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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy (S) - IASPEI - International Association of Seismology and Physics of the Earth's Interior JSS008 Poster presentation 2003 The Magnetic Storm influence on the Pre-seismic Ionosphere Anomaly (a case study) Mr. Vitali Shpakovski IZMIRAN, Russian Academy Scientist IASPEI I. E. Zakharenkova, Yu.Ya. Ruzhin, I.I.Shagimuratov, N.Yu. Tepenitsina The ionosphere total electron content (TEC) variations obtained by using the GPS measurements before Hokkaido earthquake of September 25, 2003 (M8.3) is investigated. The pre-seismic plasma anomaly appeared as the local TEC enhancement (plasma cloud) located in the vicinity of the forthcoming earthquake epicenter. These structures are generated at the similar local time in ionosphere during 5 days prior to the main shock. It is shown that according to its main parameters (locality, affinity with the epicenter, dome-shaped zone of manifestation and time of existence) the detected ionospheric anomaly may be associated to the future seismic activity. It is necessary to mention that geomagnetic storm took place one day prior to the main shock and usually it is appeared at ionosphere as global disturbance (or ionosphere storm). It is shown that the spatial-temporal TEC variations can be presented as superposition of ionospheric storm effects and the ionosphere anomaly of seismogenic origin. As result, the intensification of the pre-seismic plasma anomaly due to magnetic storm action (up to 85-90% of non-disturbed level) became visible at ionosphere 18 hours (one day) before Hokkaido earthquake Keywords: pre seismic, ionosphere, earthquake

IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy (S) - IASPEI - International Association of Seismology and Physics of the Earth's Interior JSS008 Poster presentation 2004 Analytical study on piezomagnetic effect due to 3-D magnetic structure and it's applications to the earthquakes in Japan Prof. Yasunori Nishida Institute of Seismology and Volcanology Faculty of Science IAGA Mitsuru Utsugi, Toru Mogi We developed an analytical form of the piezomagnetic field due to a non-uniformly magnetized medium. In order to represent the non-uniform distribution of the crustal magnetization, we divide the crust into a number of blocks assuming that each block has its own magnetic properties. The piezomagnetic potential derived from a single block is expressed by a definite surface integral of an integrand, which includes the magnetization change and displacement of the medium, over the boundary surface of the block (the representation theorem by Sasai, 1991). We show the surface integral is reduced analytically to the line integral which has the integrand including elliptic integrals. The line integral is calculated numerically to represent the piezomagnetic potential. This method of analysis is advantageous to fast computation of the piezomagnetic fields. No co-seismic geomagnetic changes related with the 2003 Tokachi-oki earthquake (M8.0) and the 2004 Kushiro-oki earthquake (M7.1) in Hokkaido, Japan were observed at a magnetic station whose epicentral distances were about 120 km and 50 km, respectively. Applying the above-mentioned analytical method, model calculations showed that co-seismic piezomagnetic fields did not amount to 1 nT at the station in both cases when we assumed the relevant fault parameters, in-situ Curie temperature depth, subsurface 3-D magnetic structure and stress sensitivity of rocks. Therefore, it may be reasonable that we could not detect the piezomagnetic signals at the station. We also made model calculations to forecast the piezomagnetic amplitudes caused by M7.9 and M8.5 earthquakes predicted to occur along the southern Kurile trench and by M7.8 earthquake in the central Japan (Tokai earthquake) in the future. The model calculations reveal the piezomagnetic fields up to about 4 nT and 7 nT are expected in the eastern part of the Hokkaido island for the M7.9 and M8.5 earthquakes and +25 nT on the Sagami trough for the M7.8 earthquake, encouraging magnetic observations hereafter. Keywords: piezomagnetism, theory, observations

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