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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Seismic cycle and plate margin deformation in Costa Rica: GPS observations from 1994 to 1997
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Seismic cycle and plate margin deformation in Costa Rica: GPS observations from 1994 to 1997

机译:哥斯达黎加的地震周期和板块边缘变形:1994年至1997年的GPS观测

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Global Positioning System (GPS) observations in Costa Rica from 1994 to 1997 reveal a complex pattern of motion consistent with the superposition of seismic cycle and secular plate margin deformation. In the south, velocity vectors are consistent with motion of the Panama Block plus postseismic deformation following the 1991 Limon earthquake and interseismic strain due to partial locking of the Middle America Trench (MAT) thrust. In the northwest, sites west of the volcanic arc are moving to the NW as a forearc sliver. Superimposed on this sliver motion are vertical and horizontal interseismic deformations from the adjacent Nicoya segment of the MAT. We apply two different inverse methods to understand the source of the seismic strain in NW Costa Rica. We compare fault-locking models derived using a singular value decomposition inversion with that of a simulated annealing global optimization approach. Both methods yield similar models for partial locking of the thrust interface beneath the Nicoya Peninsula. Our results define an area of nearly fully locked fault beneath the outer coast of the southern portion of the peninsula. With somewhat lower coupling beneath the northern half and with low coupling elsewhere. These initial results show the promise for detailed imaging of the locked portion of a thrust interface responsible for future large subduction zone earthquakes.
机译:1994年至1997年在哥斯达黎加进行的全球定位系统(GPS)观测发现,运动的复杂模式与地震周期和长期板块边缘变形的叠加相一致。在南部,速度矢量与巴拿马街区运动以及1991年利蒙地震后的地震后形变以及中美洲海沟(MAT)推力的部分锁定所引起的地震应变相一致。在西北部,火山弧以西的地点正以前额条的形式移至西北。在此条子运动上叠加了来自MAT相邻Nicoya段的垂直和水平间地震形变。我们应用两种不同的反演方法来了解哥斯达黎加西北部的地震应变源。我们比较了使用奇异值分解反演和模拟退火全局优化方法得出的故障锁定模型。两种方法都产生了类似的模型,用于部分锁定尼科亚半岛下方的推力界面。我们的结果确定了半岛南部外海岸下方几乎完全锁定的断层区域。在北半部下方的耦合较低,而在其他地方的耦合较低。这些初步结果表明,有望对负责未来大型俯冲带地震的推力界面的锁定部分进行详细成像。

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