The EBS was changed to the Emergency Alert System in 1997.
From wikipedia
On September 11, 2001, ”. . . the EAS was not activated nationally or regionally in New York or Washington during the terrorist attacks on the nation.” Richard Rudman, then chairman of the EAS National Advisory Committee explained that near immediate coverage in the national media meant that the media itself provided the warning or alert of what had happened and what might happen as quickly as the information could be distributed. “Some events really do serve as their own alerts and warnings. With the immediate live media coverage, the need for an EAS warning was lessened.” 34 PEP stations were kept on high alert for use if the President had decided to order an Emergency Action Notification. “PEP is really a last-ditch effort to get a message out if the president cannot get to the media.” [9]