1909.] OUTLOOK OF SEISMIC GEOLOGY. 297 



have swept over our cities, we have as yet made only partial provi- 

 sion, yet the remedy is known and the country does not hesitate to 

 make an annual expenditure conservatively estimated at $25,000,000, 

 and in addition compels its citizens to build according to approved 

 regulations. 



A single earthquake has involved us in a loss of over $350,000,- 

 000, or nearly ten times the loss from the Baltimore fire.^° Yet the 

 government has expended nothing in an attempt to safeguard the 

 future by avoiding the recurrence of such disasters. In Europe 

 within a few months an entire city has been laid in ruins with a 

 loss of life which may reach 150,000, yet the latest information 

 makes it almost certain that this quake was not an exceptionally 

 heavy one, and that most of the loss of life and property might 

 have been avoided if proper methods of construction had been 

 adopted. 



It can hardly be claimed that the comparatively recent California 

 disaster gave us our first warning of danger, for twenty years earlier 

 the earthquake in South Carolina caused a loss of over one hundred 

 lives, and property to the value of between $5,000,000 and $6,000,- 

 000. The earlier earthquakes within our territory have been far 

 heavier and the small loss of life and property is accounted for only 

 because the districts were at the time so thinly populated. We 

 must not, therefore, overlook the fact that the United States is an 

 earthquake country, and this not alone in its Pacific section. Some 

 of our largest and most prosperous cities are almost certain to pass 

 through their trials in the future, as Charleston and San Francisco 

 have so recently. On February 5, 1663, almost the entire valley of 

 the St. Lawrence and large sections of New England were visited 

 by an earthquake, which, if the country had been built up as it is 

 today, would have caused a disaster which it is not pleasant to 

 contemplate. 



Preparation of Maps of Fracture Systems. — As we have seen, 

 earthquakes register the movement of portions of the earth's crust 

 between planes of fracture. In just how far these fracture planes 

 are present in advance of the movement, and in how far they result 



^ The official figures kindly furnished by Professor J. W. Glover. 



