Saw this mentioned on one news tonight, there is an app for iOS and Android for Civil Defence starting with Auckland first and I believe will end up nation wide. The idea is for those who don't listen to the radio or watch TV is that its another way to get information to people.
Big thing that jumps to my mind, after the big christchurch earthquake one of the big things being said at the time was to only use your mobile for text only as voice and I assume data would congest the mobile networks, and given all the power cuts using wi-fi wouldn't be possible.
So to me a good idea but could be a problem during a real emergency like a big quake
Call me negative, but from experience down here in ChCh, the best app would be an A4 piece of paper, with bullet points covering provsions to have. From water to BBQ gas, from batteries and radio to spare corded phone, food, first aid, etc. While power was down here, radio and people were active, and cells came back in time.
Most of NZ is an earthquake risk, but our fellow kiwis up north also have tornado risks, saturating rain and flooding. Cut off by slips.
Get the A4 "app", everyone learn it, and be prepared.