If you live downhill of a rift zone and an eruption breaks out above your house, you will be ordered to evacuate the area at the appropriate time.
Keep in mind that the scientists of the U.S. Geological Survey's Hawaiian Volcano Observatory (HVO) have instruments that monitor the rift zones 24 hours a day. Before an eruption, the ground inflates rapidly and seismographs record volcanic tremor (underground magma flowing up towards the surface). Although there is usually an increase in seismic activity and ground deformation for several hours prior to an eruptive outbreak, residents living in remote areas may have little warning and less time to evacuate themselves and their possessions prior to a fast-moving lava flow.
The steeper the ground, the faster lava travels. When Kalapana was overrun by lava flows in the early 1990s, residents had days and sometimes weeks to plan for evacuation, because the ground was flat and the lava moved slowly. But on the west side of Maunaloa, the slopes are steeper, and lava moves faster. The 1950 lava flow at Hoʻokena mauka reached the ocean in less than six hours.
Besides destroying homes, lava flows can cut off roads—and evacuation routes. Thus, you may be asked to evacuate early and quickly to provide adequate time to reach safety. You can always replace your possessions, but not your life, so get your family and pets out of danger as quickly as possible.
Because a sudden eruption may damage transportation and communication networks, you should make advance plans with your family on where they should go and with whom they should communicate in the event an eruption occurs when the members of the family are not together.
If you live on a steep slope, you may not be able to see lava flows headed your way, as they may be obscured by trees or mist. Follow the orders of Civil Defense, who are informed by HVO scientists of the location of flows.
Keep a list of items to take with you in the event of evacuation: irreplacable documents, financial records, medications, easily transported valuables, and sufficient supplies to sustain you for several days. And remember—the only truly irreplacable thing is your life and that of your loved ones. When in doubt, get out. Also recognize that your pets and farm animals cannot be accommodated at shelters. If you live in a high lava flow hazard zone it would be wise to make arrangements ahead of time with a friend or family member living outside of the high risk zone to shelter your animals if evacuation is necessary.