2 research outputs found
Comprehensive investigation of intact, vulnerable stalagmites to estimate an upper limit on prehistoric ground acceleration
Non-intrusive in situ measurements were carried
out in caves in Hungary, Bulgaria and Slovakia in
order to determine the fundamental frequencies (FF)
and horizontal ground accelerations (HGA) resulting in
failure of intact, slim, vulnerable stalagmites. Similar investigations are planned in Austria at the Eastern Alps.
The main steps of investigation are: 1) FF of intact stalagmites were determined by in situ observation. 2)
Density, Young’s modulus and tensile fa
ilure stress of broken stalagmites ha
ve been measured in mechanical
laboratory. 3) The value of HGA resulting in failure
and FF of stalagmite were assessed by theoretical
calculations. 4) Age determination of co
re-samples. The upper limit for HGA, a
g
, for slim stalagmites
determined by theoretical calculations,
can arise even for moderate-sized eart
hquakes. The FF of the investigated
stalagmites are low. The geological stru
ctures close to the investigated caves did not excite paleoearthquakes in
the determined time period, corresponding to HGA larger than the determined a
g
values
A Kárpát-medence jelenkori és paleorengéseinek komplex vizsgálata = Integrated study of recent earthquakes and paleoerthquakes in the Carpathian basin
Három feladatot jelöltĂĽnk meg, amelyeket a 4 Ă©ves kutatás folyamán meg kĂvánunk oldani: 1. Kárpát-medencĂ©ben Ă©s a hozzá hasonlĂł földtani felĂ©pĂtĂ©sű tĂ©rsĂ©gekben keletkezett földrengĂ©sek lehetsĂ©ges okainak tisztázása. 2. TörtĂ©nelmi Ă©s paleorengĂ©sekre kutatása. 3. A földrengĂ©sekre vonatkozĂł ismeretanyag rendszerezĂ©se Ă©s számĂtĂłgĂ©pes adatbázisának elkĂ©szĂtĂ©se. RĂ©szletesebben: 1. Ă–sszegyűjtöttĂĽk Ă©s tĂ©rinformatikai rendszerbe illesztettĂĽk a földrengĂ©sekkel kapcsolatba hozhatĂł geolĂłgiai Ă©s geofizikai tĂ©rkĂ©pi adatokat. TĂ©rinformatikai elemzĂ©seket vĂ©getĂĽnk a rendszer rĂ©tegei között, mely alapján bebizonyosodott, hogy a magyarországi rengĂ©sek összessĂ©ge nem magyarázhatĂł ismert tektonikus szerkezetek mentĂ©n bekövetkezĹ‘ elmozdulásokkal. 2. A Baradla-barlangban találhatĂł, 5.1 m magas sztalagmitot az elmĂşlt 100 e Ă©v folyamán 1.14 m/s2-nĂ©l nagyobb horizontális gyorsulás nem gerjesztette. Ezt a horizontális gyorsulásĂ©rtĂ©ket figyelembe kell venni minden, erre a terĂĽletre vonatkozĂł földrengĂ©sveszĂ©lyeztetettsĂ©gi számĂtásnál. PaleorengĂ©s-vizsgálatainkat kiterjesztettĂĽk Bulgáriában találhatĂł cseppkövekre is. 3. ElkĂ©szĂĽlt a törtĂ©nelmi földrengĂ©sek Microsoft Access adatbázisa. Az adatbázis nyolc csatlakozĂł táblázatot tartalmaz. Az adatbázis kĂ©rdĹ‘Ăveinek formátuma az adatbevitelt egyszerűvĂ© teszi. | Comprehensive investigation of recent and paleoearthquake occurred in the Carpathian Basin 1. Examination the geological structures of the potential earthquake sources: A Geoinformation System (GIS) has come into existence in order to investigate the geological and geophysical surroundings of earth tremors applying ArcView 3.2 software. Analyses between different layers of the GIS were carried out. 2. Research of kinetic behaviours of stalagmites exited by horizontal acceleration. Determination of largest paleoearthquake occurred during the lifetime of investigated speleothems: From the parameters of not damaged speleothems (in the HajnĂłczy and Baradla caves in Hungary) can be determine the upper limit of peak horizontal acceleration generated by paleoearthquakes during their formation. In the laboratory the velocity of elastic waves, density and failure tensile stress of speleothem samples have been determined. The fundamental frequency and damping of speleothems have been measured in cavity. We took samples from dripstones of 5.1 m heigth in Baradla cave and determined their age. It was established that these speleothems were not excited with a horizontal acceleration more than 1.14 m/s2 during the last 100 000 years. 3. Database of historical earthquakes occurred in Hungary: The aim of this work was the systematisation of our knowledge about the historical earthquakes of Hungary and to introduce them into a database