Ingham, C.E. 1971 Tongariro power development geophysical surveys. 5. Seismic survey: Mangaio tunnel line area. [s.l.]: [s.n.]. Report / Geophysics Division 66 9 p.
Abstract: In order that the water from streams flowing through the Karioi State Forest reserve can be diverted into Lake Moawhango, it has been proposed that an open canal be dug from the Waihianoa River to a point at the foot of a scarp which lies just to the west of the Desert Road, and is a little under half a mile to the north of the Moawhango Dam Site turnoff. From this point the water would enter a vertical drop shaft and then be passed through a more or less horizontal tunnel to a point in the valley of the Mangaio Stream which will be invade by the lake. The tunnel will be about 1300 yards long and its elevation will be close to 2840 ft (Moturiki datum). The purpose of the present survey is to assist with the choice of the most favourable route for the tunnel. Seismic refraction shooting has been carried out and velocity cross-sections have been produced along five lines which are shown on the plan (Fig 1a). Ground surface contours along the canal limit the possible tunnel routes to those low lying between seismic lines A and B and it is assumed that the most favourable route will be that which has the greatest proportion of its length in Tertiary rock. The bulk of the field work was done between the 2nd and the 31st of July 1970. Some additional studies were made in November 1970 (auth)