Therefore, pyroclastic is a term used for broken pieces of rock associated with volcanic eruptions. It is a general term which covers a variety of sizes, ranging from ash to boulders. They are hot and fast, moving at speeds up to several hundred miles per hour and at temperatures of several hundred degrees Celsius. There's a pretty good chance that you couldn't outrun one of these events, which is one of the reasons why most people try to stay out of their way. Pyroclastics are common to intermediate volcanoes such as are associated with subduction of the crust.
Several examples come to mind.
The 1980 eruption of Mt. St. Helens resulted in a relatively small pyroclastic event, which deposited several hundred feet of material around the northeastern base of the mountain, with finer ash material actually circling the globe for several weeks before it finally all settled out. Mt. Pinatubo in the Philippines was a larger eruption, so the resulting pyroclastic cloud was also larger. In addition, the final eruptive scene in the movie Dante's Peak gives Hollywood's version of the event.