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FP5

MULTIMO Report Summary

Project ID: EVG1-CT-2000-00021
Funded under: FP5-EESD
Country: Spain

Real time analysis of volcanic data

Generically, volcanic process belongs to the class of far from equilibrium systems, characterized by a slow increase of mass/energy, at a variable rate, that is suddenly released. This release defines what is known as volcanic eruption that can be associated to a phase change. Previous to the eruption, volcanic processes undergo a self organizing process, giving rise to geometrical and dynamical structures that should manifest as observables. These observables and its time variations would manifest as precursory phenomena. A possible precursory activity, always present in volcanic processes, but not always preceding an eruption, is provided by volcanic tremors.

It has previously been shown that the influence of the medium properties in the information provided by a seismogram, and as a consequence a routine interpretation of spectral peaks in terms of linear models, could be misleading.

We have worked out this problem in two directions:
- A method has been devised to compute the (scattering) medium response in terms of oscillators and

- By constructing a phenomenological model able to capture the characteristics of observations in both frequency and phase space domains.

As the appearance of precursors is a dynamic process, any possible candidate has to be continuously measured, or, in other words, it has to be monitored and analysed in Real Time or in Quasi Real Time. A procedure for Real-Time analysis for any kind of continuous sequential time series has been developed.

The hardware system has been tested in live seismic servers and it is based on the implementation of diverse algorithms run using the ordinary cron facilities of Linux based systems. The diverse algorithms have been tested a posteriori using data recorded in several volcanoes.

In addition, the system has revealed as a very important tool to monitor not only incidences induced by volcanic activity but also any incidence related to malfunctioning. As a complement of the real time evolution of any parameter, suitable to be studied in Real-Time, a continuous comparison of the amplitudes of every spectral component has been also done.

The application of this methodology can characterize several aspects of the current status. On one hand, the spectral levels in absence of transitory signals are clearly determined and, on the other hand, the identification of ranges of frequencies and reflected activity are emphasized.

Related information

Reported by

Universitat de Barcelona
Marti Franques 1
08028 Barcelona
Spain
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