Once you are out of immediate danger, the most useful thing you can do in the next minute is tell somebody.
One message, to one person, outside the affected area. That person becomes the point everybody else asks. It stops six relatives ringing you in turn while you are trying to move, and it stops six relatives ringing emergency services to report you missing when you are not.
Write, do not call. In a real incident the mobile network saturates within minutes. A text message is a few dozen bytes and will queue and deliver when a voice call will simply fail. Voice calls also occupy capacity the emergency services need.
Say four things, and nothing else.
- I am safe.
- Where I am, roughly.
- Where I am going, if anywhere.
- When I will next make contact.
The fourth is the one people forget, and it is the one that prevents panic on the other end. "I will message again at six" turns silence from evidence of disaster into an expected gap.
Do this before your battery is a problem. It costs almost nothing now and may be impossible in two hours.