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On June 4, 2022, the largest earthquake ever recorded by the Kuwait National Seismic Network hit Kuwait. The quake had a magnitude of 5 on the local magnitude scale and a focal depth of 5 km. Twelve aftershocks with magnitudes ranging from 1.2 to 2.7 were also recorded later in the same area, although earthquakes here are rare. In this article, we perform a seismological investigation using modern and robust waveform inversion, seismic decomposition, and earthquake focal mechanism analysis to demonstrate the tectonic and anthropogenic earthquake components as well as the origin of the earthquake. The results obtained indicate that the mainshock had a seismic moment of 1.19 × 1023 dyn-cm equivalent to a moment magnitude Mw of 4.7. The moment tensor results indicate that the fault plane solution is strike-slip with a minor reverse component while decomposition analysis specifies both tectonic and anthropogenic components for the earthquake. The stress pattern in the vicinity of the earthquake sequence is mainly identified by obtained focal mechanism results. A peak ground acceleration of 0.0207 (g) was recorded at Al-Ahmady city 25 km from the epicenter. Using the observed local ground motion data we developed a ground motion attenuation relation for the Kuwait area. The outputs and valuable results from this earthquake and the previously studied earthquakes can be built upon to link earthquakes and oil extraction in Kuwait. [ABSTRACT FROM AUTHOR]

In order to distinguish between shallow earthquakes and quarrying activity, we evaluated 3069 seismic signals from 413 occurrences (112 explosions and 301 shallow earthquakes, depths 5 km), collected by the Aswan seismic sub-network in southern Egypt from 2010 to 2021. The spectral properties and related source parameters (e.g., seismic moment and corner frequency) using the estimated P-wave source spectra for both earthquakes and quarry blasts were investigated. The analysis showed that the P-wave source spectra of shallow earthquakes have higher corner frequencies (8.8–23 Hz) than quarry blasts (1.0–2.6 Hz) within the same magnitude range. The source spectra of quarry blasts exhibited significant misfits with the omega-square model and had steeper falloffs at high frequencies. The selected quarry blasts have a narrow seismic moment range, from 2.03 × 1011 to 1.35 × 1012 Nm. Our results demonstrate that the evaluation of misfit of P-wave spectra from the omega-square source model, based on spectral amplitude characteristics of high- and low-frequency bands, is the most reliable discriminant method in the routine data analysis of the target area. [ABSTRACT FROM AUTHOR]

The northern Red Sea in eastern Egypt is one of the world's newest marine basins. The northern Red Sea is a very active seismic region and poses a significant hazard to the nearest cities on the Red Sea coast. On June 16, 2020, a moderate earthquake (ML = 5.4), as published by the Egyptian National Seismic Network (ENSN), occurred in the northern Red Sea followed by several aftershocks, ranging in magnitude from 2.0 to 3.4. The best-fitting double-couple movement obtained using the full waveform moment tensor inversion of the main earthquake indicated strike-slip movement, with a minor normal component. The two nodal main shock planes were oriented NNE–SSW and ESE–WNW, respectively. The aftershocks sequences distribution did not coincide with the 16 Jun, 2020 main earthquake, neither in map view nor with respect to depth which may pointed to a secondary fault plane activation and stress triggered by the mainshock. The aftershocks clustered at the north western side of the main earthquakes and extend in the north western direction, which supported that the ESE–WNW plane is the fault plane. The spectral parameters of the S-wave displacement spectra of the main earthquake and its significant aftershock sequences were determined using the spectral inversion method and Brune's ω 2 modulation. The obtained spectra are flat in the frequency range from 0.8 Hz to each corner frequency, and they decreased rapidly at frequencies of < 10 Hz. The calculated seismic moment, moment magnitude, corner frequency, source radius, and stress drop vary from 8.293E+18 to 7.541E+22 dyn·cm, 2.4 to 5.0, 2.2 to 8.2 Hz, 171 to 633 m, and 0.02 to 13 MPa, respectively. The moment magnitude is equal to or slightly higher than the local magnitude reported by ENSN. The calculated stress drops for the earthquakes increased with increasing earthquake size. [ABSTRACT FROM AUTHOR]

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. 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. 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. We performed full waveform inversion for the studied seismic events, including the dominant double-couple (DC) signature, and also completed moment tensor solutions. Our results show that most triggered events demonstrated significant non-double-couple components. 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. 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. 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. [ABSTRACT FROM AUTHOR]

This study has examined the spatial and temporal distribution of seismicity recorded by Aswan seismic local network distributed around the northern part of the Lake Nasser in operation continuously for 40 years (1982–2021). This investigation shows that most of the seismicity is clustered on the Kalabsha fault and its follow up small segments. The seismicity also clustered in the Khor El-Raml area and in the junction of Seiyal fault with Kurkur faults to the North of the Kalabsha fault. The direction of the spatial distribution of the earthquakes in this study shows N–S direction. The temporal major unit is set as one year and the minor unit is set as one day. This study reveals that the accumulation and release of the energy are probably alternated between these active zones. The seismic quiescence has been detected in the Khor El-Raml and in the junction of Seiyal and Kurkur faults since 2007, also the seismic quiescence has been detected in both eastern and western parts of Kalabsha fault since 2015. Therefor, it can be expected a remarkable seismic activity in the near future in one of these active areas. The evidences of the impact of the water infiltration from the lake in triggering earthquakes have been detected in the Abu Dirwa fault, Khor El-Raml area, in the junction of Seiyal and Kurkur faults and in the Spillway fault area. In this study, also the relationship between the earthquakes and the groundwater level of the four piezometer wells in the Seiyal and Spillway fault areas have been examined. Unfortunately, we have not got a clear relation between the groundwater level and the seismicity due to the low seismicity in the Seiyal and Spillway areas during the short operation period of these wells. • This study provides an exploration of the spatio-temporal evolution trends of the earthquakes. • The most of the seismic activity is clustered on the Kalabsha fault and its follow up small segments. • The seismic quiescence has been detected in the Khor El-Raml and in the junction of Seiyal and Kurkur faults. • The evidences of the impact of the water infiltration from the lake in triggering earthquakes have been detected. [ABSTRACT FROM AUTHOR]

This work investigates the characteristics of local seismicity within the State of Kuwait and discusses its potential tectonic and anthropogenic drivers. As Kuwait is an oil-producing country, the occurrence of earthquakes simultaneously with oil extraction may suggest a case of triggered or induced seismicity. Seismic activity inside Kuwait is monitored with high accuracy and continuously after the establishment of the Kuwait National Seismic Network (KNSN) in 1997 through an ambitious plan to study the micro-earthquake activity in Kuwait. This network recorded more than 1378 micro/minor local earthquakes. Two seismogenic areas are identified, both characterized by weak magnitudes and shallow focal depths. In the current work, several modern geophysical techniques are performed including earthquake location, waveform-based moment tensor inversion, moment tensor decomposition, stress drop analysis, and stress pattern assessment. The results suggest that local earthquakes in Kuwait involve tectonic and anthropogenic components. Further densification of the network may allow a robust discrimination in the future. [ABSTRACT FROM AUTHOR]