This is a replacement for the old "Tsunami" cache that was placed to point out the Tsunami Zone warning sign nearby.
Large earthquakes can cause very large underwater landslides like those that are found in the Santa Barbara channel. These landslides can cause large tsunamis. A large earthquake in Santa Barbara in 1812 was followed by a tsunami that wiped out many coastal villages and destroyed ships in the harbor.
The local tsunami zone map (see image) shows that the top of this bluff is "safe". So, the is the cache safe, or is it in the danger zone? - There's only one way to find out...