Index Geophysics

hrv Prijedlog da se u Zagrebu i okolici uz CROPOS-ove stanice postavi i nekoliko GPS (GNSS)-permanentnih stanica za geodinamiku i moguću najavu većeg potresa u sljedećem vremenskom razdoblju

eng 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

hrv U uvodu je ukratko opisano kako su Japanci 2000. godine izgradili mrežu od čak 1200 GPS (GNSS)-permanentnih stanica. U kontrolnom centru primaju se svi podaci mjerenja, obrađuju i određuju srednje dnevne koordinate položaja X, Y i Z stanica, kako bi se odredilo pomicanje Zemljine kore. Prof. S. Murai i H. Araki patentirali su pronalaženje GPS-signala prije potresa pomoću računanja promjena površina trokuta u vrhovima kojih su GPS-stanice. Za 162 potresa veća od magnitude 6. stupnja po Richteru u Japanu su dobili prethodni GPS-signal za potres od jednog do 90 dana prije potresa. U drugom poglavlju opisan je pozicijski sustav CROPOS u Hrvatskoj, koji je uspostavljen 2008. godine. U njemu se nalazi 30 permanentnih GPS-stanica, a uz naknadnu obradu GPS-podataka pomoću Bernese GPS-softvera verzija 5.0 postiže se visoka preciznost određivanja koordinata točaka na milimetar. Slični pozicijski sustav AGROS u Srbiji, koji također ima 30 GPS (GNSS)-stanica, radio je i kad se dogodio potres magnitude 5,4 stupnja po Richteru 3.11.2010. u okolici Kraljeva. S. Đalović i J. Škrnjug obradili su podatke mjerenja 6 dana prije i 4 dana nakon potresa s Bernese GPS-softverom verzija 5.0. Rezultate promjena duljina objavili su u tablicama, a kad smo te rezultate prikazali grafički pronašli smo prethodni GPS-signal za potres 2 dana prije potresa. To znači da GPS-mjerenja daju novu kvalitetu, jer mjerenja seizmografima daju informaciju o potresima tla, a GPS-mjerenja određuju promjene udaljenosti između GPS-točaka. Tako obični seizmografi slabo određuju vrlo spore linearne pomake zemljine kore, koji nisu potresi, a GPS-prijamnici to mogu. Zato očekujemo da će se i GPS-stanice iz CROPOS-a moći koristiti u geodinamici, a i seizmologiji. Zatim se predlaže da se u Zagrebu s okolicom uz CROPOS-ove stanice postavi oko 10 novih dobro stabiliziranih GPS-stanica. Podaci mjerenja skupljali bi se i obrađivali s najnovijom verzijom Bernese GPS-softvera u CROPOS-ovu kontrolnom centru, a zatim i računale dnevne promjene udaljenosti između GPS-točaka koje mogu dati prethodni GPS-signal o potresu, prije potresa. Naravno, tu bi metodu trebalo kombinirati s drugim postojećim geofizičkim metodama. Konačnu odluku o najavi prethodnoga GPS-signala za potres dali bi seizmotektoničari, koji imaju i svoja mjerenja na rasjedima. To bi bilo bolje nego da se određuju automatski prema grubim pogreškama mjerenja, jer Zemlja nije kruta. Kad se ta metoda uhoda u Zagrebu s okolicom, ona bi se mogla proširiti na Dubrovnik, Split i Rijeku, kao i u susjednim zemljama. Vjerujemo da bi se za taj projekt mogla dobiti financijska potpora od Europske Unije.

eng 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.

Solarić, Nikola

Solarić, Miljenko

hrv seizmografi; GPS; GNSS; permanentne GPS-stanice; CROPOS-ov pozicijski sustav; AGROS-ov pozicijski sustav; najava potresa

eng seismographs; GPS; GNSS; permanent GPS stations; CROPOS positioning system; AGROS positioning system; earthquake announcement

Croatian geodetic society

2012

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https://hrcak.srce.hr/95827

hrv https://hrcak.srce.hr/file/141118

Geodetski list

ISSN 0016-710X (Print)

ISSN 1849-0611 (Online)

Volume 66 (89)

Issue 3

hrv

info:eu-repo/semantics/openAccess

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