A second theory regarding the cause of the end-Permian extinction relates to volcanism. The Siberian Traps eruptive event, 251 Million years ago, was one of the largest flood basalt events of the Phanerozoic. This event is essentially synchronous with the Permian-Triassic Boundary. (Renne, 1995)

The trap volcanisms in Siberia are thought to have occurred in less than a million years, and according to some estimates, less than 600,000 years. Additionally, a significant portion (perhaps 20%) of the Traps volcanism was in the form of pyroclastic eruptions. The effect of tuffaceous material entering the atmosphere would have caused several complications for life. Ash obscuring sunlight would harm photosynthesis, especially in auto phototrophic plankton, interfering with the food web. Additionally, ash entering marine environments would have a clogging effect on filter-feeders. (Renne, 1995)