Dr Steckler said more than 140 million people live within 60 miles of the fault.
Steckler told CNN, he fears the fault line may be active.
He said the fault was being filled by sediment from the Ganges-Brahmaputra Delta which makes it difficult to study.
However, using the GPS data, he said they were able to ‘see the motion of the plates and the deformation around the fault due to the two sides being locked together’.
Steckler claimed a 8.2 to 9.0 earthquake would have a devastating effect on the tens of millions of people living nearby – even in the Bangladeshi capital Dhaka.
He said: ‘The strain is building up and will sometime be released by an earthquake.’
The researchers cannot predict when the earthquake will strike, but he said governments in the region should be ‘building more earthquake resistant structures’ while improving ‘planning to cope with relief and supplies for the people after an earthquake’.