OP, you are asking what could have been the cause of these magnetic field anomalies, and I say, there is a "comet" named C2012 F3 that is positioned just right to cause it.

The orbit of this comet is such that it moves almost along the ecliptic, and it is located along the dark side of the earth during the months of late February and early March for 3 consecutive years, 2011, 2012, and 2013. Remember, there was an unknown source of "solar wind" at the dark side of the earth last March 12, 2012 that reversed the solar wind coming from the Sun.

Here is a pic of this comet last Feb 28, 2011 when its declination makes a straight line with the Sun, and the earth is between this line:
[link to s1203.beta.photobucket.com]
The comet was 10.868 au from the earth that time:
[link to s1203.beta.photobucket.com]

Here is a pic of this comet last Feb 22, 2011 when its right ascension makes a straight line with the Sun, and the earth is between this line:
[link to s1203.beta.photobucket.com]
The comet was 10.902 au from the earth that time:
[link to s1203.beta.photobucket.com]

I believe this comet must have ejected its own material (similar to the Sun's CME) towards earth, causing the March 11, 2011 mag 9 Japan earthquake.

Taking the average date and average distance from the earth of this comet we get this event coordinates as Feb 25, 2011 at 10.855 au from the earth. Which means the ejected material must have traveled approximately 0.77 au/day to reach earth on Mar 11, 2011.



Here is a pic of this comet last Mar 3, 2012 when its declination makes a straight line with the Sun, and the earth is between this line:
[link to s1203.beta.photobucket.com]
The comet was 8.611 au from the earth that time:
[link to s1203.beta.photobucket.com]

Here is a pic of this comet last Mar 2, 2012 when its right ascension makes a straight line with the Sun, and the earth is between this line:
[link to s1203.beta.photobucket.com]
The comet was 8.62 au from the earth that time:
[link to s1203.beta.photobucket.com]

Notice that Mars was positioned between this comet and the Earth, which I believe shielded the Earth from the comet, thus preventing a stronger earthquake (than Japan's mag 9) from occurring.

I believe this comet must have ejected its own material (similar to the Sun's CME) towards earth, causing the March 12, 2012 solar wind reversal anomaly.

Taking the average date and average distance from the earth of this comet we get this event coordinates as Mar 2, 2012 at 8.6155 au from the earth. Which means the ejected material must have traveled approximately 0.88 au/day to reach earth on Mar 12, 2012.

This means that the ejected material from this comet travels faster as it comes closer to its perihelion.