FN Archimer Export Format PT J TI Holocene marine tephra offshore Ecuador and Southern Colombia: First trench‐to‐arc correlations and implication for magnitude of major eruptions BT AF Bablon, Mathilde Ratzov, Gueorgui Nauret, François Samaniego, Pablo Michaud, François Saillard, Marianne Proust, Jean‐Noël Le Pennec, Jean‐Luc Collot, Jean‐Yves Devidal, Jean‐Luc Orange, François Liorzou, Celine Migeon, Sebastien Vallejo, Silvia Hidalgo, Silvana Mothes, Patricia Gonzalez, Miguel AS 1:1,2;2:1;3:3;4:3;5:4;6:1;7:5;8:6,7;9:1;10:3;11:8;12:6;13:4;14:9;15:9;16:9;17:10; FF 1:;2:;3:;4:;5:;6:;7:;8:;9:;10:;11:;12:;13:;14:;15:;16:;17:; C1 Université Côte d'Azur CNRS IRD Observatoire de la Côte d'Azur Géoazur Valbonne, France ISTerre IRD CNRS OSUG Université Grenoble Alpes Saint Martin d'Hères,France Laboratoire Magmas et Volcans Université Clermont Auvergne CNRS IRD OPGC Clermont‐Ferrand, France Université Côte d'Azur Sorbonne Universités CNRS Observatoire de la Côte d'Azur IRD Géoazur Valbonne, France Université Rennes 1 CNRS Géosciences Rennes Rennes, France Université de Bretagne Occidentale laboratoire Geo‐Ocean CNRS‐UBO‐Ifremer‐UBS IUEM Rue Dumont d'Urville29280 Plouzané ,France IRD Office for Indonesia & Timor Leste Jalan Kemang Raya n°4 Jakarta12730, Indonesia Université Côte d’Azur Centre Commun de Microscopie Appliquée Nice, France Instituto Geofísico Escuela Politécnica Nacional Ap. 17‐01‐2759 Quito ,Ecuador Escuela Superior Politecnica del Litoral (ESPOL) Grupo de Investigacion en Geociencias Marinas y Costeras (GEMAC) FIMCM‐FICT Campus Gustavo Galindo P.O. Box 09‐01‐5863 Guayaquil ,Ecuador C2 UNIV COTE D'AZUR, FRANCE UNIV GRENOBLE ALPES, FRANCE UNIV CLERMONT FERRAND, FRANCE UNIV COTE D'AZUR, FRANCE UNIV RENNES, FRANCE UBO, FRANCE IRD, INDONESIA UNIV COTE D’AZUR, FRANCE IGEPN, ECUADOR ESPOL, ECUADOR UM GEO-OCEAN IN WOS Cotutelle UMR copubli-france copubli-univ-france copubli-int-hors-europe copubli-sud IF 3.5 TC 1 UR https://archimer.ifremer.fr/doc/00791/90344/95874.pdf https://archimer.ifremer.fr/doc/00791/90344/95877.docx https://archimer.ifremer.fr/doc/00791/90344/95878.pdf https://archimer.ifremer.fr/doc/00791/90344/95879.xlsx https://archimer.ifremer.fr/doc/00791/90344/95880.xlsx https://archimer.ifremer.fr/doc/00791/90344/95881.xlsx LA English DT Article CR AMADEUS ATACAMES-EQUA BO L'Atalante DE ;tephrochronology;volcanology;geochemistry;land-sea correlation;Ecuador AB Tephra layers preserved in marine sediments are strong tools to study the frequency, magnitude and source of past major explosive eruptions. Thirty-seven volcanoes from the Ecuadorian and Colombian arc, in the northern Andes, experienced at least one eruption during the Holocene. The volcanic hazard is therefore particularly high for the populated areas of the Andes and in particular cases for the coastal region, and it is crucial to document such events to improve hazard assessment. The age and distribution of deposits from major Holocene eruptions have been studied in the Cordillera, but no descriptions of distal fallouts have been published. In this study we focused on 28 Holocene tephra layers recorded in marine sediment cores collected along the northern Ecuador - southern Colombia margin. New lithological, geochemical and isotope data together with 14C datings on foraminifers allow us to determine the age and volcanic source of marine tephra, and to propose a first land-sea correlation of distal tephra fallouts. We show that at least seven explosive eruptions from Guagua Pichincha, Atacazo-Ninahuilca, Cotopaxi, and Cerro Machín volcanoes left tephra deposits recorded in marine cores over 250 km away from their source. Volume estimates of emitted tephra range between 1.3 and 6.0 km3 for the 10th century Guagua Pichincha, ∼5 ka Atacazo-Ninahuilca, ∼6.7 and ∼7.9 ka Cotopaxi events, suggesting that they were eruptions of Volcanic Explosivity Index of 5. The distribution of these deposits also brings new constraints for a better evaluation of the volcanic hazard in Ecuador. Key Points We propose a first land-sea correlation of distal Holocene tephra off Ecuador based on 14C age and geochemical data Products from at least seven explosive Holocene eruptions in Ecuador and south Colombia reached the Pacific Ocean Volumes of tephra emitted by largest eruptions vary between 1.3 and 6.0 km3, suggesting they were VEI-5 eruptions Plain Language Summary During major explosive eruptions, large volumes of gases and tephra (lapilli and ash particles) are thrown into the atmosphere and can be spread by winds over hundreds of kilometers and more. Tephra fallouts can impact the population, infrastructures and climate. It is therefore essential to document the age and magnitude of past major eruptions to better assess the volcanic hazards. In this study we use the minerology, glass shard morphology, and the geochemical composition of tephra settled in marine sediments off Ecuador and Colombia to investigate their source. Thickness of tephra layers and radiocarbon ages performed on under- and over-lying marine fauna allow us to determine the age of the eruptions, whereas the distribution of tephra yields constraints on the volume of fallout deposits. We show that the largest explosive eruptions from Ecuadorian and Colombian volcanoes reached the Pacific Ocean with a recurrence rate of about 1.5 events per millennium over the past 8 kyr. PY 2022 PD SEP SO Geochemistry Geophysics Geosystems SN 1525-2027 PU American Geophysical Union (AGU) VL 23 IS 9 UT 000863588000001 DI 10.1029/2022GC010466 ID 90344 ER EF