548 



SCIENCE. 



[N. S. Vol. XXIV. No. 618. 



records, and which is ordinarily considered 

 to be typical of the so-called tectonic 

 earthquake (or earthquake independent of 

 volcanic association), took place in a 

 field which in a direct line is removed by 

 1,800 miles from the very active volcanic 

 region of Iceland — therefore, at a shorter 

 distance than Pelee is from Quetzaltenango, 

 It is significant that a few days before' the 

 destruction of Lisbon the volcano of 

 Kotlugia, in Iceland, broke out into violent 

 eruption, and it is perhaps more than a 

 coincidence that on the very day of Lis- 

 bon's fall (November 1) the activity of 

 this volcano was particularly marked,* 



It would perhaps be going in advance of 

 the facts were we to immediately assume 

 that the eruption of Kotlugia was directly 

 related to the Lisbon earthquake ; on the 

 other hand, there would seem to be nothing 

 to make this conclusion untenable. Indeed, 

 this relation acquires a strong degree of 

 confirmation from the events that a few 

 years later (1783) marked the very dis- 

 astrous earthquake of Calabria. At that 

 time, although following the great shock 

 (March 28) by several weeks, the volcano 

 of Skaptar JokuU, in Iceland, went through 

 its greatest paroxysm, discharging lava for 

 a period of four months, and relieving the 

 interior of the earth of a mass of rock- 

 material which has been estimated to have 

 been not less than 27 milliards of cubic 

 meters — the equivalent of a block six and 

 one fifth miles long, three and one tenth 

 miles broad and 1,771 feet thick! The 

 volcano of Reykjanes was likewise in erup- 

 tion. These two volcanoes are located 

 almost exactly 2,000 miles from the scene 

 of the Calabrian disturbances, when the 

 entire island of Sicily, in addition to the 

 mainland of Italy, was affected. The same 

 year witnessed also the explosion of Asama- 



* ' Royal Society Report on Krakatoa Eruption,' 

 p. 387. 



yama, in Japan, one of the most violent of 

 all recorded eruptions, when rocks meas- 

 uring 40 to 260 feet across are said to 

 have been hurled out of the crater.^ It 

 should also be noted that this year marked 

 the first recorded eruption of Irazu, in 

 Costa Rica, which was accompanied by 

 violent earthquakes." 



A partial and perhaps even very close 

 parallel to the Antillean occurrences of 

 1902 may be found in the disturbances 

 which framed the New Madrid earthquake 

 in the valley of the Mississippi in (De- 

 cember) 1811 and 1812, that wrought the 

 destruction of Caracas on March 12, 

 1812, and culminated in the great erup- 

 tion of the Soufriere of St. Vincent 

 on April 30, 1812. The association of 

 events in these cases is such as hardly 

 to permit of doubt in their reference. In- 

 deed, it has been frequently stated (but I 

 have not been able to find absolute con- 

 firmation of this assumed fact) that the 

 movements in the Mississippi Valley ceased 

 for a while, almost immediately with the 

 breaking out of the Soufriere. A similar, 

 although reversed, condition marked the 

 earthquake of Riobamba, on February 4, 

 1797— perhaps the most destructive to life 

 after that of Lisbon — when, as we are in- 

 formed by Humboldt, the volcano of Pasto, 

 situated 200 miles distant, almost im- 

 mediately ceased smoking.'^ 



The great earthquake which on February 

 20, 1835, destroyed the city of Concepcion, 

 in Chile, and which has been represented to 

 be a distinctively tectonic quake^ is almost 

 certainly one of volcanic association, and 

 so it has been referred by Milne, in his 

 work on earthquakes (p. 135). The year 

 1835 was a particularly volcanic year in 

 the Chilean Andes, and the reports of the 



' Milne, British Association Reports, 1887. 

 » Milne, 'Earthquakes,' p. 273. 

 ' ' Views of Nature,' Bohn edition, p. 175. 

 * Button, ' Earthquakes,' p. 52. 



