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Paleoseismology of the Hyde Fault, Otago, New Zealand
New Zealand Journal of Geology and Geophysics ( IF 2.2 ) Pub Date : 2021-11-22 , DOI: 10.1080/00288306.2021.1995007
Jonathan D. Griffin 1, 2 , Mark W. Stirling 1 , David J.A. Barrell 3 , Ella J. van den Berg 1, 4 , Erin K. Todd 5 , Ross Nicolls 1 , Ningsheng Wang 6
Affiliation  

ABSTRACT

We present the first paleoseismic investigation of the Hyde Fault, one of a series of north-east striking reverse faults within the Otago range and basin province in southern New Zealand. Surface traces of the fault and associated geomorphology were mapped using a lidar digital elevation model and field investigations. Trenches were excavated at two sites across fault scarps on alluvial fan surfaces. The trenches revealed stratigraphic evidence for four surface-rupturing earthquakes. Optically stimulated luminescence dating constrains the timing of these events to around 47.2 ka (37.5–56.7 ka at 95% confidence), 34.6 ka (24.7–46.4 ka), 23.5 ka (19.7–27.3 ka) and 10.5 ka (7.9–13.1 ka). We obtain a mean inter-event time of 12.4 kyr (2.3–23.9 kyr at 95% confidence) and the slip rate is estimated to be 0.22 mm/yr (0.15–0.3 mm/yr). We do not find evidence to suggest that earthquake recurrence on the Hyde Fault is episodic, in contrast to other well-studied faults within Otago, suggesting diverse recurrence styles may co-exist in the same fault system. This poses challenges for characterising the seismic hazard potential of faults in the region, particularly when paleoearthquake records are limited to the most recent few events.



中文翻译:

新西兰奥塔哥海德断层的古地震学

摘要

我们提出了对海德断层的首次古地震调查,海德断层是新西兰南部奥塔哥山脉和盆地省内一系列东北走向的逆向断层之一。使用激光雷达数字高程模型和实地调查绘制了断层和相关地貌的表面痕迹。在冲积扇表面的断层陡坡上的两个地点开挖了沟渠。这些沟槽揭示了四次地表破裂地震的地层证据。光激发光测年将这些事件的时间限制在 47.2 ka(37.5-56.7 ka,95% 置信度)、34.6 ka(24.7-46.4 ka)、23.5 ka(19.7-27.3 ka)和 10.5 ka(7.9-13.1 ka)左右). 我们获得的平均事件间隔时间为 12.4 kyr(95% 置信度下为 2.3-23.9 kyr),滑移率估计为 0.22 毫米/年(0.15-0.3 毫米/年)。我们没有找到证据表明海德断层的地震复发是偶发性的,这与奥塔哥内其他经过充分研究的断层相反,这表明不同的复发方式可能共存于同一断层系统中。这对描述该地区断层的地震危险潜力提出了挑战,特别是当古地震记录仅限于最近的少数事件时。

更新日期:2021-11-22
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