#LIBYA SEISMOLOGY EARTHQUAKE BULLETIN FULL#

In this research, we utilized the source parameter model to study the source characteristics of the Aswan seismic zone (triggered earthquakes) as well as nearby inter- and intraplate seismic events in and around Egypt. Kebeasy and Gharib ( 1991) suggested that Aswan seismicity is controlled by three main factors: pre-existing complex faults system, water load, and the pressure of pore fluid. Gupta ( 2002) pointed out that the seismic activity resulted from the impoundment of lake water as a secondary factor, in areas where the tectonic activity plays a primary role, would be classified as triggered earthquakes. ( 2002) distinguished between induced and triggered earthquakes the first, “induced’’ earthquakes, where human activity is responsible for the most energy required for failure, and the second, “triggered’’ earthquakes, where anthropogenic activity is much smaller than the shear stress causing a fault to slip. On the other hand, stress and source spectra of the studied events are used as another key to deeply study the source mechanics and physics of natural and triggered events in this area.Īswan earthquakes are regarded as triggered seismicity (Gahalaut and Hassoup 2012), controlled by the pressure of pore fluid due to the water impoundment in the second largest reservoir in the world, Lake Nasser. The focal depths of 80% of the triggered events are shallower than 10 km, while 80% of the tectonic earthquakes are deeper than 15 km. The focal depths of most Aswan seismic events calculated in the current study are significantly shallower than the estimated focal depths for inter-plate and intraplate earthquakes in and around the area under investigation. Our results show that most triggered events demonstrated significant non-double-couple components.

#LIBYA SEISMOLOGY EARTHQUAKE BULLETIN FULL#

We performed full waveform inversion for the studied seismic events, including the dominant double-couple (DC) signature, and also completed moment tensor solutions.

In the current work, we computed moment tensors and stress drop values for six recently triggered earthquakes recorded by the Egyptian National Seismic Network (ENSN) around Lake Nasser, Aswan area, with local magnitudes between 3.0 and 4.6, as well as 40 nearby earthquakes in and around Egypt with local magnitudes ranging from 4.0 to 5.5, that are known as natural events.

The earthquakes' focal mechanisms, including source mechanism parameters and source spectra, can give important information to assist in discriminating between triggered and natural seismic events. To determine whether recent seismicity around the High Dam Lake (Lake Nasser) in the Aswan region is induced or triggered by the lake reservoir or is of natural origin, we analyzed moment tensor solutions and source spectra of recent recorded earthquakes in the area.

Libya seismology earthquake bulletin