trepidatory

adjective2

1. •
   That trepidates, or that causes trepidations.

   • Unfortunately, like Guthrie he has never given a formal statement of his principles, and it is therefore up to the reader to ferret out these things for himself — always a trepidatory procedure. — 1953
2. •
   Of an earthquake, having a vertical, up-and-down motion, as opposed to a horizontal, side-to-side motion.

   • This [earthquake] was felt at Mexico at precisely the same hour, lasting there about one minute and a half, the motion there being undulatory, but at Acapulco trepidatory. — 1843