oracle error- ORA-00327: log string of thread string, physical size string less than needed string

ORA-00327:	log string of thread string, physical size string less than needed string
Cause:	A log file has shrunk in size. This is likely to have been caused by operator or operating system error.
Action:	Restore the log file from backup. If backup is not available, drop this log and re-create. If the database was shut down cleanly, no further action should be required; otherwise incomplete recovery may be required.