Unusual number of large tectonic earthquakes before and during the birth of the Paricutin monogenetic volcano. Did they trigger, maintain, and boost the volcanic long-lasting activity from 1943 to 1952?

Volcanoes can be described as falling somewhere a large spectrum ranging from polygenetic systems, which are constructed through multiple, long-lived eruptive phases, to monogenetic systems, which usually form during a single eruptive event. Within this context, several decades of observations on Earth have shown that close and strong tectonic earthquakes can precede large eruptions of polygenetic volcanoes. In contrast, only a few close and large earthquakes have been reported before the birth of new monogenetic volcanoes, since the latter are rare. Here, we describe the unusually high number of large tectonic earthquakes that preceded the birth of the Paricutin monogenetic volcano in Mexico in 1943. Thirteen large tectonic earthquakes occurred in the near field during the 20-year period spanning the decade before the birth of Paricutin to the end of its eruption, whereas only one earthquake occurred within ten years after the eruption ended. This clustering of large tectonic earthquakes in space and time before and during the eruption of Paricutin is unusual for this region of Mexico. The significant difference in the number of tectonic earthquakes before, during, and after the eruption strongly suggests that Paricutin´s birth and growth are related to these earthquakes. They may have changed the stress tensor near Paricutin´s location, facilitating magma to migrate towards the surface and sustaining Paricutin´s eruption for nine years - an unusually long period for a monogenetic volcano. We propose that changes in static and quasi-static stress fields, resulting from local faults, local tectonics, and static displacement fields generated by near-field earthquakes, may have triggered and boosted the Paricutin´s eruption. In addition, we suggest that the dynamic stress field generated by the waves emitted by earthquakes may have altered magma pathways towards the surface prior to and during the Paricutin´s eruption. • The Paricutin eruption of 1943 was triggered by tectonic earthquakes • The long-lasting eruption is explained by repeated tectonic earthquakes. • Bifurcation of magma migration due to major tectonic earthquakes.