ON SEISMOLOGICAL INVESTIGATION. 193 



earthquakes were felt, whilst others were caused by landslips, which in 

 turn may have been the result of mechanical shaking. On certain 

 sections, as for example that connecting Arica and Mollendo, fractures 

 have only taken place in certain months, which in this instance are June, 

 July, and August. Restrictions like this suggest that the cause of 

 fracture has been due to landslips brought about by the escape of fresh 

 water beneath sea-level, the action of currents, or other sub-oceanic 

 phenomena having seasonal maxima. 



The interruptions off Pescadores Point (16° S. lat.), although, when 

 recovering cables, branches of almost petritied trees have been brought 

 to the surface, Mr. R. Kaye Gray attributes to the great unevenness of 

 the bottom, there being in that neighbourhood submarine hills 3,000 and 

 4,000 feet in height. 



The following notes liearing upon the above sections were kindly 

 drawn up by Mr. W. E. Parsone, who has been engaged in cable work on 

 the west coast of South America : — 



Arica— Mollendo Section. — This section was laid in 1875. On the night of May 9, 

 1877, while the cables between Arica and Lima were being used for direct working, 

 a very distinct shock of earthquake was felt by the operator in the Lima office at 

 about 10.30 P.M., during receipt of a message from Arica, and communication 

 ceased a few seconds later. The intermediate station of Mollendo afterwards 

 reported that the shock was also felt there, and at about the same time,. and that 

 they were unable to communicate with Arica. Mr. Parson6 located the rupture of 

 the Arica— Mollendo section as close to the shore at Arica, and proceeded by first 

 opportunity to that place, where it was found that a violent earthquake shock on 

 May 9, 1877, had been accompanied by a tidal wave of unusual severity, which had 

 completely wrecked the greater portion of the town. The sea-front and harbour 

 had suffered enormous damage, the iron pier having been washed away, and prac- 

 tically all the craft in the port having parted their moorings or foundered. In 

 undertaking the repair, tons of anchor-moorings and material were picked up with 

 the cable, which had been considerably dragged out of position and twisted for a 

 considerable distance from the shore. Communication on this section was restored 

 on May 2i, 1877, and worked without interruption until it was permanently 

 repaired by renewing a portion of the shore-end and intermediate cable on 

 November 17, 1878. 



Iquique — Arica Section. — This section was laid in 1875. On May 7, 1878, a severe 

 shock of earthquake was experienced in the neighbourhood of Iquique, after which 

 the cable connecting that place with Arica was found to be interrupted. Mr. 

 Parson6 located the rupture at 6 knots from Iquique on the intermediate cable in 

 60 fathoms of water, and, after considerable difficulties working with barges, there 

 being no repairing-ship obtainable, succeeded in lifting the cable on the spot. Both 

 ends were recovered, and it was found that the cable (intermediate) had snapped 

 clean through, the compound on either side of the break being undisturbed, except 

 at, say, a distance of 18 inches on either, where the sheathing wires had made one 

 complete turn. There the compound had sprung, and some of the strands parted, 

 and the sheathing wires compressed out of position. But for these comparatively 

 slight indications of the enormous force which must have been exerted to make so 

 clean a break in heavy intermediate type, the cable was in no way damaged, the 

 rest of the cable being in as good condition as the day it left the factory. The 

 earthquake, which was undoubtedly the direct cause of the rupture, was said to 

 have a direction from south-west to north-east, and it was noticed with much surprise 

 that the base of the high cliffs on the fore-shore bore marks of recent disturbance 

 at a spot bearing due north-east from the position of the break. The disturbance 

 referred to had the appearance of a recently formed cavern or tunnel — a few feet 

 above the beach where the base of the hard rock was met — as if some enormous 

 piece of artillery had been fired point-blank into the rock, and this bad also caused 

 a falling away of the surface rock above the opening, which peels ofE in layers like 

 decomposed slate. We could not land at the place to examine it more closely on 

 account of the surf and rocks, but attempted to do so by clambering and crawling 

 over the headland of rock ; but large thin sections of decomposed surface slipped 



1897. o 



