Revised stratigraphy and eruption rates of Ceboruco stratovolcano and surrounding monogenetic vents (Nayarit, Mexico) from historical documents and new radiocarbon dates

More than a dozen new radiocarbon dates reconstruct the eruptive history of Ceboruco volcano. Six of these further constrain previous results for the important plinian Jala eruption, which occurred near 1060 ± 55 yr BP. A calibrated radiocarbon age of AD 990–1020 was obtained as best overlap range for all samples. Pottery fragments found directly underneath the pumice deposit indicate that this area was inhabited by human populations that witnessed the eruption. This age therefore represents an important time marker in the prehistory of this region, because an area of > 560 km2 was devastated and covered by a thickness of > 50 cm of pumice and ash fallout. the prominent Jala eruption (VEI = 6), at least seven major lava flows and several smaller domes were issued from Ceborucoʹs crater. Analysis of historical documents allows us to conclude that most of these eruptions took place well before the arrival of the Spanish conquerors to this area in 1528. Ceborucoʹs last historic eruption (1870–1872) produced a ca. 7 km long viscous dacite lava flow. Its emplacement was accompanied by block-and-ash flow activity and deposition of ash fallout. Because a repeat of such an eruption in the future would seriously endanger the nearby population and disrupt important life-lines, a detailed discussion of eyewitness accounts and other documents, including drawings and paintings is provided. Some of these materials are made available to the broader public for the first time in the present article. l surrounding monogenetic vents were previously dated by others using the K–Ar and the Ar–Ar methods. Because these dating methods are often not suitable for very young rocks, we also dated several Holocene monogenetic vents by the radiocarbon method. These dates together with geologic mapping allowed calculating eruption rates and recurrence intervals of different types of eruptions. Accordingly, an andesite/dacite lava flow (accompanied by block-and-ash flow activity) was erupted from Ceborucoʹs crater on average every 143 years during the last 1000 years. In contrast, a monogenetic eruption forming either a scoria cone or a dome has occurred in the area surrounding Ceboruco on average every 1000 years during the Holocene. During the period between AD 1000 and AD 1500 Ceboruco displayed an elevated activity experiencing a rhyodacite plinian eruption (3–4 km3 DRE) followed by the emplacement of six andesitic/dacitic lava flows also with a total volume of 3–4 km3. ese figures indicate that the Ceboruco volcanic region is one of the most active areas in the entire Trans-Mexican Volcanic Belt. Consequently, production of a detailed volcanic hazard map and implementation of other preventive measures aimed at reducing potential losses in case of renewed volcanic activity should be mandatory.