Recommendation: Store a 2-way radio with batteries and learn how to use it.
Option 1: 2-way radio
Total Cost: ~$50
In the event of a Cascadia Subduction Zone earthquake, our communication networks will be overloaded and possibly destroyed. This is why is it is so important to have a family plan in place. If you have not done that yet, you should do that now: LINK
If the cellular phone systems are still functional, your best chance of communication will be via text message. Be short and to the point with the text message. Another good option is to contact "out of town contact" as a point of contact. It is easier to connect with someone out of the region compared to someone within the effected area. You should use your "out of town contact" to pass along messages to people within the effected region.
A good, but limited, form of contact within the effected region is 2-way radios (FRS radios). While 2-way radios are advertised to have 30+ miles of range, you can expect to have a 1-mile range in city or around Lake Oswego. These radios are a great method to communicate within the neighborhood. It is recommended to practice radio communcation with neighbors beforehand. Establish a common radio channel and practice with your neighbors to become familiar with your radios and its performance capabilities.
Optional - Satellite Phone
A Satellite phone will allow you to communicate even if the local telecommunication systems are down. The cost of the devices and required service plans are coming down since the latest deployment of satellites. Refer to the following PrepLO presentation for all relevant information: LINK
Optional - HAM Radio
Recommendation: HAM Radio with required license
Option 1: HAM Radio
Total Cost: ~$40
You can get serious and obtain a HAM Amateur radio license. It’s actually easy to get the basic technician class license which is the minimum requirement to operate a HAM radio. These radios reach farther, much farther with repeaters, have far more usefulness, and they may be the ONLY way to get information in and out of a disaster area when the big one hits. Plus if you join a local amateur radio club, they can teach you how to send messages for others and help emergency responders, too.
Here is more information on getting your HAM radio license: ARRL
Here is a great studying resource: No-nonsense-guides