214 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 45 



the fact that no destructive earthquakes were listed earlier for that 

 place. The same is true for the Tango region. A hydrographic sur- 

 vey revealed no change in depth of the adjacent sea bottom. 



The Tango earthquake of 1927 caused 10 times as much damage as 

 the Tazima earthquake, and in the epicentral region the severity was 

 of the first rank, the acceleration being estimated at 0.5 g. Though 

 Tango was a center of the silk industry, the population was not so great 

 as that of Tazima and this reduced the losses. The earthquake was 

 remarkable for the short interval of 3 seconds from the time it was first 

 perceived until it exerted a force sufficient to throw down buildings. 

 There was no time to escape, and many of its victims were crushed. 

 The town of Minoyama established a record even for Japan : only 10 

 out of 998 buildings survived, and 1,122 persons were killed. Fires 

 were started from 15 centers, and no action was at once taken to put 

 them out. 



The earthquake was associated with visible fault slipping, which was 

 studied with great care. The Gomura fault extends from the coast 

 to the southeast, and, partly discontinuous, its fault slips, en echelon, 

 for a distance of 11 miles, having a maximum horizontal change of 

 about 9 feet. The greatest vertical change observed was only 27 inches- 

 There was evidence from repeated hydrographic surveys that the fault 

 extended seaward with greater vertical change than on land. The 

 Yamada fault, nearly at right angles to the Gomura fault, is visible 

 for 4.7 miles, but probably is 18 miles long. Its maximum vertical 

 change was 28 inches. There was some permanent uplift of the coast. 

 The epicenter of the aftershocks were studied in relation to block fault- 

 ing. The height of the tsunami was about 5 feet. The deduced 

 acceleration was 0.4 or 0.5 g. 



Region V. Japan Sea coast of Honshu, except Tazima-Tango. — Only 

 the earthquakes listed in table 1 will be considered, and they will be 

 divided into three subgroups (A-C) for geographical convenience. 

 Preseismic tilt is characteristic of many of these earthquakes, and this 

 was the more readily detectable because the occurrences were near a 

 shore with a maximum tidal range of about 1 foot. 



A. North of latitude 39°. Included here in order of descending lati- 

 tude are the earthquakes of 1793, 1704, 1694, 1810, 1939, 1914, and 1804. 

 The western Tugaru earthquake of 1793 was noted for preseismic tilt. 

 The land rose 3 to 6 feet, 4 hours before the earthquake. The ex- 

 traordinary ebbing of the tide that accompanied this was regarded as 

 warning of a tsunami. The inhabitants rushed to higher ground. 

 Then came a violent earthquake, and the people, fearing landslides, 

 rushed back to the beach, so that some were drowned by the tsunami 

 even though it was moderate and otherwise did little damage. There 



