"Supermoon" On The Rise

[PPI Brian]

It may not be faster than a speeding bullet, but tonight the moon will make its closest approach to Earth in 18 years?making the so-called supermoon the biggest full moon in years.

http://news.nationalgeographic.com/news/2011/03/110319-supermoon-full-moon-earth-science-space-biggest-closest-brightest/

[PPI Karl]

There have been unfounded claims by astrologers of this "Supermoon" being responsible for the 9.0 earthquake in Japan.  Leave the science of this to the big kids, thank you. ::|  Besides, isn't it bad enough the earthquake happened at all?  Throwing zany theories into the mix doesn't exactly help anyone! 

Thanks for posting this, Brian.

[PPI Debra]

There have been unfounded claims by astrologers of this "Supermoon" being responsible for the 9.0 earthquake in Japan.  Leave the science of this to the big kids, thank you. ::|  Besides, isn't it bad enough the earthquake happened at all?  Throwing zany theories into the mix doesn't exactly help anyone! 

Thanks for posting this, Brian.

That makes astrologers look bad! Basic astrology doesn't work that way.

Here's a "eminent geologist", featured on Fox/Faux news claiming the moon will cause quakes in the Pacifc Rim, including here:

http://www.youtube.com/watch?v=kZM5j_FgymE

[PPI Tracy]

I heard the exact same thing, Karl.  It did make me wonder.

[PPI Brian]

The moon has the same gravitational effect on the earth regardless of its phase, but when the moon reaches apogee during a full moon like it did the other night, extremely high tides have been documented. There has been a lot of research conducted on earthquakes and tides over the last few years, and some geologists have speculated that the same tidal forces that affect the ocean can deform the earth's crust and cause earthquakes. Sachiko Tanaka from the National Research Institute for Earth Science and Disaster Prevention, Tsukuba, Japan wrote a paper on tidal triggering of the December 26, 2004 9.0 Sumatra earthquake. Perhaps the scientists on Faux News got it wrong -- the earthquakes already happened in Japan.

Here's a very clear description of the gravitational influence of the moon from Wikipedia:

The Moon orbits the Earth in the same direction as the Earth rotates on its axis, so it takes slightly more than a day - about 24 hours and 50 minutes - for the Moon to return to the same location in the sky. During this time, it has passed overhead once and underfoot once, so in many places the period of strongest tidal forcing is the above mentioned, about 12 hours and 25 minutes. The high tides do not necessarily occur when the Moon is overhead or underfoot, but the period of the forcing still determines the time between high tides.

Because the gravitational field created by the Moon weakens with distance from the moon, it exerts a slightly harder tidal force on the side of the Earth facing the Moon than on the opposite side. The Moon thus tends to "stretch" the Earth slightly along the line connecting the two bodies. The solid Earth deforms a bit, but ocean water, being fluid, is free to move much more in response to the tidal force, particularly horizontally. As the Earth rotates, the magnitude and direction of the tidal force at any particular point on the Earth's surface change constantly; although the ocean never reaches equilibrium - there is never time for the fluid to "catch up" to the state it would eventually reach if the tidal force were constant - the changing tidal force nonetheless causes rhythmic changes in sea surface height.

Lunar Altitude:
The changing distance separating the Moon and Earth also affects tide heights. When the Moon is at perigee, the range increases, and when it is at apogee, the range shrinks. Every 7 1/2 lunations (the full cycles from full moon to new to full), perigee coincides with either a new or full moon causing perigean spring tides with the largest tidal range. If a storm happens to be moving onshore at this time, the consequences (property damage, etc.) can be severe.

Atmospheric Tides:
Atmospheric tides are negligible at ground level and aviation altitudes, masked by weather's much more important effects. Atmospheric tides are both gravitational and thermal in origin and are the dominant dynamics from about 80/120 kilometres (50/75 mi) above which the molecular density becomes too low to support fluid behavior.

Note: The thermal effects of atmospheric tides have been postulated by some atmospheric scientists as a factor spawning weather and winds. Atmospheric tides have caused satellites to "de-orbit" and fall to earth.

Earth Tides:
Earth tides or terrestrial tides affect the entire Earth's mass, which acts similarly to a liquid gyroscope with a very thin crust. The Earth's crust shifts (in/out, east/west, north/south) in response to lunar and solar gravitation, ocean tides, and atmospheric loading. While negligible for most human activities, terrestrial tides' semidiurnal amplitude can reach about 55 centimetres (22 in) at the equator - 15 centimetres (5.9 in) due to the Sun - which is important in GPS calibration and VLBI measurements. Precise astronomical angular measurements require knowledge of the Earth's rotation rate and nutation, both of which are influenced by Earth tides. The semi-diurnal M2 Earth tides are nearly in phase with the Moon with a lag of about two hours.

Some particle physics experiments must adjust for terrestrial tides. For instance, at CERN and SLAC, the very large particle accelerators account for terrestrial tides. Among the relevant effects are circumference deformation for circular accelerators and particle beam energy. Since tidal forces generate currents in conducting fluids in the Earth's interior, they in turn affect the Earth's magnetic field. Earth tides have also been linked to the triggering of earthquakes.

[PPI Debra]

Brian,
Thanks for posting all the correct info on the magnetics of the moon, the tides, and earthquakes.

I have been having a hard time restraining myself on other forums (not here) because the Japan disaster combined with the supermoon has led to a whole new wave of proselytizers regarding the 2012 Mayan calender end-of-time thing.

In case anyone is wondering: Jose Arguelles started the whole business with an art project, which snowballed into the new age money rakers
crying "buy now, you won't be here later!". It worked. They are rich.

The Mayan Venus calender, long count, does end, but starts at the beginning again, like any calender does.

However, astrophysicists have predicted the current solar flare cycle will peak around Dec. 2012. Brian , you probably know more about that.

[PPI Tracy]

Thanks for posting all of this.  It really helps me to understand. This big blue marble that we all live on is pretty amazing.