31. The initial phases of eruption are characterized by pyroclastic flows . 32. Pel�an eruptions are characterized most prominently by the incandescent pyroclastic flows that they drive. 33. The Pucarilla-Cerro Tipillas volcanic complex is formed by pyroclastic flows . 34. Today these volcanic products are seen as pyroclastic flow uplands and low relief hills. 35. The first pyroclastic flow was observed around 10 : 12. 36. Nineteen people died when pyroclastic flows cascaded down the mountain on June 25, 1997. 37. The solidifying lava would occasionally collapse portions of the volcano to create pyroclastic flows . 38. Known as pyroclastic flows , the material forms rivers that obliterate everything in their path. 39. Later volcanic activity buried this edifice beneath thin pyroclastic flows . 40. Pyroclastic flows of hot pumice and ash along with dome growth occurred during this period.
