  This paper concentrates on the general birth-death processes with two
different types of catastrophes. The Laplace transform of transition
probability function for birth-death processes with two-type catastrophes are
is successfully expressed with the Laplace transform of transition probability
function of the birth-death processes without catastrophe. The first effective
catastrophe occurrence time is considered. The Laplace transform of its
probability density function, expectation and variance are obtained.
