Seismic Vulnerability Index Research Articles

Seismic microtremor experiment to determine seismic vulnerability of North Aceh

North Aceh is an area in Aceh, Indonesia, which is crossed by the active Lhokseumawe Fault. The existence of Lhokseumawe fault makes North Aceh relatively vulnerable to seismic hazard. The seismic vulnerability consists of two main components, natural frequency and amplification factor. Microtremor measurement is necessary in order to obtain natural frequency and amplification factor of certain area. A microtremor experiment has been conducted to understand the seismic vulnerability in north Aceh. The seismic microtremor has been measured at 30 sites which are located relatively evenly in the Lhokseumawe City. The measurement result is processed using Horizontal to Vertical Spectral Ratio (HVSR) method to obtain the main components of seismic vulnerability. The natural frequency and amplification factor are able to be calculated. The seismic vulnerability index calculated form natural frequency and amplification factor is also successfully calculated. The area located in the south of the Lhokseumawe Fault is seismically more vulnerable which is also correlated with the rock’s formation of the area. The results are still preliminary that needs more information from the seismic wave velocity representing the characteristics of rocks or soils.

Integrated Analysis of Microtremor Horizontal to Vertical Spectral Ratio, Surface Waves Dispersion Curve, and Seismic Refraction Tomography to Estimate Weathered Layer Thickness and Seismic Vulnerability: Case Study Kalirejo Village, Kokap Sub-District, Kulon Progo Regency

Subduction of Indo-Australia plate to Eurasia plate and locally active fault nearby Kulon Progo play as major source for earthquake events. After effect due to earthquake has different level of damage which depend on the magnitude and site characteristics. The horizontal-to-vertical spectral ratio (HVSR) passive seismic method is being used drastically to help in mapping the level of site vulnerability to earthquake event. HVSR analysis results help us acquire some physical values including weathered layer thickness where Vs 30 reference came from surface waves dispersion curve analysis of the MASW method as it is used as a parameter in calculating thickness value. Seismic refraction tomography is used to create subsurface model thus we may see the extent of underlying layer and its implication to earthquake event.Data measurements distribution are scattered in Kalirejo Village with the total of 63 passive seismic data, 33 MASW data, and 7 lines of seismic refraction acquisition. Some data show inadequate quality to be taken into further processing step, so data sorting activity should be carefully done. As a result, 21 of 63 passive seismic data are considered adequate to represent site physical values. Dominant frequency values ranging from 2 to 20 Hz, amplification factor varies between 1.5-12.5, and seismic vulnerability indices varies between 0.3-20. Surface waves dispersion curve inversion results are Vs 30 values ranging from 350 m/s to 980 m/s and seismic refraction tomography model shows Vp model with velocity values ranging from 0.2 to 3.2 km/s.

ANALISIS KETEBALAN LAPISAN SEDIMEN DAN INDEKS KERENTANAN SEISMIK KOTA JAMBI BAGIAN TIMUR

A Research was carried about analysis of sediment layer thickness and seismic vulnerability index in eastern Jambi City. The purpose of this research was to determine the effect of sediment layer thickness on seismic vulnerability index in eastern Jambi City based on microtremor data. The Acquisition data of microtremor is 25 points spread in research area. Processing data was carried out using the HVSR (Horizontal to Vertical Spectra Ratio) method to obtain the H/V curve. This curve represents the value of the natural frequency (f0) and amplification factor (A0). Based on the results of data processing obtained, the range of natural frequency (f0) value is 1.04 – 3.78 Hz, the range of amplification factor (A0) value is 1.13 - 4.88 times, the range of sediment layer thickness (h) value is 16.46 – 61.45 meters, and the range of seismic vulnerability index (Kg) value is 0.70 - 20.18×10-6 cm2/s. The results showed that the distribution of seismic vulnerability index (Kg) correlated relatively well with sediment layer thickness of the research area. The high zone of seismic vulnerability index (Kg) is relatively associated with alluvial deposits and also the sediment layer thickness of more than 30 meters. The high zone of seismic vulnerability index (Kg) is concentrated in Pasir Panjang, Tanjung Raden to Olak Kemang in Danau Teluk sub-district and Tanjung Sari in Jambi Timur sub-district.

Seismic Vulnerability Mapping to Support Spatial Plans in Lhokseumawe City Area

Earthquake loads that work on building structures can be determined by doing calculations ground motion on the surface. The amplitude from ground vibration is correlated with earthquake energy and ground solidity (compaction). The ductile ground will amplify the earthquake energy so that it produces strong vibration to the ground and building on the surface. This study will provide a mapping of areas susceptible to seismic vibrations to produce sustainable Lhokseumawe City spatial management plan policies as supporting literature in City development planning. The results of the study are expected to be disseminated to the community and as input for the Regional Government in planning the development of the city of Lhokseumawe. This research contributed to the development of cross-sectoral science in the assessment of the danger of micro seismic earthquakes. The results of the study were mapping areas that were susceptible to seismic vibration as a basis for spatial planning for the city of Lhokseumawe. The essential linkages in the field of science are on geophysics and architecture. The needs of the study carried out micro seismic data collection in the Lhokseumawe area using micro seismic equipment. The results of this study are the existence of areas that are very susceptible to seismic, namely Ujong Blang and Banda Sakti villages with seismic vulnerability index values (Kg) ranging from 0 cm / s2 - 30542.32 cm / s2. The highest value is located at Ujong Blang Village start from point A10, which is 10397.1 cm / s2. This is finally related to the full damage to buildings in Lhokseumawe City during the 2004 earthquake.

Evaluation of Seismic Vulnerability Indices for Low-Rise Reinforced Concrete Buildings Including Data from the 6 February 2016 Taiwan Earthquake

Communities need seismic vulnerability indices to identify which buildings are most susceptible to severe damage during earthquakes. To be of greatest value, these indices should be easy to use and should be vetted against data from previous earthquakes. To date, more than 800 reinforced concrete buildings have been surveyed after earthquakes for the purpose of evaluating a seismic vulnerability index proposed by Hassan and Sozen in 1997. This number includes 130 buildings surveyed after the 6 February 2016 earthquake in Taiwan. The data collected during these surveys consist of descriptions and photographs of damage, structural sketches, and measurements. Analyses of the data indicate that probability of severe damage and failure increases with decreasing column index and wall index (normalized measures of column and wall areas). They also suggest that the exact form of the threshold used to distinguish more vulnerable structures from less vulnerable structures is of little consequence in terms of the probable cost and benefits of the strengthening program this threshold may inform.

Research on seismic vulnerability of buildings and seismic disaster risk: A case study in Yancheng, China

Seismic vulnerability assessment of buildings has scientific guiding significance for mitigating seismic disaster risk, making the decision-makers in prioritization their limited resources for risk reduction in the administrative units from which they are responsible for. This paper has carried out the seismic vulnerability assessment of buildings in Yancheng area. There are four typical building types in this study area which are civil structure, pure masonry structure, brick-concrete structure, frame structure. Based on the typical building structural components, eight first-level vulnerability indicators (vertical load-bearing component, ring beam, mortar of infilled wall, roof or floor structure, foundation, height of building, nonstructural component, anti-seismic joint or other anti-seismic measures) are selected to build the seismic vulnerability index system of buildings. Next, an Analytic Hierarchy Process mathematical model is developed to access the weight value of first-level and second-level vulnerability indicators. And the seismic vulnerability assessment model of building has been established. Furthermore, considering the seismic hazard, population exposure and seismic vulnerability of buildings, the seismic disaster risk distribution of Yancheng area is finally determined. The distribution map of seismic disaster risk provides a solid scientific and technological support for the government to investigate the potential risk points.

Availability of seismic vulnerability index (Kg) in the assessment of building damage in Van, Eastern Turkey

The seismic vulnerability index (Kg) is a parameter that depends on the dynamic properties of soil. With this parameter, it is possible to evaluate the vulnerability of a point-based site under strong ground motion. Since it is related to the natural vibration period and amplification factor, the parameter can be calculated for both soil and structure. In this study, HVSR microtremor measurements are recorded at more than 200 points in the Van region to generate a seismic vulnerability index map. After generating the map, it is determined that the hazard potential and seismic vulnerability index is high at the sites close to Van Lake and at the densely populated city center. Damage information of the buildings investigated after the 2011 Van earthquakes (Mw = 7.1) are placed on the seismic vulnerability index map and it is realized that there may be a correlation between the damage and the seismic vulnerability index. There is a high correlation, approximately 80 percent, between the damage rate map based on the damaged building data and the Kg values. In addition, vulnerability indexes of buildings are calculated and the eff ect of local soil conditions and building properties on the damage levels are determined. From the results of this study and the site observations after the 2011 Van earthquakes, it is found that structural damage is not only structure-dependent but is also related to the dynamic behavior of soil layers and local soil conditions.

The efficiency of an improved seismic vulnerability index under strong ground motions

This paper examines the seismic performance of a Hospital Building damaged during the Ranau earthquake in Malaysia of intensity level (VIII), through an improved empirical seismic vulnerability index (SVI). The research aims at reducing the limitations and the uncertainties associated with the GNDT and the EMS approaches related to RC buildings, which can possibly be resolved by implementing the analytical techniques via applying nonlinear parametric analysis. Nonlinear time-history analyses were performed by incorporating an array of strong ground motions divided between far-field and near-field sets to assess the influence of each category on the SVI values and then comparing with SVI values obtained from the nonlinear static analysis (NSA). For a better comparison, the results are depicted in terms of collapse fragility curves for the modeled parameters. The proposed approach has been verified through observational fragility curves after Ranau earthquake. Whereas, the obtained SVI values were similar for the near-field and far-field, but with different collapse intensities and mean damage grades.

Integrating human behaviour and building vulnerability for the assessment and mitigation of seismic risk in historic centres: Proposal of a holistic human-centred simulation-based approach

The complexity of historic centres implies that risk assessment in those areas should be based on joint analyses of the characteristics of the built environment and the population's features, exposure and interaction with the surrounding environment. Such a holistic approach is urgently needed to evaluate the impact of mitigation strategies, especially in sudden onset disasters, and, mainly, earthquakes. In fact, the effectiveness of retrofitting interventions and emergency management strategies on the safety level depends greatly on such interactions, also in relation to the path network features. This work proposes a PDCA-based methodology for earthquake risk assessment which innovatively combines built environment damage assessment with a simulation of human evacuation behaviour so as to identify potentially inaccessible evacuation paths and urban areas, define related paths/areas safety levels and evaluate the impact of proposed retrofitting and management strategies on the population's safety in an emergency. To this end, a validated seismic vulnerability index method for masonry façade walls is combined with empirical damage assessment correlations (debris depth estimation in outdoor spaces) to create post-earthquake damage scenarios. Then, these are used as input data for evacuation process assessment through an existing earthquake pedestrians' evacuation simulator. Paths and safe areas risk indices are proposed to evaluate the main behavioural issues in emergency conditions. Finally, different solutions aimed at improving evacuation safety (i.e. emergency plans, rescuers' access strategies and retrofitting of buildings) are proposed and discussed for a significant case study, the historic centre of Coimbra, Portugal.

Seismic Vulnerability Maps of Ratu Agung District, Bengkulu City, Indonesia

During the 8.6 Mw Bengkulu-Mentawai Earthquake Ratu Agung District was identified as an impacted area. This paper aims to deliver the seismic vulnerability based on geophysical observation. This study was initiated by performing the ambient noise measurement to obtain the geophysical characteristic, such as amplification and predominant frequency. Furthermore, the vulnerability index analysis was performed from the geophysical information collected from the investigation. To observe the tendency of ground damage during the earthquake, ground damages analysis is also performed. All results are depicted into the microzonation maps. The results showed that the amplification and predominant frequency on site are generally ranging from 3 to 5 and 5 to 8 Hz, respectively. The seismic vulnerability index in study area is up to 10-3. The results showed that during the Bengkulu-Mentawai Earthquake, the investigated sites could be possible to undergo crack settlement which can trigger massive sand boiling in the study area.

Horizontal-to-Vertical Spectral Ratio (HVSR) Method for Earthquake Risk Determination of Jakarta City with Microtremor Data

Jakarta is the capital of the Republic of Indonesia which lies above a thick sedimentary basin. Geographically, Jakarta is 200 km away from the Indo-Australian subduction zone that sinks under the island of Java. There are many vital buildings and with the thick sediments underlying the city of Jakarta. Therefore, this region has a considerable seismic vulnerability. This will be dangerous if there is an earthquake that has the same frequency as the natural frequency of the building. It will cause a resonance resulting in amplification of seismic waves in the area. Each building has a different natural frequency, one that affects is the height of the building. To characterize the subsurface structure of the Jakarta Basin, microtremor data processing was obtained from the recording of 95 stations which was operated in October 2013 - February 2014 using Horizontal-to-Vertical Spectral Ratio (HVSR) method. HVSR is a method for obtaining subsurface information from single station measurements by comparing the Fourier spectrum of horizontal components to its vertical components. This ratio is a function of the frequency that will produce the H/V curve. The dominant frequency value on the HVSR curve represents the natural frequency of the area. The Seismic Vulnerability Index (Kg), which serves to determine the soil weak zone, can be calculated from the H/V curve. The dominant frequency value maps generated for the Jakarta area range from 0.2-0.22 Hz for low frequencies and 1-8.6 Hz for high frequencies. The large dominant frequency correlates with the thin sediment layer. Based on the frequency range, the south and northwest regions of Jakarta have relatively shallow basement depths compared to other regions. The resulting amplification value map can be divided into 4 maps with different period ranges. From the four maps, the North Jakarta area or the area around Jakarta’s coastline is most at risk of amplification with an H/V value up to 11 because the area is associated with alluvial deposits and coastal sediments. The seismic vulnerability distribution map in Jakarta City ranges from 15-850 relatively high in northeast and north of Jakarta.

Use of post-earthquake damage data to calibrate, validate and compare two seismic vulnerability assessment methods for vernacular architecture

The paper presents and discusses the application of two large scale seismic vulnerability assessment methods on the island of Faial in Azores (Portugal). The two methods are specifically conceived to assess the seismic vulnerability of vernacular architecture. The first method follows a classical seismic vulnerability index approach and is referred as SVIVA (Seismic Vulnerability Index for Vernacular Architecture). The second method is referred as SAVVAS (Seismic Assessment of the Vulnerability of Vernacular Architecture Structures) and it is a numerical tool intended to estimate the seismic capacity of vernacular buildings in terms of seismic load factors associated with different structural damage limit states. The main reason behind the selection of Faial Island as a case study was the availability of post-earthquake reports of the building stock after the 1998 Azores earthquake, which allowed comparing the damage scenarios obtained using both methods with the post-earthquake damage data and thus helped for the calibration and validation of the two methods. The application of both methods led to a good fit between estimated versus observed damage grades, which validated their applicability as large-scale first level approaches. Moreover, as the main outcome, the paper presents the novelties of the SAVVAS method, which had not been applied before, and discusses its main advantages, namely: no need for calibration with previous post-earthquake damage data, an enhancement of the prediction capabilities, a more individualized evaluation of the buildings and the possibility to assess the seismic performance of the building in different loading directions.

A vulnerability index formulation for the seismic vulnerability assessment of vernacular architecture

The valorization and preservation of vernacular architecture, as well as traditional construction techniques and materials, is a key-element for cultural identity. Conservation efforts are often mainly focused on historical constructions and monuments. Furthermore, more detailed and sophisticated seismic vulnerability assessment approaches typically used for monumental buildings require time, cost and resources that are not commonly assigned to the study of vernacular architecture. Earthquakes come unexpectedly, endangering in-use vernacular architecture and the population who inhabits it. That is why simplified methods for the seismic vulnerability assessment of vernacular architecture are of paramount importance. The present paper presents a new formulation for the vulnerability index method particularly adapted to the characteristics of vernacular architecture: Seismic Vulnerability Index for Vernacular Architecture (SVIVA). The vulnerability index method has been used extensively in the literature using different formulations that were always defined based on empirical knowledge acquired through post-earthquake damage observation and expert judgment. The SVIVA formulation is developed by means of an analytical process instead of the traditional empirical approach. The process included an extensive numerical modeling campaign that allows adapting the method to the characteristics of vernacular architecture by gaining a deeper quantitative knowledge on their seismic behavior.

SVIM: A Program for Seismic Vulnerability Index Determination and HVSR Data Processing

The seismic vulnerability of an area is important to be determined in order to reduce the risk of earthquake disaster. Ones need to calculate the values of dominant frequency and amplification from the Horizontal to Vertical Spectral Ratio (HVSR). Currently existing software for HVSR data processing, Geopsy, does not include seismic vulnerability index calculation. Using Geopsy, ones also need additional software for mapping purposes. From that problem, we introduce a Graphical User Interface (GUI) program for seismic vulnerability index determination and Horizontal to Vertical Spectral Ratio (HVSR) data processing and plotting the results into a map of the study area. The program is called SVIM (Seismic Vulnerability Index of Microtremor). The program has been built using Matlab and successfully tested to 21 microtremor data points acquired in Lamteuba, Aceh Besar, Aceh, Indonesia. We compared our results with those resulted from the calculation by using Geopsy and validated using coefficient correlation. The validation shown that the correlation coefficient of seismic vulnerability index was 96,40%, the correlation coefficient of frequency was 84,19%, and the correlation coefficient of amplification was 95,80%. We conclude the SVIM program can be used for seismic vulnerability index determination and HVSR data processing. The mapping part will be included in the SVIM software so that the users can easily obtain the necessary map.

A microtremor analysis for microzonation of seismic vulnerability index by using horiziontal to vertical spectral ratio in the southern area of Klaten regency

The dominant frequency and amplification factor are the parameter used to determine the value of seismic vulnerability index of an area. This research aims to determine the f0 and A0 in the southern area of Klaten regency. Besides, in this research a value range of Kg in the southern area of Klaten regency is obtained.This research was done in the southern area of Klaten regency by using P.A.S.I Seismograph Mod. 16S24-P, 3D Borehole Geophone Model GFA 60/100. The data acquisition was done in 12 different locations with the interval being about 5 km. In each location, the measurement needed 20 minutes and was done with three times repetition. The microtremor data obtained were processed by using the Geopsy software so that HVSR curve was obtained. From the HVSR curve, the f0 and A0 value can be determined which then were used to determine the value of Kg. After that, the value range of f0, Ao, and Kg obtained was made into a contour map by using Software Surfer.The result of the research shows that the value of f0 in the southern areas of Klaten regency is in the range of 4.104 Hz to 9.300 Hz, the value of A0 is in the range of 1.326 to 2.328, and the value of Kg is in the range of 4.259 × 10-5 s2/cm to 59.873 × 10-5 s2/cm. The microzonation result with the minimum Kg value of 3.00 × 10-1 s2/cm is located in Pedan Subdistrict and the maximum Kg value of 15.704 × 10-1 s2/cm is spread in Prambanan Subdistrict.

Development of seismic vulnerability index methodology for reinforced concrete buildings based on nonlinear parametric analyses

This paper presents a simplified method in the seismic vulnerability assessment of reinforced concrete (RC) buildings based on proposed seismic vulnerability index (SVI) methodology. The employed procedure is derived with some modifications from the Italian GNDT and the European Macro-seismic approaches. Eight parameters were modeled in three distinct vulnerability classes to estimate the vulnerability indices of RC structures. The vulnerability classes were categorized based on the earthquake resistant design (ERD) defined as; (Low, Moderate, and High)-ERDs. Nonlinear time history analysis (NL-THA) and nonlinear static analysis (NL-SA) were carried out to define the weight of each parameter in order to calculate the seismic vulnerability index in a specific intensity (PGA) of an earthquake event. Knowing that it ranges from 0 to 1 from less vulnerable to most vulnerable with respect to the seismic intensity. In addition, the engineering demand parameter (EDP) used to determine the vulnerability index as the maximum top displacement of the structure. After determining the (SVI), The mean damage states were developed to evaluate the estimated physical damage of buildings in distinct seismic intensities.•This simplified methodology helps to manage and implements strategies for the safety of the communities before earthquake takes place by investigating the vulnerability classes for each building type.•Modeling the parameters that have an influence on the structural behavior without considering the past-damages observations through an analytical approach.•Developing the seismic vulnerability index can reduce or limit the role of the rapid visual screening methods, which is based on expert opinion decisions, and depends on observations of damages caused by earthquakes, and can be a useful framework criterion in earthquake filed.

Spatial Analysis of Seismic Hazard Based on Dynamical Characteristics of Soil in Kota Baru, South Lampung

Kota Baru, a new capital Lampung province location, planned and developed since 2012, will be a densely populated in near time. The province located in near Semangko fault, southern of Sumatra Island, is a vulnerable area to earthquake. Seismometer was deployed for 15 points in Kota Baru for recording mictrotremor. The signal was analyzed by HVSR method produced fundamental frequency f0, amplitude A0, and seismic vulnerability index Kg. The range of frequency value is about 0.56 Hz to 1.46 Hz. The range of amplitude value is about 2.3 to 6.17. There is linear relation between Kg and the damage caused by earthquake. The Kota Baru classification of seismic hazard map was generated by plotting the value of Kg. The area at the northeast of Kota Baru is more risky to be inhabited because it has higher value of Kg. The more safety area located in near T7 and T15 because it has lower value of Kg than theothers.

Evaluation of seismic vulnerability screening indices using data from the Taiwan Earthquake of 6 February 2016

Cities in seismic regions often have unknown numbers of older buildings vulnerable to strong earthquake ground motion. Simple methods are needed with urgency to screen these buildings. The problem is of immense proportions as it affects some of the largest cities in the world. Seismic vulnerability indices proposed by Hassan and Sozen (ACI Struct J 94(1):31–39, 1997), Islam et al. (Architectural Institute of Japan-Academic Lecture Collection Summary, 2017), NCREE (Chiou et al. in 16th World Conference on Earthquake Engineering, 16WCEE 2017, Santiago, 2017), and Shiga et al. (Proceedings, Tohuku District symposium, Architectural Institute of Japan, 1968) possess the required simplicity. The indices have different forms and have been calibrated through independent activities, but all imply that the key to building survival is in the relative sizes of elements resisting lateral inertial forces. Data collected after the 2016 Meinong, Taiwan, Earthquake were used to evaluate these indices. The evaluation showed that differences among indices did not lead to wide differences in the cost associated with a given benefit especially if they are used to include the effects of all lateral-load resisting elements including masonry infill.

EARTHQUAKE MICROZONATION STUDY ON BATUBESI DAM OF NUHA, EAST LUWU, SOUTH SULAWESI, INDONESIA

A study entitled to Earthquake Microzonation on Batubesi Dam of Nuha, East Luwu, SouthSulawesi, Indonesia has been conducted. The study was conducted to obtain a map of peak groundacceleration (PGA) based on the historical seismicity in Sorowako and surrounding area, as well seismicvulnerability index (Kg) based on the measurement of local microtremor on site. The study was conducted ata location between 2.71428 degree - 2.70585 degree South Latitude and 121.3013 degree - 121.3117 degreesEast Longitude. This research is expected to obtain the spatial distribution of the amplification factor (Ao),resonant frequency (Fo), PGA, and Kg to estimate the earthquake hazards potential on location. Themaximum ground acceleration value or PGA obtained by microtremor wave analysis based on Kanai formula.As for determining the Kg used Nakamura or Horizontal to Vertical Spectral Ratio (HVSR) method. Basedon the results of data processing obtained the value of PGAmin is 0.079 Gal. at the point of MSBB25,PGAmax is 0.381Gal at the point of MASBB21, and PGAavg is 0.18 Gal. As for the Kg obtained value ofKgmin is 0.28 at the point of MSBB22, Kgmax is 43.42 at the point of MSBB10, and Kgavg is 9.81. Whilebased on the interpretation by means of the PGA value has been estimated that the MMI intensity is in therange of VII-IX with seismic risk level at a medium range of III until great of III. By means of the dominantfrequency (fo) and dominant period (To) was estimated that soil classification for Kanai in the range of IIuntil IV and the range of B - C for Omote-Nakajima.

Measurement of Shear Strain in Map Liquefaction Area for Earthquake Mitigation in Bengkulu City

Bengkulu city is well-known as a high-risk area for an earthquake. One of the effects of the earthquake is liquefaction, the phenomenon in which the strength and stiffness of the soil are reduced by shock. The researchers measured the quantity of liquefaction by knowing the value of Vs30 values that can be obtained from the United States Geological Survey (USGS). In this study, however, we measured liquefaction based on the shear strain value (γ). Here, the shear strain values could be determined by measuring the seismic vulnerability index and the peak ground acceleration. The vulnerability index was obtained by measuring the resonance of the frequency and the amplification factor using a short period seismometer with 3 components (2 horizontal components and 1 vertical component), whereas the peak ground accelerationα was obtained from the earthquake data that happened in Bengkulu City in 2000. The result showed that Vs30 and shear strain negatively correlated.