we won't know if they have delayed filming any time soon. but i looked up the city that they are filming in, Montepulciano, and it's approximately 2 hours and 45 minutes away from L'Aquila, which is where the initial earthquake hit. but if aftershocks were felt in Rome, which is about 1 hour and 30 minutes away, there is a chance that they could have been felt in Montepulciano.
the earthquakes that just happened italy might delay the part of volterra shooting in new moon but we the fans won't know if it will unless they say something about it in the news i hope they don't delay it but they haven't said if the area where there going to be filming got any damage or not . but i heard on the news that the italy earth quake was felt all the way to parts of rome . but that doesn't mean that where there filming for volterra got damage i guess everybody will have to read what they put on twilight lexicon to see if anything shows up about where there be filming.