However erosion and plate tectonics have taken their toll, and many eruptions have not left enough evidence for geologists to establish their size.
[46] The lava fields of these eruptions measure 565 km2 (Laki), 700 km2 (Eldgjá) and 950 km2 (Þjórsárhraun).Highly active periods of volcanism in what are called large igneous provinces have produced huge oceanic plateaus and flood basalts in the past.
These can comprise hundreds of large eruptions, producing millions of cubic kilometers of lava in total.
Most large igneous provinces have either not been studied thoroughly enough to establish the size of their component eruptions, or are not preserved well enough to make this possible.
Many of the eruptions listed above thus come from just two large igneous provinces: the Paraná and Etendeka traps and the Columbia River Basalt Group.