xMagnetic polarity reversal : A magnetic polarity reversal is a change of the earth's magnetic field to the opposite polarity. This has occurred at irregular intervals during geologic time.
Geologists have learned that a large earthquake and tsunami that killed 192 people on September 29, 2009 in Samoa, American Samoa and Tonga was in fact a triple-whammy. The magnitude 8.1 "great earthquake"...Read more