ON SETSMOLOGICAL INVESTIGATIONS. 



35 



toPj. Observations made in the Azores, San Fernando, Bidston, Shide, 

 Messina, Rome, Tiflis, Colombo, and Irkutsk, point to an origin in the 

 Atlantic about 18° W. and 38° N., wliich is not far from the Azores, 

 where the amplitude was large. The time of the initial shock would be 

 6.4 ± 2 min., or approximately 12 min. after the Arica disturbance. 

 Now the distance from Arica to the Atlantic origin is 75°, and this would 

 be traversed by Pj in 14 min. Although it may not be certain, it seems 

 at least probable that the disturbance near to the Azores was brought 

 into existence by the arrival of preliminary tremors which had originated 

 off the western coast of Chile. A similar line of reasoning applied to 

 the records from Honolulu, Batavia, and a second maximum seen in the 

 Irkutsk seismogram suggests that a third disturbance had taken place 

 in mid-Pacific. 



Oilier Examples of Multiple Earthquakes. 



In the following list I give the date and times at which these 

 occur; after that the longitude and latitude of their origins and the 

 distances that these are apart expressed in degrees. Lastly, I give 

 the time we should expect P^ P 2 , or P 3 to traverse the distance between 

 any two origins and compare this with the difference in time between 

 the occurrence of each pair of earthquakes. 



d2 



