史前における地滑りと,ワシントン州シアトルの急激な地質変動の間の樹輪相関
Science (New York, N.Y.)
|December 4, 1992
まとめ
およそ1000年前の史前地震は,おそらくワシントン湖の地滑りやプージェット・サウンドの津波を引き起こした. この地震は,また,シアトル地域の急激な土地沈没を引き起こした.
科学分野:
- 地質学 地質学 地質学
- パレオシズモロジー (Paleoseismology) とは
- 四次科学とは四次科学である.
背景:
- ワシントン湖の地滑り積層に沈んだ木は地質学的証拠を提供している.
- これらの堆積物の年代付けは,シアトル地域の過去の地震を復元するのに役立ちます.
研究 の 目的:
- ワシントン湖で最近起きた山崩れのタイミングを把握するためです.
- プージェット・サウンド地域における,これらの山体滑りと他の地震現象の間の潜在的な関連性を調査する.
主な方法:
- 地滑りによる沈没した木の放射性炭素年代測定.
- 樹輪の交差は,樹木の死亡率の正確な日付を決定する.
- 津波の堆積と沈没に関する地質学的証拠の分析.
主要な成果:
- 放射性炭素年代は,およそ1000年前,ワシントン湖の3つの地域で同時に地滑りが起こったことを示唆しています.
- 樹輪の分析により,滑り落ちた土壌と津波がもたらした土壌の樹木が,同じ季節,同じ年に枯れてしまったことが明らかになった.
- 証拠によると,湖の地滑り,津波の可能性,そして急落の沈没が偶然に起こったことを示している.
結論:
- シアトル地域では1000年ほど前に強烈な史前地震が起きました.
- この地震は,ワシントン湖の地滑りとプジェット・サウンドの津波の原因とされている.
- この発見は,太平洋北西部の地震の危険性を理解するための重要なデータを提供します.
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