簡易三成分ひずみ計

Abstract

既設のトンネルなどを利用して地殻ひずみの多点観測を行う目的で比較的設置の簡単な短スパンひずみ計の試作を行った。これまでに逢坂山観測所観測坑道内に設置した一成分の短スパンひずみ計により潮汐変動や地震波が観測できることが確認されたので，今回はさらに三成分による簡易短スパンひずみ計を試作し，前回と同じ逢坂山観測所のより堅固な岩盤内に設置して観測を行い従来の長スパンひずみ計による観測記録との比較を行った。約3 ヶ月間の短スパンひずみ計による観測の結果，潮汐変動および遠地地震の波動が記録され，長スパンひずみ計の観測結果と良い一致を示した。

We made a trial manufacture of a improved short span strainmeter with three components by using a mechanical magnification system. The cylinder of the short span strainmeter was installed into hard rock deeper than before at Osakayama Observatory. The orientations of the short span strainmeter with three components were N38E(SpE3), N52W(SpE1) and N83W(SpE2). The N38E(SpE3) and N52W(SpE1) were at the same orientation as the long span strainmeter E3 in the tunnel and E1 which is perpendicular to the tunnel direction. But, unfortunately, the N83W(SpE2) was different, 90 degrees from the long span strainmeter E2 with N07W. The tidal changes and long changes obtaining by SpE1 components of the short span strainmeter correspond to those of the E1 long span strainmeters. And the strain seismographs of the earthquake with M7.1 2006/04/20 in Koryaka, Russia, the SpE1 and E1 show the clear correspondence in relative amplitude and phase.