The eruption of Iceland's Eyjafjallajökull volcano in 2010 left millions of travellers stranded and cost airlines an estimated €900 million. It was a wake-up call to the world that communities don't need to be perched on the side of a volcano to be profoundly affected by its activity. Geophysicist Dr Juliet Biggs is one of many scientists responding to that wake-up call.
She and her colleagues in the School of Earth Sciences are using radar satellite imagery to look at deformations in the Earth’s surface caused by underground magma flow and seismic activity – signs of volcanic unrest. The research could help establish a global monitoring system for volcanoes, which would help provide advance warning of eruption, particularly for the majority of the world’s volcanoes that are left unmonitored.
There are about 1,500 volcanoes in the world and only 100 volcano observatories. Installing ground-based monitoring equipment isn’t always possible due to the geographical remoteness of the volcano or the political climate of the region and priority is often given to volcanoes with nearby communities. However, the Iceland events illustrated the large extent of disruption that an eruption can have, and demonstrated the risk posed by leaving all these volcanoes unmonitored.
“I’ve been working recently in Ethiopia and Kenya on volcanoes that are not monitored at all, yet are showing signs of unrest,” said Biggs. “These volcanoes have no eruptive history and no hazard assessments have been done, yet they could seriously disrupt cities such as Addis Ababa and Nairobi – populations that are very vulnerable to disasters.”
Biggs and her colleagues have placed ground-based monitoring equipment on these volcanoes so that they can collect data to compare with the satellite imagery. This will help them understand the geophysical processes behind the deformation signals. Satellite technology is already used to remotely monitor erupting volcanoes and for early detection of eruption plumes, but it is not yet used operationally as a monitoring tool for identifying signs of unrest.
Typically, before a volcano erupts it will start to inflate, have a number of little earthquakes and start to release gases. This activity causes the Earth’s surface to move up and down. By comparing two radar satellite images taken at different times, Biggs can measure these deformations in the Earth’s surface and track how they change over time.
The satellites collect data from points on an imaginary grid covering the Earth’s surface with each of those points spaced about 90 meters apart. The satellite will collect data from each of those points every 35 days or so, providing a considerable amount of data to be managed and analysed. Currently, analysis is possible at the scale of whole countries, but in order to consider monitoring at a global scale, the analysis will need to be scaled up and automated.
However, one of the challenges that Biggs has had is that many of the radar satellites have come out of operation or have had limited life spans. Investing the time and money to scale up the data management and analysis systems has not been worthwhile with satellites being operational for only a couple of years. However, the launch of the multi-satellite project, Sentinel, offers new hope in terms of data acquisition. The first Sentinel satellite is scheduled to be launched by theEuropean Space Agency at the end of this year with a commitment to collect data every six days over the next twenty years.
I’ve been working recently in Ethiopia and Kenya on volcanoes that are not monitored at all, yet are showing signs of unrest. These volcanoes have no eruptive history and no hazard assessments have been done, yet they could seriously disrupt cities such as Addis Ababa and Nairobi – populations that are very vulnerable to disasters.
But Biggs and her colleagues aren’t waiting for the launch of Sentinel to start watching the world’s forgotten volcanoes. In 2006, Biggs picked up some deformation signals in a volcano in Ecuador that wasn’t being monitored. She contacted the observatory who sent someone out to assess the situation: “When they got there they found a seismometer that had been placed there about 30 years ago and was still working. They downloaded the data and found that there had been a high number of long-period events, which are an indicator that magma is really moving.”
In fact, the volcano was showing more activity than Tungurahua, which has been erupting regularly since 1999, with major eruptions in 2006, 2008, 2010, 2011 and 2012: “Right now much of our work is retrospective. I saw the signal in Ecuador in 2006 and informed the Ecuadorian observatory in 2008. However, in the future we want to be able to monitor in real time and make it globally available for all volcanoes.”
Key facts:
- The Sentinel satellites, being developed for Europe’s Global Monitoring for Environment and Security programme, are due to be released in 2013 and are expected to acquire data every six days over the next twenty years. The satellite data is provided by the European Space Agency through the Changing Earth Science Network. Radar satellite can see through cloud cover, making it particularly useful for monitoring tropical volcanoes where the summits are frequently covered by cloud.
- Dr Juliet Biggs holds a New Investigator’s Grant and a Small Grant and is part of COMET+, the National Centre for Earth Observation and the STREVA (Strengthening Resilience in Volcanic Areas) project funded by the NERC/ESRC Increasing Resilience to Natural Hazards Programme.