Exactly. And Twitter is also in the best position to build a dedicated alert system since many times they have the mobile location of each user tweeting. They could even have the app tell the user to then set the phone on a flat surface and use that to try and crowdsource a magnitude/validate the quake. I don't think any other company/org is in a position to be even remotely as accurate than Twitter is for real-time.

If a bad enough erathquake hit the network would probably malfunction or overload due to distress and "are you OK" calls. I guess there is need for satelite or some long wave RF system.