Geodetski list, Vol. 66 (89) No. 3, 2012.
Izvorni znanstveni članak
Proposal for Setting up in Zagreb and its Surroundings a few GPS (GNSS) Permanent Stations for Geodynamics and Possibility of the Announcement of Larger Earthquake in the Future Period
Nikola Solarić
; Geodetski fakultet Sveučilišta u Zagrebu, Zagreb, Hrvatska
Miljenko Solarić
; Geodetski fakultet Sveučilišta u Zagrebu, Zagreb, Hrvatska
Sažetak
It is described in the introduction how the Japanese established in 2000 the network of even 1200 GPS (GNSS) permanents stations. All measurement data are received in the control centre, where they are also processed and the daily positional coordinates of the stations X, Y and Z determined, with the aim to determine the movements of the Earth's crust in this way. Prof. S. Murai and H. Araki patented the detection of GPS signal before the earthquake by means of computing the changes of the triangle areas which had GPS stations at their vertices. For 162 earthquakes larger than 6.0 magnitudes on the Richter’s scale in Japan, the preceding GPS signal was received before the earthquake of 1 to 90 days. The second chapter describes the positional system CROPOS in Croatia that was established in 2008. There are 30 permanent stations in it, and by means of subsequent processing of GPS data by means of the Bernese GPS software version 5.0, high precision in determining the point coordinates to millimetre is obtained. Similar positioning system AGROS in Serbia has also 30 GPS (GNSS) stations that were in operation at the time of the earthquake measuring 5.4 magnitudes on the Richter's scale on 3.11.2010 in the surroundings of Kraljevo. S. Đalović and J. Škrnjug processed the measurement data 6 days before and 4 days after the earthquake by means of Bernese GPS software version 5.0. The results of length changes between GPS stations were published in the form of numerical tables, and when we these results were presented graphically, the preceding GPS signal for the earthquake was found 2 days before the earthquake. It was explained that the GPS measurements yield new quality because the measurements with seismographs give the information about the ground earthquakes, but GPS measurements determined the changes in distances between GPS points. Hence, normal seismographs determine poorly very slow linear movements of the Earth's crust that are no earthquakes, while GPS receivers can do that. We expect therefore that it will be possible to use also the GPS stations from CROPOS in geodynamics, as well as in seismology. It is furthermore suggested, that 10 new well stabilized GPS station should be set up in Zagreb and its surroundings. The measurement data would be collected and processed by means of the most recent version of Bernese GPS software in CROPOS control centre, and then the daily change of the distances between the GPS points would be computed that can yield the preceding GPS signal, before the earthquake itself. Of course, this method should be combined with other available geophysical methods. The final decision about the announcement of the preceding GPS signal before earthquake would be given by seismotectonic experts that also have the measurements on faults at their disposal. It would be better than to determine them automatic from gross errors of measurement, because the Earth is not solid body. When this method will be organised in Zagreb and its surrounding, it could be possibly extended this method to Dubrovnik, Split and Rijeka, as well as to the neighbouring countries. We believe that this project could get the financial support from the European Union.
Ključne riječi
seismographs; GPS; GNSS; permanent GPS stations; CROPOS positioning system; AGROS positioning system; earthquake announcement
Hrčak ID:
95827
URI
Datum izdavanja:
21.9.2012.
Posjeta: 2.081 *