Comparison of the Dynamic and Static Corner Frequencies in Ground Motion Simulation: Cases Study of Jiuzhaigou Earthquake and Northridge Earthquake

By using the stochastic finite-fault method based on static corner frequency (Model 1) and dynamic corner frequency (Model 2), we calculate the far-field received energy (FRE) and acceleration response spectra (SA) and then compare it with the observed SA. The results show that FRE obtained by the two models depends on the subfault size regardless of high-frequency scaling factor (HSF). Considering the HSF, the results obtained by Model 1 and Model 2 are found to be consistent. Then, similar conclusion was obtained from the Northridge earthquake. Finally, we analyzed the reasons and proposed the areas that need to be improved.

Preliminary Evaluation of the Impact of Eurocode 8 Draft Revision on the Seismic Zonation of Romania

This study is focused on the impact of the Eurocode 8 draft revision on the seismic zonation of Romania, one of the countries with the highest hazard levels in Europe. In this study, the design response spectra are evaluated for a number of sites in Romania for which both shear wave velocity profiles and ground motion recordings are available. The impact of the proposed changes on the structural design for structures situated in the southern part of Romania is also discussed. The results show considerable differences between the design response spectra computed according to the Eurocode 8 draft revision and the design response spectra from the current Romanian seismic code P100-1/2013. The differences are larger in the case of the sites situated in the southern part of Romania and those which have large design values for the control period TC. In Bucharest, for instance, it was found that the maximum design spectral accelerations would correspond to those from the 2006 version of the code while the maximum design spectral displacements would be significantly smaller than the levels produced by the 1981 or 1992 versions of the code. The results presented herein show that the differences in the seismic hazard and design ground motions are mainly due to the effects of local soil and site conditions and the associated site amplification proposed in the current Romanian seismic code and EC8 draft revision. Moreover, it has been shown that more analyses are needed to apply the seismic actions proposed in Eurocode 8 revision specifically for the sites in Romania under the influence of Vrancea intermediate-depth earthquakes so as to ensure an increased level of seismic safety for structures designed and built in the future.

Seismic Analysis of Moderate Size Earthquakes Recorded on Stations at Close Epicentral Distances

In this study, we analyzed the near-field seismic records of two moderate sized earthquakes in the Western Balkan region: the September 2016 Skopje earthquake, magnitude ML5.3 and the March 2020 Zagreb earthquake, magnitude ML5.5. Such recordings at close epicentral distances are rare and are thus very useful for testing some of the theoretical assumptions used in modeling earthquake risk. Firstly, response spectra were computed using the digital time histories for the three closest stations to the Skopje 2016 earthquake and the two closest stations to the Zagreb 2020 earthquake. Their characteristics were examined in terms of frequency and peak amplitude ranges. Secondly, the Nakamura method was applied to the records from the selected five stations coded SKO, FCE, IZIIS, QUHS, and QARH. The results of the spectral analysis were compared with interpretations from the geological and geotechnical maps at each location. Our findings support the idea that these combined methods can be used to categorize the underlying structural profile to a first approximation and can be used to derive velocity models.

Response Spectra-Based Post-Earthquake Rapid Structural Damage Estimation Approach Aided with Remote Sensing Data: 2020 Samos Earthquake

Effective post-event emergency management contributes substantially to communities’ earthquake resilience, and one of the most crucial actions following an earthquake is building damage assessment. On-site inspections are dangerous, expensive, and time-consuming. Remote sensing techniques have shown great potential in localizing the most damaged regions and thus guiding aid and rescue operations in recent earthquakes. Furthermore, to prevent post-earthquake casualties, heavily damaged, unsafe buildings must be identified immediately since in most earthquakes, strong aftershocks can cause such buildings to collapse. The potential of the response spectrum concept for being associated with satellite-based remote sensing data for post-earthquake structural damage estimation was investigated in this study. In this respect, a response spectra-based post-earthquake structural damage estimation method aided by satellite-based remote sensing data was proposed to classify the buildings after an earthquake by prioritizing them based on their expected damage levels, in order to speed up the damage assessment process of critical buildings that can cause casualties in a possible strong aftershock. A case study application was implemented in the Bayrakli region in Izmir, Turkey, the most affected area by the Samos earthquake, on 30 October 2020. The damage estimations made in this research were compared with the in situ damage assessment reports prepared by the Republic of Turkey Ministry of Environment and Urbanization experts. According to the accuracy assessment results, the sensitivity of the method is high (91%), and the necessary time spent by the in situ damage assessment teams to detect the critical buildings would have been significantly reduced for the study area.

Dynamic seismic analysis of nuclear power plant buildings and bearing stratum

Various approaches are used for simulating seismic loading and collaboration of a structure and a bearing stratum when carrying out dynamic seismic analysis in specialized software. In the present work, the kinematic parameters of various structures and bearing stratum were calculated using SCAD and STAR_T software. Seismic performance of a reference tower type supporting frame was calculated for 7 grade earthquake. As a result, the floor accelerograms were calculated, and the floor response spectra were built. The calculation results obtained by various methods and structure models were analyzed and compared.

CHINGIZ EARTHQUAKE on January 20, 2015, KR=12.2, mb=5.6, I_0^P=5–6 NEAR the SEMIPALATINSK POLYGON (Eastern Kazakhstan)

The work presents the results of data analysis of the earthquake on January 20, 2015, mb=5.6 occurred at the low-active region of Eastern Kazakhstan near the border of the former Semipalatinsk Test Site. The work briefly describes the seismicity of the Semipalatinsk Test Site related to aseismic regions according to the acting map of general seismic zoning. The earthquake was recorded by permanent seismic stations of the Institute of Geophysical Research of the Ministry of Energy of the Republic of Kazakhstan and by two strong-motion accelerometers. The earthquake was felt at distances up to 300 km from the epicentre, its maximum intensity was noted at Medeu settlement where the shaking intensity was 56 by the MSK-64 scale. The earthquake focal mechanism is shown, the parameters of seismic effects and response spectra are calculated.

Photocatalytic Removal of Antibiotics on g-C3N4 Using Amorphous CuO as Cocatalysts

Amorphous CuO is considered as an excellent cocatalyst, owing to its large surface area and superior conductivity compared with its crystalline counterpart. The current work demonstrates a facile method to prepare amorphous CuO, which is grown on the surface of graphitic carbon nitride (g-C3N4) and is then applied for the photocatalytic degradation of tetracycline hydrochloride. The prepared CuO/g-C3N4 composite shows higher photocatalytic activities compared with bare g-C3N4. Efficient charge transfer between g-C3N4 and CuO is confirmed by the photocurrent response spectra and photoluminescence spectra. This work provides a facile approach to prepare low-cost composites for the photocatalytic degradation of antibiotics to safeguard the environment.