A New Look at Evidence for a Wadati–Benioff Zone and Active Convergence at the North Panama Deformed Belt
A New Look at Evidence for a Wadati–Benioff Zone and Active Convergence at the North Panama Deformed Belt
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DOI：
10.1785/0120090204
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发表时间：
2010-02
影响因子：
3
通讯作者：
E. Camacho;W. Hutton;J. Pacheco
中科院分区：
文献类型：
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作者：
E. Camacho;W. Hutton;J. Pacheco
巴拿马微板块北方边界的性质，通常被称为北巴拿马变形带（NPDB），一直是许多推测的主题。以前的研究已经使用了各种数据，包括重力，水深，海洋磁力，以及对隆起和海啸沉积物的实地研究，以及从历史地震中修改的Mercalli强度分布，以揭示NPDB的性质。数据已经收集了30多年，但NPDB的性质仍然不清楚。目前的分析和解释提供了一些相互排斥的选择和许多争议。在这篇文章中，我们检查当地和区域的地震活动性，结合地震观测和历史地震数据，为NPDB提供另一种分析。利用当地网络记录的小地震，我们成像了一个明确的Wadati-Benioff带，该带在巴拿马微板块下方向南倾斜。这些数据提供了关于巴拿马微板块-加勒比板块边界运动学性质的新证据，并证明存在一个活跃的俯冲带。今后的地震危险评估应包括对巴拿马近海NPDB沿着地震活动和板块相互作用的性质的更全面了解，包括能够产生7级以上地震的俯冲带。
The nature of the northern boundary of the Panama microplate, often referred to as the north Panama deformed belt (NPDB), has been the subject of much speculation. Previous studies have used a variety of data, including teleseismic, gravity, bathymetric, marine magnetic, and field studies of uplift and tsunami deposits, as well as modified Mercalli intensity distributions from historic earthquakes to reveal the nature of the NPDB. Data have been collected for over 30 yrs and yet the character of the NPDB remains unclear. Current analyses and interpretation provide a number of mutually exclusive options and much controversy. In this article we examine local and regional seismicity combined with teleseismic observations and historic earthquake data to present an alternative analysis for the NPDB. Using small earthquakes recorded by a local network we image a well-defined Wadati–Benioff zone dipping southward beneath the Panama microplate. These data provide new evidence regarding the nature of Panama microplate–Caribbean plate boundary kinematics and demonstrate the existence of an active subduction zone. A more complete understanding of the nature of the seismicity and plate interactions along the NPDB offshore Panama, including a subduction zone capable of producing earthquakes of M >7, should be included in future earthquake hazard assessments.