* Astronomy

Wvogeler · New

RE: Earthquake

Blobrana · L

In nature, random signals often fall mysteriously in step. Fireflies flashing sporadically in early evening soon flash together, and the same harmonic behaviour can be seen in chirping crickets, firing neurons, swinging clock pendulums and now, it turns out, rupturing earthquake faults.
Scientists have well established that big earthquakes can trigger other big quakes by transferring stress along a single fault, as successive earthquakes in Turkey and Indonesia have shown. But some powerful quakes can set off other big quakes on faults tens of kilometres away, with just a tiny nudge, says a new paper. Christopher Scholz, a seismologist at Columbia University's Lamont-Doherty Earth Observatory, explains how: the faults are already synchronised, he says.
Scholz argues in the most recent issue of the Bulletin of the Seismological Society of America that when a fault breaks, it may sometimes gently prod a neighbouring fault also on the verge of fracturing. The paper finds evidence for synchronised, or "phase locked," faults in southern California's Mojave Desert, the mountains of central Nevada, and the south of Iceland. Drawing on earthquake patterns as far back as 15,000 years, the paper identifies strings of related earthquakes, and explains the physics of how faults separated by up to 50 kilometres, and rupturing every few thousand years, might align themselves to rupture almost simultaneously.
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Blobrana · L

Earthshaking Theory: Moon Phases Cause Earthquakes

Tom Jordan, a USC professor and director of the Southern California Earthquake Centre, says that while some studies indicate tidal effects may have an effect on smaller quakes, there's no evidence they have an effect on bigger quakes like the one April 4 centred in Baja California.
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Blobrana · L

There are two flavours of tidal stressing that have been claimed to generate enhanced rates of earthquakes - diurnal and biweekly tides. The diurnal correlations would arise from more earthquakes only during the hours when the tidal stress is pushing in an encouraging direction, in contrast, biweekly effects would be based on earthquakes occurring during the days when the sinusoidal stressing oscillations are largest. The former, as most easily observed in the twice-daily rise and fall of the ocean tides, have occasionally been shown to influence tides, this paper shows there may be some weak tidal triggering of shallow, oceanic thrust-faulting earthquakes). The latter, which arises from the periodic alignment of the Sun and Moon, has often been claimed in the popular press to incubate earthquakes (sometimes termed the "syzygy" effect) and occasionally for small datasets in the scientific literature, but generally such effects do not appear in careful studies of large datasets.
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Blobrana · L

2005

Is the observed correlation between the moon's position in its 18.6-year cycle (or any other lunar phase) and earthquake activity a coincidence or something more? That question, Chester said, is best answered by the U.S. Geological Survey.

"There's no evidence to support that. There were some studies in the past that tried to link lunar effects to seismicity [the relative frequency and distribution of earthquakes] and there was nothing found" - John Bellini, a geophysicist with the survey's National Earthquake Information Centre in Golden, Colorado.

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Wvogeler · New

I am the author of the referenced article, which evolved from a book I wrote called "An Amateur Astronomer's Guide to Gravity." In the book, I published the results of an experiment I commissioned at the University of Montana. Dr. Xioabing Zhou took measurements for the experiment, which revealed a daily gravity variance that I predicted between Jan. 2 and Jan. 4, 2009. I wanted the measurements taken during this time period because the Earth passes closest to the Sun about this time each year, and I predicted that the gravity variance would be most apparent.

With the results from the experiment, I extrapolated the idea that the Earth's weight shifts each day most notably as it nears the Sun and that his "wobble" would affect earthquakes most significantly during the months of December and January. I published the article in September 2009. After the earthquake in Haiti in January 2010, I began reviewing seismic readings to determine whether there were further correlations. Based upon my review of five years of seismic readings around the globe, I believe there are other correlations between gravity variances and earthquakes.

In particular, there seems to be increased earthquake activity when the Earth traverses the Sun's equatorial plane at the ascending and descending nodes. Applying this theory, I believe the next most significant effect will be in the last week of September 2010.

Blobrana · L

Recent Earthquake Activity Not Unusual

With major earthquakes reported in Chile, Haiti, Indonesia and southern California and Mexico this year, earth scientists continue to hear the question: is it unusual?
The short answer is no.
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Blobrana · L

The 1960 Valdivia earthquake or Great Chilean Earthquake (Spanish: Gran terremoto de Valdivia) of 22 May 1960 is to date the most powerful earthquake ever recorded, rating 9.5 on the moment magnitude scale. It occurred in the afternoon (19:11 GMT, 14:11 local time) and its resulting tsunami affected southern Chile, Hawaii, Japan, the Philippines, eastern New Zealand, southeast Australia, and the Aleutian Islands in Alaska.
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Blobrana · L

Can the Sun and Moon Trigger Faults?

UC Berkeley Scientists have discovered that the faint gravitational tug of the sun and moon can set off tremors deep underground in one of the world's most dangerous earthquake zones.
A study of the San Andreas Fault has found a link between the gravitational tug that creates the tides and small tremors A study of the San Andreas Fault has found a link between the gravitational tug that creates the tides and small tremors beneath the ground Although the pull of planetary objects is too weak to set off a full blown quake, the findings suggest that they could set in motion a chain of events, leading to devastation on the surface.
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Blobrana · L

There is no direct correlation between large earthquakes and the orbital mechanics of the Earth around the Sun.
The largest recorded earthquake was the Great Chilean Earthquake of May 22, 1960.