Seismic Vulnerability Index Research Articles

Analysis of landslide in Bungkah, Sepakung, Banyubiru using ground shear strain method and shear wave profile from HVSR method

In Bungkah, Sepakung, Banyubiru there was a landslide several times Monday to Thursday, 17 to 20 October 2017 which occurred due to the high intensity of rain in the region within 2 consecutive days. The landslide material was able to close the road that became access to local residents’ settlements. Besides that, in Bungkah, there is a resident’s house made of permanent walls that are curved on the wall due to ground movement while the house next to it does not occur. To analyze these phenomena, a single station microtremor method is used, namely the HVSR analysis with amplification values and dominant ground frequency of the curves obtained can be used to determine the peak ground acceleration and seismic vulnerability index which can then be used to analyze ground shear strain value or the ability of the soil layer to stretch and shift when receiving elastic wave propagation. Based on the ground shear strain value, Bungkah has values ranging from 10−3 to 10−1, the phenomenon that will occur is landslides with the dynamic nature of the soil included in the category of soil or rock collapse. Based on the results of frequency and amplitude inversion, the profile of Vs is obtained to the depth that can accurately image the shape of the slip surface from landslide that occurred in October 2017. The sensitivity of Vs to the presence of fluid imaged an accumulation of water below the landslide limit. The mechanism of land movement in the Bungkah hamlet is a rotational slide avalanche type. The movement of the soil which causes the curvature of the walls of one of the permanent houses in Bungkah due to the existence of a vertical soil layer with very low Vs which is directly bordered by massive Vs. The boundary of this layer may be cavity or cavity. The existence of a massive layer in the east of the area makes no continuity of soil movement to the east.

Analysis of Earthquakes Potential Damages as a Disaster Mitigation Effort

Muara Bangkahulu District is one of Bengkulu Province Subdistricts, which is used as a place for higher education service centers, government office centers, and community residential areas. Muara Bangkahulu has the risk of being affected by an earthquake caused by its geological conditions. To avoid the potential damage due to earthquake, the PGA parameters, seismic vulnerability index, ground shear strain, and thickness of sediment layer (h) were analyzed in Muara Bangkahulu District as an effort to mitigate earthquakes. The purpose of this study is to describe the potential damage caused by the earthquake in Muara Bangkahulu District as a disaster mitigation effort. This research was a qualitative descriptive study using the literature study method. The results of the literature study which showed the value of PGA produced between 184.22 gal to 532.92 gal. Distribution of seismic vulnerability index values between 0.56 to 7.95. Distribution of ground shear strain values between 5.14 x10-5 to 7.42 x10-4. The thickness of the sediment layer (h) ranged from 8.13 meters to 61.31 meters. The largest PGA, IKS, GSS and h values are in Kualo Beach which is estimated to have a high level of risk for earthquake disasters with a correlation more than 74%. Thus, it can be concluded that the vicinity of Kualo Beach is the most potential and prone to earthquake damage.

Mapping of weathered layer thickness and Seismic Vulnerability in Tegal using HVSR method

The Baribis-Kendeng-Tegal fault is part of the Baribis-Kendeng fault segment that extends from West to East in the north of Java Island. The existence of this fault segment affects seismic activity in Tegal. The research was conducted by microtremor measurement to determine the earthquake susceptibility index and the thickness of the weathered layer in Tegal City. The data collection method in the study used the HVSR (Horizontal-to-Vertical Spectral Ratio) method to determine the subsurface conditions of the study area. The results of the horizontal component analysis of the vertical component showed a spectrum peak at the dominant frequency and amplification factor. The thickness of the weathered layer was obtained from the comparison of the value of Vs 30 of the study area to its natural frequency value. The seismic vulnerability index was obtained by squaring the amplification and dividing it into its natural frequency. Measurements carried out at 37 points in Tegal City obtained varying thickness of the weathered layer, ranging from 4.29 meters to 88.14 meters and seismic vulnerability values ranging from 0.08 to 16.65.

Assessment of seismic vulnerability index of RAJUK area in Bangladesh using microtremor observations

Microtremor Horizontal to Vertical spectral ratio technique, also known as the Nakamura’s method is growing in status for site response analysis. 500 locations in RAJUK area (1530 km2) have been selected for microtremor observations. Microtremor data have been compiled and studied to estimate the predominant resonance frequency and H/V peak amplitude following the SESAME (2004) guideline. Finally, seismic vulnerability index of site soil using Nakamura’s technique has been determined from predominant resonance frequency and H/V peak amplitude parameter. The calculated seismic vulnerability index for the studied 500 locations varies between 0.16 and 7.28. The low seismic vulnerability index (Kg) value means that the areas are relatively stiff and underlain by substantial deposit of sediments. The relatively higher Kg values are spread in the soft alluvial deposit areas. The areas with high Kg values are considered as fragile zones that may initiate significant damage to infrastructure situated in those areas during an earthquake.

LOCAL GEOLOGY AND SITE CLASS ASSESSMENT BASED ON MICROTREMOR DATA IN NORTH LOMBOK

Lombok Island is an active seismic area in Indonesia potentially hit by an earthquake due to located between two earthquake generators from the south and the North. Several large earthquakes rocked Lombok, an earthquake with a magnitude of 6.4 on July 29, 2018, and 7.0 on August 5, 2018. This study aims to determine the characteristics of the local site effect based on the dominant frequency value ( ), soil amplification ( ), sediment layer thickness (d), , dominant period (T0), and seismic vulnerability index ( ) and to comprehend the soil class (site class) based on the thickness of the sediment layer (d), and in the North Lombok region. The data used is secondary data from microtremor signal recordings in North Lombok Regency in 2018. Data processing used Geopsy software, and microtremor data were analyzed using the HVSR method. From processing the HVSR data, the dominant frequency value about (0.8 - 18) Hz, amplification value (1.7 – 9.7), dominant period value (0.05 – 1.2) seconds, seismic vulnerability index value (0.4 – 71) , and the value of in the study area (20.05 – 287.04) m/s. Based on microtremor analysis, the local site effect indicates that alluvium rocks caused stronger earthquake vibrations and more damage. Whereas the Kalibabak and Lekopiko formations caused fewer earthquake vibrations and less wear. Based on the dominant period and , area study classify as Site Class IV class E and Site Class III class D Copyright © 2021 IPR. All rights reserved.

Improved Vulnerability Index Methodology to Quantify Seismic Risk and Loss Assessment in Reinforced Concrete Buildings

ABSTRACT An improved seismic vulnerability index methodology is formulated on the basis of eight modeled parameters that are designed according to earthquake-resistant design concept and derived from the empirical vulnerability index that was initiated by the Group of National Defense against earthquake, named as GNDT Level approach. The results indicated that there is a good correlation between the analytical modeling approach and the observed fragility features during in-situ field investigations. To prove that the proposed methodology is accurate and reliable, the verification of the current methodology is performed through the experimental testing related to school building damages during Ranau Earthquake.

Mapping of Potential Damages Area in Lombok Island Base on Microtremor Data

Lombok Island and its surrounding is an area that has a high seismicitys level because it is located in the Eastern Sunda Arc. Tectonically, Lombok Island located between the Indo-Australia plate collision zone with Eurasia in the south and the fult of the backarc Bali-Flores in the north. This research’s purposed to determine the distribution of vulnerability index and peak ground acceleration value are used to determine the GSS value, so mapping of potential damage areas could be done. The microtremor data taken on 32 observation points distributed in Lombok Island. Microtremor data is analysed using Horizontal to Vertical Spectral Ratio (HVSR) method to get seismic vulnerability index (Kg) and dominant period. Determination of Peak Ground Acceleration (PGA) value using data from the MASE Stasion measurement results based on earthquake events on August 5, 2018. Seismic vulnerability index and peak ground acceleration value are used to determine the GSS value. Determination of potential damage area using analysis of the dominant period, seismic vulnerability indexs and Ground Shear Strain values. The results of this research showed that seismic vulneribility index value in research area is about 0,029 sekon to 1,360 sekon, seismic vulneribility index value is about 0,56 to 189,92 and GSS value is about 2,52 x 10-5 to 8,46 x 10-3. The results show that the light damage dominated in East Lombok Districts, the moderate damage is on Mataram City and it dominated in West Lombok Districts. The heavy damage present in the most parts of West Lombok Districts.

Post-earthquake fire risk assessment of historic urban areas: A scenario-based analysis applied to the Historic City Centre of Leiria, Portugal

Recent natural and anthropic disasters have aroused the interest of the scientific and governmental community in seeking more efficient and effective risk mitigation strategies. Index-based approaches have received particular attention in the field of disaster risk because of their extraordinary capacity to synthesise and spatially contextualise vulnerability. Motivated by the massive impacts of earthquakes, the seismic risk field has gained popularity over the last few decades. However, little attention has been paid so far to a potentially highly impacting phenomenon: post-earthquake fires. Historical records have shown that fire ignitions triggered by earthquakes present a significant likelihood of ending up in massively destructive urban fires whose consequences are even more dreadful than those of the earthquake itself. This paper aims to contribute to the body of knowledge in the field of post-earthquake fires by presenting a scenario-based analysis in the Historic City Centre of Leiria. Firstly, two seismic vulnerability index methodologies are applied to obtain post-earthquake damage scenarios. Then, a risk matrix is used to identify the buildings that are more prone to suffer post-earthquake fire ignitions. Finally, fire spreading and suppression conditions are examined and discussed through a detailed analysis where fire risk outputs, damages, and the accessibility conditions of the area are combined to obtain an integrated post-earthquake fire analysis. The results show that for a seismic event of intensity IEMS−98 = VIII, 33% of the total surveyed buildings could present a moderate or high risk of post-earthquake fire ignition.

Comparative seismic RISK assessment of existing RC buildings using seismic vulnerability index approach

The implementation of seismic risk management is becoming increasingly important all over the world, and especially in East-Asia as the structures aging surpass. In this context, three existing reinforced concrete buildings located in Malaysia have been selected for seismic vulnerability assessment. This work aims to apply the Seismic Vulnerability Index (SVI) via a Non-Linear Parametric Analysis (NL-PA) for each of the 3 RC existing buildings having different storey levels and clusters; low-rise (BLR), mid-rise (BMR), and high-rise (BHR). This approach can be achieved by undertaking a NL-PA as an analytical strategy instead of the empirical approach, which relies primarily on physical vulnerability parameters, earthquake-resistant design (ERD), and engineering demand parameters (EDP) by simulating a set of seismic records that can define the fragility features. The assessed SVI values for three different clusters of buildings are obtained for Far-Field (FF) and Near-Field (NF) seismic scenarios. With regards to the non-linear static analysis (NL-SA), the SVI values interact very well with the findings acquired from the NL-DA which are in good compliance with the low-rise building, in contrast for the two mid- and high-rise buildings. According to the obtained probabilistic vulnerability curves, the reference buildings are classified to be in D2 and D3 damage grades with dominancy of D3 level for the mid-rise and high-rise structures.

Landslide Vulnerability Analysis Due to Earthquake Based on Seismic Vulnerability and Slope of the Slip Surface in Tritis, Yogyakarta

Tritis is a hamlet in Kulon Progo Regency, located in an area with steep slope topography making it vulnerable to landslides. Ground movement vulnerability due to earthquakes is controlled by several factors, one of which is the seismic vulnerability index whose value can be obtained through microtremor measurements by H/V analysis. In addition, the dynamic trigger factor for landslides is the slope. The slope of the surface is not always the same as the slope of the slip surface because it is observed from the surface, while the slip surface is under the soil layer and requires measurements using the geophysical method to determine the surface model. For this reason, an analysis is needed to compare the landslide vulnerability between these two factors, the slope of the surface and the slope of the slip surface. From the measurement results, there is a significant difference between the slope and the slope of the slip surface at the same site in the north of the slope by 15.17 with a seismic vulnerability index (kg) of 2.5. The distribution of seismic vulnerability index in all slopes ranges from 0.075 to 7.33, dominated by areas with slopes > 18. High landslide vulnerability is in the southern and northern areas.

Site Effect Estimation Using Microtremor Measurements at New Luxor City Proposed Site, South Egypt*

The present study aims mainly at investigating the site effect at the new Luxor city, Egypt, using microtremor measurements. Accordingly, 41 ambient noise recordings were implemented covering the investigated area in a reasonable manner with spacing nearly 1 km between each measurement station. The data were analyzed using Nakamura’s technique. The results show that; the investigated area exhibits low fundamental frequency values ranging between 0.28 - 0.47 Hz and its corresponding amplification factor values vary between 2.3 and 6.8. Consequently, the studied site is characterized by the presence of thick soft sediments overlying a hard bed rock. The seismic vulnerability index (Kg) was estimated, relying on the estimated fundamental frequency (F0) and amplification factor (A0), through the range between 11 and 95 across the mapped area. The obtained Kg values were noticed to be compatible with amplification level results. The central part of the investigated area reflects the higher Kg and A0 values.

Earthquake and tsunami potential levels in Sulawesi (lesson learned earthquake West Sulawesi)

Earthquake and tsunami disasters always bring negative impacts and losses for humans. The high frequency of earthquake disasters in Sulawesi and the massive impact of destruction and damage to infrastructure, loss of homes and property, and death of people are partly due to the lack of knowledge of this potential disaster by the surrounding community. Therefore, it is necessary to study the potential for earthquake and tsunami disasters on Sulawesi Island, and Lesson Learned about the Earthquake Disaster that has occurred in past. This study uses a qualitative method with a descriptive analysis design of secondary data obtained through a comprehensive literature review. The results showed that Sulawesi Island has a high potential for earthquake disasters, which is in the historical records of disasters, some of these earthquakes were accompanied by tsunami waves. The lesson that can be drawn from the earthquake in West Sulawesi is the potential for aftershocks after the opening earthquake and the main earthquake. In addition, the urgency of building earthquake-resistant housing structural mitigation is the key to safety during an earthquake. The post-earthquake recovery program in West Sulawesi requires further studies related to soil classification surveys, soil dominant periods, and soil seismic vulnerability index, as part of rebuilding a better and safer post-disaster area.

Seismic Vurnerability in Telanaipura and Kotabaru Jamby City

Geologically the city of Jambi lies in the formation of Air Benakat, Muara Enim, Kasai, and alluvium deposits. The rock units that make up this formation were all composed by fine sediment. Based on these geological conditions, the Jambi City region has a high level of seismic priority. This research was conducted to study seismic vulnerability in this region, using the microtremor method. Microtremor is a ground vibration that can be produced by natural resources. This natural resource consists of wind and sea waves that have a long period of time or like traffic, factory machinery, and so on. Based on the results of the study obtained from the Kotabaru and Telanaipura regions have natural frequencies in the range 1.24 Hz - 4.35 Hz. The amplification factor was 1.13 - 3.34 and it was included in the low category. seismic vulnerability index in both regions was 0.50 - 8.58 x 10-6 cm / s2. seismic vulnerability index values were relatively high in Kelurahan Penyengat Rendah (Telanaipura). It was not recommended for skyscraper construction.

Proposed Method and Framework for Evaluating and Calculating a Seismic Vulnerability Index of Malaysia

There are various constraints and challenges faced in conducting seismic vulnerability assessment studies in Malaysia due to key factors related to appropriate data availability, methods and frameworks. This paper would highlight on the proposed method and framework for assessing and calculating the seismic vulnerability index at district level for Malaysia condition. A set of vulnerability index indicators that incorporate exposure, resilience and capacity elements had been constructed to identify and evaluate local features that would contribute to the vulnerability of populations and properties to the occurrence of earthquakes. Specifically, a multivariate data analysis method would be performed to identify and assess the relative contribution (weightage value) of respective indicators and following with the use of Geographical Information System (GIS) technology to map and generate the spatial heterogeneity of total vulnerability index map and potential seismic vulnerability index map. Finally, the derived maps could provide preliminary information on the seismically vulnerable area classifications in order to improve the disaster mitigation and preparedness strategies by response disaster agencies.

Ambient Noise Analysis During Nyepi in Denpasar Using Horizontal-to-Vertical Spectral Ratio (HVSR) Method

Nyepi Day is a unique tradition where outdoor human activities stop 24 hours a day. Denpasar City is the region that has the most significant impact on this change because it is the capital province. This study aims to determine the effect of Nyepi on ambient noise in Denpasar on March 25, 2020. We installed a TDS sensor at the Denpasar Geophysics Station for 3x24 hours ie when Nyepi Day, before and after Nyepi as comparative data. The data is processed by the HVSR method to get the value of dominant frequency and amplification factor every hour. Compared to the day before and after Nyepi, the dominant frequency increased during Nyepi and the amplification factor decreased during Nyepi. Seismic vulnerability index value at Nyepi is 24 where there is a decrease of index 3,904 with a day before and after Nyepi. This is showed that Nyepi Day affected ambient noise in Denpasar.

Dynamic behavior of vertically irregular sloping ground buildings

This paper examines the level of vertical irregularity and the influence of the frequency content of earthquakes on the vertically irregular reinforced concrete step-back, step-back–setback building frames. The regularity indices of these frames determined first to assess the level of irregularity and then the dynamic responses of the buildings under three distinct earthquakes of low, intermediate, and high-frequency contents are evaluated. It is noted that the irregularity of step-back frames is decreasing as the number of storeys increasing, whereas the irregularity of step-back–setback frames is increasing as the number of storeys and bays increasing. And the step-back frames are seismically responsible for low and medium frequency content earthquakes. In contrast, the step-back–setback frames are responsible for medium and high-frequency content earthquakes. The seismic vulnerability indices of these building frames are also determined and it is observed that there is rarely any correlation existed between the seismic vulnerability index, regularity index, and the influence of the earthquake frequency content.

Soft Sediment Characterization using Seismic Techniques at Beni Suef City, Egypt

It is well known that the local geological characteristics in terms of topographic setting and the existence of soft sediments over bedrock may affect earthquake waves and cause seismic amplification. These effects are called “site effects”. Microtremors which provide an efficient practical tool for site effects estimation were recorded at 43 sites in Beni Suef City, Egypt. The recorded seismic signals were analyzed using the Horizontal-to-Vertical Spectral Ratio (HVSR) method. The targeted site parameters are the fundamental frequency ( f0) and the corresponding amplitude of seismic waves ( A0). Selected H/V curves with clear peak frequency have been inverted to infer the S-wave velocity profile of the underlying sediments. Information about subsurface sediments needed for the inversion process was extracted from available boreholes data. Moreover, the estimated values of f0and A0have been used for a preliminary calculation of the seismic vulnerability index ( Kg) which represents an indicator of soil liquefaction potentiality in the event of future earthquakes at the study area.The estimated H/V curves reveals significant variations in f0and A0parameters, reflecting variations in the soil characteristics (thickness and type) at the study area. The estimated values of f0are (0.4–3.7 Hz), and commonly decrease from east to west. The A0values vary from flat H/V curves (without any clear peak) at rock sites to 7.8 near to the Nile River and in the cultivated areas. The obtained velocity profiles could investigate S-wave structure down to 200 m depth. The estimated Kgvaries from 10 to more than 50 μstrain/gal. The highest Kgvalues are noticed in the west and northwest in the study area were the soft sediments exist with considerable thickness, while the smallest Kgvalues are noticed in the south east where limestone and stiff soil occur near the ground surface.

Seismic Vulnerability Mapping of the Lhokseumawe Region to Support the Spatial Plan of Lhokseumawe City

Microtremor is a weak vibration on the surface of the earth that takes place continuously due to sources of vibration such as earthquakes, human activities, industry and traffic (Daryono, 2009). Microtremor data measured obtained 3 signals whose components are vertical (Up and Down), horizontal (North-South), and horizontal (East-West) components. After the signal is obtained it can then be analyzed using the HVSR method and the dominant frequency and amplification values are obtained. The HVSR method compares the spectrum ratio of the horizontal component microtremor signal to its vertical component (Nakamura, 1989). Lhokseumawe City is administratively included in the Province of Nangroe Aceh Darussalam (NAD). In 2004 there was an earthquake of magnitude 9.2 on the Richter Scale in the southern waters of the city of Banda Aceh, which caused a devastating Tsunami. In this event many people lost about 250 thousand lives and lost property that is not small in number (Logan, 2014) Due to the active regional tectonic pattern, the NAD region is a disaster-prone region. The tectonic area of NAD is strongly influenced by the subduction area between the Indian-Australian oceanic plate (Indian Australian Plate) against the European-Asian continental plate (Eurasian plate). The tectonic pattern greatly influences the geological conditions in the waters of the study area. The purpose of this research is to provide preliminary knowledge in the use of microtremors for mapping seismic microzonation. This microzonation mapping is needed for earthquake disaster mitigation purposes, microtremor data analysis can provide information on the value of a place that is very important for earthquake resistant building planning. Building structures that have the same value as the land value will experience resonance in the event of an earthquake. Then the last is the Seismic Vulnerability Index Mapping which is useful for predicting unconsolidated sediment zones at the ground surface when an earthquake occurs, so that further studies for earthquake prone areas can be carried out. The stages of the research method carried out are measuring field data which is divided into several measurement points in each district in the city of Lhokseumawe. At each measurement point, a three-component seismometer is installed to obtain the results of the soil’s vulnerability in the area. Each measurement data is observed for 30 minutes at each point. The results of this study are the existence of areas that are very susceptible to seismic namely Ujung blang and Banda Sakti villages with seismic vulnerability index values (Kg) ranging from 0 cm/s2-30542.32 cm/s2The highest value is located at Ujong Blang villages which is 10397.1 cm/s2This is closely related to the total amount of damage to buildings in Lhokseumawe City due to the 2004 earthquake.

Vulnerability Of The Garut District Region In Tarogong Kalam, Tarogong Kidul, Garut Kota, And Karang Pawitan Sub-District Based On Microtremor Measurement

The Tasikmalaya M 7.3 earthquake on September 2, 2009 had an impact on Garut, damaged infrastructure and claimed many lives. From the search results there were five areas that were severely damaged by tectonic earthquake shocks, which included Pemeungpeuk, Cisompet, Cikelet, Peundeuy and Banjarwangi Subdistricts, so that earthquake mitigation measures were needed. One of the mitigations that can research how the impact is if the potential for earthquake disasters occur below the southern surface of Java. The final objective of this research is to map disaster-prone zones in Tarogong Kaler, Tarogong Kidul, Garut City, and Karang Pawitan, Garut Subdistrict, based on dominant frequency values, Vs30, seismic vulnerability indexes, and GSS (Ground Shear Strains) so that they can know the land movement that is. Retrieval of data in this study by measuring geophysicaly methods in the field. Processing data using HVSR (Horizontal to Vertical Spectra Ratio) method, then mapped with ArcGis to interpret the zoning of the study area. Based on the research, we known that the dominant frequency distribution value is between 1-5.2 Hz. The seismic vulnerability index values calculated the study area are between 3 – 45, GSS values in the study area between 3 ×10-4 - 42×10-4. By looking at the spatial distribution of the values of f0, Kg and GSS the areas of Karangmulya, Jatiasih, Sidanggalih and Godog villages are types of young volcanic sediments classified as soft soils that are easily to wave amplification and earthquake vibrations, so that they are easily damaged during large earthquakes. in this region qualify as earthquake resistant buildings to minimize damage and losses, while Sukabakti, Kersamenak, Sukajaya, and Mekargalih villages in the west with the geological conditions of the surrounding area which is hard land so that it will be safer when an earthquake occurs.

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.