Read this and answer the question. If the question is unanswerable, say "unanswerable".

In August 2005, Houston became a shelter to more than 150,000 people from New Orleans who evacuated from Hurricane Katrina. One month later, approximately 2.5 million Houston area residents evacuated when Hurricane Rita approached the Gulf Coast, leaving little damage to the Houston area. This was the largest urban evacuation in the history of the United States. In September 2008, Houston was hit by Hurricane Ike. As many as forty percent refused to leave Galveston Island because they feared the traffic problems that happened after Hurricane Rita.

The evacuation of the West coast before Hurricane Rita was what type of evacuation?
unanswerable