Geospatial warning systems
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Project > Methodologies > Oceanographic and Geophysical Surveys
Oceanographic and Geophysical Surveys
The Ocean Floor Mapping System Using Sea Beam
Seismic Activity and Monitoring within the Kos - Yali - Nisyros - Tilos Volcanic Field
The seismic activity in the south-easternmost part of the Aegean Volcanic Arc is very high, both at shallow and at intermediate focal depths. Figure 3 shows the epicenter distribution of the earthquakes with surface magnitude Ms>4.0 for the time period 1900-2000; data are taken from the monthly Bulletin of the Institute of Geodynamics of the National Observatory of Athens.
Fig. 15 Seismic activity within the Kos-Yali-Nisyros-Tilos
volcanic field during the period 1900 - 2000 (earthquakes with surface magnitudes
MS>4). National Observatory of Athens, Institute of Geodynamics (NOAIG)
In 1995, significant seismic activity began in the area surrounding Nisyros
island. Specifically, on August 22, 1995, a moderate offshore earthquake of
magnitude M=5.3 occurred at a distance of about 40 km west of the island, at
a focal depth of 165 km.
The microseismic activity in that region was monitored by a dense digital portable
network consisting of 22 three-component onshore stations. Numerous micro-earthquakes
(M<3) were recorded. Most of the hypocenters have shallow depths (<15
km) and are distributed in the marine environment between Nisyros and Kos.
Several significant observations and interpretations can be made on the basis of the spatial distribution of the micro-seismic foci:
1) Very weak micro-earthquakes at shallow crustal depth are concentrated around
Nisyros with a general shift towards north and east.
Fig. 16 Focal depth (km), micro-hypocentres (M: 1-3.9) 2000-2001.
(55) total number of events. National Observatory of Athens (NOAIG)
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