北陸地方南部の地殻構造について -手取川ダム砕石発破および琵琶湖発破-

Abstract

Since 1975 several tons of quarry blasts have been detonated many times at Tedori riverin the southern part of Ishikawa Prefecture. On the other hand, in October 1978 fourexplosives were blasted in the northern part of Shiga Prefecture for the purpose of the inves-tigations of the basement of Lake Biwa. The crustal structure along the profile from Tedoririver to Lake Biwa was investigated using the seismic waves generated by those explosions.A gap in travel times about the middle of the profile shows that a granitic layer may bedivided into two parts. At the southern part of the profile a granitic layer is descend northwardwith a dip of 2.3° and the velocity of this layer is 5.85 km/sec. At the northern part thedip angle of a granitic layer is 2.50 and the velocity is 6.05 km/sec.