There are several resources available to aid in contacting or located family and friends in Japan.
Inquiries concerning U.S. citizens living or traveling in Japan should be referred to the U.S. Department of State, Office of Overseas Citizens Services at 1-888-407-4747 or 202-647-5225. http://travel.state.gov/travel/tips/emergencies/emergencies_1212.html
The Google Person Finder site is available at: http://japan.person-finder.appspot.com/?lang=en
If you have the mobile phone number of your family member in the affected areas, you may utilize the following services to check whether he/she has registered his/her message(s) on this service. Services are available in English and Japanese.
Please note that when you enter the mobile phone number for search on the webpage, you should remove the country code 0081 and add 0 at the beginning. For example, if you dial the number internationally as follows, 0081-90-8877-6655, enter it into the website as: 090-887-6655