From the USCIS:
This advisory is for Japanese and other foreign nationals from the Pacific stranded in the United States due to the earthquakes and tsunami devastation in the Pacific. If you have exceeded or are about to exceed your authorized stay in the U.S. you may be permitted up to an additional 30 days to depart.
Visitors traveling under the Visa Waiver Program (VWP):
• If you are at an airport, contact the U.S. Customs and Border Protection office at the airport.
• All others, please visit the local U.S. Citizenship and Immigration Services office. Visitors traveling under a nonimmigrant visa:
• Visit the local U.S. Citizenship and Immigration Services office. • Bring your passport, evidence that you are stranded (such as an itinerary for the
cancelled flight), and your I-94 departure record.