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
The GPS network
The Global Positioning System (GPS) has also been applied on Nisyros for the surveillance of the Kos - Yali - Nisyros - Tilos volcanic field. Since Nisyros is a small island, an accuracy of ±5 mm for the horizontal, and ±10 mm for the vertical direction is expected.
Fig.18 GPS Network for the Nisyros Volcano surveillance.
National Kapodistrian University of Athens (Greece), Department of Geophysics
and Geothermics (NKUA)
A geodetic GPS network consisting of 17 stations was established in the area
in June 1997. Fifteen of these were established on Nisyros and two on Kos (Fig.
17 and 18). The settlement of the GPS stations in Nisyros was principally based
on the need for a homogeneous coverage.
Magma Chamber Inflation/Deflation Processes - The Mogi Point Source Model
In active volcanic environments, a magma chamber inflation/deflation process
model is usually applied to the data. The “Mogi” point source model,
which is based on an elastically expanded point source in a half space (called
a “Mogi point source”), usually serves to explain the observed deformation
in such cases. In the case of Nisyros, the "Mogi model" was applied
in order to explain the observed deformation deduced by DGPS measurements (Fig.
The Mogi (red) arrows are expected to point radially outwards from the Mogi source (Fig. 19). It was found that the calculated Mogi displacements for the horizontal component (red arrows) seemed to generally fit quite well the observed displacements (black arrows) in the southern part of the island.
Fig. 19 The Horizontal deformation is represented with the
arrows, while the vertical displacement is presented with colour contouring.
National Kapodistrian University of Athens (NKUA)
When using the year 1997 as the reference point, the shape of the ground deformation
does not significantly change, indicating an "opening up" of the island
along the two major faulting zones F1 and F2. The deformation at the NE half
of the island was almost to ESE, turning progressively to the SE at its southern
Taking into consideration the tectonic structure of the sub-marine area north
of Nisyros, the presence of major faulting zones north of Nisyros and south
of Yali island, and the concentration of shallow seismic activity in that area,
a second Mogi point source was finally adopted.
created by geopublic
|© 2003 eth zürich||Legal Disclaimer|