I could be wrong, according to Lady Maude it has happened before, but wouldn't simply resting your hand (or a finger) on the snare skin stop it resonating, in much the same way as resting your hand on your strings mutes them?
I assume it's the skin vibrating against the snare, or is it the actual snare that sets up the resonance? Even if it was the snare, damping the skin with a digit would surely stop it being amplified.
Too simple?