248 HOVEY— EARTHQUAKES : [April 24, 



Besides throwing down walls and chimneys and moving houses 

 bodily on their foundations, the earthquake caused wooden posts 

 and brick piers to sink vertically into the earth ; compressed railroad 

 tracks into more or less complicated curves or stretched them apart ; 

 opened innumerable fissures in the ground, and formed hundreds 

 or craterlets at many places out of which gushed water, sand and 

 mud in copious streams. 



The earthquake waves traversing Charleston were localized as 

 coming from the northwest and from the west. The principal 

 epicentrum was determined as being about sixteen miles northwest 

 of the city and one mile from the little railway station at Woodstock, 

 and a secondary epicentrum about fourteen miles due west of town. 

 The focus of disturbance was a line or plane estimated as being 

 twelve miles below the surface " with a probable error of less than 

 two miles." The velocity of the wave motion throughout the 

 eastern half of the United States was calculated as averaging 190 

 miles per minute. The intensity reached No. 2 of the Rossi-Forel 

 scale as far away as New Orleans, Clinton, Mo., La Crosse, Wis., 

 Saginaw, Mich., Burlington, Vt., and Boston — an extreme radius of 

 about 1,000 miles. The Charleston earthquake is classed as a tec- 

 tonic quake, though no evidence of faulting was apparent on the 

 surface. 



(Lantern slides were shown depicting the destruction of build- 

 ings in Charleston and vicinity and the formation of fissures and 

 craterlets.) 



The San Francisco Earthquake. 

 California has always been known as a seismic region. Pro- 

 fessor E. S. Holden has catalogued 514 shocks, 254 of which afifected 

 the region of San Francisco alone, within the period between 1850 

 and 1886. During the nineteenth century there were ten severe 

 quakes; that of 1868, known as the Mare Island quake, having 

 such a disastrous effect upon the city of San Francisco that serious 

 doubts were entertained of the advisability of rebuilding on the same 

 site, but these fears were soon forgotten and the city rapidly rose 

 again. It was rebuilt, however, without much reference to the 

 lessons that might have been learned from the experience. 



