Ground Shaking Intensity Research Articles

Lake Tutira paleoseismic record confirms random, moderate to major and/or great Hawke’s Bay (New Zealand) earthquakes

Robust regional seismic-hazard assessments require millennial-scale paleoseismic histories that extend far beyond the range of historical and instrumental data. However, it is difficult to resolve the probability density functions for earthquake recurrence from the limited number of major to great earthquakes most paleoseismic records contain. Lake sediment records are repositories of information about paleoearthquake recurrence, with a sensitivity and fidelity over millennial time scales that suggest that they have the potential to yield reliable estimates of the recurrence distribution. We present a 7000 yr paleoseismic record from Lake Tutira (North Island, New Zealand) that ranks among the most detailed Holocene paleoearthquake chronologies available worldwide, and use it to empirically constrain the recurrence distribution of earthquakes with a minimum ground-shaking intensity of MMI 7 in one of New Zealand’s most seismically active areas. Our analysis confirms that a Poisson process describes the waiting times of single moderate to major and/or great paleoearthquakes in the Hawke’s Bay region.

블록별 부지분류 적용 해안시설 영역에서의 HAZUS 기반 지진피해 추정

HAZUS-MH is a GIS-based computer program that estimates potential losses from multi-hazard phenomena: earthquakes, floods and hurricanes. With respect to seismic disaster, characteristics of a hypothetical or actual earthquake are entered into 2014년 8월 30일 접수 Received on August 30, 2014 / 2014년 9월 29일 수정 Revised on September 29, 2014 / 2014년 10월 7일 심사완료 Accepted on October 7, 2014 1 한국지질자원연구원 지진연구센터 Earthquake Research Center, Korea Institute of Geoscience and Mineral Resources 2 대림산업(주) 기술개발원 Technology Research and Development Institute, Daelim Industrial Co., Ltd. ※ Corresponding Author E-mail : pungsun@kigam.re.kr 블록별 부지분류 적용 해안시설 영역에서의 HAZUS 기반 지진피해 추정 / 선창국· 천성호 11 HAZUS. Then HAZUS estimates the intensity of ground shaking and calculates the correspondent losses. In this study, HAZUS was used as a part of the preparations of the future seismic events at a coastal plant facility area. To reliably characterize the target facility area, many geotechnical characteristics data were synthesized from the existing site investigation reports. And the buildings and facilities were sorted by analyzing their material and structural characteristics. In particular, the study area was divided into 17 blocks taking into account the situation of both land development and facility distribution. The ground conditions of blocks were categorized according to the site classification scheme for earthquake-resistant design. Moreover, seismic fragility curves of a main facilities were derived based on the numerical modeling and were incorporated into the database in HAZUS. The results estimated in the study area using HAZUS showed various seismic damage and loss potentials depending on site conditions and structural categories. This case study verified the usefulness of the HAZUS for estimating earthquake losses in coastal facility areas.

Damage potential and vulnerability functions of strategic buildings in the city of Algiers

The estimation of losses resulting from an earthquake requires that for each building class, the relationship between the intensity of ground shaking and damage degree must be known or developed. Potential earthquake damage to structures, human beings and personal property have been the scope of numerous studies. Different approaches have been employed so far to estimate earthquake casualties and damage. This paper describe the basic concept for development of analytical vulnerability functions based essentially on so called damage model which was performed from probabilistic studies on seismic capacity of existing buildings in the city of Algiers (Algeria). Regarding the developed model for assessing the seismic damage, vulnerability functions of specific losses (potential losses for a specific urban area in terms of meter square area of building slabs which may involve causalities) were developed in order to predict the expected seismic risk for a given ground motion scenario.

Seismic microzonation of a nuclear power plant site with detailed geotechnical, geophysical and site effect studies

This paper highlights the seismic microzonation carried out for a nuclear power plant site. Nuclear power plants are considered to be one of the most important and critical structures designed to withstand all natural disasters. Seismic microzonation is a process of demarcating a region into individual areas having different levels of various seismic hazards. This will help in identifying regions having high seismic hazard which is vital for engineering design and land-use planning. The main objective of this paper is to carry out the seismic microzonation of a nuclear power plant site situated in the east coast of South India, based on the spatial distribution of the hazard index value. The hazard index represents the consolidated effect of all major earthquake hazards and hazard influencing parameters. The present work will provide new directions for assessing the seismic hazards of new power plant sites in the country. Major seismic hazards considered for the evaluation of the hazard index are (1) intensity of ground shaking at bedrock, (2) site amplification, (3) liquefaction potential and (4) the predominant frequency of the earthquake motion at the surface. The intensity of ground shaking in terms of peak horizontal acceleration (PHA) was estimated for the study area using both deterministic and probabilistic approaches with logic tree methodology. The site characterization of the study area has been carried out using the multichannel analysis of surface waves test and available borehole data. One-dimensional ground response analysis was carried out at major locations within the study area for evaluating PHA and spectral accelerations at the ground surface. Based on the standard penetration test data, deterministic as well as probabilistic liquefaction hazard analysis has been carried out for the entire study area. Finally, all the major earthquake hazards estimated above, and other significant parameters representing local geology were integrated using the analytic hierarchy process and hazard index map for the study area was prepared. Maps showing the spatial variation of seismic hazards (intensity of ground shaking, liquefaction potential and predominant frequency) and hazard index are presented in this work.

Protocol for testing of cold-formed steel wall in regions of low-moderate seismicity

Loading protocols have been developed for quasi-static cyclic testing of structures and components. However, it is uncertain if protocols developed for conditions of intense ground shaking in regions of high seismicity would also be applicable to regions of low-moderate seismicity that are remote from the tectonic plate boundaries. This study presents a methodology for developing a quasi-static cyclic displacement loading protocol for experimental bracing evaluation of cold-formed steel stud shear walls. Simulations presented in the paper were based on conditions of moderate ground shaking (in Australia). The methodologies presented are generic in nature and can be applied to other regions of similar seismicity conditions (which include many parts of China, Korea, India and Malaysia). Numerous response time histories including both linear and nonlinear analyses have been generated for selected earthquake scenarios and site classes. Rain-flow cycle counting method has been used for determining the number of cycles at various ranges of normalized displacement amplitude. It is found that the number of displacement cycles of the loading protocol increases with increasing intensity of ground shaking (associated with a longer return period).

연속 지진에 의하여 손상된 필로티 RC 건축물의 BRB 보강 전/후의 취약성 평가

This paper presents the seismic evaluation and prediction of a damaged piloti-type Reinforced Concrete (RC) building before and after post-retrofitting under successive earthquakes. For considering realistic successive earthquakes, the past records measured at the same station were combined. In this study, the damaged RC building due to the first earthquake was retrofitted with a buckling-restrained brace (BRB) before the second earthquake occurred. Nonlinear Time History Analysis (NTHA) was performed under the scaled intensity of the successive ground motions. Based on the extensive structural response data obtained form from the NTHA, the fragility relationships between the ground shaking intensity and the probability of reaching a pre-determined limit state was were derived. In addition, The the fragility curves of the pre-damaged building without and with the BRBs were employed to evaluate the effect of the successive earthquakes and the post-retrofit effect. Through the seismic assessment subjected to the successive records, it was observed that the seismic performance of the pre-damaged building was significantly affected by the severity of the damage from the first earthquake damages and the hysteresis behavior of the retrofit element.

Sensitivity measures for optimal mitigation of risk and reduction of model uncertainty

This paper presents a new set of reliability sensitivity measures. The purpose is to identify the optimal manner in which to mitigate risk to civil infrastructure, and reduce model uncertainty in order to improve risk estimates. Three measures are presented. One identifies the infrastructure components that should be prioritized for retrofit. Another measure identifies the infrastructure that should be prioritized for more refined modeling. The third measure identifies the models that should be prioritized in research to improve models, for example by gathering new data. The developments are presented in the context of a region with 622 buildings that are subjected to seismicity from several sources. A comprehensive seismic risk analysis of this region is conducted, with over 300 random variables, 30 model types, and 4000 model instances. All models are probabilistic and emphasis is placed on the explicit characterization of epistemic uncertainty. For the considered region, the buildings that should first be retrofitted are found to be pre-code unreinforced masonry buildings. Conversely, concrete shear wall buildings rank highest on the list of buildings that should be subjected to more detailed modeling. The ground shaking intensity model for shallow crustal earthquakes and the concrete shear wall structural response model rank highest on the list of models that should be prioritized by research to improve engineering analysis models.

The potential for induced seismicity in energy technologies

The great majority of earthquakes that occur each year around the world have natural causes. A small number of lesser-magnitude seismic events have been related to human activities and are called “induced seismic events” or “induced earthquakes” (NRC, 2012). Of concern are induced events that are large enough to be noticed by the public, typically events larger than magnitude 3 (note the range earthquake sizes that are felt can widely vary depending on project location and site characteristics). Induced seismic activity has been described since at least the 1920s and attributed to various human activities including the impoundment of water reservoirs, controlled explosions related to mining and construction, underground nuclear tests, and energy technology developments that involve injection or withdrawal of fluids from the subsurface. Historically known induced seismicity has generally been small in both magnitude and intensity of ground shaking.

Seismic vulnerability of the Himalayan half-dressed rubble stone masonry structures, experimental and analytical studies

Abstract. Half-Dressed rubble stone (DS) masonry structures as found in the Himalayan region are investigated using experimental and analytical studies. The experimental study included a shake table test on a one-third scaled structural model, a representative of DS masonry structure employed for public critical facilities, e.g. school buildings, offices, health care units, etc. The aim of the experimental study was to understand the damage mechanism of the model, develop damage scale towards deformation-based assessment and retrieve the lateral force-deformation response of the model besides its elastic dynamic properties, i.e. fundamental vibration period and elastic damping. The analytical study included fragility analysis of building prototypes using a fully probabilistic nonlinear dynamic method. The prototypes are designed as SDOF systems assigned with lateral, force-deformation constitutive law (obtained experimentally). Uncertainties in the constitutive law, i.e. lateral stiffness, strength and deformation limits, are considered through random Monte Carlo simulation. Fifty prototype buildings are analyzed using a suite of ten natural accelerograms and an incremental dynamic analysis technique. Fragility and vulnerability functions are derived for the damageability assessment of structures, economic loss and casualty estimation during an earthquake given the ground shaking intensity, essential within the context of risk assessment of existing stock aiming towards risk mitigation and disaster risk reduction.

Applications of airborne and terrestrial laser scanning to paleoseismology

Paleoseismic investigations aim to document past earthquake characteristics such as rupture location, frequency, distribution of slip, and ground shaking intensity—critical parameters for improved understanding of earthquake processes and refined earthquake forecasts. These investigations increasingly rely on high-resolution ( 2 /m. This situation refines interpretations of PBR exhumation rates and thus their effectiveness as paleoseismometers. Given that earthquakes disrupt Earth9s surface at centimeter to meter scales and that depositional and erosional responses typically operate on similar scales, ALS and TLS provide the absolute measurement capability sufficient to characterize these changes in challenging geometric arrangements, and thus demonstrate their value as effective analytical tools in paleoseismology.

GIS-Based Seismic Damage Estimation: Case Study for the City of Kelowna, BC

AbstractThis study integrates risk assessment tools for diagnosis of urban areas against seismic disasters (RADIUS) and geographic information system (GIS), hence forth denoted as GBR (GIS based RADIUS). The GBR is applied for seismic damage estimation of city of Kelowna, in the interior of British Columbia, Canada. Ground-shaking intensity in the area was developed utilizing the seismic source zones defined by the Geological Survey of Canada and opinions from the local experts. Building inventories were compiled by aggregating data from municipal databases as well as sidewalk surveys and surveys through Google Maps. The GIS tool came in to be handy to provide a basis for effective decision making and gauge the vulnerable areas. Estimated damage and damage distributions were mapped on a block-by-block (5×5 km) basis. The assessment revealed that an earthquake scenario of M8.5 in the Cascadia Zone may potentially damage around 58 buildings within the city, causing 12 injuries. Plus, the study showed some d...

Vulnerability of Reinforced-Concrete-Frame Buildings and Their Occupants in the 2009 L’Aquila, Italy, Earthquake

Reinforced-concrete-frame buildings, particularly midrise multifamily condominium structures, experienced significant damage in the 2009 L’Aquila, Italy earthquake. The most frequently observed damage was cracking and failure of nonstructural masonry infill walls, but some buildings also experienced structural damage, including column shear failure and collapse. Fieldwork conducted approximately 3 weeks after the earthquake was used to collect data from approximately 483 concrete frame structures in L’Aquila, including building location, characteristics, damage, and postearthquake occupancy. A second survey 1 year later investigated whether buildings had been repaired or reoccupied. These results show that the building damage is correlated to height, usage, elevation irregularities in strength and stiffness, and the ground-shaking intensity at each site. This information provides the basis for empirically derived fragility functions for this typology of concrete frame. Approximately 0.2% of concrete structures collapsed. The study also shows that occupants of tall and older condominium structures in areas north and west of the city center were particularly affected; single-family homes were less damaged and more likely to be occupied during fieldwork. Damaged concrete buildings have led to significant disruption of the community and social fabric, causing the temporary or permanent closure of small businesses, medical offices, restaurants, churches, and schools.

Earthquake catastrophe models in disaster response planning, risk mitigation and financing in developing countries in Asia

Abstract Earthquake catastrophe models combine simulated earthquake hazard intensity parameters, such as ground-shaking intensity and liquefaction potential, with spatial data layers describing the geography and vulnerability of exposed assets at risk (property, populations and infrastructure) to calculate the probability of loss. There is significant scope for applying catastrophe models to disaster relief planning, risk mitigation and financing, especially for earthquake-prone developing economies in Asia. Potential uses of earthquake catastrophe models in these areas include the following. Estimating probable levels of damage across an area resulting from a range of possible earthquake events. These estimates are useful in assessing the scale of the response required when an earthquake event actually occurs and for devising a realistic plan for the disaster response effort. Quantifying the humanitarian and economic benefit of introducing or upgrading existing risk mitigation measures in advance of their introduction; and assessing the loss potential of possible sites for future infrastructure and/or industrial facilities. Quantifying risk metrics fundamental to the pricing of financial risk transfer solutions that enable the transfer of the cost of relief and reconstruction away from the damaged national economy, thereby cushioning it from financial shock caused by major earthquake damage.

Probabilistic seismic performance assessment of code-compliant multi-story RC buildings

Fragility analyses are conducted in this study to evaluate the relative seismic safety margins of seismic code-designed multi-story reinforced concrete (RC) buildings with varying input motion intensity, ductility level and configuration. Structural variations are accounted for by using twelve buildings [13] with diverse structural systems, heights and ductile detailing. The design peak ground acceleration (PGA) is also varied. The reference structures also include regular and irregular buildings in order to cover a wide spectrum of contemporary mid-rise buildings. Incremental dynamic analyses (IDAs) are deployed using the twelve inelastic fiber-based simulation models of the reference structures and sixty natural ground motions recorded on different soil conditions with a wide range of spectral amplifications. The regression analyses of the selected response quantities show that the soil condition has a marginal effect on the demand-ground motion intensity relationships when adopting spectral acceleration to characterize the ground shaking intensity. The damage state probabilities of wall-frame structures designed to high PGA and ductility levels do not satisfactorily achieve the most favorable safety objectives. Fragilities are reduced by decreasing the design PGA due to the higher contribution of gravity loads to the details of the building design. Using extensive results from twelve buildings subjected to sixty ground motions, a relationship is proposed to enable the quantifying of the Life Safety limit state probabilities of code-compliant mid-rise RC buildings.

Nonlinear site response evaluation procedure under the strong motion: A case study of Miyaneh, Azarbayjan Sharghi Province, Iran

The objective of a site response analysis is to estimate the ground shaking intensity during an earthquake. The Miyaneh city and its suburban areas are located in the northwest of Iran in Azarbayjan-Sharghi province. This area is prone to high seismic risk due to the presence of several active faults. In this paper, a case study on ground response analysis of a geotechnical site in Miyaneh region during the Ardabil earthquake (28 February, 1997, Mw6.1) is presented. For sitecharacterization, deep site investigations have been undertaken and a seismic geotechnical procedure for the proposed bridge over the rivers at the mentioned site, which is performed for Iran railway network, subjected to earthquake provokes, has been notified. The effect of nonlinearity on site response analysis for the selected site with the assumption of elastic and rigid half space bedrock (by use of nonlinear standard hyperbolic model) was evaluated and the results obtained over a number of geotechnical areas were compared to each other. Test of the capability of designed computer codes by authors, namely; “Abbas converter”, which describes and evaluates the nonlinearity of the subsurface soil conditions encountered at the sites to analyze, evaluate the obtained test, site response and quantify the site effect on the surface over a number of geotechnical areas, were the targets of this study. The results clearly showed that the effect of bedrock and local soil conditions on soil behavior under the earthquake excitation is one of the main effective factors on computed response spectra in ground response prediction. The key factor in this work was to develop and use “Abbas converter”. It has several advantages, which can make and render the study easier, than previous studies done, and take over the encountered problem. Key words: Miyaneh city, “Abbas Converter”, Ardabil earthquake, site response, site amplification.

Retesting of Liquefaction and Nonliquefaction Case Histories from the 1976 Tangshan Earthquake

A field investigation was performed to retest liquefaction and nonliquefaction sites from the 1976 Tangshan earthquake in China. These sites were carefully investigated in 1978 and 1979 by using standard penetration test (SPT) and cone penetration test (CPT) equipment; however, the CPT measurements are obsolete because of the now nonstandard cone that was used at the time. In 2007, a modern cone was mobilized to retest 18 selected sites that are particularly important because of the intense ground shaking they sustained despite their high fines content and/or because the site did not liquefy. Of the sites reinvestigated and carefully reprocessed, 13 were considered accurate representative case histories. Two of the sites that were originally investigated for liquefaction have been reinvestigated for cyclic failure of fine-grained soil and removed from consideration for liquefaction triggering. The most important outcome of these field investigations was the collection of more accurate data for three nonliquefaction sites that experienced intense ground shaking. Data for these three case histories is now included in an area of the liquefaction triggering database that was poorly populated and will help constrain the upper bound of future liquefaction triggering curves.

Simulating soil stiffness degradation in transient site response predictions

A series of nonlinear seismic ground response analyses are conducted to investigate the effect of soil degradation on the seismic response of typical sedimentary deposits in Southern California. For this purpose, three downhole array station sites at the Los Angeles basin are subjected to broadband synthetic ground motion excitations. A characteristic strain measure, defined as the averaged maximum shear strain in the top 30 m of the soil profile ( γ 30 ), is proposed to enable the correlation between the ground shaking intensity level (here measured by means of the peak ground acceleration on the surface of rock-outcrop, PGA RO ) and the average deviation in ground motion response spectral predictions (denoted as e SA ) attributed to the effect of modulus degradation due to cyclic loading. It is shown that strong linear correlations exist among log ( PGA RO ) , log ( γ 30 ) and log ( e SA ) for the sites investigated. On the other hand, the number of loading cycles typically employed to indicate the importance of soil degradation is shown to play a much less important role. This becomes more apparent for near-field large amplitude ground motions characterized by a dominant pulse and overall low number of cycles, which nonetheless impose strains large enough to trigger modulus degradation effects. Based on this observation, it is suggested that the soil degradation effect in seismic ground motion is primarily controlled by the ground shaking intensity. The level of PGA RO beyond which soil degradation should be accounted for and incorporated in seismic ground response analysis is also depicted for the sites investigated.

Influence of inelastic seismic response modeling on regional loss estimation

This study investigates the implications of the use of alternative damage prediction methodologies to correlate ground shaking intensity to socio-economic losses in regional seismic loss analyses. In particular two methodologies are investigated: the over-damped Capacity Spectrum Method (CSM), and a modified version of a Parameterized Fragility Method (PFM) based on dynamic nonlinear analysis to reflect the generalized effects of degradation in hysteretic response. Investigations include comparisons of a variety of structural systems first assuming full hysteresis to minimize the discrepancies in modeling approaches, as well as parametric variations in ground motion intensity and degradation effects. The study culminates with an investigation of the influence of the application of each methodology on regional loss estimates, using a seismic risk analysis performed for the state of South Carolina as a case study, by comparing seismic loss estimates obtained using the over-damped CSM with estimates obtained by application of a modified PFM (MPFM). It is shown that the estimates obtained from the two methodologies are different, and that the over-damped CSM displays increased sensitivity to key analysis parameters relative to the MPFM method both in terms of displacement demands and estimated socio-economic losses.

Microzonation Study in Balıkesir

A microzonation methodology is developed for Balikesir based on available geological and geotechnical data and applied for microzonation of the areas de fined as BPH (the area covering Bahcelievler, Plevne and Hasan Basri Cantay districts) and 18-02 in Balikesir. Acceleration records are simulated compatible with target acceleration spectra estimated for Balikesir design earthquake. Representative soil profiles are modelled by a grid system for each cell based on geotechnical data. Spectral accelerations on the ground surface are calculated by two different approaches using site response anal ysis and NEHRP amplification factors. Microzonation maps are produced with respect to ground shaking intensity taking into account the variation of the spectral accelerations calculated based on these two procedures.

The Muzaffarabad, Pakistan, earthquake of 8 October 2005: surface faulting, environmental effects and macroseismic intensity

Abstract The Mw 7.6 Muzaffarabad earthquake of 8 October 2005, occurred on a lateral equivalent of the main ramp of the Hymalaia frontal thrust, and is the result of the collision tectonics between the Indian and Eurasian plates. The epicentre was located near the town of Basantkot (Muzaffarabad), and the focal depth was about 13 km. The Muzaffarabad earthquake provides unequivocal evidence about the localization of severe damage, intense ground shaking and secondary environmental effects near the surface expression of the source fault. We analyse its nature, and impact on man-made structures and the physical environment, on the basis of a detailed survey and macroseismic study of the affected areas conducted by the Micro Seismic Studies Programme (MSSP) Team (Ishfaq Ahmad Research Laboratories, Pakistan Atomic Energy Commission) immediately after the mainshock, assisted by a careful review of the subsequent data and literature. In the course of the field survey, the displacement and surface expression of the causative fault, and accompanying secondary environmental effects were observed at a number of places along a capable thrust fault structure. We refer to this structure as the Kashmir Thrust (KT) capable fault following the terminology of local research geologists in Pakistan; the seismological evidence of this structure is already known in the literature as the Indus–Kohistan Seismic Zone. A complex, clearly segmented, at least 112-km-long surface rupture was mapped along the KT. The maximum values of vertical displacement (on the order of 4 to 7 m) were observed mainly between Muzaffarabad and Balakot, along the central segment of the rupture (52 km) associated with maximum slip at depth and a major portion of the energy release. Both the NW Alai segment (38 km) and SE Bagh segment (22 km) are characterized by scattered minor surface ruptures with a few centimetres of displacement, accompanied by extensive surface cracking, landslides and severe damage, concentrated in a narrow belt along the fault trace. A maximum intensity of XI on the Modified Mercalli Intensity (MMI) scale and on the Environmental Seismic Intensity scale (ESI 2007) was recorded in the epicentral area between Muzaffarabad and Balakot. Extremely severe damage and very important secondary environmental effects in the hanging wall adjacent to the trace of the causative fault plane are mainly due to near-fault strong motion and rupture directivity effects. To our knowledge, this is the first study to present field observations over the whole near-field of the earthquake, and to include the intensity map of the entire meizoseismal region.