Tailstrikes
The list of tailstrikes from The Aviation Herald in recent years posted by thcrozier makes interesting reading.
Of 45 incidents, 18 are on landing, 20 on takeoff, and 7 unspecified. Despite a non-engineering background, it would seem likely that a landing tailstrike carries a much greater risk of damage to the aircraft's structure, with possible long term consequences. Indeed some take off incidents are described as "tailscrapes"
Certain aircraft types seem more prone to these incidents, though the denominator number of fleet size must also be factored in. For most types there have only been one or two incidents, but the B738 has had 8 takeoff tailstrikes and two landing tailstrikes (fleet 3800+) compared to A320/321 with zero takeoff tailstrikes and four landing tailstrikes for each variant (fleets 4000+ and 1100+) The A319 seems to have been tailstrike free for the years that this list covers.
My question for the professionals would be this - is there any objective way of measuring the force involved in a particular tailstrike?