some encouraging news!
I just received an email from a man in Canada whose brother lives in Sumita. He found me online on another forum. The power of the internet is pretty amazing! Sumita is a mountain village of about 6500 people, and there are very few foreigners.
The good news is that his brother was able to make a phonecall out, and verified that most of Sumita was still standing. He even knows my sister, and said her house was not destroyed. He did not see her though.
I am still waiting to hear from my sister, but this is the best news we could have received.
Thanks to everyone for the encouragement and support- I'll post again when I have more information.