Understanding the connectivity and migration of shallow magma

Volcanic eruptions present risks to human life and welfare, especially in rapidly growing urban areas. Detecting the rhythms and cycles of magma movement beneath a volcano is crucial to understanding their future behaviour.

Magma - the molten rock that builds the Earth's crust and feeds volcanoes - spends most of its existence as part of a 'mush' zone under the surface, comprising a complicated mixture of crystals, liquid molten rock and volcanic gases. We know from investigating patterns in the texture and composition of volcanic rocks, that fluids can move through mushes, especially in the periods before and during eruptions. This process is important because it allows the accumulation of the type of mobile magma that reaches the Earth's surface during eruptions. However, we do not know exactly what effects this movement produces at the Earth's surface where we are best positioned to detect them.

Measuring tiny movements of the Earth's surface is an important way of assessing how active a volcano is, and is widely used by volcano observatories to forecast eruptions. My research uses satellite data to make these measurements over very large areas. A particularly exciting aspect of this is that I can make displacement measurements globally and in poor and inaccessible regions where there is no or limited instrumentation installed on the ground. I and my colleagues have found an increasing number of examples of subsidence (caused by volume loss under the surface) and uplift (volume gain) occurring within a short time interval, but at a distance of many kilometres apart. These observations provide unique pieces of information about the time and distance over which magma travels underground that I will use to develop new models for interpreting displacement measurements. I will use these models to determine what displacements measured from satellites look like when magma is accumulating before a volcanic eruption.

This project contributes to the long-term goal of increasing resilience to volcanic hazard in cities at risk from volcanic eruptions. I will achieve this by developing a framework for better interpretation of surface displacements in terms of magmatic processes that can be incorporated into decision-making. The ultimate beneficiaries of developing these approaches will be people living in areas with high levels of volcanic hazard and high risk of volcanic impacts. To achieve this, the direct impact of this work must be with the organisations responsible for volcano monitoring and hazard assessment: volcano observatories, civil protection and local authorities.

Context: There are an estimated 800 million people who today live within 100km radius of a volcano with potential for eruption. A large proportion of these people live in low to middle income countries with increased vulnerability to such geohazards. Volcanic hazards cause loss of life and livelihood, and present barriers to development including displaced populations, environmental damage, disrupted business and infrastructure. The uncertainty associated with long duration volcanic unrest also prevents investment. Forecasting the occurrence and characteristics of volcanic eruptions is essential for mitigating societal and economic impacts.

My contribution: My proposal will transform the way we interpret displacement measurements at volcanoes. This will result in more physically realistic assessments of eruptible magma in the shallow crust, and an improved understanding of which magmatic processes are detectable and useful for forecasting. Satellite data provide a powerful, lower cost and safer alternative to building and maintaining ground-based monitoring networks. Specific impacts will involve:

- Volcano observatory staff. A primary outcome of my fellowship proposal will be the practical improvement to the interpretation of monitoring data, which will have an impact on volcano monitoring practise, including in poorer countries where investment in geophysical monitoring has historically been low. In the short term the immediate beneficiaries of my proposal will be the scientists at monitoring organisations associated with my case study areas, including in New Zealand (GNS), Ecuador (Instituto Geofisico), Ethiopia (University of Addis Ababa) and Papua New Guinea (Rabaul Volcano Observatory). In the longer term, the framework for interpreting volcanic deformation produced during this fellowship will provide benefits to a wider range of monitoring organisations around the world.

- Civil protection and Disaster Risk Reduction practitioners. Advances in monitoring methodology and data interpretation at volcano observatories have a secondary impact on decision makers with responsibilities for mitigating hazard and risk. My research has the potential to provide improved interpretations in particular of volcanoes that deformation continuously or episodically during unrest.