Kate, In response to your general question on the effect of hurricanes
on plate motion and seismicity see the post above.

In response to your specific question regarding seismicity
associated with the Passage of Hurricane Andrew:

Hurricane Andrew was a strong but powerful hurricane which
made landfall on the eastern Coast of Florida on the morning
of August 24, 1992. A general summary can be found at:
http://www.nhc.noaa.gov/1992andrew.html
OR
http://water.usgs.gov/nwsum/WSP2425/andrew.html

Within minutes of Andrew's hit in Florida an earthquake of Ml 4.3 occurred
in Southern California in the Angelus Oaks area. It was felt at
intensity IV. The earthquake occurred at 6:51 am PDT at 34.2N 116.8W.

More interesting was the effect of Andrew on the east coast, however.
As Andrew was approaching the east Coast on 21 August, the first
reference above states:

"Significant changes in the large-scale environment near and
downstream from Andrew began by 21 August. Satellite imagery in the
water vapor channel indicated that the low aloft to the east-southeast of
Bermuda weakened and split. The bulk of the low opened into a trough
which retreated northward. That evolution decreased the vertical wind
shear over Andrew. The remainder of the low dropped southward to a
position just southwest of Andrew where its circulation enhanced the
upper-level outflow over the tropical storm. At the same time, a strong and
deep high pressure cell formed near the U.S. southeast coast. A ridge built
eastward from the high into the southwestern Atlantic with its axis lying just
north of Andrew. The associated steering flow over the tropical storm
became easterly. Andrew turned toward the west, accelerated to near 16
kt, and quickly intensified."

The high pressure cell that formed over the U.S. southeast coast
was associated with the strongest earthquake in South Carolina
in the 26 year period 1975 - 2001 - a Ml 4.4 which was strongly felt at
North Charleston on the 21st of August.

After Hurricane Andrew unleashed it's destructive power on Florida, it
moved into the Gulf of Mexico and made a second landfall in southern
Louisiana between 5 and 8:30 UTC. on August 25, 1992. At the moment
of landfall at 05:41 UT on August 26, 1992, a Ml 3.5 occurred in the
New Madrid region, the largest earthquake in that area in more than
a year - a Ml 5.0 had occurred in the area on May 4, 1991.

Coincidence - I leave that up to you ...