"HEAR THE MOUNTAIN?"

Taupo Times, Volume III, Issue 131, 30 July 1954, Page 1

"HEAR THE MOUNTAIN?"

BUT NOT EVERYONE CAN The cleep rumbling sounds, familar to those who live in the Taupo Country as accompaniments of Ngauruhoe's volcanic activity, and which were particularly notieeable on Thursday night, July 15, have an interesting characteristic which they share with the sound-pheno-mena associated with earthquakes. This is that many of them are inaudible to many people not otherwise deaf. Knowledge of this fact may do something to smooth away the domestie arguments that have been not infrequent in Taupo since such remarks as "There's the mountain again!" became common. The vibrations which are perceptible as sound have a wide range of periods, the lowest audible note being produced by about thirty vibrations per second, and the highest by about seventy thousand. Both limits are, however, subject to variation, in different persons as well as in different races. The chief characteristic oi the sound which accompanies an earth-quake is its extraordinary depth. It is almost too low to be heard. It is described as a rumble that can be felt, and many of the noises heard recently in Taupo have been so described. This characteristic earthquake sound is heard by some observers and not by others. To one the sound seems like that of a loud explosion, to another in the same place like distant thunder, to a third there may be no sound audible. While the inaudibility of the earthquake sound to some observers is often attributed to inattention, this explanation obviously fails when the sound appears to some as a cieafening noise or as louder than the loudest thunder. In addition to such sounds accompanying • earthquakes, similar "earth sounds" are known in which sounds alone are observed without the slightest accompanying tremor. Often these occur as part of the after-phenomena of a series of earthquakes, and this was the case in the well-known earthquake series in Taupo in June-December 1922. The "earth sounds" reported recently in Auckland, Te Ngae (near Rotorua), and elsewhere may probably be connected with the activity of Ngauruhoe, either as results of it or, perhaps more probably, as common effects, with it, of other causes deep-seated within the earth. Earth sounds have often been experienced in areas far removed from volcanos. In the eighteenth century they were often heard in a district of Connecticut, U.S.A., resembling thunder, or the noise of a cannon-shot. In the delta of the Ganges they are known as Barisalguns, on the coasts of Belgium as mist-poeffeurs, in central Italy as marinas. They were common for a period forty or fifty years ago in the Oropi Ranges, between Tauranga and Rotorua. But residents of Taupo who cannot always hear the sounds their friends hear can be sure of two things. One, that their friends are not necessarily "imagining things," and two, that they themselves are not necessarily becoming deaf.