IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

3P2_2E-O2Room A3

Date/Time: July 23 17:15-17:30

Inventory of gas emission rate measurements from volcanoes of the global Network for
Observation of Volcanic and Atmospheric Change (NOVAC) - present status of thenetwork and some study cases
Bo Galle1 , Santiago Arellano1 , Ulrich Platt2 , Gustavo Garzon3 , Silvana Hidalgo4 , Yalire Mapendano5 ,NOVAC Partners61

Department of Earth and Space Sciences, Chalmers University of Technology, Sweden, 2 Institut furUmweltphysik, University of Heidelberg, Germany, 3 Servicio Geologico Colombiano, Colombia,
4Instituto Geofisico, Escuela Politecnica Nacional, Ecuador, 5 Observatoire Volcanologique de Goma, D.
R. Congo, 6 The NOVAC Team, Global
E-mail: bo.galle@chalmers.se

Measuring the magnitude, intensity and distribution of volcanic gaseous emissions is important for a number ofreasons. On one hand, it provides information on the amount of magma involved in an eruption, as well as on theconditions in the conduit and eruptive vent that determine if magma would erupt explosively or effusively. On theother hand, volcanic gases may have an important impact on the surrounding human and natural environment,
either directly for the case of acid, corrosive or suffocating species; or indirectly, due to their role in atmosphericchemistry, radiative balance and potentially climate on different scales. Despite of its importance, continuous
monitoring of volcanic gases has traditionally not been the major focus of volcanological studies, due mainly totechnological, logistical or economical reasons. This situation is changing in recent years, due to the adventof robust, affordable, automatic remote sensing instruments, like the Scanning Mini-DOAS. This instrument iscapable of measuring the emission rate of SO2 emitted by a volcano by the scanning-DOAS method with sufficientaccuracy to detect passive emission plumes a few km downwind their sources.

NOVAC, the Network for Observation of Volcanic and Atmospheric Change, was initiated in 2005 as a
4.5-years-long project financed by the European Union. Its main purpose was to implement a global network forthe study of volcanic atmospheric plumes and related geophysical phenomena by using the Scanning Mini-DOAS
instrument. Up to 2013, 68 instruments have been installed at 26 volcanoes in Central and South America, Italy,
Democratic Republic of Congo, Reunion Island, Iceland, and Philippines, and efforts are being done to expand thenetwork to other active volcanic zones. NOVAC has been a pioneer initiative in the community of volcanologists,
involving research institutes and volcanological observatories in 18 countries.

We present the results of the batch evaluation of measurements of SO2 gas emission rates carried out
within NOVAC, which for some volcanoes represent a record of more than 7 years of continuous monitoring, withan average of 40 flux measurements every day. The network comprises some of the most strongly degassing
volcanoes in the world, covering a broad range of tectonic settings, levels of unrest, and potential risk. Besides
showing the present status of the global database, the source strengths and statistical distribution of emissions
from the volcanoes in the network, some results of specific studies are presented, including a complete trackingof the recent reactivation of Nevado del Ruiz volcano, the characterization of open-closed degassing regimes ofTungurahua volcano, and the long-term variations of gas emissions from Nyiragongo volcano.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

413