Hi Usmivka thank you very much for this information. I will contact them.
I know some students in China received offer on Feb 20. On the same day, i received a letter from eapsinfo@mit , notifying as follows
Earth, Atmospheric and Planetary Sciences is in the process of evaluating the applications received for our graduate programs. Decisions on all applications wlll be made by March 15, 2013. Our process involves consultation among a number of individuals and committees before a recommendation is sent to the Admissions Committee. Notification is sent out to the applicant as soon as a decision is reached.
So I don't know its meaning. Maybe they have made the decisions on that day and just inform me? just put me on the waitinglist or some others?