Front Air Bag Sensor Control problems of the 2001 Volvo S40

I am reporting this incident because the front driver and passenger airbags fully deployed when the undercarriage of the car and right front tire struck pavement at approx. 45 miles per hour. The car did not stop, and the driver had to manually beat the airbags back with his hands to see and bring the car to a stop. This incident was reported to Volvo USA, they removed the sensors for investigation, then reported back to me in writing that they operated normally, and that there was sufficient impact to the undercarriage to cause deployment. I disagree, and feel that the car is unsafe to drive. Either the design of the S40 or it's sensors are defective. Everyone that saw the car after the incident was very surprised that the airbags deployed at all, since there was no collision involved -- damage to the outside body of the car was minor. All damage was to the undercarriage and interior (due to the airbags). Had there been any cars traveling in the opposite direction, very serious injury would have resulted since the driver was blinded and would have only had the protection of already deflating airbags had a head on collision occured with another vehicle. I have all documentation reported to Volvo, and their written response.