Jose Luis Palma

Constraints on the rates of degassing and convection in basaltic open-vent volcanoes

Variations in gas emissions of open-vent volcanoes are investigated using a model of magma convection in narrow conduits. Laboratory experiments with both vertical and inclined conduits and dimensional analysis show that for Grashof numbers lower than 100 the volumetric rate of magma ascent is a simple function of equivalent conduit radius, density difference between the magmas, and viscosity of the degassed magma that descends back to the reservoir. The rate of magma ascent depends on the flux coefficient, estimated as 0.1 and 0.2 for vertical and inclined conduits, respectively. The equivalent radius parameter accounts for the dimensions of the conduit(s) regardless of its geometry, thus extending the treatment by previous models that used flow in pipes. The volume flow rate of convection increases with higher density difference and conduit size, but is also highly influenced by the large variations in viscosity of the degassed magma as volatile content and crystallinity change. The model presented here can be used to constrain the degassing and ascent rates of volatile-rich magma when combined with petrologic data on magmatic volatile content. Application of the model to Villarrica volcano (Chile) reveals that the background degassing levels observed (∼3 kg s−1 SO2) are associated with convective ascent of a relatively degassed magma (0.04 wt% S, ∼0.5 wt% H2O), while episodes of higher SO2 emissions (measurements up to 15 kg s−1) can be explained by the ascent of magma with higher volatile content (up to 0.09 wt% S, ∼1.5 wt% H2O).

Vhub: a knowledge management system to facilitate online collaborative volcano modeling and research

Knowledge of volcanic systems and the hazards they produce is rapidly advancing as internet resources become more readily accessible, new and more sensitive field techniques are developed, and ever greater amounts of data are collected. Such rapid advances drive the need for an online collaborative knowledge management system that enables the sharing of volcanological information, and modeling and analysis tools. Vhub (http://vhub.org) is a community cyberinfrastructure platform designed for collaboration in volcanology research, education, outreach, and discovery that complements existing volcano databases and other cyberinfrastructure projects. Vhub is unique in its functionality as a nucleus for the creation of collaborative groups focused on issues such as code development, field research, education, and hazard mitigation. In addition, Vhub serves as a clearinghouse and virtual platform for computational tools relating to volcanic processes and data analysis, as well as documentation to aid in the use and understanding of these tools. By providing a means for scientists to easily disseminate data, models, and ideas, Vhub aims to promote collaboration amongst scientists and to provide resources for science education while advancing the state of understanding of volcanoes and the hazards they produce. This paper introduces the Vhub cyberinfrastructure and provides an overview of select hub features and resources.