Büyük Depremlerle İlişkili Öncül Kabuk Hareketleri

Yıl 1992, Cilt: 16 Sayı: 2, 109 - 117, 15.11.1992

Hayrettin Koral

Öz

Büyük depremler öncesi anormal kabuk hareketlerinin var olduğu bilinmektedir. Japonya’daki Kanto (1930; M=6.9), Niigate (1964; M=7.0), İzo-Oshima (1978, M=6.8), Çindeki Tangshan (1976, M=7.8), Haicheng (1976; M=8) ve Songpan (1976; M=7.2) depremleri öncesi görülen kabuk hareketleri bunların güzel örneklerinden birkaçıdır. Benzer hareketler Güney Kaliforniyada da gözlenmiştir. Deneysel çalışmalar, kayaların deformasyon etkisiyle elastik ve elastik olmayan hacim büyümesine maruz kaldıklarını göstermiştir. Sismik bölgelerde gözlenen gravite azalması, kaynak su boşalımları ve radon gazı kaçaklarındaki artışlarda kayaların bir tür hacim büyümesine uğradıklarını göstermektedir. Bu nedenle öncül kabuk hareketleri kayalardaki hacim büyümesinin yüzeysel ifadesi olarak değerlendirilebilirler.

Anahtar Kelimeler

Deprem, Öncül Kabuk Hareketleri, Sismik

Precursory Crustal Movements Associated with Major Earthquakes

Öz

A history of anomolous crustal motion precedes major earthquakes. Crustal movements prior to the Kanto (1930; M = 6.9), Nigate (1964; M = 7.0) and Izu-Oshima (1978; M = 6.8) earthquakes in Japan and the Tangshan (1976; M = 7.8), Haicheng (1976; M = 8.0) and Songpan (1976; M = 7.2) erathquakes in China are only a few examples. Similar movements have also been reported in Southern California. Experimental studies suggest rock deformation under simulated crustal conditions produces a combination of elastic and inelastic volume dilatancy. Field evidence for gravity decrease, water expulsion and radon emission in seismic regions suggests a mode of volume dilatancy occur during precursory stages of major earthquakes. Preseismic crustal movements can therefore be interpreted as surficial expressions of volume dilatancy at subcrustal levels in a 'slip-deficient seismic zone.

Anahtar Kelimeler

Earthquake, Precursor Crustal Movements, Seismic

Kaynakça

• Areshidze, G.F., Bella, P.F., Biagi, M., Caputo, V., Chkuaseli, G., Della Monica, A., Ermini, P., Mandjgaladze, G., Melikadze, V., Sgrigna, L., Slavina and D. Zilpimiani, 1992, Anomalies in geophysical and geochemical parameters revealed on the occasion of the Paravani (M = 5.6) and Spitak (M = 6.9) earthquakes (Caucaus), Tectonophysics, 202, 23-41.
• Aytun, A., 1972, Bingöl depremi raporu, İmar İskân Bakanlığı, 80 s.
• Brace, W.F., B.W. Paulding and C. Scholz, 1966, Dilatancy in the fracture of crystalline rocks, J. Geophysical Res., 71, 3939-3952.
• Brace, W.F., 1978, Volume changes during fracture and frictional sliding: a review, Pure Appl. Geophys., 116, 603-614.
• Castle, R.O., J.P. Church and M.R. Elliot, 1976, Aseismic uplift in Southern California, Science, 192, 251-253.
• Crampin, S., Evans, R. and Atkinson, B.Kb., 1984, Earthquake prediction: a new physical basis, Geophys. J.R. Astr. Soc., 76, 147-156.
• Dambara, T., 1973, Vertical movements before some inland earthquakes in Japan presented at US-Japan Conference, earthquake prediction and control, 1973, Boulder, Colorado.
• Dambara, T., Geodesy and earthquake prediction, 1981, in Current Research in Earthquake Prediction I, edited by T. Rikitake, Center for Academic Publications, Japan/D. Reidel Publishing Compang, Tokyo, 167-220.
• Earthquake Research Institute, 1980, Seismic activity in the Izu Peninsula and its vicinity (November, 1979-April, 1980). Rep. Coord. Comm. Earthquke Prediction, 24, 108-112, (in Japanese).
• Evans, R., 1984, Anisotropy: a pervasive feature of fault zones? Geophys. J.R. Astr. Soc., 76, 157-163.
• Fyfe, W.S., Price N.J. and Thompson, A.B., 1978, Fluids in the Earth’s Crust, Elsevier, Amsterdam.
• Hagiwara, Y., Tajima H. and Hanada, H., 1978, Gravity changes in the eastern part of Izu Peninsula during 1975-1976, J. Geod. Soc. Japan, 22, 201-209.
• Hauksson, E., 1981, Radon content of groundwater as an earthquake precursor: evaluation of world-wide data physical basis, J. Geophys. Res., 86, 9397-9410.
• McGarr, A. and Ga, N.C., 1978, State of stress in the earth's crust, Ann. Rev. Earth Planet Sei., 6, 405-436.
• McGarr, A., 1980, Some constrains on levels of shear stress in the crust from observations and theory, J. Geophys. Res., 85, 6185- 6222.
• Mogi, K., 1977-, Dilatancy of rocks under general triaxial stress states with special reference to erathquake precursors, J. Phys. Earth, 25, supp., S203-S217.
• Mogi, K., Oyagi, N., 1991, Prediction and prevention of geological hazards, Episodes, 293- 298.
• Nur, A., 1974, Matsushiro, Japan, earthquake swarm: confirmation of the Dilatancy Diffusion Model, Geology, 217-221.
• Nur, A., 1975, A note on the Constitutive law for Dilatancy, Pure Appl. Geophys., 113, 197- 206.
• Raleigh, B„ Bennet, G., Craig, H„ Hanks, T„ Molnar, P„ Nur, A., Savcage, J., Scholz, C, Turner, R. and Wu, F., 1977, Prediction of the Haicheng earthquake, EOS, 58, 236-272.
• Savage, J.C., Prescott, W.H., Lisowski, M. and King, N.E., 1977, Strain accumulation in southern California, 1973-1980, J. Geophys. Res., 86, 6991-7001.
• Sibson, R.H., McMoore, J. and Rankin, A.H., 1975, Seismic pumping a hydrothermal fluid transport mechanism, J. Geol. Soc. London, 131, 653-659.
• Sibson, R.H., 1981, Fluid flow accompanying faulting: field evidence and models, in Earthquake Prediction, Maurice Ewing Ser., vol. 4, edited by D.W. Simpson and R.G. Richards, 593-603, AGU Washington D.C.,
• Sibson, R.H., 1983, Fault zone models, heat flow and depth distribution of earthquakes in the continental crust of the United States, Bull. Seism. Soc. Am., 73, 152-163.
• Scholz, C.H., Sykes, L.R. and Aggarwal, Y.P., 1973, Earthquake prediction-a physical basis, Science, 181, 803-810.
• Thatcher, W., 1981, Crustal deformation studies and earthquake prediction research, in Earthquake Prediction, Maurice Ewing Ser., vol. 4, edited by D.W. Simpson and R.G. Richard, 394-410, AGU, Washington, D.C.,
• Walsh, J.B., 1975, An Analysis of Local Changes in Gravity due to Deformation, Pure Appl. Geophys., 113, 97-106.
• Wessson, R.L. and Wallace, R.E., 1985, Predicting the next great earthquake in California, Scientific American, 252, 35-43.
• Wilkins, J.S., 1980, Slow crack growth and delayed failure of granite, Abstr. Int. J. Rock Mech. Min. Sei. Geomech., 17, 365-369.
• Zhang, G., 1979, The study of creep along the fault near Tangshan before the Tangshan earthquake, in Research in Earthquake Sciences, 1, Seismology Press, 51-52.
• Zhang, G. and Fu, Z., 1981, Some features of medium and a short-term anomalies before great earthquakes, in Earthquake Prediction, Maurice Ewing Ser., Vol. 4, edited by D.W. Simpson and R.G. Richards, 497-509, AGU, Washington D.C..