Volcanic Activity in Japan Monitored by the Japan Meteorological Agency Using Detected Precursory Phenomena

Author(s):  
Y. Sawada ◽  
Y. Tanaka ◽  
M. Seino
2012 ◽  
Vol 12 (1) ◽  
pp. 121-127 ◽  
Author(s):  
Y. Orihara ◽  
M. Kamogawa ◽  
T. Nagao ◽  
S. Uyeda

Abstract. For the prediction of the expected Tokai Earthquake (EQ), Japan Meteorological Agency (JMA) has been observing volumetric strain changes to detect its presumed pre-slip phenomena in Tokai and South Kanto regions. In 1998, an anomalous volumetric strain change, lasting for 5 days, which initially attracted much attention as a possible precursor to the Tokai EQ, was observed at Shimizu station in the Tokai area. Eventually, the Tokai EQ did not occur and the causal mechanism of the observed anomaly was unknown. However, we found variations of geoelectric potential differences (GPD) possibly associated with the anomaly by applying Principal Component Analysis (PCA) to the GPD data taken in the same area. From the polarities of the observed GPD changes, we infer that these GPD variations were caused by electrokinetic effects of groundwater motion, which might have been related with the strain changes. These results imply that the GPD observations may assist us in understanding the nature of EQ precursory phenomena.


1996 ◽  
Vol 6 (10) ◽  
pp. 1391-1402 ◽  
Author(s):  
Anders Johansen ◽  
Didier Sornette ◽  
Hiroshi Wakita ◽  
Urumu Tsunogai ◽  
William I. Newman ◽  
...  

Palaeobotany ◽  
2015 ◽  
Vol 6 ◽  
pp. 48-67 ◽  
Author(s):  
L. B. Golovneva ◽  
A. A. Grabovskiy

Plant fossils from the volcano-clastic deposits of the lower part of the Tanyurer Formation and lower part of the Tavaivaam Unit in the Anadyr city area (Northeastrn Russia) are described for the first time. This assemblage was named as the Temlyan flora. It consists of 25 taxa and includes ferns, horsetails, lycophytes, ginkgoaleans, czekanowskialeans, cycadophytes, conifers and angiosperms. The Temlyan flora is similar in systematic composition to the Rarytkin flora from the upper part of the Rarytkin Formation which was dated as the late Maastrichtian-Danian. But it is distinguished from the latter by presence of the numerous relicts (Lokyma, Nilssonia, Encephalartopsis, Phoenicopsis and Ginkgo ex gr. sibirica). Probably the presence of relicts in the Temlyan flora is connected with influence of volcanic activity. Age of the Temlyan flora is determined as the late Maastrichtian-Danian on the basis of systematic similarity with the Rarytkin Flora. However this age may be slightly younger, possibly only early Paleocene, because the Tanyurer Formation superposes the Rarytkin Formation. Stratigraphic range of Lokyma, Nilssonia, Encephalartopsis, Phoenicopsis and Ginkgo ex gr. sibirica is extended from its previously known latest records in the early Campanian or middle Maastrichtian up to as late as the latest Maastrichtian or early Paleocene. It is very possible, that these typical Mesozoic taxa may have persisted into the Paleogene.


1995 ◽  
Author(s):  
Michael P. Doukas ◽  
Robert G. McGimsey ◽  
Joseph M. Dorava
Keyword(s):  

Author(s):  
James P. Dixon ◽  
Cheryl Cameron ◽  
Robert G. McGimsey ◽  
Christina A. Neal ◽  
Chris Waythomas

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