Hurricanes ...

As storms will occur from time to time, as a hiker you should be familiar with the expressions that describe them. Here are the most important ones:
A "cyclone" is any rotating feature. If wind speed is below 39 mph, it is called a "tropical depression". If wind speed exceeds 39 mph, it is called a "tropical storm". If 74 mph are exceeded, then it is called a "hurricane". Hurricanes use to proceed from east to the west, with a peak of occurance in September. Click here to see a hurricane eye-to-eye.

Link: Hurricane Hunters Home Page: the people that fly into the eye of the hurricane.

... and Tsunamis

A tsunami is another destructive phenomenon that can occur on the coastline suddenly. Submarine earthquakes can generate waves that can devastate a coastal city within a few moments. This happened to Hilo, Big Island, already twice in the last few decades. In case of a Tsunami warning you have to leave the lower regions of the shoreline. See the Kalalau Trail description for a photo of a Tsunami marker.

Link: Pacific Tsunami Museum Homepage