^9°9.] THEIR CAUSES AND EFFECTS. 



239 



thirty-five years, indeed, it was the general belief that volcanic earth- 

 quakes were by far the most numerous and destructive of all. This 

 idea controlled and vitiated Mallet's work, but it is now known to 

 be erroneous, for although it is true that earthquake zones coincide 

 in part with belts of volcanic activity, shocks are more frequent and 

 more severe in non-volcanic regions. The severest quakes of South 

 America have not happened around the great volcanoes ; the shocks 

 of California are evidently independent of the now extinct or at 

 any rate dormant volcanoes of the Cascade Range; the recent 

 (1899) great earthquakes of Alaska were in the vicinity of Yakutat 

 Bay, at a long distance from the active vents of the Aleutian Islands 

 or any recent volcanicity ; the earthquakes of Japan are most numer- 

 ous and severe in the non-volcanic parts of the islands; the great 

 disasters of the Caribbean Sea have occurred in Jamaica and at 

 Caracas, hundreds of miles from Mt. Pele and St. Vincent's Sou- 

 friere, and have not been contemporaneous with any eruptions. 



On the other hand, some of the most violent of historic volcanic 

 eruptions have been unattended by severe earthquakes or have given 

 rise to shocks of merely local significance. The Island of Mar- 

 tinique in the French West Indies lies within a markedly seismic 

 zone, but the great eruptive activity of 1902-1903 was free from 

 earthquake shocks. This fact is of particular interest, because the 

 eruptions were of the most highly explosive character. Although, 

 however, no vibrations were felt upon the island of Martinique and 

 no subterranean noises were heard there, dull sounds like the boom- 

 mg of distant cannon were heard the morning of the great eruption 

 of May 8, 1902, at Caracas, Venezuela, 450 miles distant, south- 

 west, where people feared that a naval battle was in progress off 

 their coast. Similar booming was reported from St. Kitts, 200 

 miles northwest of Martinique and from other regions. I myself 

 was on the island of St. Vincent, 100 miles due south of Pele when 

 the great eruption of June 6, 1902, occurred, and I felt several dull 

 thuds, as if some heavy object had fallen in a neighboring room. 

 The noises seemed to come from beneath the ground, and they 

 were due, in all probability, to subterranean explosions or to the 

 rushmg of lava into underground cavities, somewhat on the prini- 

 ciple perhaps of the water hammer. On the island of St. Vincent 



