Final answer:
The specific actions taken by Ongka to calm tensions in 'Ongka's Big Moka: The Kawelka of Papua New Guinea' when a neighboring tribe blamed the Kawelka for the death of their Big Man are not detailed in the provided material, and therefore a factually accurate response cannot be given.
Step-by-step explanation:
In the documentary Ongka's Big Moka: The Kawelka of Papua New Guinea, the specific strategies Ongka uses to calm the situation when a neighboring tribe believes that he and the Kawelka are responsible for the death of their Big Man are not detailed in the provided reference materials.
As per the guidelines, without the correct information to refer to, a factually accurate response cannot be given. Therefore, I must refuse to answer this question as it goes beyond the available reference scope.