The Long Valley volcanic region, eastern California, has been characterized by recurrent and generally explosive eruptions in the past 180,000 years, originating from a N/S elongated area ~50 km in extent, including the Mammoth Mountain lava dome complex, the Mono‐Inyo volcanic chain, and their peripheries. Several temporal clusters of activity have been observed in a relatively well‐preserved time‐stratigraphic record, which is nevertheless affected by uncertainties. This study has two main objectives: (1) to fully describe the past eruption record by using a stochastic model capable of combining radiometric ages and stratigraphic constraints and, (2) based on the uncertainty assessment, to develop a doubly stochastic, long‐term temporal model based on the current situation. Multiple approaches are described and compared, and multimodel forecasts are also presented. Our findings provide fundamental information for hazard assessment and forecasting of the next eruption in the Long Valley volcanic region, of which the mean probability of occurrence is estimated to be ~2.5% in the next 10 years and ~22.5% in the next 100 years.

Tephra is a unique volcanic product with an unparalleled role in understanding past eruptions, long-term behavior of volcanoes, and the effects of volcanism on climate and the environment. Tephra deposits also provide spatially widespread, high-resolution time-stratigraphic markers across a range of sedimentary settings and thus are used in numerous disciplines (e.g., volcanology, climate science, archaeology). Nonetheless, the study of tephra deposits is challenged by a lack of standardization that inhibits data integration across geographic regions and disciplines. We present comprehensive recommendations for tephra data gathering and reporting that were developed by the tephra science community to guide future investigators and to ensure that sufficient data are gathered for interoperability. Recommendations include standardized field and laboratory data collection, reporting and correlation guidance. These are organized as tabulated lists of key metadata with their definition and purpose. They are system independent and usable for template, tool, and database development. This standardized framework promotes consistent documentation and archiving, fosters interdisciplinary communication, and improves effectiveness of data sharing among diverse communities of researchers.