Acccretionary Wedge Aseismicity: The Seismic Front and Failure Modes of Sedimentary Rocks

增生楔抗震性：沉积岩的地震锋和破坏模式

• 批准号: 8721045
• 负责人: Daniel Davis
• 金额: $ 9.99万
• 依托单位: SUNY at Stony Brook
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-03-01 至 1990-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8721045&HistoricalAwards=false
• 关键词: Acccretionary; Wedge; Aseismicity; Seismic; Front

A fundamental understanding of the deformation behavior and failure modes of sediments and porous rocks is important in understanding the distribution of seismicity in a number of geological settings. This is particularly true of the deepest, arcward ends of accretionary wedges, the aseismic masses of accreted sediments beneath the landward slopes of many convergent plate boundaries. This problem is particularly important in accretionary wedges because of their aseismicity, and because of the importance of understanding the nature of the 'seismic front', which marks the trenchward limit of plate-boundary thrust earthquakes at or near the back of the wedge. Although the lower, thermally controlled, boundary of the thrusting seismogenic zone is reasonably well understood, the shallow limit has not been properly explained. Because of the very small dip of the plate boundary at such shallow depths, this leads to a great deal of uncertainty about the total width of the seismogenic zone, upon which the maximum possible earthquake size depends very strongly.

对沉积物和多孔岩石的变形行为和破坏模式的基本理解对于理解地震活动在许多地质环境中的分布是重要的。这一点在增生楔的最深处、向外的末端尤其正确，增生楔是在许多会聚板块边界的向陆斜坡下的大量增生沉积物。这个问题在增生楔中尤为重要，因为它们具有抗震性，而且了解“地震锋”的性质也很重要。“地震锋”标志着楔背或楔背附近板块边界逆冲地震的向沟极限。虽然对逆冲发震带的下部热控边界有相当好的了解，但对其浅部边界还没有适当的解释。由于在如此浅的深度，板块边界的倾角非常小，这就导致了孕震带总宽度的很大不确定性，而最大可能的地震规模很大程度上取决于孕震带的总宽度。