98 



REPORT — 1892. 



total number of earthquakes in the year were severe, 42 per cent, mocie- 

 rate, and 49 per cent, feeble. 



Notes on Special Earthqual-es. 



1. On February 5, at 1 a.m., an earthquake was felt over nearly the 

 whole of North Japan, extending from Tezo in the north to Tokio in the 

 south. The area shaken was 9,670 square ri. This is the first time since 

 1884, Avhen extended observations were commenced, that so large an area 

 was disturbed. Whatever damage occurred was slight. 



2. On April 11, at 3 a.m., an area of 2,190 square ri was shaken in 

 Central Japan. The provinces of Tango and Tanba were most seriously 

 affected. 



3. On April 29, at 10 a.m., North Japan was disturbed by a shock 

 ■extending over 1,930 square ri. In Nasu-gori river banks gave way, at 

 Utsonomiya walls were cracked, and to the south, in Tokio and other 

 places, clocks were stopped and articles overturned. The motion was 

 generally horizontal. 



4. On July 15, at 7.30 a.m., an elliptical area of 600 square ri near 

 Lake Inawashiro was suddenly shaken. This was followed by a second 

 shaking, and whilst this continued Bandaisan, which overlooks the lake, 

 exploded, and in a few minutes buried nearly 28 square miles of country 

 beneath a sea of earth and boulders 30 to 100 feet in depth. 



Whether the preliminary shakings were unsuccessful efforts of the 

 steam beneath Bandaisan to obtain a vent, or whether they were shakings 

 due to faulting or other causes, which destroyed the equilibrium between 

 internal forces and the rocky cover which restrained them, is a matter 

 for speculation. It may here be mentioned that one result of the Ban- 

 daisan explosion has been to form a lake which is 83 miles long and from 

 1 to 3 miles in breadth. 



Earthquakes Observed at the Central Ohservatory in Tohio 



in 1888. 



A list of the earthquakes felt in Tokio in 1888 has been published in 

 a previous Report. Between January and December 101 disturbances 

 were recorded. 



1. Earthqual-e Frequency per Month. 



During the year 1888 the number of earthquakes in each month was 

 as follows : — 



From the above it is seen that the maximum frequency occurred in 

 February, and the minimum frequency in January, October, and 

 December. 



