These are generated by the NTA module. if the baseline analysis setting is enabled you will get these traps whenever the traffic drops below the baseline.
This feature is most useful where interfaces have a faily constant level of traffic. If its variable then you will have times when the baseline is higher than the current level.
Go to the Traffic Analysis Service > Settings > Task Management > Modify Traffic Analysis Task and disable the baseline analysis
Then goto the Service > Settings > Server Management and deploy the configuration