ASTORIA, Ore. — With construction underway in Seaside to build schools outside the tsunami inundation zone and a bond on the ballot in Warrenton in November to do the same, preparing schools for a disaster is in the limelight. But as schools look for opportunities to relocate to higher ground to be safer in an earthquake and tsunami, administrators will face a new task: how to prepare to be a community’s default shelter when disaster strikes. Schools are at the center of the state’s emergency planning strategy.