Earthquake Hazard Maps Research Articles

Comparison of Seismic and Structural Parameters of Settlements in the East Anatolian Fault Zone in Light of the 6 February Kahramanmaraş Earthquakes

On 6 February 2023, two very large destructive earthquakes occurred in the East Anatolian Fault Zone (EAFZ), one of Türkiye’s primary tectonic members. The fact that these earthquakes occurred on the same day and in the same region increased the extent of the destruction. Within the scope of this study, twenty different settlements affected by earthquakes and located directly on the EAFZ were taken into consideration. Significant destruction and structural failure at different levels were induced in reinforced concrete (RC) structures, the dominant urban building stock in these regions. To determine whether the earthquake hazard is adequately represented, the PGA values predicted in the last two earthquake hazard maps used in Türkiye for these settlements were compared with the measured PGAs from actual earthquakes. Subsequently, the damage to reinforced concrete structures in these settlements was evaluated within the scope of construction and earthquake engineering. In the final part of the study, static pushover analyses were performed on a selected example of a reinforced concrete building model, and target displacement values for different performance levels were determined separately for each earthquake. For the 20 different settlements considered, the displacements were also derived based on the values predicted in the last two earthquake hazard maps, and comparisons were made. While the target displacements were exceeded in some settlements, there was no exceedance in the other settlements. The realistic presentation of earthquake hazards will enable the mentioned displacements predicted for different performance levels of structures to be determined in a much more realistic manner. As a result, the performance grades predicted for the structures will be estimated more accurately.

Comparison of 5 and 10 Storey Frame Buildings and 5 and 10 Storey Shear Wall-Frame Buildings Under the Effect of Maras Earthquake According to the Turkish Building Earthquake Code 2018

In this study, the differences in the displacements, base shear forces, relative storey drifts and foundation stresses under different earthquake data on different storeys of shear wall frame systems and framed systems are investigated by using SAP2000 program. Within the scope of the study, four buildings with 5-storey frame, 5-storey shear wall frame, 10-storey frame and 10 storey shear wall frame are modelled. All four buildings were designed to be identical with 4 spans in X and Y directions and each span was designed as 5 meters. The height of each floor is designed as 3 meters for all four buildings. In sheared structures, shear walls are designed to be 4 meters from the corner columns to the columns closest to them. The earthquake data to be influenced on all four structures are the earthquake data from the Earthquake Hazard Map of Turkey published by AFAD at the coordinates of 41° latitude, 27° longitude of Kırklareli province, Luleburgaz district. Another earthquake parameter was taken from station 4615 during the earthquake in Kahramanmaras. The data recorded by station 4615 for the 7.6 Mw earthquake in Kahramanmaras was applied to all four structures. These two earthquake data were imposed on these four structures in order to compare the resulting displacements, relative storey drifts, base shear forces and foundation stresses. Since the structures are all symmetrical in both X and Y directions, only one direction of the displacements was calculated. As a result, when both the earthquake data from the Earthquake Hazard Map and the Kahramanmaras earthquake data were applied to these four structures, it was observed that the maximum values of the displacements occurred at the top floors of all structures and the effect of the Kahramanmaras earthquake data was higher in the displacements, relative storey drifts, base shear forces and foundation stresses than the effect of the other earthquake data.

Optimizing Interpolation Methods and Point Distances for Accurate Earthquake Hazard Mapping

Earthquake hazard mapping assesses and visualizes seismic hazards in a region using data from specific points. Conducting a seismic hazard analysis for each point is essential, while continuous assessment for all points is impractical. The practical approach involves identifying hazards at specific points and utilizing interpolation for the rest. This method considers grid point spacing and chooses the right interpolation technique for estimating hazards at other points. This article examines different point distances and interpolation methods through a case study. To gauge accuracy, it tests 15 point distances and employs two interpolation methods, inverse distance weighted and ordinary kriging. Point distances are chosen as a percentage of longitude and latitude, ranging from 0.02 to 0.3. A baseline distance of 0.02 is set, and other distances and interpolation methods are compared with it. Five statistical indicators assess the methods. Ordinary kriging interpolation shows greater accuracy. With error rates and hazard map similarities in mind, a distance of 0.14 points seems optimal, balancing computational time and accuracy needs. Based on the research findings, this approach offers a cost-effective method for creating seismic hazard maps. It enables informed risk assessments for structures spanning various geographic areas, like linear infrastructures.

A note on the seismicity of Sumatra, western Sunda Arc, Indonesia, in relation to the potential for back-arc thrusting

The existence of back-arc thrust faults along the eastern part of the Sunda Arc, ranging westwards from Flores to the western tip of Java, has been recognised for decades. In contrast, it is still unknown whether such back-arc thrust faults exist in Sumatra, which is located in the western part of the Sunda Arc. To investigate the possible existence of back-arc thrusts in Sumatra, we examine regional earthquake data reported by the Agency for Meteorology, Climatology and Geophysics of Indonesia, as well as global earthquake data reported by the International Seismological Centre and the United States Geological Survey. It appears that back-arc thrusts in the study area are not extensively developed, unlike in the eastern Sunda Arc, which may be caused by oblique subduction beneath the Sumatran forearc. The stress associated with the trench-parallel component of subduction is largely accommodated by the ~ 1650-km-long dextral strike-slip fault zone of the Great Sumatran Fault. The seismicity data from various sources do, however, show that there is a dipping seismogenic zone in several parts of the back-arc region of Sumatra, in the opposite direction to the NNE subduction of the Indo-Australian plate. This new observation may be related to the presence of spatially intermittent back-arc thrust faults in the study area, which may need to be taken into account when improving Indonesia's national earthquake hazard maps.

Studi Komparasi Bangunan Tahan Gempa Berdasarkan SNI 1726-2012 dan SNI 1726-2019

Indonesia is an archipelago that is flanked by oceanic plates and land plates that cause the two plates to often collide. This causes Indonesia to be an earthquake-prone area and has many volcanoes. Research related to earthquakes in Indonesia continues to develop. This has resulted in several points such as new earthquake hazard maps and the latest regulations related to earthquake-resistant building planning, resulting in the building planning process having to follow the latest applicable regulations. The purpose of this study is to analyze changes in SNI, structural dimension requirements, reinforcement requirements, and structural behavior and internal forces due to the application of SNI 1726:2012 and SNI 1726:2019 in a building. The research method used was to conduct a literature study on the changes from SNI 1726:2012 to SNI 1726:2019 using the SNI 2847:2019 planning which will be used in the structural analysis. The results obtained from this study show that there are differences in the earthquake maps used in SNI 1726:2012 and SNI 1726:2019, there are differences in parameters in SNI 1726:2012 and SNI 1726:2019 which result in an increase in the forces acting on the structure which affects the need for reinforcement. Structural planning is carried out by following SNI 1726:2019 and SNI 2847:2019, for existing buildings that have been built based on SNI 1726:2012, it is necessary to carry out a re-examination or assessment to determine the condition of the existing building in relation to earthquake in Indonesia.

Comparison of peak ground acceleration using deterministic and probabilistic approach in the coastal area of Loh Buaya, Rinca Island, Indonesia

An area located near an active volcano, subduction zone, and/or active fault has a risk of an earthquake. Earthquakes can cause damage to buildings with a large number of losses. One of the earthquake-related parameters required in planning an earthquake-resistant building is the Peak Ground Acceleration (PGA). The objective of this study is to compare the PGA value at the coastal area of Loh Buaya, Rinca Island, Indonesia, using Probabilistic Seismic Hazard Analysis (PSHA) and Deterministic Seismic Hazard Analysis (DSHA). The DSHA is calculated based on earthquake data series from the United States Geological Survey (USGS) in the period between 1922 to 2022. Also, it is calculated using 10 data of Ground Motion Prediction Equation (GMPE). Data from the USGS is constrained with magnitude > 5.0 MW and earthquake distance < 200 km from the study site. The PSHA is based on the Indonesian earthquake hazard map and the de-aggregation map from the National Earthquake Study Centre of Indonesia with a probability exceeding 2% in 50 years. Based on the parameters of PGA maximum, distance, and magnitude, the DSHA by Kanno method has the closest result to the PSHA. It is concluded that this area has a high earthquake risk with a PGA maximum of more than 0.5 g.

Seismic Load Design of Rukoh Dam Suppletion Tunnel in Pidie Regency, Aceh, Indonesia, Based on Deterministic and Probabilistic Seismic Hazard Analyses

The Rukoh Dam suppletion tunnel construction site in Pidie Regency, Aceh province, is located 5.6 kilometers from the Seulimeum-South segment of the active Sumatran fault. The active fault features a strike-slip fault mechanism with a slip rate of 7.0 millimeters per year and a maximum earthquake-recorded magnitude of 6.9 Mw. Considering that the construction site is located less than 10 kilometers from the active fault, which may cause earthquakes with a magnitude of at least 6 Mw, the SNI 1729:2019, which describes the procedures for planning earthquake resistance for buildings and non-building structures, requires the seismic load to be designed based on the site-specific responses analysis. Determination of the seismic load using a deterministic seismic hazard analysis was the objective of this study. The seismic load based on the probabilistic seismic hazard analysis by Pusat Studi Gempa Nasional (PusGen) in 2017 is also compared. The 2017 Indonesian Earthquake Source and Hazard Map were used to find out about the fault mechanism, slip rate, deterministic magnitude, orientation, and coordinates of traces. The deterministic seismic hazard analysis was conducted using EZ-FRISK 8.07 software and attenuation equations with shallow crustal earthquake sources for fault and shallow background earthquake sources, i.e., the Boore-Atkinson NGA 2014, the Campbell-Bozorgnia NGA 2014, and the Chiou-Youngs NGA 2014 equations. The deterministic analysis based on those attenuation equations predicted the active fault to result in a peak ground acceleration (PGA) value of 0.66 g at the construction site of the Rukoh Dam suppletion tunnel. In comparison, the probabilistic hazard analysis conducted by Pusat Studi Gempa Nasional (PusGen) in 2017 indicated a peak ground acceleration (PGA) of 0.537 g. Therefore, the seismic load is recommended for the structural designs of the embankment dam and the other infrastructures, particularly the suppletion tunnel.

Investigation of the Effects of Important Factors in Suburban Rail Route Determination with MCDM

Thorough evaluation of suburban rail route alternatives is essential for determining the appropriate route. Suburban lines provide transportation services to suburban areas; that is, they provide transportation services to distant points of the city where demand is high. In this study, five alternative suburban rail routes in the commuter rail standard, starting from the Fatih Sultan Mehmet Bridge’s European exit and ending at Istanbul Airport, were determined as a sample corridor in the province of Istanbul. High-standard suburban rail routes and their infrastructure construction costs were determined, and route options were delineated according to their construction costs. Multi-criteria decision-making (MCDM) methods were examined, including the application of the decision matrix method (DMM) and analytical hierarchy process (AHP) to rank the routes in terms of the factors examined in the study. These routes were ranked according to the construction costs and according to the DMM and AHP methods, and the results were compared. In the decision matrix application, geomorphological-geological, geotechnical, infrastructural, and environmental factors were considered in the evaluation and determination process. A solution was developed in which all aspects were weighted to indicate their relevance, and these factors contributed to the determination of the results. The AHP method was also applied, in which five criteria were included in the evaluation: geology (including geomorphology and soil properties), engineering structures, construction costs, population values addressed by the routes, and railroad length. In addition, the distances to the active faults were examined according to the Turkey Earthquake Hazard Map specified in the Turkish Building Earthquake Code (TBDY) 2018. Depending on the factors studied, the ordering of the routes was the same for all three methods.

ASCE/SEI 7‐compliant site‐specific evaluation of the seismic demand posed to reinforced concrete buildings with real and simulated ground motions

AbstractState‐of‐the‐art seismic design and assessment methodologies rely on the utilization of ground‐motion records scaled to site‐specific risk‐targeted spectra to perform nonlinear time‐history analyses and estimate mean structural demands. Motivated by the discrepancies in structural response estimates resulting from different selection and scaling methods, this study assesses the implications of utilizing site‐specific simulated ground motions from 3‐D physics‐based wave‐propagation models as opposed to historical records from worldwide catalogs in ASCE/SEI7‐compliant procedures for seismic performance evaluations. A suite of validated realizations of an M7 Hayward Fault earthquake in the San Francisco Bay Area and two modern reinforced concrete moment‐resisting frame buildings are utilized as a case study. The 2014 USGS earthquake hazard and probability maps are employed for the hazard calculations, and the PEER NGA‐West2 database is used for the selection of the real ground motions. The building models are coupled with the simulated and real ground motions to perform a total of 30,552 nonlinear time‐history analyses. Structural demands obtained from real and simulated motions are examined and compared at the regional‐scale in terms of peak interstory drift ratio median and dispersion, and localization along the building height. The correlations between observed structural responses and ground‐motion features are discussed to potentially inform current code‐compliant methodologies for ground‐motion selection. Results show that utilizing site‐specific simulated ground motions that incorporate path, fault geometry, and site‐condition effects as opposed to historical ground‐motion records may lead to differences in the structural demands above 50%. Such differences are highly spatially variable throughout the region and difficult to predict.

Pemanfaatan Data Penginderaan Jauh dan Sistim Informasi Geografis Untuk Identifikasi Perkembangan Lahan Terbangun pada Wilayah Rawan Gempa Bumi di Kota Ambon

Earthquakes are natural disasters that often occur in Indonesia, including in Ambon City which is located in an earthquake-prone area. This research aims to identify the development of built-up land in earthquake-prone areas in Ambon City by utilizing remote sensing data and geographic information systems. This research uses data on built-up land in Ambon City in 2019 and 2023 as well as earthquake hazard maps. The results show that built-up land in Ambon City in 2013-2023 experienced a significant increase in area from 4,718.17 ha in 2013 increasing in area in 2023 to 6,762.57 ha. The area of built-up land located in earthquake-prone areas in Ambon City has a relationship that is directly proportional to the year of development of built-up land. So that as the year increases, the area of built-up land located in earthquake-prone areas also increases. The results of this research are expected to serve as a basis for developing policies and mitigation strategies aimed at the sustainability of the Ambon City area amid the existing earthquake threat.

Turkey's disaster and emergency profile: Settlement information and analysis of earthquake parameters

Thousands of people die and billions of dollars of financial loss occur every year in Turkey and the world due to natural disasters. Although many reports and regulations have been prepared to eliminate the negative situations caused by natural disasters, changing climate conditions, technological advances and social habits require these measures to be developed, renewed, and made sustainable over time. In this context, creating a data pool to prevent the loss of life and property caused by disasters and performing the necessary studies becomes even more important. In addition to disaster-related information, this data pool should include physical and geographic information such as the distances of people's communal living areas to the administrative centers, the population in these living areas, and transportation facilities. In this study, a disaster and emergency profile for Turkey has been tried to be presented. For this, the distances of all settlements to the districts and provincial centers they are connected to, the transportation times and speeds of these centers, the altitudes of the settlements, earthquake zone numbers, earthquake hazard map parameters, populations, and areas were compiled or calculated. The evaluation was made separately according to the districts and provinces, taking into account the determined limits. Based on the profile reached at the end of the study, suggestions were developed for planning and projects for disasters and emergencies.

Scenario Seismic Hazard Analysis (SSHA) in Cilegon City for post-major earthquake 2019 and 2022 infrastructure construction development

The major earthquake events on August 2, 2019, and January 14, 2022, which devastated Banten City, gave an earthquake warning to the surrounding area, including Cilegon City. As an area with several vital infrastructures, such as Merak Port, chemical factories, steel industries, and power plants, Cilegon City requires a seismic study that can provide information for the planning and retrofitting of building structures. In this study, an earthquake analysis will be carried out using the Scenario Seismic Hazard Analysis (SSHA) for Cilegon City to calculate the bedrock acceleration. The earthquake sources modelled include the source of the Semangko Graben, Cimandiri and the Sunda Strait Megathrust Segment. This study provides several conclusions, included (1) results of seismic analysis using SSHA produced a maximum PGA value 0.05 - 0.1 g, 0.00 - 0.05 g and 0.3 - 0.4 g, for the Semangko Graben, Cimandiri and the Sunda Strait Megathrust Segment sources respectively. So, Cilegon City’s infrastructure layout system must be located designed in the area with a minimum ground acceleration. The existing buildings also need to be re-analyzed based on the earthquake hazard map.

28th September 2018 Mw 7.5 Sulawesi Supershear Earthquake, Indonesia: Ground effects and macroseismic intensity estimation using ESI-2007 scale

The 28th September 2018 Sulawesi Supershear earthquake (MW 7.5) was one of the deadliest earthquakes in the recent history of Indonesia causing ∼4000 causalities. The earthquake caused a ∼ 177 km long surface rupture along the Palu-Karo fault. Apart from surface rupture, the earthquake caused extensive earthquake environmental effects (EEEs) around the Palu-Donggala area of Central Sulawesi, Indonesia, which includes tsunami, coastal landslide, liquefaction, ground cracks and more than 7300 landslides in hilly areas. Initial post-event analysis and reports assigned a Modified Mercalli Intensity (MMI) of VII to VIII in Palu City and the surrounding area. Building damage and ground effects caused by the earthquake suggested that seismic intensity was understated. Here we applied the EEEs information from field survey data, published reports, and remote sensing tools to determine macroseismic intensity using the Environmental Seismic Intensity (ESI-07) Scale. The ESI-07 intensity derived from the ground effects suggests the maximum intensity of X-XI, which is 3–4° higher than the traditional intensity estimated by the United States Geological Survey (USGS) and the Indonesian Agency for Meteorology, Climatology, and Geophysics (BMKG). ShakeMaps were generated considering the ESI-07 values. The ShakeMap was compared with the instrumentally derived ShakeMap for the Palu earthquake, which proves that the ShakeMap prepared from the instrumental data or structural damage data is underrated. We argue that proper documentation of the EEEs is necessary for such damaging earthquakes for future earthquake hazard mapping and planning in the study area and other earthquakes in Indonesia. In addition, this will help in defining the on-fault and off-fault damage zone towards reducing the seismic risk of the Palu Donggala area.

Analisis Probabilitas Bahaya Gempa di Ibu Kota Baru Indonesia

Efforts to move the Capital of Indonesia to Kalimantan are intended to solve the problem of overpopulation in Jakarta, so it’s possible there are massive infrastructure development in the future. In this study conducted Probabilistic Seismic Hazard Analysis (PSHA) and made an earthquake hazard map that serves to analyze earthquake-resistant buildings for the New Capital of Indonesia. The PSHA and earthquake map was developed for 2% probability exceeded in 50 years or 2500-return period. The results of the analysis on three important periods, comprised of PGA, Ss, and S1 with a return period of 2500 years have higher acceleration at bedrock if performed by GMPE 2017 rather than GMPE 2010 for the period between PGA and 0.1s. Maximum earthquake acceleration on bedrock resulting from the creation of earthquake hazard maps in New Capital of Indonesia for period of PGA, 0.2s, and 1.0s at bedrock for return period of 2500 years is 0.2-0.25g, 0.4-0.5g, and 0-0.15g, respectively. The earthquake threat index in the New Capital of Indonesia is categorized as low according to Indonesia's National Board for Disaster Management (BNPB) regulations (PGA&lt;0.2501g).

A Comparative Probabilistic Seismic Hazard Analysis for Eastern Turkey (Bitlis) Based on Updated Hazard Map and Its Effect on Regular RC Structures

Determining the earthquake hazard of any settlement is one of the primary studies for reducing earthquake damage. Therefore, earthquake hazard maps used for this purpose must be renewed over time. Turkey Earthquake Hazard Map has been used instead of Turkey Earthquake Zones Map since 2019. A probabilistic seismic hazard was performed by using these last two maps and different attenuation relationships for Bitlis Province (Eastern Turkey) were located in the Lake Van Basin, which has a high seismic risk. The earthquake parameters were determined by considering all districts and neighborhoods in the province. Probabilistic seismic hazard analyses were carried out for these settlements using seismic sources and four different attenuation relationships. The obtained values are compared with the design spectrum stated in the last two earthquake maps. Significant differences exist between the design spectrum obtained according to the different exceedance probabilities. In this study, adaptive pushover analyses of sample-reinforced concrete buildings were performed using the design ground motion level. Structural analyses were carried out using three different design spectra, as given in the last two seismic design codes and the mean spectrum obtained from attenuation relationships. Different design spectra significantly change the target displacements predicted for the performance levels of the buildings.

Earthquake Risk Assessment of Sabah, Malaysia Based on Geospatial Approach

Sabah is located in the northeast region of East Malaysia and recognized as the most active seismic area in Malaysia. The scalability and frequency of earthquakes are growing due to the existence of both local and distant ground motions from active faults, with more than 67 earthquake occurrences with light to moderate magnitude (Mw larger than 3.5)recorded since the 1900. On the other hand, the skewed socio-economic development process associated with the rapid population growth and changes in the family structure, inequality issues, and the lack of adaptation measures would intensify the vulnerability of the earthquakes. Key elements linked to socio-economic vulnerability need to be addressed in order to reduce the risk of earthquake. Based on previous studies, we identified vulnerabilities from a multi-dimensional perspective consisting of exposure, resilience and capacity across districts. Subsequently, a holistic indicator system with 18 variables was constructed to assess the potential earthquake vulnerability in Sabah, Malaysia. The accumulated data will present an earthquake vulnerability classification using the Geographical Information System (GIS) approach. Finally, the earthquake risk was derived by integrating the earthquake vulnerability map with earthquake hazard map proposed by the Department of Mineral and Geoscience (JMG) Malaysia. The results of the analysis revealed that the highest level of earthquake risk, which accounts for 15.5 %, were concentrated in the eastern part of the Sabah region; the high-risk areas account for 7.7 %; the moderate-risk areas account for 11.3 %; and the low to very low risk areas account for 65.4 %. Accordingly, it is expected that the derived earthquake vulnerability and risk map will allow the policymakers and response teams to improve the earthquake disaster mitigation and management in Sabah.

Kırıkkale İli Özelindeki Betonarme Konutların DBYBHY-2007 ve TBDY-2018 Yönetmeliklerine Göre Depremsel Açıdan Mukayesesi

According to the 1996 Earthquake Zones Map, more than %90 of our country is in the earthquake zone in terms of area and population, while according to the Turkey Earthquake Hazard Map (TDTH) published in 2018, our whole country is under the risk of earthquakes. According to AFAD, in the TDTH, it is stated that the earthquake hazard has been reduced for 46 cities and increased for 6 cities. According to TDTH, although the earthquake hazard has decreased somewhat in some regions, existing buildings should be strengthened against earthquake, considering that the earthquake performance of our building stock may not be enough.&#x0D; Within the scope of this study, 3, 4, 5, 6, 10 and 14 storey houses with a symmetrical plan, high ductility level and reinforced concrete frame were modeled for Merkez, Bahsili, Baliseyh, Celebi, Delice, Karakecili, Keskin, Sulakyurt and Yahsihan town centers in Kirikkale province. According to both the Regulations on Buildings to be Built in Earthquake Zones (DBYBHY-2007) for the local soil classes Z1, Z2, Z3 and Z4, and the Turkish Building Earthquake Code (TBDY-2018) for the local soil classes ZA, ZB, ZC, ZD and ZE equivalent earthquake loads were calculated separately using the SAP2000 analysis program. In general, it is seen that the buildings designed according to DBYBHY-2007 are stronger than those of TBDY-2018, while the earthquake performance analysis of some houses according to the number of floors and soils in some districts should be re-made and the buildings that do not have enough performance requirement should also be strengthened.

The effect of local soil conditions on structure target displacements in different seismic zones

The local soil conditions of the region where the structure is located are one of the important parameters taken into account in the evaluation and design of structures under the influence of earthquakes. In this study, the effect of different local soil conditions on target displacement values of reinforced-concrete (RC) structures in different seismic regions was investigated. For this purpose, four different settlements within each earthquake zone specified in the previous earthquake zone map were taken into account. Structural analyzes for a sample reinforced concrete structure using four different local soil conditions were performed for all residential units separately. The values predicted in the current earthquake hazard map for the considered locations were repeated for four different local soil classes. For the settlements, the predicted values in the last two maps were compared. As the soil properties improved as a result of the structural analysis, the displacement values predicted for the building performance level took lower values.

Seismicity and magnitude recurrence hazard assessment in Eastern Nepal, Northeast India and Tibet Himalaya

The regions of eastern Nepal, northeast India and Tibet Himalaya (26°-30°N, 85°-97°E) are one of the most earthquake hazardous areas in the Indian subcontinent. The seismicity of this region is analyzed using Gumbel's third asymptotic distribution (GIII) method of extreme values to assess the earthquake hazard. A uniform and complete seismic data covering the time span of 120 years (i.e. 1900-2019) is used for the appraisal of earthquake magnitude recurrence in different return periods. The expected largest earthquake magnitudes during the next 20 (M20), 50 (M50) and 100 (M100) years with their 90% probability of not being exceeded (PNBE) are spatially mapped to create a brief atlas of short- and long-term regional earthquake magnitude recurrence hazard maps. The obtained results of maximum magnitude during 20, 50 and 100-years are expected to exceed the values of Mw 7.1, 7.7 and 8.2, respectively in two prominent blocks of eastern Nepal and Arunachal Himalaya in the examined region. These blocks are also more prominent for the results of 20, 50 and 100 years earthquake magnitudes with 90% PNBE i.e. return periods of 190 (M190), 475 (M475) and 950 (M950) years along with two additional blocks in the Eastern Himalayan Syntaxis (EHS) and Yadong-Gulu rift near Lhasa in the Tibet Plateau. These earthquake magnitudes are expected to exceed Mw 8.5, 8.6 and 8.9 during the next 190, 475 and 950 years, respectively in these blocks. The spatial distribution of earthquake hazards in the region reveals the complex seismotectonic setup and high crustal heterogeneity.

Geomorphology, Three-Dimensional Geology, and Seismologic Hazards of the New Madrid Seismic Zone in Dyer County, Tennessee

ABSTRACTGeomorphic and three-dimensional geologic mapping reveals two major fault systems of the seismically active Reelfoot rift pass beneath Dyer County in northwestern Tennessee, the Reelfoot South fault, and the east-bounding faults of the Reelfoot rift. The Dyer County mapping also indicates that the two principal Reelfoot South fault hanging wall structures, the Lake County uplift and Tiptonville dome, pass beneath the county. Quaternary displacement was identified on southeastern Reelfoot rift margin faults in Dyer County, thus indicating that this rift margin has been active during the Quaternary from adjacent Obion County through Dyer County to Lauderdale County, Tennessee, for a distance of at least 60 km. The three-dimensional geologic mapping also provides stratigraphic thicknesses of surface sediment and underlying Paleogene and Cretaceous strata that significantly contribute to the estimation of ground motion in the event of a future large New Madrid seismic zone earthquake. The new ground motion maps using the three-dimensional geology of Dyer County are compared to the current U.S. Geological Survey earthquake hazard maps. This comparison reveals generally lower acceleration for buildings less than four stories high and greater acceleration for buildings greater than 10 stories high in the event of a large New Madrid seismic zone earthquake.