital Warsaw.||unknown|
|8||memorial W from České Budějovice, S Czech Republic||unknown|
|9||1989||26 km N from Vilnius, the capital of Lithuania, towards Moletai, near the Purnuskes village||Jean-George Affholder, Institut Géographique National, Paris, France||
54° 51' N, 25°19' E
below the Earth surface
|10||1-MAY-2005||Kleinmaischeid, near Neuwied, 40 km SE from Bonn, N of Koblenz, Germany||Center of EU: Institut Géographique National, Paris, France|
There was a strong (MAG 9.0) earthquake on the Indian Ocean floor in South-East Asia, at the site where the India + Australia lithospheric plates are subducted beneath the south-east margin of the Eurasia plate, which is there separated by the microplates of Burma and Sunda (tectonic settings). See also EQflyer.doc.
On Sunday, 26-DEC-04, the Earth, in its slightly elliptical orbit around the Sun, our nearest star, was approaching its closest distance from the Sun, which is attained on 4-JAN. In so doing, the Earth movement accelerated. The curvature of its path developed exactly the centrifugal force that maintains the orbit in which the Earth will neither fall onto the Sun nor escape from it.
On Sunday, 26-DEC-04, the Moon, in its elliptical orbit around the Earth which is nearly in the same plane as ecliptic, the Earth's orbital plane (only 5° tilt), arrived at a position outside of the Earth's orbit around the Sun. In fact, it was located almost exactly on the Sun - Earth line, but on the opposite side from the Sun. This time from the Earth, we see that the Moon is completely illuminated by the Sun and call it full moon. In this arrangement of these three cosmic bodies, due to their extreme mutual closeness, they interact by their force of gravity.
Though the Sun is huge and the Moon is small, we see both in a similar angular size (as known from the solar eclipse). This "apparent (angular) size compensation" is caused by their inversely related distances. The Earth - Moon distance is 3.844 x 105 km ±5.5% and the Earth - Sun distance is 1.495979 x 108 km ±1.7%. The Moon's diameter is 3.476 x 103 km and the Sun's diameter is 1.392 x 106 km, enough to swallow the Moon's orbit around the Earth. Similarly, even the incredibly great ratio of the masses (responsible for their gravitational forces) of the Sun (1.989 x 1030 kg) to that of the Moon (7.35 x 1022 kg) is overcompensated by the inverse proportionality of their cubed distances to the Earth, mathematically: (mSun/mMoon)x(aMoon/aSun)3 ≈ 0.46, where m is mass of the Sun and Moon respectively, a is the distance to the Earth of the Sun and Moon respectively (equation 4.17 in MURRAY & DERMOTT, 1999, page 135). This is why the Sun's gravity pull on the Earth is 45.9 % of the Moon's gravity pull only. Dermot states that the tide raised in the Earth's crust by the Moon is 36 cm, while that by the Sun is 16 cm.
At 7:58h local time at the earthquake site, the Sun rose to about 30° above the eastern horizon and the full Moon set to that same angle below the western horizon. These two cosmic bodies, at 180° around the Earth, have been strongly stretching (flexing) our planet by their gravity. This gravitational (tidal) force is acting not only on the waters, but also on the atmosphere and lithosphere (solid Earth's surface, see above). Within the solid Earth's surface, the flexing (changing deformation) has to focus on the large lithospheric discontinuities (faults), preferably those with an approximate North - South direction in the given location. The extraterrestrial gravity forces strongly change their pressure on the plates, the Burma plate overriding westwards the India and Australia plates (the movement direction of the celestial bodies in the sky due to the Earth's rotation). There is a probability that a crustal slip on a major discontinuity causing earthquake could be triggered by the tidal flexing forces, particularly when the tide is strongest, such as the full and new moon positions of the nearby cosmic bodies. According to the standard rebound theory of earthquakes, a temporarily blocked plate drifting, leading to an increasing rock compression has abruptly been released: perhaps by the tidal flexing.
That devastating megathrust earthquake occurred at the interface of the India and Burma plates. The India plate as a gigantic spring released its stress, which developed as the India plate was subducted beneath the Burma microplate. The India plate begins its descent into the mantle at the Sunda trench, which lies about 100 km to the west of the earthquake’s epicenter. The trench is the surface (submarine) expression of the Australia & India plate subduction beneath the Burma & Sunda plates, situated to the northeast.
In the region of the earthquake, the India plate moves toward the northeast at a rate of 6.1 cm/year relative to the Burma plate. This results into oblique convergence at the Sunda trench. The oblique motion is partitioned into thrust-faulting, which occurs on the plate-interface and which involves slip directed perpendicular to the trench, and strike-slip faulting, which occurs several hundred km to the east of the trench and involves slip directed parallel to the trench. The December 26 earthquake occurred as the result of thrust-faulting. Approximately 1200 km of the plate boundary slipped and caused the earthquake – Earth’s crust vibration. The average displacement on the fault plane was about 15 meters.
The abrupt motion of a gigantic mass also influenced the whole Earth. Both USGS and NASA scientists calculated it. First, the masses on the equator moved closer to the Earth's center and the bulging at the equator decreased (by one part in 10 billion): the Earth became more spherical, and spins faster by 2.68 microseconds per day.
This is like a spinning skater drawing arms closer to the body resulting in a faster spin. This effect is common in astronomy, of course, in a clearly visible manner. This explains why the gaseous (Jupiter-like) planets, although giants, spin rapidly (Jupiter's day is <10 hours only): they consist of gases which are easily compressible, and therefore were subject to a much stronger compression than the slowly rotating Earth-like planets. We see the fastest rotation on neutron stars which experienced the strongest imaginable compression: from the diameter of about 2 million km to 20 km, a ratio of about 100,000 : 1 and therefore their spins are in the range of milliseconds.
Because the abruptly moved gigantic plate mass was located close to equator but on one side only (asymmetric "glitch"), it also shifted the Earth's rotational axis: mean North Pole moved about 2.5 centimeters (1 inch) in the direction of 134° east longitude (toward Guam in the Pacific Ocean). See the NASA report:
Here is probably the best reference literature for the above subjects:
Carl D. MURRAY & Stanley F. DERMOTT, Solar System Dynamics; Cambridge University Press, 1999, 592 pages; ISBN 0-521-57597-4; especially:
Chapter 4, Tides, Rotation, and Shape (130 - 188 pp), written by Prof. Stanley Dermott.
How do Earthquakes Generate Tsunamis?
A tsunami (pronounced tsoo-nah-mee) is a wave train, or series of waves that form when the sea floor abruptly deforms and vertically displaces a body of overlying water. Earthquakes, landslides, volcanic eruptions, explosions, and even the impact of cosmic bodies such as meteorites, can generate tsunamis. Tsunamis can savagely attack coastlines, causing devastating property damage and loss of life. Tsunamis are unlike wind-generated waves, which many of us may have observed on a local lake or at a coastal beach, in that they are shallow-water waves with long periods & wavelengths. The wind-generated swell one sees at a California beach, for example, spawned by a storm out in the Pacific and rhythmically rolling in, one wave after another, might have a period of about 10 seconds and a wavelength of 150 m. A tsunami, on the other hand, can have a wavelength in excess of 100 km and period on the order of one hour. Tsunamis are only about a meter high at the most in the open ocean.
description of the tsunami physics, see:
Harald Ulrik SVERDRUP, Martin W. JOHNSON & Richard H. FLEMING: The Oceans, Their Physics, Chemistry, and General Biology; Prentice-Hall Inc., New York, 1942, 1087 pages (Chapter 14, Waves & Tides, p. 516 - 604, especially 542 - 545),
As a result of their long wavelengths, tsunamis behave as shallow-water waves. A wave becomes a shallow-water wave when the ratio between the water depth and its wavelength gets very small. Shallow-water waves move at a speed that is equal to the square root of the product of the acceleration of gravity (9.8 m/s/s) and the water depth - let's see what this implies: In the Pacific Ocean, where the typical water depth is about 4000 m, a tsunami travels at about 200 m/s, or over 700 km/hr. Because the rate at which a wave loses its energy is inversely related to its wavelength, tsunamis not only propagate at high speeds, they also travel great transoceanic distances with limited energy losses.
Tsunami fault photographed: http://www.geotimes.org/current/NN_sumatrafault.html
USGS Earthquake Hazard Reports: http://earthquake.usgs.gov/eqinthenews/2004/usslav/
Physics of Tsunamis: http://www.geophys.washington.edu/tsunami/general/physics/characteristics.html
|Epicenter location:||250 km||SSE of Banda Aceh, Sumatra, Indonesia|
|310 km||W of Medan, Sumatra, Indonesia|
|1260 km||SSW of BANGKOK, Thailand|
|1605 km||NW of JAKARTA, Java, Indonesia|
|Coordinates (GPS):||N latitude||3.30°||
= 3° 18'
= 95° 52' 12"
|Earthquake Date + Time:||26-DEC-04||
|3 to 4 minutes||subjectively|
|Rupture length||1200 km||
along the Sunda trench
|Maximum plates displacement||20 meters||
of the overriding Burma plate
to the west-southwest
|Dip of the subducting India plate||10° to the east-northeast||at the focus; up to 45° at greater depth|
|Maximum sea floor displacement||10 meters|
|Earthquake's Energy:||20 x 1017 Joules||475 megatons TNT||23,000 Hiroshima bombs|
|Length of day||-2.676 microseconds||>20 microseconds are measurable only|
|Polar motion excitation X||-0.670 milliarcseconds||due to the closeness to the equator, the total effect (0.82 milliarcseconds) is also negligible and hardly detectable|
There was a strong (MAG 5.4) earthquake in SW Germany early tonight:
|Epicenter location:||5.45km||ESE of Waldkirch|
|14.2 km||ESE of Emmendingen|
|17.4 km||NE of Freiburg im Breisgau|
|Focus depth:||<12km||within gneisses of Hochschwarzwald|
|Coordinates (GPS):||N latitude||48°05'||=48.08333°|
|E longitude||8°02'||= 8.03333°|
|Arrival Time at my LAB:||02:53:45||MET|
|Earthquake Duration:||5 seconds|
|Damages||until 6-DEC-04, 13:38||Stuttgarter Nachrichten||>10,000,000 EURO|
|Mostly gas pipelines, hospital,|
The delay at my LAB was due to the propagation velocity of
the Secondary seismic waves causing the main shaking. These S waves propagate
within hard rocks (gneisses etc.) at a velocity of about 3.5 km/sec, whereas
the P (Primary) waves are faster (about 7 km/sec), but usually are passing sites
at longer distances such as my LAB (200 km).
Have you observed this earthquake?
I had been sitting at my PC at home and suddenly felt a strong wavy shaking, causing me a slight vertigo lasting about 5 seconds. My first impression was that my wife had lost her patience with me and was strongly shaking my spring chair while I was sitting at my PC. This spring chair even hit the other chair nearby and caused a ringing (clinking) sound. But my wife was quite innocent, quietly sleeping. It was an earthquake.
Geophysical / seismological studies:
Seismological Service, Feiburg im Breisgau: Mr. Wolfgang Brüstle
GeoCenter, Potsdam, Prof. Jochen Zschau
You may find maps, seismographic records
and other info under:
Earth's Inner Core is Layered ...
Seismic evidence for an inner core transition zone by Xiaodong SONG, at
Lamont-Doherty Earth Observatory, and Don V. HELMBERGER, at Seismological Laboratory,
California Institute of Technology;
Science (AAAS, Washington D.C.), vol. 282, Nr. 5390/30 Oct. 98, p. 924 - 927 (short summary by Phil Szuromi, Ibiden, p. 841).
Reviewed in Geotimes, published by AGI (Alexandria VA), January 1999 issue,
See also: Geophysical dynamics at the center of the Earth,
by Raymond JEANLOZ and Barbara ROMANOWICZ, Physics Today, August 1997, pp. 22 - 27;
Undestanding the Earth: When North Goes South: http://www.psc.edu/science/glatzmaier.html/
showcases famous computer simulations of how the inner core gives rise to Earth's magnetic field.
This recent discovery is important to:
Currently, it is known that the Earth's core is composed of iron (probably of an iron and nickel alloy), that the outer core is liquid, and that the inner core is solid.
The liquid state is a special type of fluid state of matter. In solids, particles (atoms, ions, molecules) are so close to each other that they are fixed in regular positions, called crystal structure. In fluids, particles are more distant from each other so that they are not fixed but slide past each other. The particles of liquids attract each other so that they just slide at a constant distance from (in contact with) each other. Therefore, liquids maintain nearly the same volume and are almost incompressible.
The authors suggest that the inner core is composed of two distinct layers: the upper one completely isotropic, and the lower anisotropic.
Isotropy is a feature of a medium whereby all or certain medium properties are identical in all directions. Fluids are typically isotropic. Glass, being a stiff liquid, is also isotropic. In optics, the isotropy of a medium implies that the velocity of light is the same in all directions. We say that a medium has the same index of refraction in all directions. In the case of solids, only those crystallizing in the cubic (isometric) system are optically isometric. Solids crystallizing in other systems than cubic are optically anisometric. In seismic isotropy, the velocity of seismic waves is the same in all directions within the given medium. Anisotropic media have certain properties that change with the direction.
The thin isotropic outermost shell of the inner core probably consists of randomly oriented iron grains (of about 200 kilometer maximum thickness). It surrounds an anisotropic inner core of iron grains aligned along a north-south direction. Such a model can be used to test theories about the geodynamo, the cooling of the core, and the structural transition between the inner and outer core.