In October 1790, a destructive earthquake occurred near Oran city in the western part of Algeria （MSK, Medvdev-Sponheuer-Kamik macroseismic intensity： X）. It generated a tsunami that inundated the Spanish and North...In October 1790, a destructive earthquake occurred near Oran city in the western part of Algeria （MSK, Medvdev-Sponheuer-Kamik macroseismic intensity： X）. It generated a tsunami that inundated the Spanish and North Africa coasts. The regional tectonic includes NW-SE compressional stress in Algeria and NE-SW strike-slip structures in the Alboran basin. In this work, we identified tsunami sources for the Alboran from numerical modeling. The sea bottom displacement is calculated from the Okada equations. The tsunami＇s propagation is simulated with the SWAN code. The identified tsunami source for the 1790 event is a 7.5 magnitude earthquake at the entrance of the Oran harbor, with a pure reverse faulting, probably associated with the Murdjajo fold The tsunami wave height profile that is obtained for the city of Oran showed an initial withdrawal of the sea that was followed by tsunami waves reaching 2 meters in height. The results obtained in Spain agree with the observations reported in the literature. Finally, the simulations led to a better understanding of the interdisciplinary approach to be considered as for tsunami sources in the Alboran. Sedimentary mass-movements should be now included as an additional component in the tsunami hazard assessment for the West Mediterranean. The contribution of sedimentary disturbance due to the series of canyons offshore the western margin could induce water waves higher than 2 meters in Western Algeria.展开更多
We expose the results of the study of the south-western Alboran seismic sequence of January-March 2016 and the stress perturbations it caused by means of Coulomb modeling. The use of data from numerous stations allowe...We expose the results of the study of the south-western Alboran seismic sequence of January-March 2016 and the stress perturbations it caused by means of Coulomb modeling. The use of data from numerous stations allowed us to relocate the largest events (Mw ≥ 3.8) south of those determined by IGN (Spain). The main shock of 25 January 2016 (Mw = 6.3) was relocated at 35.6133°N × 3.6888°W, at a hypocentral depth of 15.5 ± 6.0 km. The epicenters are aligned along two distinct clusters: The first runs N-S towards the Moroccan coast along Al-Idrissi fracture zone, while the second is centered on the Alboran ridge northern thrust fault. The focal mechanisms determined by different agencies correspond to a strike-slip/normal/reverse motion in the western cluster and thrusting in the eastern one. Coulomb stress change modeling shows that the main earthquake: (1) may have been triggered by stress accumulation by the 1994 and 2004 earthquakes;(2) has induced stress perturbations that provide a suitable explanation for the distribution of the aftershock clusters, including the eastern cluster. The prediction of the next event shows that it is likely to occur near the Moroccan coast.展开更多
文摘In October 1790, a destructive earthquake occurred near Oran city in the western part of Algeria （MSK, Medvdev-Sponheuer-Kamik macroseismic intensity： X）. It generated a tsunami that inundated the Spanish and North Africa coasts. The regional tectonic includes NW-SE compressional stress in Algeria and NE-SW strike-slip structures in the Alboran basin. In this work, we identified tsunami sources for the Alboran from numerical modeling. The sea bottom displacement is calculated from the Okada equations. The tsunami＇s propagation is simulated with the SWAN code. The identified tsunami source for the 1790 event is a 7.5 magnitude earthquake at the entrance of the Oran harbor, with a pure reverse faulting, probably associated with the Murdjajo fold The tsunami wave height profile that is obtained for the city of Oran showed an initial withdrawal of the sea that was followed by tsunami waves reaching 2 meters in height. The results obtained in Spain agree with the observations reported in the literature. Finally, the simulations led to a better understanding of the interdisciplinary approach to be considered as for tsunami sources in the Alboran. Sedimentary mass-movements should be now included as an additional component in the tsunami hazard assessment for the West Mediterranean. The contribution of sedimentary disturbance due to the series of canyons offshore the western margin could induce water waves higher than 2 meters in Western Algeria.
文摘We expose the results of the study of the south-western Alboran seismic sequence of January-March 2016 and the stress perturbations it caused by means of Coulomb modeling. The use of data from numerous stations allowed us to relocate the largest events (Mw ≥ 3.8) south of those determined by IGN (Spain). The main shock of 25 January 2016 (Mw = 6.3) was relocated at 35.6133°N × 3.6888°W, at a hypocentral depth of 15.5 ± 6.0 km. The epicenters are aligned along two distinct clusters: The first runs N-S towards the Moroccan coast along Al-Idrissi fracture zone, while the second is centered on the Alboran ridge northern thrust fault. The focal mechanisms determined by different agencies correspond to a strike-slip/normal/reverse motion in the western cluster and thrusting in the eastern one. Coulomb stress change modeling shows that the main earthquake: (1) may have been triggered by stress accumulation by the 1994 and 2004 earthquakes;(2) has induced stress perturbations that provide a suitable explanation for the distribution of the aftershock clusters, including the eastern cluster. The prediction of the next event shows that it is likely to occur near the Moroccan coast.
