Since 1953 the Institut de Recherche Scientifique du Zaire (I. R. S.), formerly Institut pour la Recherche Scientifique en Afrique Centrale (I. R. S. A. C.), operates a seismological network in the Kivu region of the Zaire Republic within the western branch of the East African Rift System. Between 1960 and 1970 a few data related to the Lake Moero and Upemba Rifts were obtained by the intermittent operation of three stations in the Shaba region. Based mainly on the data collected by the above mentioned network, the authors analyze the seismicity of the Western Rift Valley of Africa and related problems. The distribution of earthquakes within the considered region is examined and evidence is given for the existence of high seismic zones. Furthermore, the vertical distribution of earthquakes reveals some regional characteristics within the Western Rift Valley. The Investigation of the focal mechanism of the earthquakes which have occurred in the Western Rift Valley of Africa shows the existence of an uniform system of tectonic stresses pulling apart the rift margins. The distribution of the direction of tension and pressure axes within the Western Rift Valley and its vicinity is presented.
100 years have past since Edmund NAUMANN discovered the Fossa Magna in 1876. He thought it as a kind of large rift dividing the Japanese arc into the northeastern and southwestern limbs. He regarded the islands as a single Palaeozoic folded zone and afterwards transversed by the rift accompanied by volcanic zones. On the other hand Edward SUESS and Toyokichi HARADA considered the islands in terms of two tectonic units, the northern Sachalin System and the southern Chinese System, joined in the manner of syntazis in the Fossa Magna. Since the argument of NAUMANN vs. HARADA concerning the tectonic units of Japanese islands, hot discussions have continued concerning the tectonic signifficance of the Fossa Magna. After structural analyses of the folded zones in the Akaishi Mts., the senior author has confirmed the Fossa Magna as a large meridional left lateral fault, holding 100 km's of displacement. It is accompanied by a large and wide drag zone in the western side, consisting of minute and numerous faults and cracks. Owing to the fragmentation of the drag zone, there has been no large earthquake in these areas. In order to confirm very slow crustal movements and regional strains of the fault zone, we measure precise distances among several radial and triangular nets in the zone by means of an electro optical instrument “Geodimeter 700”. Results of surveys are also summerized in this paper.
The late Dr. Shingo YEHARA's Collections of fossils from various (mostly Mesozoic) localities of Japan, excluding those of the described types, are now preserved in the Tenri High School, Nara Prefecture. In response to the request of the High School, I identified fossil cephalopods and some inoceramids among others. 72 cephalopod species, along with some inoceramid species, are listed, with brief notes, under the following grouping : I. Cephalopoda from the Lower Cretaceous of the Miyako area, Northeast Japan II. Cephalopoda from the Lower Cretaceous of Southwest Japan III. Cephalopoda from the Cenomanian of Southwest Japan IV. Cephalopoda from the Turonian of Southwest Japan V. Cephalopoda from the Coniacian and Santonian of Southwest Japan VI. Cephalopoda from the Campanian and Maastrichtian of Southwest Japan VII. Cephalopoda from the Upper Cretaceous of Hokkaido VIII. Some inoceramid species IX. Tertiary Cephalopoda X. Jurassic Cephalopoda XI. Triassic Cephalopoda