-
Article type: Photogravure
1981 Volume 26 Issue 2 Pages
App3-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
Tatsuhiko WADA, Keiichi NISHIMURA
Article type: Article
1981 Volume 26 Issue 2 Pages
83-92
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
The Aso Volcanological Laboratory is situated within the gigantic Aso Caldera, and many records have been obtained for events occurred around the Kyushu Island. By analyzing those records, a certain systematic azimuthal deflection of P wave has been clearly discerned and seems to reflect some structural feature beneath the caldera. It has been shown that the systematic azimuthal deflection can be interpreted based on the following structural model : a tectonic line or zone runs across the center of the caldera from east to west and splits the basement of caldera into two blocks ; the interface of basement of the northern block inclines nearly eastward with the dip of about 15° and that of the southern block toward NNE with the dip of about 25°. In order to estimate the depth of interface, seismograms of an artificial explosion and earthquakes occurred northward outside of caldera rim were analyzed and then a transversely polarized phase was found in P-coda waves. The phase was interpreted as SV wave converted from P wave incident at the inclined interface of the northern block basement. Based on time difference t
sv-p, the interface of the basement was supposed to be about 2.5km deep in the western part of caldera. It has been suggested, taking into consideration the dip angle of interface assigned by the twin-block model, that the interface extends downward to a depth of 4km or so below the central cone situated rather eastward inside the caldera. It has been also suggested that the magma chamber below the central cone, proposed by one of authors, is located along the tectonic line mentioned above and swells nearly by half above the inclined interface. The tectonic line might have played an important role, such as a feeding channel, in the process of formation of the central cone.
View full abstract
-
Tohru HARADA
Article type: Article
1981 Volume 26 Issue 2 Pages
93-110
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
Usu volcano, Hokkaido, Japan, burst into eruption on August 7 (09
h12
m local time), 1977, after 32 years’ dormancy since Showa-Sinzan lava dome was formed. In the present paper, focal mechanism solutions of 759 earthquakes (M : 2.8-4.3), which swarmed associating with the 1977-1978 eruptions of the volcano, are analyzed for the periods of October 1977, March and August 1978, and January and June 1979, using P-wave first motions at 8-12 seismometric stations. The results show that the focal mechanisms were almost equal to each other for each seismic cluster and each locality throughout 20 months, irrespective of the occurrence of major explosions (July to September 1978) and sudden increase in seismic activity and crustal deformations (the end of January 1978). The distribution of the principal stress axes can not be explained by the tectonic stress in this region. The spatial distribution of the compressional stress axes may suggest the intrusion of inclining magma body beneath the volcano. Remarkable uplift and northeastward deformation of the volcano may support this model.
View full abstract
-
Takeo MORIYA
Article type: Letter
1981 Volume 26 Issue 2 Pages
111-112
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
Tatsuo SASAKI, Yoshio KATSUI, Sumio KUMANO
Article type: Letter
1981 Volume 26 Issue 2 Pages
113-116
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
Tatsuo SASAKI, Yoshio KATSUI
Article type: Letter
1981 Volume 26 Issue 2 Pages
117-118
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
Yoshiro ITO, Chikataka KAWAKAMI, Teruo SAITO, Ko ICHIKAWA, Tetsuya HOS ...
Article type: Letter
1981 Volume 26 Issue 2 Pages
119-121
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
T. Kagiyama, T. Takeda, N. Osada
Article type: Abstract
1981 Volume 26 Issue 2 Pages
123-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
J. Iriyama, S. Shimoge, T. Saito
Article type: Abstract
1981 Volume 26 Issue 2 Pages
123-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
Y. Matsumoto, M. Hayashi, T. Yamasaki
Article type: Abstract
1981 Volume 26 Issue 2 Pages
123-124
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
S. Taguchi, M. Hayashi, T. Yamasaki, Y. Matsumoto, T. Fujino
Article type: Abstract
1981 Volume 26 Issue 2 Pages
124-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
H. Umehara, Hm. Okada
Article type: Abstract
1981 Volume 26 Issue 2 Pages
124-125
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
Hm. Okada
Article type: Abstract
1981 Volume 26 Issue 2 Pages
125-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
M. Seino
Article type: Abstract
1981 Volume 26 Issue 2 Pages
125-126
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
H. Yamashita
Article type: Abstract
1981 Volume 26 Issue 2 Pages
126-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
H. Imai
Article type: Abstract
1981 Volume 26 Issue 2 Pages
126-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
N. Fujii
Article type: Abstract
1981 Volume 26 Issue 2 Pages
126-127
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
S. Nakada
Article type: Abstract
1981 Volume 26 Issue 2 Pages
127-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
M. Yamamoto
Article type: Abstract
1981 Volume 26 Issue 2 Pages
127-128
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
S. Togashi
Article type: Abstract
1981 Volume 26 Issue 2 Pages
128-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
K. Uto
Article type: Abstract
1981 Volume 26 Issue 2 Pages
128-129
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
H. Fukuyama
Article type: Abstract
1981 Volume 26 Issue 2 Pages
129-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
E. Takahashi, I. Kushiro
Article type: Abstract
1981 Volume 26 Issue 2 Pages
129-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
I. Kushiro, E. Takahashi
Article type: Abstract
1981 Volume 26 Issue 2 Pages
129-130
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
Y. Tatsumi
Article type: Abstract
1981 Volume 26 Issue 2 Pages
130-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
K. Shiraki, S. Maruyama, K. Kuramoto
Article type: Abstract
1981 Volume 26 Issue 2 Pages
130-131
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
M. Sakuyama
Article type: Abstract
1981 Volume 26 Issue 2 Pages
131-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
T. Suzuki
Article type: Abstract
1981 Volume 26 Issue 2 Pages
131-132
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
M. Kamada, H. Sakamoto, Y. Sugiura
Article type: Abstract
1981 Volume 26 Issue 2 Pages
132-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
T. Onishi, M. Kamada, K. Ota
Article type: Abstract
1981 Volume 26 Issue 2 Pages
132-133
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
K. Chihara
Article type: Abstract
1981 Volume 26 Issue 2 Pages
133-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
T. Ui
Article type: Abstract
1981 Volume 26 Issue 2 Pages
133-134
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
S. L. Bhushan, K. Yagi
Article type: Abstract
1981 Volume 26 Issue 2 Pages
134-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
Y. Oba, H. Yamagishi
Article type: Abstract
1981 Volume 26 Issue 2 Pages
134-135
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
S. Umino
Article type: Abstract
1981 Volume 26 Issue 2 Pages
135-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
T. Kobayashi, T. Soya
Article type: Abstract
1981 Volume 26 Issue 2 Pages
135-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
H. Taniguchi
Article type: Abstract
1981 Volume 26 Issue 2 Pages
135-136
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
H. Tsunakawa, K. Heki
Article type: Abstract
1981 Volume 26 Issue 2 Pages
136-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
S. Suto
Article type: Abstract
1981 Volume 26 Issue 2 Pages
136-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
S. Tamanyu, T. Shirahase, S. Togashi
Article type: Abstract
1981 Volume 26 Issue 2 Pages
136-137
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
H. Kurasawa, T. Konda
Article type: Abstract
1981 Volume 26 Issue 2 Pages
137-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
K. Notsu
Article type: Abstract
1981 Volume 26 Issue 2 Pages
137-138
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
S. Yanai
Article type: Abstract
1981 Volume 26 Issue 2 Pages
138-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
S. Ehara, K. Yuhara
Article type: Abstract
1981 Volume 26 Issue 2 Pages
138-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
A. Takeuchi
Article type: Abstract
1981 Volume 26 Issue 2 Pages
138-139
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
Y. Kobayashi, N. Fujii
Article type: Abstract
1981 Volume 26 Issue 2 Pages
139-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
D. Shimozuru, N. Kubo
Article type: Abstract
1981 Volume 26 Issue 2 Pages
139-140
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
H. Watanabe
Article type: Abstract
1981 Volume 26 Issue 2 Pages
140-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
Y. Hayakawa
Article type: Abstract
1981 Volume 26 Issue 2 Pages
140-141
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS
-
J. Sato, K. Sato
Article type: Abstract
1981 Volume 26 Issue 2 Pages
141-
Published: July 01, 1981
Released on J-STAGE: January 15, 2018
JOURNAL
FREE ACCESS