After a solar storm strikes the Earth a geomagnetic storm erupts. The increased magnetic field strength of the magnetosphere pushes down on the ionosphere, which pushes against the oceans. It is due to the electromagnetic properties of sea water that the oceans become temporarily heavier. The extra heaviness of the sea water, coupled with the daily tidal forces of the Sun and Moon cause greater than normal forces to press against both the eastern and western boundaries of the Pacific Plate, but more so the western boundary in the South Pacific Islands region.
Below are earthquake maps showing global earthquakes of magnitude 5 or greater for the five days following a geomagnetic storm. Notice the clear pattern of quakes in the South Pacific Islands region along with activity around the Pacific Rim. There is also a clear pattern of earthquake activity along the fault running from Greece to the Pacific Plate.
The five dates selected below were the first five dates I found for geomagnetic storms and were selected completely at random. There is a list of solar storms where you can choose a date and check the earthquake database yourself to verify this theory.
Geomagnetic Storm Date: September 24, 1981
Geomagnetic Storm Date: August 26, 1998
Geomagnetic Storm Date: September 25, 1998
Geomagnetic Storm Date: January 22, 1999
Geomagnetic Storm Date: May 18, 1999