Any ski area operator shall be liable for injury, loss or damage caused by failure to follow the duties set forth in section three of this article where the violation of duty is causally related to the injury, loss or damage suffered. A ski area operator shall not be liable for any injury, loss or damage caused by the negligence of any person who is not an agent or employee of such operator, nor shall a ski area operator be liable for any injury, loss or damage caused by any object dropped, thrown or expelled by a passenger from an aerial passenger tramway. Every ski area operator shall carry public liability insurance in limits of no less than $100,000 per person, $300,000 per occurrence and $10,000 for property damage.