巻号一覧
36 巻, 12 号
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Akira HAYASHIDA1984 年 36 巻 12 号 p. 585-608
発行日: 1984年
公開日: 2010/09/14
ジャーナル フリーDetailed paleomagnetic studies have been carried out on two sections of the Pleistocene sediments in the Kinki district, central Japan: the Takashima Formation exposed on the northwest coast of Lake Biwa, and the terrace forming deposits distributed in the northern area of Akashi City, about 150km west of Lake Biwa. While these strata are assigned to the late Brunhes normal epoch, reversed polarity zones are observed in both sections. Based on correlation of volcanic ash layers intercalated in the sections, these reversed polarity zones are identified as the records of a reversed polarity episode, the Biwa I ‘event’, which was previously reported from a 200-m-long core sample from Lake Biwa. This result confirms occurrence of a fully reversed geomagnetic field in the late Brunhes Epoch at least in central Japan. The Biwa I episode is possibly correlated to the Jamaica ‘event’ known from several deep-sea cores, and then the episode is suggested to be a global geomagnetic phenomenon in the late Brunhes epoch.抄録全体を表示PDF形式でダウンロード (2216K) -
J. L. LE MOUEL, M. MENVIELLE, J. P. POZZI, G. SIMON, J. ZLOTNICKI1984 年 36 巻 12 号 p. 609-619
発行日: 1984年
公開日: 2010/09/14
ジャーナル フリーSince 1978 the routine surveillance of La Soufrière volcano (Guadeloupe, F.W.I.) is performed using measurements of the total intensity (B) of the Earth magnetic field made at 3 stations radio-transmitted to the Fort Saint-Charles observatory. Differences ΔB between values of B measured at two of these stations and the one simultaneously measured at the third one (Matouba, the reference station) are computed; values of ΔB recorded around 2:00a.m. are used to monitor the volcano-magnetic field. These 3 stations are installed in areas where (1) the reduction and projection errors are as weak as possible (2) the volcano-magnetic signal is expected to be noticeable during a volcanic crisis.
The observations made using this network during the years 1979 to 1981 are presented. During these 3 years of no abnormal volcanic activity, the volcano-magnetic field, if any, remains below the experimental noise level.抄録全体を表示PDF形式でダウンロード (841K) -
L. R. ALLDREDGE1984 年 36 巻 12 号 p. 621-633
発行日: 1984年
公開日: 2010/09/14
ジャーナル フリーIt is shown that if many dipole core sources are oscillating with periods from 15 to 35 years, their combined effect could confuse our understanding of secular variation and be a real contributor to the rapid deterioration of predictive models. High harmonics are more important in the discription of secular variation than they are in the description of the main field.抄録全体を表示PDF形式でダウンロード (818K)
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