In this paper a different type of crisis in random map is studied. The trigger of this crisis is the tunnel effect induced by a backward tangent bifurcation, while the previously reported crises are all caused by the collision of the chaotic attractor with an unstable orbit. In studying the intermittency behaviors induced by the crisis, two different characteristic times are defined. The scaling laws of the characteristic times are calculated numerically. Comparing the present crisis with the previously reported cases, the difference between their mechanisms is shown. Corresponding to this difference, two groups of crises are classified.