Contents 1
Papers and Reports． 1
1．T．USAMI,Study of Swarm Earthquakes in Japan from 416 to 1867．(in Japanese) 1
2．Hokushin Observatory of Microearthquakes and Crustal Deformation,An Observation of Microearthquakes at Nagawado Dam in Nagano Prefecture． (in Japanese) 47
3．Y．KOTAKE,M．YOSHIDA,Y．SAT？ and K．HAMADA,Digital Map for Japan and the World．(in Japanese) 53
4．T．YUKUTAKE,S．KOYAMA and T．YOSHINO,Geomagnetic Environment of Yatsugatake Geomagnetic Observatory．(in Japanese) 73
5．T．HATORI,Sources of Tsunamis generated off Boso Peninsula．(in Japanese) 83
6．I．MURAI and S．KANEKO,Active Fault Systems Developed in the Area around Lake Biwa．(in Japanese) 93
7．S．ARAMAKI and H．HARAMURA,Geochemical Notes(1):Chemical and Mineral Compositions of Ejecta of 1978 Eruption,Asama Volcano．(in English) 109
8．D．SHIMOZURU,S．UTIBORI,N．GYODA,E．KOYAMA,T．MIYAZAKI,T．MATSUMOTO, N．OSADA and H．TERAO,The 1973 Explosive Activity of Asama Volcano．—General Description of Volcanie and Seismic Events-,(in Japanese) 115
