Losing power for extended periods of time was a regular occurrence when I lived in South-Central Alaska, sometimes for days. There, it was common to see private homes with backup generators. Some were fueled by natural; gas and many were designed to kick in automatically when the power went off. Many, if not most filling stations had backup gen sets. Lavarock probably has a similar situation in HI.
Many years ago we had 2 very large earthquakes, A 6.7 just north of town. We lost power state-wide. Most islands generate their own power but there are safetys installed so that a quake will shut down power to the island to avoid catastrophic cascade effects, etc.
Most places had no generators, although some large stores did. Gas stations usually don’t have emergency power. Most radio stations serve their own islands and all but a few went dark. I had to rely upon AM radio from Honolulu which was spotty reception to say the least. I did not have my Ham radio equipment available at the time, nor a safe indoor location to use it. My home power and internet were out after the quake and I had some trouble calling the mainland via cellphone. Telephone service was prioritized for OUTBOUND calls as I remember but still, remember that most of us were trying to call the mainalnd and other countries to tell relatives we were safe. I did that because my friend in Florida could tell me how strong the quake was. CNN was just reporting it. The airports shut down. TSAs had to manually inspect all bags and people. Road crews were very busy with landslides. I used my own tractor to remove some debris from the county road, without asking 
Although this is an uncommon event, it shows what can happen.