Potential Earthquake Research Articles

Cost\u2013benefit analyses to assess the potential of Operational Earthquake Forecasting prior to a mainshock in Europe

In the past couple of decades, Operational Earthquake Forecasting (OEF) has been proposed as a way of mitigating earthquake risk. In particular, it has the potential to reduce human losses (injuries and deaths) by triggering actions such as reinforcing earthquake drills and preventing access to vulnerable structures during a period of increased seismic hazard. Despite the dramatic increases in seismic hazard in the immediate period before a mainshock (of up to 1000 times has been observed), the probability of a potentially damaging earthquake occurring in the coming days or weeks remains small (generally less than 5%). Therefore, it is necessary to balance the definite cost of taking an action against the uncertain chance that it will mitigate earthquake losses. In this article, parametric cost–benefit analyses using a recent seismic hazard model for Europe and a wide range of inputs are conducted to assess when potential actions for short-term OEF are cost–beneficial prior to a severe mainshock. Ninety-six maps for various combinations of input parameters are presented. These maps show that low-cost actions (costing less than 1% of the mitigated losses) are cost–beneficial within the context of OEF for areas of moderate to high seismicity in the Mediterranean region. The actions triggered by OEF in northern areas of the continent are, however, unlikely to be cost–beneficial unless very large increases in seismicity are observed or very low-cost actions are possible.

Earthquake damage as a catalyst to abandonment of a Middle Bronze Age settlement: Tel Kabri, Israel.

For years there has been much speculation surrounding the abandonment of the Middle Bronze Age IIB palace of Tel Kabri, ca. 1700 BCE. There are no weapons, hoards of money and jewelry, or visible evidence for fire, which rules out hostile attack or conquest. There are also no indications of drought or environmental degradation that might have forced the inhabitants to vacate the site, nor mass graveyards to indicate a pandemic. The current study uses micro-geoarchaeological methods to show that the demise of the palace was rapid, with walls and ceilings collapsing at once prior to abandonment. Macroscopic data (stratigraphic and structural) from five excavation seasons were reexamined, showing that at least nine Potential Earthquake Archaeological Effects (PEAEs) are found and associated with the last occupation phase of the site’s palace. All lines of evidence point to the possibility that an earthquake damaged the palace, possibly to a point where it was no longer economically viable to repair. This conclusion is compounded by the discovery of a 1–3 m wide trench that cuts through the palace for 30 m, which may be the result of ground shaking or liquefaction caused by an earthquake. This study shows the importance of combining macro- and micro-archaeological methods for the identification of ancient earthquakes, together with the need to evaluate alternative scenarios of climatic, environmental, and economic collapse, as well as human-induced destruction before a seismic event scenario can be proposed.

Integration of earthquake risk- sensitivity into landuse planning: An approach for a local level area at development phase

Earthquake risks in cities are compounded due to unplanned development in high-risk areas. To address this issue, Risk-sensitive landuse planning (RSLUP) has been considered very important in recent years. It is the process of mainstreaming disaster risk reduction and management parameters in landuse planning is termed as Risk-sensitive Land Use Planning (RSLUP). This research aims to propose a methodology to integrate earthquake risk sensitivity in landuse planning (RSLUP strategies) for a local level area at the development phase. For this purpose, Uttara Residential Model Town (URMT) (third phase), Dhaka, Bangladesh has been selected as the study area considering its earthquake risk for exposure to a potential earthquake. The area is in the process of development. So there is still scope to integrate risk sensitivity in the proposed landuse plan. This research has been carried out in two steps. Firstly, assessment of the earthquake risk sensitivity of the proposed landuse plan of the study area on the basis ofbased on the risk themes: macro-form risks, risks in urban texture, risks in land-use incompatibilities, risks in hazardous uses, special risk areas, risks in building stocks, open space scarcity risk, and risks in critical facilities. Secondly, formulate RSLUP strategies to be incorporated in the proposed plan addressing the assessed risks accordingly. Here, a combination of analytical and participatory approaches has been applied to ensure applicability as well as acceptability. This research will may guide policymakers to understand the importance and application of RSLUP and thereby take necessary steps for this purposeto mainstream RSLUP in the process of landuse planning and thereby to increase earthquake resiliency of an area.

Conditional Probabilities of Hellenic Arc Earthquakes Based on Different Distribution Models

The 27 November 2019 Mw 6.0 earthquake that occurred in the southwestern part of the Hellenic Arc near Crete Island provided evidence of the high potential for strong earthquakes and active seismicity in the Hellenic Arc. In addition, tsunamis have been reported to occur for the region after major earthquakes in the historical past, so the seismic hazard of the Hellenic Arc should be evaluated in detail. The aim of this study is to evaluate the seismic hazard of the Hellenic Arc more reliably and accurately by estimating the conditional probabilities of a strong earthquake based on Weibull, gamma, log-normal, exponential, Rayleigh, and inverse Gaussian distribution models for the inter-event time of Mw ≥ 6.0 earthquakes that occurred between 1900 and 2019 in the study area. The fit between each model and the data was tested using four different test criteria, namely the log-likelihood value, Akaike information criterion, Bayesian information criteria, and Kolmogorov–Smirnov test. According to the results, the inverse Gaussian distribution was selected as the best, the log-normal distribution as the second best, the Weibull and gamma distributions as intermediate, and the Rayleigh and exponential distribution as the poorest and second poorest model, respectively. The conditional probability of an earthquake with magnitude Mw ≥ 6.0 is estimated to be higher than 0.70 according to all of the models used in this study for the base year te = 0 (te = 2015) and t > 5 years (t > 2020). Moreover, the results obtained based on the inverse Gaussian, exponential, log-normal, and Weibull distribution models are close to each other and are higher than 0.60 for te = 0 and t ≥ 3 years (t ≥ 2018). The outcomes of this study when using the different distribution models will contribute to assessments of the seismic as well as tsunami hazards for the region.

Rapid visual assessment of building vulnerability due to earthquake potential hazard in Surabaya

This article studies about Rapid Visual Assessment using android application RViSITS. The Institut Teknologi Sepuluh Nopember team has developed this application, and the purpose is to conduct a more accessible assessment survey in the digital version instead of using the standard form, applying the same standard called FEMA 154. This building vulnerability research was carried out using the application, due to data requirement for mitigation action needed by Surabaya government, due to two newly discovered faults passing the city, namely Surabaya and Waru faults. These two new faults concealed by the National Earthquake Research Centre (PuSGeN) lead to higher earthquake potential hazards in Surabaya, as stated in the SNI 1726. In this research, a two-phase survey was conducted to a total of 366 buildings. From the development of the result mapping of the application, it is discovered that the buildings built after SNI 1726 regulation issued have a higher level of resistance toward earthquake loads, especially the buildings in Surabaya, where gradual seismic risks keep increasing. Therefore, it is necessary to develop mitigation strategies due to the earthquake potential hazard in Surabaya.

Coastal and settlement typologies-based tsunami modeling along the northern Sumatra seismic gap zone for disaster risk reduction action plans

Since after the 2004 Indian Ocean tsunami, multiple efforts have been carried out to investigate the occurrence potential of tsunami-generating earthquakes. One of the studies concluded that large earthquakes are expected to occur along the seismic gap zone in the west coast of Sumatra and thus have the potential to generate tsunamis. The objectives of the research are to (1) investigate the existence of the seismic gap zone and to calculate the potential energy of expected earthquakes along the zone; (2) develop a tsunami model based on the relation between tsunami amplitude, arrival time, and coastal and settlement typologies; and (3) suggest tsunami mitigation action plans for surrounding areas in order to reduce the risk of disaster. The earthquake distribution in Aceh indicates the presence of a seismic gap zone in the west coast of Aceh, indicated by the decrease in seismic activities within the area since 2008. The potential energy is equivalent to an Mw 8.7 earthquake. The earthquake has the potential to generate a tsunami with a maximum amplitude of 20 m in the west coast of Aceh. An analytic hierarchy process (AHP) analysis was applied to determine the hazard and vulnerability levels. Having the information of hazards and vulnerability, we derived the priority level of the study area and suggested the tsunami mitigation action that needs to be applied to the area. The results indicate that the AHP method gave stable results in the determination of the vulnerability, hazard, and priority levels and thus can be used for other regions of similar coastal and settlement typologies.The results also show that Banda Aceh, Calang, and Meulaboh cities are zones of priority level 1, where all components of tsunami action plans should be implemented, comprising (1) the provision of an early warning system and related information; (2) the construction of evacuation routes and buildings; (3) the improvement of knowledge of disaster risk; and (4) the strengthening of awareness and preparedness. All action plans should be applied for Blang Pidie, as the city is included in an area of priority level 2. For the areas with priority level 3, including Tapak Tuan, and Singkil, the government should improve knowledge of disaster risk and strengthen community awareness and preparedness.

Seismic Performance Assessment of an Existing RC Wall Building with Irregular Geometry: A Case-Study of a Hospital in Croatia

Buildings of strategic importance should be able to resist seismic forces in accordance with potential earthquakes that may occur at the location and remain fully operational afterwards. However, many of them were constructed before the modern principles of seismic design were known (especially regarding detailing and ductility), and therefore may be considered substandard. The first step in mitigating the seismic risk of such structures is to assess their seismic performance and, in particular, to identify their structural deficiencies. This study presents a comprehensive methodology for the seismic performance assessment of individual buildings, applied to an existing reinforced concrete (RC) hospital. This building is of an irregular layout, constructed as a structural wall system, and it is located in the seismically active region of Croatia. It includes the assessment of seismic hazards on the location, ambient noise measurements, experimental determination of structural modal parameters, creation of a detailed numerical model calibrated with experimental data, and a seismic performance assessment using various analysis methods. As a result, the building collapse mechanisms were determined and critical structural elements identified, which is the basis for future actions directed to the reduction of its risk (e.g., applications of specific measures for a target retrofit, proposal of evacuation routes and safe places inside the building, etc.).

Assessing the Potential Earthquake Precursory Information in ULF Magnetic Data Recorded in Kanto, Japan during 2000-2010: Distance and Magnitude Dependences.

In order to clarify ultra-low-frequency (ULF) seismomagnetic phenomena, a sensitive geomagnetic network was installed in Kanto, Japan since 2000. In previous studies, we have verified the correlation between ULF magnetic anomalies and local sizeable earthquakes. In this study, we use Molchan’s error diagram to evaluate the potential earthquake precursory information in the magnetic data recorded in Kanto, Japan during 2000–2010. We introduce the probability gain (PG′) and the probability difference (D′) to quantify the forecasting performance and to explore the optimal prediction parameters for a given ULF magnetic station. The results show that the earthquake predictions based on magnetic anomalies are significantly better than random guesses, indicating the magnetic data contain potential useful precursory information. Further investigations suggest that the prediction performance depends on the choices of the distance (R) and size of the target earthquake events (Es). Optimal R and Es are about (100 km, 108.75) and (180 km, 108.75) for Seikoshi (SKS) station in Izu and Kiyosumi (KYS) station in Boso, respectively.

Earthquake hazard model with AVS30 in Sukabumi, West Java Province

The potential surface shocks due to the earthquake in Sukabumi is quite high. The purpose of this study is to provide an overview of the potential distribution of earthquake hazards on the earth’s surface. The methodology used for the potential earthquake hazard is the Peak Ground Acceleration (PGA) approach which is corrected by AVS30 analysis. The final results of the study can provide an overview of the potential of earthquake surface shocks grouped into three categories, namely low, medium, and high hazards. The variables used in this study were four types, namely: subsurface earthquake potential, slope shape, slope texture, and slope gradient. The study results of the potential for earthquake shocks can provide information on the potential hazards of earthquakes on the largest land surface in the Sukabumi City area and around the Cimandiri fault.

Simulation of strong ground motion for a potential Mw7.3 earthquake in Kopili fault zone, northeast India

In this study, we present the results of strong ground motion simulation carried out for a potential earthquake (Mw7.3) in the Kopili source zone of northeast India using the stochastic finite fault modeling technique. Prior to simulation of the potential event, the technique was validated by simulating a recorded earthquake Mw5.3, which was located close to the Nagaon district of Assam, India. The earthquake records (Mw5.3) of ten stations in the study region were analyzed, and average source parameters, namely corner frequency, seismic moment, stress drop and source radius, estimated to be 0.48 Hz, 1.44E + 24 dyne-cm, 103.4 bar and 2.7 km, respectively. While estimating the source parameters, the path attenuation parameters (Q and ko) also constrained at each seismic station. Using the constrained attenuation parameters, site amplification factors and source parameters, we simulated strong ground motion time histories for Mw5.3 event at individual sites and found them comparable with amplitude and frequency content of the respective observed records satisfactorily. The results, therefore, validated the technique used in the study. Further, the fault parameters, site amplification factors and average of the constrained attenuation parameters were used in simulation of the potential event (Mw7.3) and strong ground motion predicted for the entire northeast region (NER) at a grid interval of 0.5°. We used average values of constrained quality factor (Q) and Kappa parameter (ko) equivalent to 182f 0.95 and 0.038, respectively, in the simulation. It is apparent that the simulated PGA conditionally followed the attenuation curves of the region, and hence, we suggest developing an appropriate attenuation curve for the NER. The study reveals that the sites located up to 250 km distance away from the source zone may experience significant PGA ranging between 160 Gals and 360 Gals. The cities located within this zone, viz., Tezpur, Nagaon, Udalguri, Diphu and Bomdila, may witness strong to very strong ground shaking associated with substantial damage to buildings and other important structures in the region.

Spatial distribution of earthquake potential along the Himalayan arc

To determine the spatial distribution of earthquake potential along the active Himalayan arc, we utilize GPS measurements and earthquake data. We derive horizontal velocity field and 2-D strain rates from a new set of 41 regional GPS stations along with 446 published velocities. We convert these strain rate tensors to geodetic moment rate build-up within 24 contiguous segments and compare to the seismic moment rate release derived from a reassessed earthquake catalog of 900 years. The geodetic to seismic moment rate ratio, an indicator of stored strain energy, varies from below unity to more than 50 in different segments. The estimated geodetic moment rate ranges from 1.7 × 1018 Nm/yr to 10.2 × 1018 Nm/yr, whereas the seismic moment rate ranges from 3.7 × 1016 Nm/yr to 5.1 × 1019 Nm/yr. This variation between the geodetic and seismic moment rate corresponds to a moment deficit rate of ~1.15×1017 Nm/yr to 7.97 × 1018 Nm/yr along various segments of the study region. The above moment deficit rate provides an equivalent earthquake potential of magnitude 5.7 − 8.2 in different segments. Specifically, the higher earthquake potential (Mw≥8.0) corresponds to the segments in the central seismic gap and the northeast part of Himalaya, whereas the lower earthquake potential (Mw<7.0) corresponds to the segments encompassing the rupture areas of recent large events. The present findings not only provide input constraints on the contemporary crustal deformation but also contributes to the time-dependent seismic hazard analysis along the Himalaya.

Rapid identification of tsunamigenic earthquakes using GNSS ionospheric sounding.

The largest tsunamis are generated by seafloor uplift resulting from rupture of offshore subduction-zone megathrusts. The rupture of the shallowest part of a megathrust often produces unexpected outsize tsunami relative to their seismic magnitude. These are so called ‘tsunami earthquakes’, which are difficult to identify rapidly using the current tsunami warning systems, even though, they produce some of the deadliest tsunami. We here introduce a new method to evaluate the tsunami risk by measuring ionospheric total electron content (TEC). We examine two Mw 7.8 earthquakes (one is a tsunami earthquake and the other is not) generated in 2010 by the Sunda megathrust, offshore Sumatra, to demonstrate for the first time that observations of ionospheric sounding from Global Navigation Satellite System (GNSS) can be used to evaluate the tsunamigenic potential of earthquakes as early as 8 min after the mainshock.

Scenario ensemble modelling of possible future earthquake impacts in Bhutan

Recent large earthquakes in the Himalaya have resulted in tens of thousands of fatalities, yet these events are thought to have had relatively moderate magnitudes for the region. Evidence suggests multiple events throughout the Himalaya in the last 1000 years have had M > 8.0 and at least two have had M > 8.5. Despite this, understanding of earthquake risk in the region is poorly constrained, particularly in Bhutan, where research on both past and future earthquakes is notably scarce. While recent work has clearly shown the potential for large earthquakes here, the impacts from potential future earthquakes in Bhutan are entirely unknown. This study attempts to address this by modelling the potential fatalities associated with a range of plausible earthquakes through a scenario ensemble analysis in order to inform contingency planning and preparedness. The results show that both the timing and location of future earthquakes are critical factors in determining the number of fatalities, with night-time earthquakes, and those located in the west of the country proving most fatal. The worst case involves ~ 9000 fatalities and results from an M8.5 earthquake directly beneath Bhutan. Nevertheless, at the local scale the number of fatalities appears to saturate at ~ M7.5, since larger earthquakes do not result in significantly larger modelled fatalities. This suggests that local-scale impacts approaching the worst case may be relatively common and emergency planning could focus on comparatively moderate-sized earthquakes since larger, less frequent events may not necessarily result in significantly more fatalities.

GETTING READY FOR EARTHQUAKE DISASTER WITH TABLETOP EXERCISE FOR DISASTER MANAGEMENT

Disaster is an event that can destruct the community living. Malang is a city which have an active seismic, that have high potential of earthquake. To reduce the risk or effect of disaster we need tabletop exercise for disaster management as a mitigation activity. The purpose of this study was to knowing the effect of tabletop exercise on staff readiness once deal with earthquake disaster. This study was quasy experimental with purposivesampling technique. We obtained 24 respondents from administrative staff of medical Faculty Universitas Brawijaya. They were devided into intervention group (n=12) dan control group (n=12). The readiness was measured with knowledge and attitude score pre and post table top exercise. Wilcoxon signed rank test showed that there were significant differences between score pre and post test of knowledge about disaster management in control group (p value= 0.033) and in intervention group (p value=0.005). Dependent Ttest showed that there were significant effect on attitude pre and post table top exercise for disaster management simulation (p value =0,001), but no significant effect in control group (p value =0.376). Independent T-test for attitude and mann whitney test showed that there is no difference between intervention and control group in attitude (p value= 0.318) and knowledge (p value =0.680). In conclusion there is significant effect of tabletop exercise to readiness of the staff medical faculty Universitas Brawijaya once deal withearthquake disaster. But there is no difference in both method of education

Analisis Pengaruh Gempa Tektonik 10 Juli 2013 Terhadap Perubahan Koordinat Stasiun Pantau Segmen Mentawai

Mentawai Segment is located in Mentawai Islands, Sumatra, Indonesia. This segment is a subduction zone between Indo-Australian plate and Eurasian plate. This subduction zone can lead to high potential of tectonic earthquake in Mentawai Segment. The high potential of tectonic earthquake has negative impact for the community, so it is necessary to monitor the risk of tectonic earthquake in Mentawai Segment. This monitoring can be done by using GPS data of monitoring station that spread in Mentawai Segment. Therefore, this research aims to analyze the effect of tectonic earthquake on the coordinate change of Mentawai Segment, so that it can reduce the risk of negative impact of tectonic earthquake in Mentawai Segment. This research use observation data of 10 continuous GPS monitoring station (Sumatran GPS Data Array / SuGAr) in Mentawai Segment. Day of observation data was day of year (doy) at the time of tectonic earthquake occurence on July 10, 2013. Data processing used GAMIT / GLOBK software. The results of this research indicate that the tectonic earthquake (July 10, 2013) affected coordinates changes of the SuGAr station significantly two hours after the tectonic earthquake occurred.

Kesiapsiagaan Masyarakat dalam Menghadapi Gempa Bumi (Mengenang 14 Tahun Silam Gempa Bumi Bantul, Yogyakarta)

The earthquake hit Bantul regency, Yogyakarta, has brought life lesson for us that preparedness is urgently demanded to face potential earthquake in the future. This publication aims to discover how is both government and society readiness to act when earthquake strikes on unprecedented times. Method employed was literature study method by conducting in-depth analysis towards literatures related to earthquake disaster in Bantul in the year of 2006. This study revealed that Bantul dwellers have been high alerted to face earthquake. The disaster preparedness covers a range of fields which are on public facility, information system, physics or building, economy, education, society’s capacities enhancement, and religion.

Life-cycle cost assessment of conventional and hybrid sliding-rocking bridges in seismic areas

This article investigates the impacts of the column system on bridge life-cycle costs in high seismic areas. It focuses on hybrid sliding-rocking (HSR) columns, which are an accelerated bridge construction (ABC) technology. The authors conduct a life-cycle cost assessment, quantifying costs of bridge construction and potential earthquake damage and subsequent repairs, as well as the cost of bridge closure time due to construction or repairs. Two prototypical modern seismically designed bridges are considered, each designed with both conventional reinforced concrete (RC) and HSR columns. Construction costs of HSR columns are higher. However, drift demands on the HSR columns are generally lower, damage is less severe and costs of repairing the columns are greatly reduced. Moreover, construction times are about 80% quicker for HSR columns, and repair times are reduced relative to conventional construction. The results suggest substantial advantages to the HSR column system, reducing construction time and expected costs and time for seismic repairs sufficiently to counteract the increase in upfront construction costs. The benefits of the HSR, and by extension other ABC column systems, are particularly significant for highly trafficked bridges in high seismic areas, but hold for a wide range of input assumptions.

Multifractal Characteristics of Seismogenic Systems and b Values in the Taiwan Seismic Region

Seismically active fault zones are complex natural systems and they exhibit multifractal correlation between earthquakes in space and time. In this paper, the seismicity of the Taiwan seismic region was studied through the multifractal characteristics of the spatial-temporal distribution of earthquakes from 1st January 1995 to 1st January 2019. We quantified the multifractal characteristics of Taiwan at different scales and defined them as ΔD values. Furthermore, we studied the relationship between the ΔD and b values, which signifies the average size distribution of those earthquakes. The results are as follows. (1) The temporal multifractal curve changes substantially before and after the strong earthquakes. (2) The maximum ΔD value of the seismic region in Taiwan occurs at depths of 0~9 km, indicating that geological structures and focal mechanisms is the most complex at these depths compared with other depths. (3) ΔD values for different regions range from 0.2~1.5, and b values range from 0.65~1.3, with a significant positive correlation between them (ΔD = 1.5 × b − 0.68). For this purpose, a statistical relationship is developed between b and ΔD values, and regional and temporal changes of these parameters are analyzed in order to reveal the potential of future earthquakes in the study region.

Analisis Kekuatan Struktur Atas Jalan Layang terhadap Beban Gempa (Studi Kasus: 6 Ruas Tol Dalam Kota Jakarta Tahap 1 Seksi A)

The high potential earthquake in Indonesia made the earthquake an important factor in the planning of a building. The study aims to do the way of modeling, analyzing the inner style, displacement occurring in the current earthquake structure and knowing the vibration period and the stiffness of the structure. Research conducted in Kelapa Gading North Jakarta. Research using secondary data obtained from KSO Jaya Konstruksi-Adhikarya by using CSI Bridge. The flyover modeling is based on secondary data. The results show that 12 vibration modes may occur in the flyover structure. The largest period occurred in mode 1 that was equal to 0.84 sec which represented the behavior of the structure so that the total stiffness value of the structure was 275512.95 kN/m. Structures can be categorized as a flexible structure. Displacement is the structure of 92.5 mm and is still below the value of allowable displacement so it could be classified as the safe category. The force that occurs in the structure of the axial force, shear force, torsion, and flexure moment. Keywords: CSI Bridge, displacement, earthquake, flyover, force.

A study on the potential of tsunamigenic earthquakes in Java Subduction Zones

Subduction zone is a source of tectonic earthquakes that has potential to cause a tsunami. The study aims to obtain the estimation of earthquake parameter as a tsunami generator. Earthquake parameters were analyzed by using the scaling law theory for thrust fault type in the subduction zone. This study employed three magnitude scenarios, namely 8.9, 9.0 and 9.2 taken from the National Earthquake Study Center (Pusgen) of Indonesia and Blaser’s Equation. The results of model design in a vertical displacement indicated that deformation occurred on the seafloor. The results of source modeling illustrated the variations in maximum vertical displacement values for all three scenarios, namely 4,123; 5,309 and 4,831 meters based on the Blaser’s equation and 3,517; 3,183 and 4,526 meters based on the Pusgen’s data. The results of the study indicated that the value of vertical displacement can provide an estimate of the tsunami wave height at sea level.