A few years ago, the Big Island of Hawaii experienced a 6.8 earthquake followed shortly by a 6.2. Although there was some damage, generally everything made it through pretty well.
Unfortunately, most radio stations did not have emergency power and were off the air. Imagine spinning the dial (or pushing buttons) and finding nothing! Actually, I think there was one AM station on another island that was running.
So I was able to access the internet but the earthquake site we use was either offline or horribly overloaded with requests. I ended up calling a friend in Florida to look up the quake and where it was.
Soon our cellphones had trouble making calls as the world tried to call us and we tried to call the world. I believe that the cell companies and phone companies and limit inbound calls and limit the mass calls that happen after a major event. Unlike the East coast with their storm, here it is a simple thing to limit all calls to a single area code.
In any event, decades ago I used to work in radio at a station on the Kentucky/Virginia state line. We had "emergency power and telephone service" because we had power and phones come up both sides of the mountain which allowed completely different circuits. The KY and VA power were on different parts of the grid.
I used to be quite active in Ham Radio and have been a network control operator (dispatcher) during many emergencies. With that said, I could not believe that in an area with tsunamis, earthquakes (daily), hurricane possibilities and flowing liquid rock (lava) are a way of life. On my island, a single car accident can block the only road that gets you to town and an alternative could take hours to traverse. That car accident can also take down telephone, cable tv, internet and electric.
So in this kind of atmosphere, it is unbelievable that we are not better prepared.
Then again, we are very prepared in other areas. Without electric, many of us can still eat because we have grills or know how to create and use an imu (underground oven). We also generally don't require air conditioning or heating - we just open or close the windows, because of our weather.
So yes, being prepared and having a backup plan is important. However, you have to think things through. If you have a cable modem and you lose power, your having a UPS for your Obi and cordless phone and router may not help if the amplifiers that supply that cable signal to your house have no power.
When I lost cable access for a month, I was able to use my Verizon cellphone with unlimited data plan, to tether to my computer where I could still get online. I was also able to use a LAN connection out of my computer to the router and with a few cable swaps, could get a laptop online too.
One item that helps me when the power goes off is a UPS with a LED light and a laptop. The LED light uses drastically less power than a regular light bulb.
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On a different side, I once worked for a very large computer company in Atlanta. The computer room was the size of a football field with hundreds of servers. The new computer room had a big red button which would immediately shut down all computers in the room and the air conditioning, to be used in case of a fire.
We had a water leak and called one of those well-known companies to suck up water under the raised floor. The guys were working and our company reps were off in another part of the massive room, when one of the service guys needed to exit the room and go to the bathroom. The "startrek" type glass doors required a security card swipe to enter and exit (thus showing who was accessing the secure area). The guy waved his hands and walked to and fro and when the doors did not open, he decided that the "big red button" must open the doors. It released the door alright as all major lights, all air and all power was turn off.
In response, my company installed a plastic cover over the button. They created a guide on how to use the emergency system in case of emergency. A few days later a computer operator and a security guard were reviewing the instructions. As the operator lifted the plastic cover, a sonolert beep went off. The operator was going to just lower the cover, when the guard pointed at the button and said, I'll turn off the alarm and, you guessed it, pressed the "big red button" again throwing the room in darkness and quiet as we system managers again made the trek to the room to restart hundreds of computers. The guard was reassigned. A better sign was installed with a warning of what the big red button does".
Always have a backup plan, even if it is just a new security guard waiting in the wings.