| 講演要旨(和文) | | 秋田県秋ノ宮地熱地帯にて取得の反射法弾性波探査にて認められる深部楔形状反射イベントは固結マグマと解釈した。その検証のため総合的な重磁力解析を行った。ブーゲー重力異常と空中磁気異常をクロスプロットすることで基盤岩とその上面を覆う凝灰岩との磁化の違いを反映する地域的傾向が認められる。この傾向を取り除く事で深部無磁化マグマの磁気異常値への影響を抽出、解析できる。解析結果はマグマ分布や上面の凸凹、或いは主に基盤岩が浅い地域に偏在するシル、陥入を評価する上で有益でまた現在活動中の火山との関連性も良い。固結マグマ層厚推定結果は反射法解釈結果にも十分整合している。 |
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| | 講演要旨(英文) | | The wedge type events were interpreted as deeply situated consolidated magma in the seismic survey of the Akinomiya geothermal area in the Akita prefecture in northern Japan. For its verification, the gravity and air-magnetic data was analyzed integrally. The cross plots of the Bouguer gravity anomaly and the air-magnetic anomaly show the regional trend which reflects the magnetic effects from the magnetization difference between basement rocks and overlying tuff rocks. By applying the formula representing the trend, the portion of magnetic anomaly reflecting only from the underground non-magnetized magma can be extracted and analyzed. The results are encouraging to assess and draw the distribution and uneven surface of the magma and the sills and intrusions as well, mainly situated on basement high areas rather than those of depression and connecting well to the areas of currently active volcanos. The results of the estimated consolidated magma thickness also fit satisfactorily in the results of seismic interpretation. |
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