88 COGGIH BROWN: THE BURMA EARTHQUAKES OF MAY 1912. 



of the quake upon mankind in general, upon structures of all 

 sorts, and upon movable objects which they contain. 



The plotting of the isoseismal curves upon the map has been 

 carried out almost entirely from the collated reports of various 

 individuals who experienced the shock in different parts of Burma, 

 and, following the custom hitherto adopted in similar investigations 

 in this country, use has been made of the modified Rossi-Forel 

 scale. The curves of course enclose zones of equal intensity, and 

 in passing from one to the next we proceed through belts of 

 neater intensity until the pleistoseismic area, or that portion of 

 the earth's crust which is immediately above the seat of the dis- 

 turbance, is reached. Indeed, one of the many reasons for deli- 

 neating intensity systematically is to locate this position and to make 

 known any fault with which the earthquake may be connected. The 

 study of the distribution of intensity may lead to the recognition 

 of deep-seated portions of a fault not recognisable at the surface, 

 or reveal other dislocations which happened at the time of the 

 shock, by the sudden release of molecular strain in neighbouring 

 portions of the region, or, again, auxiliary faults which bear some 

 relationship to the main system. 



I.— Microseismic Shock— recorded by a single seismograph, or 



by some seismographs of the same pattern 



•Lhoiiossi-uorci scale. but not by scveml g^^pfc of different 



kinds; the shock felt by an experienced observer. (This number 

 of the scale is now obsolete owing to improvements in seismo- 

 graphs. ) 



11.— Extremely Feeble Shock— recorded by seismographs of differ- 

 ent kinds ; felt by a small number of persons at rest. 



111. — Very Feeble Shock— felt by several persons at rest; strong 

 enough for the duration or the direction to be appreciable. 



IV.— Feeble Shock— -felt by persons in motion ; disturbance of 

 movable objects, doors, or windows ; cracking of ceilings, 



\\— Shock <>j Moderate Intensity felt generally by everyone ; 

 disturbance of furniture and beds ; ringing of some bells. 



VI. — Fa4rkf Strom/ Shock— general awakening of those asleep ; 

 general ringing of bells ; oscillation of chandeliers ; stopping of 

 clocks; visible disturbance of trees and shrubs. Some startled 

 persons leave their dwellings. 



VII.-— Strong Shock overthrow of movable objects; fall of plas- 

 ter ; ringing of church bells ; general panic, without damage to 



