Analysis of Tsunami Wave Height, Run-up, and Inundation in The Coastal of Blitar and Malang Regency

Indonesia is an archipelago located at the meeting point of 3 tectonic plates which constantly collide over time, the energy due to the collision will accumulate and be able to cause large earthquakes that can generate tsunamis. The island of Java is in the subduction zone of these plates, which causes the southern part of Java to have a high earthquake potential. On April 10, 2021, an earthquake measuring M 6.1 occurred in the south of Blitar and Malang. This earthquake was felt by most of the people of East Java, If the earthquake is large enough, it can cause a tsunami on the southern coast of East Java. Therefore, modeling was carried out using the FLOW module of Delft3D software while using earthquake parameters with a strength of M 9.1 which is the worst possible scenario on the southern coast of East Java. The results of this study indicate the fastest tsunami arrival time is 21 minutes, the highest maximum tsunami height is 20 meters, the highest run-up reaches 17,5 meters, and the furthest inundation reaches 765 meters along the southern coast of Blitar and Malang Regency.

Mw 6.4 Petrinja earthquake in Croatia: Main earthquake parameters, impact on buildings and recommendation for their structural strengthening

Strong Mw 6.4 Petrinja earthquake from 29.12.2020. took 7 lives and caused catastrophic damage in the Banovina area. The paper presents and analyses the most important earthquake parameters and highlights their importance in understanding the damage and demolition of buildings, as well as creating an optimal structure for their reconstruction. A contribution is made to the understanding of the complex mechanism of earthquake formation through the analysis of the stress-strain state in a rock mass during tectonic plate conflict. The causes of demolition and damage to buildings are explained by the combination of the properties of their structure, soil and the earthquake itself. Solutions for optimal structure of new buildings, as well as solutions for structural renovation of damaged buildings are proposed and described.

Seismic and Structural Analyses of the Eastern Anatolian Region (Turkey) Using Different Probabilities of Exceedance

Seismic hazard analysis of the earthquake-prone Eastern Anatolian Region (Turkey) has become more important due to its growing strategic importance as a global energy corridor. Most of the cities in that region have experienced the loss of life and property due to significant earthquakes. Thus, in this study, we attempted to estimate the seismic hazard in that region. Seismic moment variations were obtained using different types of earthquake magnitudes such as Mw, Ms, and Mb. The earthquake parameters were also determined for all provincial centers using the earthquake ground motion levels with some probabilities of exceedance. The spectral acceleration coefficients were compared based on the current and previous seismic design codes of the country. Additionally, structural analyses were performed using different earthquake ground motion levels for the Bingöl province, which has the highest peak ground acceleration values for a sample reinforced concrete building. The highest seismic moment variations were found between the Van and Hakkari provinces. The findings also showed that the peak ground acceleration values varied between 0.2–0.7 g for earthquakes, with a repetition period of 475 years. A comparison of the probabilistic seismic hazard curves of the Bingöl province with the well-known attenuation relationships showed that the current seismic design code indicates a higher earthquake risk than most of the others.

Rapid Estimation of Earthquake Magnitude using GNSS Data

Earthquake parameters such as the hypocenter location and the magnitude size are important in the development of reliable Earthquake Early Warning (EEW) and Tsunami Early Warning System (TEWS). The Global Navigation Satellitte System (GNSS) data have been used to estimate the earthquake parameters rapidly over the last 15 years. In this study, we present the result and analysis of the scaling properties of Peak Ground Displacement (PGD) as measured by high-rate (sampled at 1 Hz or higher) GPS recordings from Lombok earthquake on August 05 th , 2018. The earthquake magnitude from the kinematic solution of CMAT GNSS station is equal to Mw 6.8. This value is achieved between 15 - 20 seconds after the origin time of the earthquake. Our result shows that the displacements from kinematic GNSS data can be used to rapidly determine the earthquake magnitude, typically within the first minute of rupture initiation. Rapid earthquake magnitude determination will be very useful to support EEW and TEWS.

Estimation of date and magnitude of four major earthquakes using integration of precursors obtained from remote sensing data

A single precursor is not usually an accurate, precise and adequate measure to predict earthquake parameters. Therefore, it is more appropriate to exploit parameters extracted from several other single precursors, so that their simultaneous combinations may reduce the uncertainty of the prediction. In this study, remote sensing observations in different modalities acquired from several days before impending earthquakes have been investigated to extract earthquake parameters. They are observations in electron and ion density, electron temperature, Total Electron Content (TEC), Land Surface Temperature (LST), Sea Surface Temperature (SST), Aerosol Optical Depth (AOD), Surface Latent Heat Flux (SLHF), and Outgoing Longwave Radiation (OLR) clear sky. Regarding the ionospheric precursors, the geomagnetic indices Dst, Kp, Ap and F10.7 were used to detect pre-earthquake disturbances from frequent anomalies associated with geomagnetic activity. In this study, three methods of median, support vector regression (SVR) and random forest (RF) have been used to detect anomalies. When anomalies associated with impending earthquakes are detected, the number of prior days associated with the earthquake is estimated based on the type of precursor. Then, by estimation of the amount of anomaly deviation from the normal state, the magnitude of the impending earthquake is estimated. The final earthquake parameters (such as date and magnitude) can be obtained by integrating the earthquake parameters extracted from different earthquake precursors using mean square error (MSE) method.

Study on Earthquake-Induced Sloshing Waves in Moraine-Dammed Lakes

Large surface water waves can be triggered in moraine-dammed lakes during earthquakes and may lead to the overtopping failure of moraine dams. In the earthquake-prone Himalayas, there are thousands of moraine-dammed lakes; their outburst may lead to catastrophic disasters (e.g. floods and debris flow), posing severe threats to humans and infrastructures downstream. This paper experimentally studied earthquake-induced water waves (EWWs) in moraine-dammed lakes and examined the effects of several factors (e.g. water depth, earthquake parameters, and uneven lake basin). The experimental results suggest that the EWWs positively correlate to the earthquake wave, and the maximum height of the EWWs increases by 10%–15% when the effect of the uneven lake basin is considered. Based on the experiment data, we derived a calculation equation to estimate the maximum amplitude of EWWs considering the basin effect, and proposed a fast risk assessment method for moraine lakes due to overtopping EWWs. Finally, based on the method, we assessed the failure risk of the moraine lakes located in the Gyirong river basin where the China–Nepal corridor crosses. The study broadens understandings of the risk source of moraine-dammed lakes.

West Pacific Earthquake Forecasting Using NOAA Electron Bursts With Independent L-Shells and Ground-Based Magnetic Correlations

Recent advances in statistical correlations between strong earthquakes and several non-seismic phenomena have opened the possibility of formulating warnings within days or even hours. The retrieved correlations have been discovered for those ionospheric physical observations which lasted a long time and realized using the same instruments, including multi-satellite recordings. One of those regarded the electron burst phenomena detected by NOAA, for which the conditional probability of a seismic event was calculated. Then an earthquake probability greater than its frequency was assigned when a satellite realized such a phenomenological observation. This approach refers to the correlations obtained between high-energy electrons detected using the NOAA POES and strong Indonesian and Philippine earthquakes. It is reformulated here to realize a test of earthquake forecasting. The fundamental step is obtained by using a unique electron L-shell interval of 1.21 ≤ L ≤ 1.31, which decouples the electron parameters from the earthquake parameters. Then, the optimized correlation was recalculated to be 1.5–3.5 h early, between electron bursts and an increased number of seismic events with M ≥ 6, therein improving the significance too. Moreover, this methodology is reconnected to the frequency theory, and to Molchan’s error diagram, by the probability gain, where a comparison among the significances of various methods is given. The previously proposed physical link between the crust and the ionosphere through magnetic interaction, presumably operating 4–6 h before strong earthquakes, is examined quantitatively on the basis of recent magnetic pulse measurements. Consequently, the probability gain of earthquake forecasting is hypothetically calculated for both the dependent measurements of electron bursts using NOAA satellites and possible ground-based magnetic pulse detection. This method of combining probability gains for earthquake forecasting is general enough that it can be applied to any pair of observables from space and the ground.

A homogeneous earthquake catalogue for Turkey

A new homogenized earthquake catalogue for Turkey is compiled for the period 1900–2018. The earthquake parameters are obtained from the Bulletin of International Seismological Centre that was fully updated in 2020. New conversion equations between moment magnitude and the other scales (md, ML, mb, Ms, and M) are determined using the general orthogonal regression method to build up a homogeneous catalogue, which is the essential database for seismic hazard studies. The 95 % confidence intervals are estimated using the bootstrap method with 1000 samples. The equivalent moment magnitudes (Mw*) for the entire catalogue are calculated using the magnitude relations to homogenize the catalogue. The magnitude of completeness is 2.7 Mw*. The final catalogue is not declustered or truncated using a threshold magnitude in order to be a widely usable catalogue. It contains not only Mw* but also the average and median of the observed magnitudes for each event. Contrary to the limited earthquake parameters in the previous catalogues for Turkey, the 45 parameters of ∼378 000 events are presented in this study.

Hydrogeological precursors of earthquakes and volcanic activations according to observation data in Kamchatka Peninsula wells

The purpose of the study is generalization of data on the manifestations of hydrogeological earthquake precursors and volcanic activations based on long-term observations in the wells of the eastern part of the Kamchatka Peninsula. The main problem under consideration is the connection between the manifestations of hydrogeological precursors in several wells with the values of the magnitude Mw and epicentral distance of earthquakes to the wells de as well as with the parameters of seismic action in the observation area including specific density of seismic wave energy e and macroseismic intensity of shaking IMSK-64. The study results revealed that hydrogeological precursors in two-four wells had been manifesting for the period from 1 to 9 months before the strongest earthquakes with Mw = 6.6–7.8 at the epicentral distances de = 90–300 km. Such earthquakes were accompanied by the shakings of the intensity of IMSK-64 = 4–6 points. The specific density of seismic energy under such earthquakes was minimum 0.1 J/m3. The hydrogeological precursors were confined to the area for which the ratios of the earthquake epicentral distance de to the maximum linear size of the earthquake source L, km ranged from 1 to 3.7. Using the established relationships between the manifestations of hydrogeological precursors and earthquake parameters, weekly prognostic conclusions were made for expert earthquake prediction councils based on the data of current observations in wells. The well located at the distance of 15 and 20 km from the Koryaksky and Avacha active volcanoes featured the anomalous rise of groundwater pressure before the eruptions in 1991 and 2008– 2009. Therefore, a conclusion can be drawn that observation equipment operating in wells, the study results of hydrogeological precursors of earthquakes and volcanic eruptions as well as their application experience in the work of expert councils can form the scientific and technical basis for the development of geoinformation prediction technology for natural disasters in the Kamchatka Krai.

First-Motion Focal Mechanism Solutions for 2015–2019 M ≥ 4.0 Italian Earthquakes

A list of 100 focal mechanism solutions that occurred in Italy between 2015 and 2019 has been compiled for earthquakes with magnitude M ≥ 4.0. We define earthquake parameters for additional 22 seismic events with 3.0 ≤ M < 4.0 for two specific key zones: Muccia, at the northern termination of the Amatrice–Visso–Norcia 2016–2018 central Italy seismic sequence, and Montecilfone (southern Italy) struck in 2018 by a deep, strike-slip Mw 5.1 earthquake apparently anomalous for the southern Apennines extensional belt. First-motion focal mechanism solutions are a good proxy for the initial rupture and they provide important additional information on the source mechanism. The catalog compiled in the present paper provides earthquake parameters for individual events of interest to contribute, as a valuable source of information, for further studies as seismotectonic investigations and stress distribution maps. We calculated the focal mechanisms using as a reference the phase pickings reported in the Italian Seismic Bulletin (BSI). We visually checked the reference picks to accurately revise manual first-motion polarities, or include new onsets when they are not present in the BSI dataset, for the selected earthquakes within the whole Italian region, with a separate focus on the Amatrice–Visso–Norcia seismic sequence area from August 24, 2016 to August 24, 2018. For the Montecilfone area, we combined the information on the geometry and kinematics of the source of the 2018 Mw 5.1 event obtained in this study with available subsurface and structural data on the Outer Apulia Carbonate Platform to improve understanding of this intriguing strike-slip sequence. Our analysis suggests that the Montecilfone earthquake ruptured a W–E trending strike-slip dextral fault. This structure is confined within the Apulia crystalline crust and it might represent the western prolongation of the Mattinata Fault–Apricena Fault active and seismogenic structures. The calculated focal mechanisms of the entire catalog are of good quality complementing important details on source mechanics from moment tensors and confirming the relevance of systematically including manually revised and more accurate polarity data within the BSI database.