Flood basalts are continuous eruptions of magma through long fissures in the Earth's crust. The huge volume of magma required for these eruptions is thought to come from a destabilized layer of the core and mantle boundary.
Flood basalts create a lava plateau, filling in depressions with basaltic magma hardening into igneous rock. These flows sometimes cover thousands of square miles. They are often several miles deep. Flood basalts cover large areas of both the continental and oceanic crusts.
The step-like hills known as the Siberian Traps in Russia were created by flood basalts. The Deccan Traps of India and the Columbia Plateau in the Pacific Northwest are other examples of flood basalts.
Flood basalts have been discovered on all terrestrial planets. The dark areas of the moon are basaltic lava fields called maria. These basaltic fields cover 16 percent of the moon's surface. Basalts larger than those on Earth have been identified on the highly volcanic surface of Venus.
According to a 2010 article in the Proceedings of the National Academy of Sciences, massive flood basalt eruptions may have contributed to prehistoric mass extinctions. Eruptions cover large areas of land and disrupt the immediate area. They also release greenhouse gases that affect climate. These large emissions of greenhouse gases make flood basalt eruptions a possible culprit for mass extinctions.