Geospatial warning systems
|Project | GEOWARN Design | Transferability | Final Product | Innovation/Outlook|
Project > Methodologies > Oceanographic and Geophysical Surveys
Oceanographic and Geophysical Surveys
The Ocean Floor Mapping System Using Sea Beam
Sea Floor Seismic Reflection Soundings (Generation of a Local Velocity Model)
Deep seismic soundings and active tomography provided the data needed for developing
a velocity-depth model of the volcanic structure, the crust and the upper mantle.
This could only be achieved by sub-sea floor seismic investigations, which is
a new method used for the first time world-wide.
Ocean Bottom Seismographs (OBS)
The installation of ocean bottom seismographs (OBS) on the sea floor for seismic
recording yielded unique, one of a kind information. Ocean bottom seismographs
(OBS) for this experiment not only correspond to the latest state of the art
but are technologically unique world-wide and allow very accurate active seismic
experiments if deployed in a dense network.
Fig. 8 Ocean bottom seismograph (OBS). GeoPro GmbH Hamburg
Fig. 9 Deployment of OBS from R/V AEGAEO
Fig. 10 Ship tracks of "Wide Aperture Reflection/Refraction
Profiling (WARRP) seismic surveys" and deployment of OBS within the Kos-Yali-Nisyros-Tilos
volcanic field. University of Hamburg (UHIG), GeoPro, NCMR and NOAIG
Wide Aperture Reflection/Refraction Profiling (WARRP)
Three Wide Aperture Reflection/Refraction Profiling (WARRP) seismic surveys
were carried out within the GEOWARN project, using 36 OBS (Ocean Bottom Seismographs)
and 22 seismic land stations on the islands of Astipalea, Kalimnos, Pserimos,
Kos, Nisyros, Tilos, Simi and Rhodos. 7,000 airgun-shots were fired along 8
profiles, along a total length of 1,000 km and covering the area of 120 x 120
km for the purpose of obtaining a 3D tomography model.
Fig. 11 The 49 litre airgun for "Wide Aperture Reflection/Refraction
A total of 42,000 seismograms were recorded. The data recovered form OBS and
land stations were extracted, processed and written in SEG-Y format on DAT tapes.
Fig. 12 Local velocity model down to 15km depth, shown as
a tomographic cross-section of the Kos-Yali-Nisyros volcanic field. University
of Hamburg (UHIG) and GeoPro
Fig. 13 Tomographic cross-section through Nisyros volcanic
island down to 6,000 m. New "Tomographic Software Tool" developed
by the Institute of Cartography, Swiss Federal Institute of Technology Zurich
created by geopublic
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