著者

Y. Sue

出版者

Society of Atmospheric Electricity of Japan

雑誌

Journal of Atmospheric Electricity (ISSN:09192050)

巻号頁・発行日

vol.29, no.1, pp.53-62, 2009 (Released:2010-07-09)

参考文献数

9

被引用文献数

2 1

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The question of whether earth tides trigger earthquakes has been the subject of debate for years. Recent studies, at last, have proven the significance of the earth tide effect in triggering earthquakes, and they further reported that the direction of the compressional stress at a region created by the earth tide almost coincides with that of the dominant principal pressure axes of the focal mechanisms at the region. This suggests that there might be specific positions of the Moon, Sun and Earth, known as lunar phases that create effective tidal force for earthquakes at each fault. So that, this paper examines the relationship between earthquakes and the lunar phases in some specific regions of Japan, and the significant effect of earth tide in triggering earthquakes is confirmed.

著者

本島 邦行

出版者

Society of Atmospheric Electricity of Japan

雑誌

Journal of Atmospheric Electricity (ISSN:09192050)

巻号頁・発行日

vol.31, no.1, pp.37-49, 2010 (Released:2012-11-12)

参考文献数

14

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This paper was intended to find out any relation between anomalous line-of-sight propagations in the VHF band and occurrences of earthquakes near the VHF propagation path. The broadcasting waves from Tokyo tower were monitored continuously for 1155 days at Kiryu Gunma. Anomalous propagations were distinguished from the received data by using a statistical analysis. After the statistical thoughtful consideration, it was found out that earthquakes associated with anomalous propagations were characterized by (1) magnitude of earthquakes M≧4.5, (2) distance from epicenters L≦75km and (3) depth of hypocenters D≦50km.

著者

酒井 英男 上坂 麻子 黒沢 尚美 高橋 貞夫 三宅 幸博

出版者

Society of Atmospheric Electricity of Japan

雑誌

Journal of Atmospheric Electricity (ISSN:09192050)

巻号頁・発行日

vol.17, no.2, pp.103-111, 1997 (Released:2021-03-12)

著者

鈴木 智幸 平野 竜貴 谷口 泰也 木村 貴光

出版者

日本大気電気学会

雑誌

Journal of Atmospheric Electricity (ISSN:09192050)

巻号頁・発行日

vol.41, no.1, pp.1-10, 2022 (Released:2022-06-16)

参考文献数

10

著者

Tomoki Higuchi Nozomi Haga Kuniyuki Motojima

出版者

日本大気電気学会

雑誌

Journal of Atmospheric Electricity (ISSN:09192050)

巻号頁・発行日

vol.34, no.2, pp.87-100, 2014 (Released:2014-08-28)

参考文献数

10

---

Recently, electromagnetic phenomena associated with earthquakes have gotten a lot of attention. So, we have been observed VHF band propagation for long timeand analyzed statistical relation between anomalous line-of-sight propagation in the VHF band and occurrences of earthquakes using quantitative evaluation. Now, we need to detect the anomalous propagation from received data. Therefore, we used a statistical analysis to judge anomalous propagation in a previous study. In this paper, we judged the anomalous propagation by continuous wavelet transform and evaluated the relationship with earthquakes. Furthermore, we introduced hit rate and alarm rate to simplify the relationship between anomalous propagation and earthquakes. As a result, relation between anomalous propagation and earthquakes became clear.

著者

大澤 祐輝 小倉 佑哉 本島 邦行

出版者

日本大気電気学会

雑誌

Journal of Atmospheric Electricity (ISSN:09192050)

巻号頁・発行日

vol.38, no.1, pp.11-21, 2019 (Released:2020-04-16)

参考文献数

12

著者

大村 潤平 山口 弘輝 大山 佳織 韓 鵬 吉野 千恵 小島 春奈 服部 克巳 下 道國 小西 敏春 古屋 隆一

出版者

日本大気電気学会

雑誌

Journal of Atmospheric Electricity (ISSN:09192050)

巻号頁・発行日

vol.38, no.1, pp.37-52, 2019

著者

Satoshi Ujigawa Hiroyuki Nakata Shin Shimakura

出版者

Society of Atmospheric Electricity of Japan

雑誌

Journal of Atmospheric Electricity (ISSN:09192050)

巻号頁・発行日

vol.29, no.2, pp.115-123, 2009 (Released:2011-04-12)

参考文献数

10

被引用文献数

1 1

---

Observation of 48.25-MHz radio waves transmitted from Bangkok, Thailand, was carried out at Tateyama, Japan, during 2001. Since the radio wave propagates through a crest of equatorial anomaly, which disturbs stratified structure of the ionosphere, it is conceivable that the propagation of the radio wave is affected by three-dimensional structure of the ionosphere. Seasonal and diurnal variations of the signal intensity are quite similar to ƒ0F2 above Guangzhou and also Okinawa, which are located on the great circle path between Bangkok and Tateyama. Using ray-tracing calculations with the distribution of the electron density determined by IRI model, it is also confirmed that the radio wave propagates to Tateyama because of one-hop reflection in the ionosphere and that MUF is mainly dependent on ƒ0F2 above the midpoint between Bangkok and Tateyama. Although the value of ƒ0F2 is almost constant, MUF calculated by the ray-tracing treatment decreases around 14 JST in fall and winter. This decrease is also detected in the observational result of the signal intensity of the radio wave received at Tateyama. The ray tracing calculation shows that the decrease of MUF is due to tilt of the distribution of electron density, which is noticeable in developing the equatorial anomaly. Then discussing the propagation characteristics of 48.25-MHz radio waves crossing equatorial anomaly region, it is important to consider not only the parameters of the ionosphere, e.g. ƒ0F2, but also the tilt of the distribution of electron density.

著者

畑 雅恭 内匠 逸 太田 健次 井筒 潤 藤井 隆司 佐藤 時康 矢橋 清二 渡辺 伸夫

出版者

Society of Atmospheric Electricity of Japan

雑誌

Journal of Atmospheric Electricity (ISSN:09192050)

巻号頁・発行日

vol.30, no.1, pp.37-52, 2010 (Released:2012-04-07)

参考文献数

16

被引用文献数

1

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ELF (30-300 Hz) band three-axial magnetic-flux receiver was developed for detecting electromagnetic-wave precursor of earthquakes and volcanic eruption. The receiver attained a high sensitivity of 0.4pT/√Hz (223Hz) and 4.5 pT/√Hz (17Hz) for the ground based observation of the ambient magnetic flux anomaly. The receiver was extended to detect ultra-low-frequency (ULF) variation (0.1 to 10-7Hz) of crust magnetic flux by through MMD (Modulated Magnetic-flux Detection) reception. It detects the modulated components of the ELF band atmospheric signal which are produced by the crust ULF magnetic-flux variation. The receiver noise due to the artificial noise can be smoothed out from the objective ULF magnetic flux signal by introducing long term integration for the period of 107 seconds of the detected signal. The receiver detected the ULF anomaly of magnetic variation and the Schumann Resonance variation appeared before the two earthquakes of the class M7 occurred in Japan in 2005 and 2007 respectively.

著者

大曽根 暖 小川 潤也 羽賀 望 本島 邦行

出版者

日本大気電気学会

雑誌

Journal of atmospheric electricity (ISSN:09192050)

巻号頁・発行日

vol.33, no.2, pp.115-125, 2013-08-01

参考文献数

16

被引用文献数

1

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In our previous paper, statistical relation between anomalous line-of-sight propagation in the VHF band and occurrences of earthquakes was presented. Basically, the anomalous propagation is mainly caused by anomalous refractive index of low atmosphere. In the present paper, the anomalies of the refractive index is captured by both the direct observation of radio ducts and the anomalous propagation in the VHF band, and the relation between them and the earthquakes are statistically clarified. Furthermore, the influences of meteorological conditions, which may disperse the anomalies of refractive index in the low atmosphere, are discussed. As a result, relation between anomalous propagation and earthquakes became increasingly clear by using anomalous propagation that concurrent with S-type ducts and meteorological conditions, wind velocity.

著者

Kyosuke Ishii Syugo Hayashi Fumiaki Fujibe

出版者

日本大気電気学会

雑誌

Journal of Atmospheric Electricity (ISSN:09192050)

巻号頁・発行日

vol.34, no.2, pp.79-86, 2014 (Released:2014-08-28)

参考文献数

24

被引用文献数

2 20

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The temporal and spatial distributions of cloud-to-ground (CG) lightning in and around Japan were examined for a seven-year period (2002?2008) by using lightning location data from the Lightning Detection Network System operated by the Japan Meteorological Agency. The frequency of CG flashes was found to be high over land area in summer. During winter, many CG flashes were located along the coast of the Sea of Japan of central Honshu (Hokuriku area) and off the coast of the Pacific side (Kanto-Tokai area). A detailed analysis of the Hokuriku and Kanto-Tokai areas revealed diurnal variations characterized by a peak in the afternoon for inland areas, and a peak in early morning for coastal and offshore areas of the Hokuriku area in summer. For winter, the diurnal variation of CG flash density is indistinct in the Hokuriku region, where CG flashes are strongly concentrated within 20 km from the coastline, whereas it has a maximum in the early morning off the coast of the Kanto-Tokai area.