Late Quaternary episodic displacement on a sackung scarp in the central Spanish Pyrenees. Secondary paleoseismic evidence?
Late Quaternary episodic displacement on a sackung scarp in the central Spanish Pyrenees. Secondary paleoseismic evidence?
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西班牙比利牛斯山脉中部萨贡陡坡上第四纪晚期的间歇性位移。
DOI：
10.3166/ga.21.187-202
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
M. Soldati
中科院分区：
文献类型：
--
作者：
F. Gutiérrez;M. Ortuño;P. Lucha;J. Guerrero;E. Acosta;Paola Coratza;D. Piacentini;M. Soldati
在西班牙比利牛斯山脉中部，人们通过挖沟调查了一个陡峭的悬崖。这一特征位于北马拉迪塔断层西南18公里处，该断层最有可能是1923年5.3级维耶哈地震的震源。根据崩积楔地层学和断层截断理论，推断了槽状凹陷的三个位移事件。每次连续断裂事件中变形量的增加可能与边坡随时间的逐渐减弱有关。计算得出，沙岗陡坡的最小垂直滑移率为0.19 mm/年。有几个观点认为，所分析的麻袋构造的幕式位移受强震控制：(a)麻袋构造特征与北马拉代塔断裂的空间联系；(b)具有千年复发（5.6 kyr）的幕式位移，与低滑动率断层（如邻近的北马拉迪塔断层）的预期地震复发间隔一致。在未来的研究中，证明该地区的凹陷特征构成了大地震的档案，将对地震危险性评估有很大的兴趣。它们可能有助于改进古地震的目录，并可能提供有关地震复发间隔和最近事件（MRE）年龄的信息。
A sackung scarp has been investigated by trenching in the central Spanish Pyrenees. This feature is located 18 km to the SW of the North Maladeta Fault, which is the most probable source of the Mw 5.3 Vielha earthquake of 1923. Three displacement events have been inferred for the trenched sackung based on colluvial wedge stratigraphy and fault truncation. The increasing amount of deformation in each successive faulting event may be related to the progressive weakening of the slope through time. A minimum vertical slip rate of 0.19 mm/yr has been calculated for the sackung scarp. Several arguments suggest that the episodic displacement of the analysed sackung is controlled by strong seismic shaking: (a) Spatial association of the sackung features with the North Maladeta Fault; (b) Episodic displacement with a millennial recurrence (5.6 kyr) consistent with the expectable earthquake recurrence interval for a low slip rate fault, like the neighbouring North Maladeta Fault. Demonstrating in future investigations that the sackung features in the area constitute archives of large paleoearthquakes would be of great interest for seismic hazard assessments. They might help to improve the catalogue of paleoearthquakes and might provide information on earthquake recurrence intervals and the age of the most recent event (MRE).