164 F. OMORI AND K. HIRATA : 



T denotes Period of Vibration.^ 



(EW) ,, East-West Component. 



(NS) „ North-South „ 



(V) „ Vertical 



4. Eqke. No. 1. The 15tli June, 1896 ; 7.32.30 p. m. In- 

 tensity,^ iveak. 



The seismographic record evidently indicates a distant 

 shock, the motion consisting entirely of slow undulations, free 

 from superposed ripples. According to Mr. T. Iki, who inves- 

 tigated the fearful sea-waves caused by this earthquake, the 

 origin of disturbance was situated at a point, long. 144°30'' E, 

 lat. 39° N, that is to say, at about 240 km. ESE of Miyako. 

 Judging, however, from the isoseismal lines,^ the origin of the 

 earthquake seems to be situated at about 170 km. ESE of 

 Miyako. (See fig. 8). 



The H.M. was four to six times greater in the EW than 

 in the NS component, the V^.M. being very small. The motion 

 was, therefore, practically horizontal and in the EW direction, 

 there being occasional fluctuations in the range of motion. The 

 maximum la was 4.0 mm. As the rotation of the record- 

 receiving drum was unfortunately irregular, we can not measure 

 exactly the period of vibration. The duration was probably 

 not less than 5 minutes. 



o. Eqke. No. 2. The 17th June, 1896 ; 0.46.2Ô p. m. In- 

 tensity, slight. (See fig. 1). The origin of the earthquake was 

 probably close to that of Eqke. No. 1. (See fig. 8). 



1. In this paper, the perml signities always the complete period. 



2. The intensity of an eartliqnake is, in this paper, indieatcd as slron;;, ueak or slight. 

 A slight shock is one which is very feeble and just strong enougli to te felt ; a icea/c sliock 

 is one whose motion is well-prononncecl hut not so severe as to cause general alarm ; and 

 finally a strong shock is one whicli is sufficiently strong to knock down some furnitures, to 

 cause people to run out of doors, etc. 



3. All the distances between the origins of disturhance and ^liyako, given in H 4- 

 34, have been estimated from the isoseismal lines of the respective earthquakes. 



