6:15 PM - 7:30 PM
[SEM33-P09] Geomagnetic three-component secular changes in eastern Hokkaido, NE Japan
Keywords:geomagnetic three-component absolute measurements, geomagnetic secular change, eastern Hokkaido
In the total field, the values at each station have been subtracted from values at the reference station Memambetsu Magnetic Observatory (MMB) of Japan Meteorological Agency to remove the variations of extra-terrestrial origins. We applied the same procedure also to declination, horizontal and vertical components. We then recognized that the rate of secular change in individual component also differs from site to site. Now, it is clear that the anomalous secular changes in the total field in this area were not brought by the so-called orientation effect. Trends of horizontal and vertical components were steeper near the southern coast as in the case of the total field. Declination seemed more complicated, presumably showing clockwise rotation in the northern area, while anti-clockwise in the south.
Current results are still preliminary because the number of absolute measurements is small yet. It is necessary to add further data in order to make the discussion more accurate. In addition, numerical modeling of piezomagnetic effect in three-component will contribute to constrain the mechanism of the anomaly.