As circular as it sounds, rare events are rare primarily because they don't occur very often, and not because of any preventive security measures.

CNN: Stop the panic on air security

Examples of preventive conservation are: appropriate measures and actions for registration, storage, handling, packing and transportation, security, environmental management (light, humidity, pollution and pest control), emergency planning, education of staff, public awareness, legal compliance (source: ICOM-CC definition).

UNESCO: CULTURE