Missing persons in Sapporo Hokkaido Japan?

Question:

My family in California USA, had some friends whose last address was in Sapporo Hokkaido, Japan.
The friends last wrote a letter ( through the postal service) early this year before the large earthquake. When my family mailed a reply back to the family, a few weeks after the large earthquake- the letter was mailed to Japan and was send back to my family members as letter being undeliverable a few weeks later. We are trying to locate these Japanese friends just to see if they are safe and survived the earthquake. We did not have their phone number and did not have an e-mail address. The only address was their home address. If anybody has any information on these people or anybody has a way to check to see if they are safe- please reply.
The couple's names are Koji Miyaoka and Miho Miyaoka. ( Early 30's). The child's name is Komei.
In about the year 2000, my family met this couple in Marina Del Rey, California before they were married. Any information on how to locate this couple would be appreciated.

Answer:

There are only a few (the total number in Japan is about 20,000) casualties in Hokkaido. So I'm sure they survived.

I don't think there are effective ways to find where they are now, without phone number of email address.