Accelerated uplift and magmatic intrusion of the Yellowstone caldera, 2004 to 2006

Improved Real-Time Natural Hazard Monitoring Using Automated DInSAR Time Series

As part of the collaborative GeoSciFramework project, we are establising a monitoring system for the Yellowstone volcanic area that integrates multiple geodetic and seismic data sets into an advanced cyber-infrastructure framework that will enable real-time streaming data analytics and machine learning and allow us to better characterize associated long- and short-term hazards. The goal is to continuously ingest both remote sensing (GNSS, DInSAR) and ground-based (seismic, thermal and gas observations, strainmeter, tiltmeter and gravity measurements) data and query and analyse them in near-real time. In this study, we focus on DInSAR data processing and the effects from using various atmospheric corrections and real-time orbits on the automated processing and results. We find that the atmospheric correction provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) is currently the most optimal for automated DInSAR processing and that the use of real-time orbits is sufficient for the early-warning application in question. We show analysis of atmospheric corrections and using real-time orbits in a test case over the Kilauea volcanic area in Hawaii. Finally, using these findings, we present results of displacement time series in the Yellowstone area between May 2018 and October 2019, which are in good agreement with GNSS data where available. These results will contribute to a baseline model that will be the basis of a future early-warning system that will be continuously updated with new DInSAR data acquisitions.

The lateral growth and coalesence of magma systems

Thermal and mechanical models of magma reservoir growth need to be reconciled with deformation patterns and structural relationships observed at active magma systems. Geophysical observations provide a series of short time-scale snap-shots (10⁰-10² years) of the long-term growth of magmatic bodies (10³-10⁶ years). In this paper, we first review evidence for the growth of magmatic systems along structural features and the associated deformation patterns. We then define three distinct growth stages, (1) aligned melt pockets, (2) coalesced reservoirs, (3) highly evolved systems, which can be distinguished using short-term surface observations. We use two-dimensional thermal models to provide first-order constraints on the time scales and conditions associated with coalescence of individual magma bodies into large-scale reservoirs. We find that closely spaced intrusions (less than 1 km apart) can develop combined viscoelastic shells over time scales of 10s kyr and form laterally extensive mush systems over time scales of 10-100 kyr. The highest temperatures and melt fractions occur during a period of thermal relaxation after melt injection has ceased, suggesting that caldera-forming eruptions may preferentially occur long after the main intrusive activity. The coalescence of eruptible melt-rich chambers only occurs for the highest melt supply rates and deepest systems. Thus, these models indicate that, in most cases, conductive heat transfer alone is not sufficient for a full coalescence of magma chambers and that other processes involving mechanical ruptures and mush mobilization are necessary; individual melt lenses can remain isolated for long periods within growing mush systems, and will only mix during eruption or other catastrophic events. The long-term history of the magmatic system is therefore critical in determining rheological structure and hence short-term behaviour. This framework for the development of magmatic systems in the continental crust provides a mechanical basis for the interpretation of unrest at the world's largest volcanoes. This article is part of the Theo Murphy meeting issue 'Magma reservoir architecture and dynamics'.

Volcanology. The Yellowstone magmatic system from the mantle plume to the upper crust

The Yellowstone supervolcano is one of the largest active continental silicic volcanic fields in the world. An understanding of its properties is key to enhancing our knowledge of volcanic mechanisms and corresponding risk. Using a joint local and teleseismic earthquake P-wave seismic inversion, we revealed a basaltic lower-crustal magma body that provides a magmatic link between the Yellowstone mantle plume and the previously imaged upper-crustal magma reservoir. This lower-crustal magma body has a volume of 46,000 cubic kilometers, ~4.5 times that of the upper-crustal magma reservoir, and contains a melt fraction of ~2%. These estimates are critical to understanding the evolution of bimodal basaltic-rhyolitic volcanism, explaining the magnitude of CO2 discharge, and constraining dynamic models of the magmatic system for volcanic hazard assessment.

Sombrero uplift above the Altiplano-Puna Magma Body: evidence of a ballooning mid-crustal diapir

The Altiplano-Puna ultralow-velocity zone in the central Andes, South America, is the largest active magma body in Earth's continental crust. Space geodetic observations reported an uplift in the Altiplano-Puna proper at a rate of ~10 mm/year; however, the nature of the inferred inflation source has been uncertain. We present data showing that the uplift has persisted at a nearly constant rate over the past two decades, and is surrounded by a broad zone of subsidence. We show that the ongoing uplift and peripheral subsidence may result from a large mid-crustal diapir fed by partial melt from the Altiplano-Puna Magma Body.