Gavazzi and Jaffe found that late-type spiral galaxies in rich clusters are radio sources 10 times more powerful than spirals outside clusters. Gavazzi and Jaffe propose that ram pressure from the cluster medium causes collapse of dense molecular clouds, star formation, and other activity in the spirals disks. Bothun and Dressler similarly explain blue H I poor disk galaxies found in the central regions of the Coma Cluster via ram pressure effects. With computer simulations, it is shown in the present work that the tidal field of the cluster as a whole is physically sufficient to trigger cluster spiral nuclear and disk activity. It is shown that tidally induced collisions of disk gas clouds should be much more effective than ram pressure in causing activity. The observed tendency for disk galaxies in centers of rich clusters to be barred and S0 is explained as due to the cluster tidal field. Metals in the cluster medium would be enhanced by the expulsion of spirals enriched gas via tidally induced activity. 36 refs.