656 BEPOHT— 1886. 



5. Note on the recent Earthquake in the United States, inchiding a tele- 

 graphic dispatch from Major Poivell, Director of the United States 

 Geological Survey} By "W. Topley, F.G.S., Assoc. Inst. C.E., Geological 

 Survey of England. 



This paper described the effects of the earthquake at Charleston, which took 

 place on the evening of August 31, so far as they could be gathered from telegrams 

 received to date. The most important of these was one kindly sent by Major 

 Powell, the Director of the United States Geological Survey, in reply to inquiries 

 cabled by the author : this telegram is printed in full below, and the information 

 therein contained need not he given here. 



Mr. Topley observed that during the last ten days there had been earthquake 

 disturbances over a very wide area of the earth's surface. On the night of Friday, 

 August 27, there were shocks all over Greece and in a smaller degree all over the 

 east Mediterranean area. This earthquake wave apparently travelled from west to 

 east. It was felt at Malta, Calabria, and Naples, and thence it travelled eastwards 

 as far as Alexandria. It did not appear to have been felt west of southern Italy, 

 probably because its westward area of propagation was there beneath the sea. 

 Possibly it was only a coincidence, but if so a very curious one, that the earliest 

 important earthquake disturbauces in the United States were on Thursday, the 27th, 

 and Friday, the 28th, but there had been slight premonitory shocks for two or three 

 days before. The principal shock was that of Tuesday night, August 31. This had, 

 however, been succeeded by shocks, fortunately of less intensity, which had been felt 

 over a still wider area. As late as Sunday night there were shocks at Charleston. 

 An important point in Major Powell's despatch was the evidence of the rapid trans- 

 mission of the main earthquake wave. According to the telegram it travelled over 

 the 900,000 square miles at from 2.5 to 65 miles per minute ; but there might be 

 some error in the telegram here, as by comparing the times given in the telegram 

 with the distances on a map he (Mr. Toplej-) found that the velocity varied from 

 36 to 140 miles per minute. [The greatest velocities since ascertained are : — To 

 Toronto, 170 miles per minute ; to Washington, 148 miles.] There did not seem 

 to be any relation between the intensity and time and the surface distance from the 

 area of origin. This last, indeed, they would not have expected to find. They would 

 rather have looked for rapid transmission along certain lines or through certain 

 rock masses. The last important earthquake in the eastern United States, that on 

 August 10, 1884, was carefully investigated by Professor Carvill Lewis. This was 

 found to range along the eastern side of the Appalachian Mountains, nearly along 

 the line where the old earth-movements had been greatest. The area most affected 

 by the recent earthquake was a vast plain of Tertiary and Cretaceous rocks. The 

 older rocks underlay these at unknown depths. [At least 2,000 feet, and may be 

 as much as one mile,] It might perhaps be fouud that the transmission of the 

 shock to distant points had depended in part upon the range of the harder and 

 older rocks beneath. This was very evidently the case with the East Anglian earth- 

 quake. In this earthquake the great structural damage was confined to a small 

 area. The distant points at which it was felt were in most cases upon or near to 

 the exposure of the Palaeozoic rocks, and Birmingham was one of these distant points. 

 In other cases earthquakes were known to be related to lines of fault. Mr. M'Gee 

 had been sent by Major Powell to investigate the effects of the earthquake at 

 Charleston, and he found the local evidence, such as the direction of the fissures, 

 contradictory and difficult of explanation. They need uot wonder, therefore, at 

 being yet unable to understand the wider question connected with its range and trans'- 

 mission. The local phenomena were in part described in Major Powell's telegram. 

 Fissures had been opened in the ground, some of which ranged north and south, 

 others east and west. From these fissures mud and sand were ejected. Several 

 telegrams spoke of stones falling from the air, and, although there was plainly 

 much exaggeration in these accounts, it was possible that some stones were ejected 



' A few important corrections necessitated by subsequent researches (chiefly by 

 the United States Geological Survey) are inserted within brackets. 



