8/8/2019 Eerthquakes Counts Increase When Moon at Perigee

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S & T Science

Earthquake counts go up as moo n comes closer: BAARC

PTI

APThis image provided by NASA Wednesday shows the new Moon passing between the Sun and the Solar Dynamics Observatory's space telescope. File photo

BAARC seismologists have discovered that ear th, not just water, responds to the moon

Seismologists at the Bhabha Atomic Research Centre have found that the earthquake counts go up steadily as the moon comes closer to the Earth (perigee) andalso when it is Full Moon.

The scientists have also found that major earthquakes occur more in numbers when perigee coincides with Full Moon and New Moon than at apogee (position ofmoon farthest from earth) with similar combination, going up to a magnitude of 6.0 on the Richter scale, Dr. Vinayak G. Kolvankar, senior seismologist fromBARC said.

His latest papers are published in New Concepts in Global Tectonics Newsletter and Journal of Indian Geophysics Union

It has also been shown that most of the global earthquake catalogue data when examined systematically indicated seismicity variation with local time over 24hours basis and observed the occurrence of earthquakes to be more during the night than during the day.

The earthquake counts go down during the day and it is minimum in the afternoon (between 3 pm and 4 pm) and then steadily goes up till midnight, Dr.Kolvankar said.

This typical signature of the diurnal seismicity plots (DSP) seem to be consistent for the global earthquake data for different periods, seasons, longitudes anddepths.

The drop in earthquake counts during the day, reduces for latitudes away from the equators and larger effect is seen for smaller earthquakes, which proportionally

reduces for earthquakes with higher magnitude up to 5.0, Dr. Kolvankar said.BARC scientists made an attempt to realign the earthquake data from standard catalogs for 36 years (1973-2008), to the different periodicities of the moon tocheck if any consistent patterns emerge out of this exercise, Dr. Kolvankar said.

Moon is the nearest planetary body to the Earth which also produces the largest gravitational force on the Earth.

The quakes occurring on the moon were found to be largely governed by the Earth position particularly when moon is at perigee.

However the role of moon on the occurrences of earthquakes had not been clearly established, and therefore this study was taken up with colleagues fromBARC, Dr. Kovlankar said.

We have made an attempt to realign the earthquake data obtained from large sets of standard earthquake catalogues, to the different periodicities of the Moon tocheck if any consistent patterns emerge out of this exercise, he said.

When the world earthquakes are aligned to new moon to full moon, the second half of all three sections provide increasing earthquake counts till full moon.

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8/8/2019 Eerthquakes Counts Increase When Moon at Perigee

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Dr. Kolvankar said, in the first half, both Sun and Moon lie in the same quadrant with respect to Earth and in the second half portions they are in two differentquadrants and net effect is that they both provide some sort of opposite pull resulting in the steady increasing number of earthquakes as Moon moves from firstquarter to full Moon position, where Moon aligns with the Sun and Earth in opposite direction.

During transition from Full Moon to New Moon, the number of quakes progressively reduces till Moon reaches the third quarter. This increase in the Earthquakecounts from mid position (first and third quarters to full Moon) is about 5-6 per cent.

This increase was observed up to the magnitude of 6.0 on the Richter scale and for shallow focused events up to 10 km and feebly seen up to the depth of 35 km.Again this rise is observed for all latitude ranges and most longitude ranges.

For earthquakes aligned to apogee-perigee-apogee (APA) cycles, the increase in the number of earthquakes counts from apogee to perigee was observed forearthquake magnitude range of 4-6 on the Richter scale.

Keywords: lunar cycle,

earthquakes,

seismology

Page 2 of 2The Hindu : Sci-Tech / Science : Earthquake counts go up as moon comes ...

10/24/2010http://www.thehindu.com/sci-tech/science/article842579.ece