Impacts do not initiate volcanic eruptions: Eruptions close to the crater

A theme that runs through many papers on meteorite impact is the idea that large impacts can induce volcanic eruptions through decompression melting of the underlying rocks. We perform numerical simulations of the impact of an asteroid with a diameter of 20 km striking at 15 km s-1 into a target with a near surface temperature gradient of 13 K km-1 (“cold ” case) or 30 K km-1 (“hot ” case). The impact ultimately creates a 250 to 300 km diameter crater with approximately 10,000 km 3 of impact melt. However, the crater collapses almost flat and the pressure field returns almost to the initial lithostat. Even an impact this large is insufficient to raise mantle material above the peridotite solidus due to decompression only. We also discuss the probability that such an impact coincides with the much more frequent occurrence of Large Igneous Provinces and conclude that it is unlikely that a large impact struck such a province any time in post-heavy bombardment Earth history. A theme that runs through many papers on meteorite impact is the idea that large impacts can induce volcanic eruptions (one of the first was Ronca, 1966). This idea probably got its start in pre-Apollo days when early observers of the moon noted the common occurrence of dark material—usually supposed to be basaltic lava—filling the nearside impact basins (Baldwin, 1963). A logical inference is that this is a genetic