COMING TO GRIPS WITH THE EARTHQUAKE PROBLEM 



By N. H. Heck 



Chief, Division of Terrestrial Maijneiism and Seismology, U. S. Coast and 



Geodetic Survey 



[With 8 plates] 



On February 2, 1931, we had another reminder that the problem 

 of safeguarding cities against damage from severe earthquakes is 

 as yet unsolved when the beautiful coast resort city of Napier, North 

 Island, New Zealand, was nearly destroyed by a great earthquake. 

 This earthquake also demonstrated that in designing structures to 

 resist earthquakes the possible cumulative effects of a number of 

 severe shocks must not be overlooked, since there were at least three 

 aftershocks comparable with the main shock. 



The earthquake is always of absorbing interest to the seismologist, 

 but we are rapidly approaching a condition in which the heretofore 

 sporadic interest of the average citizen is being converted into con- 

 tinuous interest in many parts of the earth, and accordingly the 

 engineer and architect in the regions concerned are beginning to be 

 quite as much interested as the seismologist. 



The two fields of activity w^ith regard to earthquakes — geophysics 

 and engineering — although having different purposes, are not inde- 

 pendent, and results in either field may throw light on the problems 

 of the other. Prominent engineers have begun to criticize the seis- 

 mologist for not giving them the information that they need, and 

 the time now seems ripe for closer coordination of activity. 



From the viewpoint of the geophysicist, earthquake investigation 

 is for the purpose of learning all that there is to know about the 

 nature of the earthquake itself as a physical phenomenon and the 

 transmission of waves, and, incidentally, the nature of the trans- 

 mitting medium, with consequent information about the interior of 

 the earth, which is obtainable in no other way. From the view- 

 point of the engineer, the important factors are the probable occur- 

 rence of a severe eartliquake in a given locality, the effect of earth- 



» Lecture presented at a meeting of the Franklin Institute held on April 2, 1931. 

 Reprinted by permission, with considerable alterations, from the Journal of the Franklin 

 Institute, vol. 2V2., No. 3, September, 1931. 



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