The present data are subsurface velocity structures retrieved by applying the theory of diffuse field concept to the strong motion data of earthquakes observed at 1744 sites of K-NET and KiK-net (operated by the National Institute of Earth Science and Disaster Resilience) in Japan. Additionally, the data include peak fundamental and predominant frequencies as identified from the observed and theoretical horizontal-to-vertical spectral ratios for earthquakes (eHVSR). Based on our novel proposed quarter wavelength approach, we could define the effective bedrock depths and correlate them with the corresponding peak frequencies. For better usefulness of the present data, we classify the sites into four categories based on the correlation coefficients and residuals between the observed and theoretical eHVSR. The potentiality of these data could be reused by other researchers to develop new approaches related to the limitations of the established bedrock regressions and the uncertainty associated with the retrieved subsurface velocity structures, particularly at sites with low correlation coefficients and high residuals. Moreover, the data of the subsurface velocity structures could be reused as initial models for future microtremor applications and better enhance the retrieved velocity structures and the associated theoretical eHVSR curves. The data of the present paper is associated with original published article by Thabet et al. [1], which is presented in the Soil Dynamics and Earthquake Engineering under the title “A computational approach for bedrock regressions with diffuse field concept beneath the Japan Islands” [1].

Retrieving detailed subsurface velocity structures down to the seismic bedrock at any given site is a crucial step to delineate the site amplification factors accurately and precisely. The present research work contributes first new estimations for detailed velocity structures down to the seismic bedrock beneath the Egyptian National Seismological Network (ENSN) stations, which are distributed in Egypt nationwide. We used the diffuse field assumption for earthquakes to reproduce the horizontal to vertical spectral ratios (EHVSR) at these stations. We accepted waveform database of 424 earthquakes recorded at 75 ENSN stations. After achieving the inverted subsurface velocity structures, we establish site-specific frequency-depth regression and map the V_S30 and seismic bedrock depth beneath Egypt. Because of comparability regarding the seismic site class of B and C, the regression coefficients of the newly established frequency-depth regression exhibit similarity with those achieved from previous regressions in Japan. Furthermore, we observe modest consistency between the seismic bedrock depths and the various geologic features, particularly agreement between basin-shape seismic bedrock depths and the existence of Cretaceous and Jurassic extensional basins. Our findings suggest that the Precambrian basement rocks can be interpreted as the seismic bedrock in Egypt. One of the most significant obstacles in the present work is the low-dense distribution of ENSN stations nationwide. However, the achieved results raise new questions and challenges regarding precise and accurate future estimations for site amplification calculations at different localities in Egypt, particularly for urban planning by engineers.

We present in this paper four versions of chaotic and hyperchaotic modified nonlinear Schrödinger equations (MNSEs). These versions are hyperchaotic integer order, hyperchaotic commensurate fractional order, chaotic non-commensurate fractional order, and chaotic distributed order MNSEs. These models are regarded as extensions of previous models found in literature. We also studied their dynamics which include symmetry, stability, chaotic and hyperchaotic solutions. The sufficient condition is stated as a theorem to study the existence and uniqueness of the solutions of hyperchaotic integer order MNSE. We state and prove another theorem to test the dependence of the solution of hyperchaotic integer order MNSE on initial conditions. By similar way, we can introduce the previous two theorems for the other versions of MNSEs. The Runge-Kutta of the order 4, the Predictor-Corrector and the modified spectral …