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| Titel |
Continuous recording of seismic signals in Alpine permafrost |
| VerfasserIn |
Helmut Hausmann, K. Krainer, M. Staudinger, E. Brückl |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250028309
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| Zusammenfassung |
| Over the past years various geophysical methods were applied to study the internal structure
and the temporal variation of permafrost whereof seismic is of importance. For most seismic
investigations in Alpine permafrost 24-channel equipment in combination with long data and
trigger cables is used. Due to the harsh environment source and geophone layouts are
often limited to 2D profiles. With prospect for future 3D-layouts we introduce an
alternative of seismic equipment that can be used for several applications in Alpine
permafrost.
This study is focussed on controlled and natural source seismic experiments
in Alpine permafrost using continuous data recording. With recent data from an
ongoing project (“Permafrost in Austria”) we will highlight the potential of the
used seismic equipment for three applications: (a) seismic permafrost mapping of
unconsolidated sediments, (b) seismic tomography in rock mass, and (c) passive seismic
monitoring of rock falls. Single recording units (REFTEK 130, 6 channels) are used
to continuously record the waveforms of both the seismic signals and a trigger
signal. The combination of a small number of recording units with different types of
geophones or a trigger allow numerous applications in Alpine permafrost with
regard to a high efficiency and flexible seismic layouts (2D, 3D, 4D). The efficiency
of the light and robust seismic equipment is achieved by the simple acquisition
and the flexible and fast deployment of the (omni-directional) geophones. Further
advantages are short (data and trigger) cables and the prevention of trigger errors. The
processing of the data is aided by ‘Seismon’ which is an open source software
project based on Matlab® and MySQL (see SM1.0). For active-source experiments
automatic stacking of the seismic signals is implemented. For passive data a program
for automatic detection of events (e.g. rock falls) is available which allows event
localization.
In summer 2008 the seismic equipment was used for the three different types of
applications. It enabled fast and efficient field work and provided excellent seismic data at
two permafrost sites. At Krummgampen Valley (Ötztal Alps, Tyrol) 13 seismic profiles were
measured at altitudes ranging from 2400 to 2900 m to assess information on the permafrost
occurrences. At the crest of Hoher Sonnblick (3106 m, Hohe Tauern, Salzburg) seismic
signals were recorded on 15 borehole geophones deployed in three 20 m deep boreholes
for the application of seismic tomography and passive monitoring of rock falls. |
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