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New Insights into Composition of Volcanic Products at Mt. Etna, Italy, from Geochemical Pattern Classification
Author(s)
Type
Poster session
Language
English
Obiettivo Specifico
1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
Status
Published
Conference Name
Issued date
May 31, 2010
Conference Location
Puerto de la Cruz,Tenerife, Canary Islands, Spain
Alternative Location
Abstract
Geochemical analyses of volcanic products erupted by
Mt. Etna, Italy, have been carried out by INGV-CT (formerly
CNR-IIV) staff since three decades. The need to
realize a near-real time monitoring of the basic compositional
features of a magma compelled since the 1990s
an organization of personnel engaged for sampling and
analyzing the collected rocks in laboratories. Geochemical
monitoring has been outstandingly improved with
the application of sophisticated, but quick, analytical
techniques which take into account both oxides as well
as trace elements of lavas. The geochemical monitoring
offers up-to-date information on processes and dynamics
of magma, and allows documenting the evolution of
different eruptive styles throughout an eruptive event.
Accordingly, changes in chemical parameters have become
a key information for the Italian Civil Defence to
highlight any hazardous evolution of volcanic activity at
Etna, and promptly warn potential endangered populations.
Compared to traditional classification methods,
where compositional patterns are defined by selecting
oxides and/or elements in binary and ternary petrologic
systems, we can handle a statistics with many components,
in our specific case thirteen (SiO2, K2O, CaO/
Al2O3, Mg, Th, La, Nb, Nd, Sr, Tb, Cr, Ni, Rb/Nb). The
statistical treatment of geochemical patterns exploits
Kohonen Maps and Fuzzy Clustering, which are applied
to samples collected at Etna between 1995 and 2005.
We present a comprehensive picture of the evolution
of these products in time and space with a convenient
visualization of the results. The application of multivariate
classification allows us to identify a signature in the
compositional characteristics of magma erupted from
the four summit craters and/or flank eruptive vents,
even in the time spans in which volcanic activity was
concurrent. Dubious compositional changes are also
considered in the light of earthquakes and volcanic
tremor characteristics, which offer independent evidence
of the significance of the results.
Mt. Etna, Italy, have been carried out by INGV-CT (formerly
CNR-IIV) staff since three decades. The need to
realize a near-real time monitoring of the basic compositional
features of a magma compelled since the 1990s
an organization of personnel engaged for sampling and
analyzing the collected rocks in laboratories. Geochemical
monitoring has been outstandingly improved with
the application of sophisticated, but quick, analytical
techniques which take into account both oxides as well
as trace elements of lavas. The geochemical monitoring
offers up-to-date information on processes and dynamics
of magma, and allows documenting the evolution of
different eruptive styles throughout an eruptive event.
Accordingly, changes in chemical parameters have become
a key information for the Italian Civil Defence to
highlight any hazardous evolution of volcanic activity at
Etna, and promptly warn potential endangered populations.
Compared to traditional classification methods,
where compositional patterns are defined by selecting
oxides and/or elements in binary and ternary petrologic
systems, we can handle a statistics with many components,
in our specific case thirteen (SiO2, K2O, CaO/
Al2O3, Mg, Th, La, Nb, Nd, Sr, Tb, Cr, Ni, Rb/Nb). The
statistical treatment of geochemical patterns exploits
Kohonen Maps and Fuzzy Clustering, which are applied
to samples collected at Etna between 1995 and 2005.
We present a comprehensive picture of the evolution
of these products in time and space with a convenient
visualization of the results. The application of multivariate
classification allows us to identify a signature in the
compositional characteristics of magma erupted from
the four summit craters and/or flank eruptive vents,
even in the time spans in which volcanic activity was
concurrent. Dubious compositional changes are also
considered in the light of earthquakes and volcanic
tremor characteristics, which offer independent evidence
of the significance of the results.
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