JAPANESE EARTHQUAKES — HECK 209 



building of a great breakwater has been considered, but an effective 

 one is scarcely practicable. The earthquakes of 1911 and 1936 may 

 have produced large tsunamis, but, since they occurred off small 

 islands, the damage occasioned was not great. The submarine shock 

 of 1944 was stronger than the destructive 1923 earthquake. 



Region III. The Kwanto region. — This region, named for a great 

 plain which covers most of the region, includes the Idu Peninsula west 

 of Sagami Bay. For the years from 818 to 1930, Imamura lists 28 

 destructive earthquakes, including 9 of those listed in table 1. The 

 persistence of destructive earthquakes in the region for more than 

 1,900 years is evidenced by a series of horizontal lines of drill holes 

 in a cliff on a recent inlet of Sagami Bay near Misaki. The holes 

 were made by a marine borer which operates only between high and 

 low water. The lowest row indicates an uplift of 17 feet in 1703 ; the 

 next, of about the same amount in 81.8 ; and a less definite one which, 

 on fairly good evidence, is assigned to about A. D. 33. In 1923 the 

 uplift was about 6 feet. In the earthquake of this year, and probably 

 in the others, there was lowering elsewhere, indicating block tilting. 

 This is probably the clearest example of successive uplift to be found 

 anywhere. 



The 1703 earthquake was submarine, with its origin south of Boso 

 Peninsula (east of Tokyo Bay). There was a tsunami of some vio- 

 lence over a moderate length of coast, possibly due to sea-bottom 

 changes which at that time could not be measured. The earthquake 

 was destructive in nine provinces. There was uplift at many places 

 along the coast, and some previously outlying reefs became dry land. 

 The loss of life and property damage was heavy, but not so great as 

 it would have been under the conditions of industrialization of 1923. 



The earthquake of 186'5 was noteworthy in that, though it was local 

 in extent, its epicenter was nearer to Tokyo than that of 1923 and 

 therefore it caused important damage. Many fires were started when 

 charcoal braziers were upset by the earthquakes, but most of them 

 were brought under control though a square mile of the city's area was 

 burned. The shock was of very short duration. 



Books have been written about the earthquake of 1923, generally 

 known as the Kwanto earthquake (pi. 1, fig. 2 ; pi. 2) . An elaborate re- 

 port of the engineering features, published in Japanese, was translated 

 into English by the American Society of Civil Engineers; but the 

 translation has not been published, though it is available at the So- 

 ciety's library in New York. Only a bare outline of the principal facts 

 of the earthquake can be given. The epicenter of the first main shock 

 was in the middle of Sagami Bay, where the changes that took place 

 were great, though perhaps not so great as the comparative hydro- 

 graphic surveys taken before and after the event seem to indicate. 



