scholarly journals A new probabilistic seismic hazard assessment for greater Tokyo

2006 ◽  
Vol 364 (1845) ◽  
pp. 1965-1988 ◽  
Author(s):  
Ross S Stein ◽  
Shinji Toda ◽  
Tom Parsons ◽  
Elliot Grunewald
Keyword(s):  
Active Faults ◽  
Plate Boundary ◽  
Seismic Hazard Assessment ◽  
Historical Record ◽  
Probabilistic Seismic Hazard Assessment ◽  
Earthquake Hazards ◽  
Seismic Behaviour ◽  
Ground Acceleration ◽  
The Past ◽  
The Pacific

Tokyo and its outlying cities are home to one-quarter of Japan's 127 million people. Highly destructive earthquakes struck the capital in 1703, 1855 and 1923, the last of which took 105 000 lives. Fuelled by greater Tokyo's rich seismological record, but challenged by its magnificent complexity, our joint Japanese–US group carried out a new study of the capital's earthquake hazards. We used the prehistoric record of great earthquakes preserved by uplifted marine terraces and tsunami deposits (17 M ∼8 shocks in the past 7000 years), a newly digitized dataset of historical shaking (10 000 observations in the past 400 years), the dense modern seismic network (300 000 earthquakes in the past 30 years), and Japan's GeoNet array (150 GPS vectors in the past 10 years) to reinterpret the tectonic structure, identify active faults and their slip rates and estimate their earthquake frequency. We propose that a dislodged fragment of the Pacific plate is jammed between the Pacific, Philippine Sea and Eurasian plates beneath the Kanto plain on which Tokyo sits. We suggest that the Kanto fragment controls much of Tokyo's seismic behaviour for large earthquakes, including the damaging 1855 M ∼7.3 Ansei-Edo shock. On the basis of the frequency of earthquakes beneath greater Tokyo, events with magnitude and location similar to the M ∼7.3 Ansei-Edo event have a ca 20% likelihood in an average 30 year period. In contrast, our renewal (time-dependent) probability for the great M ≥7.9 plate boundary shocks such as struck in 1923 and 1703 is 0.5% for the next 30 years, with a time-averaged 30 year probability of ca 10%. The resulting net likelihood for severe shaking ( ca 0.9 g peak ground acceleration (PGA)) in Tokyo, Kawasaki and Yokohama for the next 30 years is ca 30%. The long historical record in Kanto also affords a rare opportunity to calculate the probability of shaking in an alternative manner exclusively from intensity observations. This approach permits robust estimates for the spatial distribution of expected shaking, even for sites with few observations. The resulting probability of severe shaking is ca 35% in Tokyo, Kawasaki and Yokohama and ca 10% in Chiba for an average 30 year period, in good agreement with our independent estimate, and thus bolstering our view that Tokyo's hazard looms large. Given $1 trillion estimates for the cost of an M ∼7.3 shock beneath Tokyo, our probability implies a $13 billion annual probable loss.

scholarly journals Probabilistic seismic hazard assessment of the Canterbury region, New Zealand

2001 ◽  
Vol 34 (4) ◽  
pp. 318-334 ◽  
Author(s):  
Mark Stirling ◽  
Jarg Pettinga ◽  
Kelvin Berryman ◽  
Mark Yetton
Keyword(s):  
New Zealand ◽  
Seismic Hazard ◽  
Hazard Assessment ◽  
Regional Scale ◽  
Active Faults ◽  
Seismic Hazard Assessment ◽  
Historical Seismicity ◽  
Probabilistic Seismic Hazard Assessment ◽  
Probabilistic Seismic Hazard ◽  
Ground Acceleration

We present the main results of a probabilistic seismic hazard assessment of the Canterbury region recently completed for Environment Canterbury (formerly Canterbury Regional Council). We use the distribution of active faults and the historical record of earthquakes to estimate the levels of earthquake shaking (peak ground acceleration and response spectral accelerations) that can be expected across the Canterbury region with return periods of 150, 475 and 1000 years. The strongest shaking (e.g. 475 year peak ground accelerations of 0.7g or more) can be expected in the west and north to northwest of the Canterbury region, where the greatest concentrations of known active faults and historical seismicity are located. Site-specific analyses of eight towns and cities selected by Environment Canterbury show that Arthur's Pass and Kaikoura are located within these zones of high hazard. In contrast, the centres studied in the Canterbury Plains (Rangiora, Kaiapoi, Christchurch, Ashburton, Temuka and Timaru) are generally located away from the zones of highest hazard. The study represents the first application of recently-developed methods in probabilistic seismic hazard at a regional scale in New Zealand.

scholarly journals Methodology for Earthquake Rupture Rate estimates of fault networks: example for the Western Corinth Rift, Greece

2017 ◽  
Author(s):  
Thomas Chartier ◽  
Oona Scotti ◽  
Hélène Lyon-Caen ◽  
Aurélien Boiselet
Keyword(s):  
Active Faults ◽  
Slip Rate ◽  
Seismic Hazard Assessment ◽  
System Level ◽  
Fault System ◽  
Normal Faults ◽  
Accurate Estimation ◽  
Probabilistic Seismic Hazard Assessment ◽  
Earthquake Rupture ◽  
Multiple Faults

Abstract. Modelling the seismic potential of active faults is a fundamental step of probabilistic seismic hazard assessment (PSHA). An accurate estimation of the rate of earthquakes on the faults is necessary in order to obtain the probability of exceedance of a given ground motion. Most PSHA studies consider faults as independent structures and neglect the possibility of multiple faults or fault segments rupturing simultaneously (Fault to Fault -FtF- ruptures). The latest Californian model (UCERF-3) takes into account this possibility by considering a system level approach rather than an individual fault level approach using the geological , seismological and geodetical information to invert the earthquake rates. In many places of the world seismological and geodetical information long fault networks are often not well constrained. There is therefore a need to propose a methodology relying only on geological information to compute earthquake rate of the faults in the network. In this methodology, similarly to UCERF-3, a simple distance criteria is used to define FtF ruptures and consider single faults or FtF ruptures as an aleatory uncertainty. Rates of earthquakes on faults are then computed following two constraints: the magnitude frequency distribution (MFD) of earthquakes in the fault system as a whole must follow an imposed shape and the rate of earthquakes on each fault is determined by the specific slip-rate of each segment depending on the possible FtF ruptures. The modelled earthquake rates are then confronted to the available independent data (geodetical, seismological and paleoseismological data) in order to weigh different hypothesis explored in a logic tree. The methodology is tested on the Western Corinth Rift, Greece (WCR) where recent advancements have been made in the understanding of the geological slip rates of the complex network of normal faults which are accommodating the ~15 mm/yr North-South extension. Modelling results show that geological, seismological extension rates and paleoseismological rates of earthquakes cannot be reconciled with only single fault rupture scenarios and require hypothesising a large spectrum of possible FtF rupture sets. Furthermore, in order to fit the imposed regional Gutenberg-Richter MFD target, some of the slip along certain faults needs to be accommodated either with interseismic creep or as post-seismic processes. Furthermore, individual fault’s MFDs differ depending on the position of each fault in the system and the possible FtF ruptures associated with the fault. Finally, a comparison of modelled earthquake rupture rates with those deduced from the regional and local earthquake catalogue statistics and local paleosismological data indicates a better fit with the FtF rupture set constructed with a distance criteria based on a 5 km rather than 3 km, suggesting, a high connectivity of faults in the WCR fault system.

scholarly journals Evaluation of The Seismic Hazard in The Marmara Region (Turkey) Based on Updated Databases

Geosciences ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 489 ◽  
Author(s):  
Şeşetyan ◽  
Tümsa ◽  
Akinci
Keyword(s):  
Seismic Hazard ◽  
Seismic Hazard Assessment ◽  
Probabilistic Seismic Hazard Assessment ◽  
Probabilistic Seismic Hazard ◽  
Earthquake Activity ◽  
Marmara Region ◽  
Ground Acceleration ◽  
Intensity Measures ◽  
Ground Shaking ◽  
Fault Characterization

The increase in the wealth of information on the seismotectonic structure of the Marmara region after two devastating earthquakes (M7.6 Izmit and M7.2 Duzce events) in the year 1999 opened the way for the reassessment of the probabilistic seismic hazard in the light of new datasets. In this connection, the most recent findings and outputs of different national and international projects concerning seismicity and fault characterization in terms of geometric and kinematic properties are exploited in the present study to build an updated seismic hazard model. A revised fault segmentation model, alternative earthquake rupture models under a Poisson and renewal assumptions, as well as recently derived global and regional ground motion prediction equations (GMPEs) are put together in the present model to assess the seismic hazard in the region. Probabilistic seismic hazard assessment (PSHA) is conducted based on characteristic earthquake modelling for the fault segments capable of producing large earthquakes and smoothed seismicity modelling for the background smaller magnitude earthquake activity. The time-independent and time-dependent seismic hazard results in terms of spatial distributions of three ground-shaking intensity measures (peak ground acceleration, PGA, and 0.2 s and 1.0 s spectral accelerations (SA) on rock having 10% and 2% probabilities of exceedance in 50 years) as well as the corresponding hazard curves for selected cities are shown and compared with previous studies.

scholarly journals Geomorphic expression and slip rate of the Fairweather fault, southeast Alaska, and evidence for predecessors of the 1958 rupture

Geosphere ◽  
2021 ◽  
Author(s):  
Robert C. Witter ◽  
Adrian M. Bender ◽  
Katherine M. Scharer ◽  
Christopher B. DuRoss ◽  
Peter J. Haeussler ◽  
...  
Keyword(s):  
Active Faults ◽  
Plate Boundary ◽  
Slip Rate ◽  
Strike Slip ◽  
Tectonic Deformation ◽  
Plate Boundaries ◽  
Slip Rates ◽  
Southeast Alaska ◽  
The Past ◽  
Show Evidence

Active traces of the southern Fairweather fault were revealed by light detection and ranging (lidar) and show evidence for transpressional deformation between North America and the Yakutat block in southeast Alaska. We map the Holocene geomorphic expression of tectonic deformation along the southern 30 km of the Fairweather fault, which ruptured in the 1958 moment magnitude 7.8 earthquake. Digital maps of surficial geology, geomorphology, and active faults illustrate both strike-slip and dip-slip deformation styles within a 10°–30° double restraining bend where the southern Fairweather fault steps offshore to the Queen Charlotte fault. We measure offset landforms along the fault and calibrate legacy 14C data to reassess the rate of Holocene strike-slip motion (≥49 mm/yr), which corroborates published estimates that place most of the plate boundary motion on the Fairweather fault. Our slip-rate estimates allow a component of oblique-reverse motion to be accommodated by contractional structures west of the Fairweather fault consistent with geodetic block models. Stratigraphic and structural relations in hand-dug excavations across two active fault strands provide an incomplete paleoseismic record including evidence for up to six surface ruptures in the past 5600 years, and at least two to four events in the past 810 years. The incomplete record suggests an earthquake recurrence interval of ≥270 years—much longer than intervals <100 years implied by published slip rates and expected earthquake displacements. Our paleoseismic observations and map of active traces of the southern Fairweather fault illustrate the complexity of transpressional deformation and seismic potential along one of Earth’s fastest strike-slip plate boundaries.

scholarly journals Probabilistic seismic hazard assessment in Greece – Part 1: Engineering ground motion parameters

2010 ◽  
Vol 10 (1) ◽  
pp. 25-39 ◽  
Author(s):  
G-A. Tselentis ◽  
L. Danciu
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Peak Ground Acceleration ◽  
Seismic Hazard Assessment ◽  
Peak Ground Velocity ◽  
Probabilistic Seismic Hazard Assessment ◽  
Probabilistic Seismic Hazard ◽  
Arias Intensity ◽  
Ground Acceleration ◽  
Cumulative Absolute Velocity

Abstract. Seismic hazard assessment represents a basic tool for rational planning and designing in seismic prone areas. In the present study, a probabilistic seismic hazard assessment in terms of peak ground acceleration, peak ground velocity, Arias intensity and cumulative absolute velocity computed with a 0.05 g acceleration threshold, has been carried out for Greece. The output of the hazard computation produced probabilistic hazard maps for all the above parameters estimated for a fixed return period of 475 years. From these maps the estimated values are reported for 52 Greek municipalities. Additionally, we have obtained a set of probabilistic maps of engineering significance: a probabilistic macroseismic intensity map, depicting the Modified Mercalli Intensity scale obtained from the estimated peak ground velocity and a probabilistic seismic-landslide map based on a simplified conversion of the estimated Arias intensity and peak ground acceleration into Newmark's displacement.

scholarly journals Seismic hazard for the Trans Adriatic Pipeline (TAP). Part 2: broadband scenarios at the Fier Compressor Station (Albania)

2021 ◽  
Author(s):  
L. Moratto ◽  
A. Vuan ◽  
A. Saraò ◽  
D. Slejko ◽  
C. Papazachos ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Hazard Assessment ◽  
Transfer Functions ◽  
Active Faults ◽  
Seismic Hazard Assessment ◽  
Probabilistic Seismic Hazard Assessment ◽  
Compressor Station ◽  
Damage Functions ◽  
Worst Case

AbstractTo ensure environmental and public safety, critical facilities require rigorous seismic hazard analysis to define seismic input for their design. We consider the case of the Trans Adriatic Pipeline (TAP), which is a pipeline that transports natural gas from the Caspian Sea to southern Italy, crossing active faults and areas characterized by high seismicity levels. For this pipeline, we develop a Probabilistic Seismic Hazard Assessment (PSHA) for the broader area, and, for the selected critical sites, we perform deterministic seismic hazard assessment (DSHA), by calculating shaking scenarios that account for the physics of the source, propagation, and site effects. This paper presents a DSHA for a compressor station located at Fier, along the Albanian coastal region. Considering the location of the most hazardous faults in the study site, revealed by the PSHA disaggregation, we model the ground motion for two different scenarios to simulate the worst-case scenario for this compressor station. We compute broadband waveforms for receivers on soft soils by applying specific transfer functions estimated from the available geotechnical data for the Fier area. The simulations reproduce the variability observed in the ground motion recorded in the near-earthquake source. The vertical ground motion is strong for receivers placed above the rupture areas and should not be ignored in seismic designs; furthermore, our vertical simulations reproduce the displacement and the static offset of the ground motion highlighted in recent studies. This observation confirms the importance of the DSHA analysis in defining the expected pipeline damage functions and permanent soil deformations.

scholarly journals Probabilistic seismic hazard assessment of Bishkek, Kyrgyzstan, considering empirically estimated site effects

2015 ◽  
Vol 58 (1) ◽  
Author(s):  
Shahid Ullah ◽  
Dino Bindi ◽  
Marco Pilz ◽  
Stefano Parolai
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Hazard Assessment ◽  
Site Effects ◽  
Response Spectrum ◽  
Seismic Hazard Assessment ◽  
Geological Structure ◽  
Probabilistic Seismic Hazard Assessment ◽  
Site Classification ◽  
Ground Acceleration

<p>It is well known that variability in the surface geology potentially leads to the modification of earthquake-induced ground motion over short distances. Although this effect is of major importance when seismic hazard is assessed at the urban level, it is very often not appropriately accounted for. In this paper, we present a first attempt at taking into account the influence of the shallow geological structure on the seismic hazard assessment for Bishkek, Kyrgyzstan, using a proxy (Vs30) that has been estimated from in situ seismic noise array analyses, and considering response spectral ratios calculated by analyzing a series of earthquake recordings of a temporary seismic network. To highlight the spatial variability of the observed ground motion, the obtained results are compared with those estimated assuming a homogeneous Vs30 value over the whole urban area. The seismic hazard is evaluated in terms of peak ground acceleration (PGA) and spectral acceleration (SA) at different periods (frequencies). The presented results consider the values obtained for a 10% probability of exceedance in 50 years. The largest SA estimated considering a rock site classification of the area (0.43 g) is observed for a period of 0.1 s (10 Hz), while the maximum PGA reaches 0.21 g. When site effects are included through the Vs30 proxy in the seismic hazard calculation, the largest SA, 0.67 g, is obtained for a period of 0.3 s (about 3.3 Hz). In terms of PGA, in this case the largest estimated value reaches 0.31 g in the northern part of the town. When the variability of ground motion is accounted for through response spectrum ratios, the largest SA reaches a value as high as 1.39 g at a period of 0.5 s. In general, considering site effects in the seismic hazard assessment of Bishkek leads to an increase of seismic hazard in the north of the city, which is thus identified as the most hazardous part within the study area and which is more far away from the faults.</p>

scholarly journals Probabilistic Seismic Hazard Assessment (PSHA) for Lesvos Island Using the Logic Tree Approach

2019 ◽  
Vol 55 (1) ◽  
pp. 109 ◽  
Author(s):  
Nikolaos Vavlas ◽  
Anastasia Kiratzi ◽  
Basil Margaris ◽  
George Karakaisis
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
High Efficiency ◽  
Seismic Hazard Assessment ◽  
Aegean Sea ◽  
Peak Ground Velocity ◽  
Probabilistic Seismic Hazard Assessment ◽  
Probabilistic Seismic Hazard ◽  
Building Stock ◽  
Ground Acceleration

We carry out a probabilistic seismic hazard assessment (PSHA) for Lesvos Island, in the northeastern Aegean Sea. Being the most populated island in the northern Aegean Sea and hosting the capital of the prefecture, its seismic potential has significant social-economic meaning. For the seismic hazard estimation, the newest version of the R-CRISIS module, which has high efficiency and flexibility in model selection, is used. We incorporate into the calculations eight (8) ground motion prediction equations (GMPEs). The measures used are peak ground acceleration, (PGA), peak ground velocity, (PGV), and spectral acceleration, (SA), at T=0.2 sec representative of the building stock. We calculate hazard curves for selected sites on the island, sampling the southern and northern parts: Mytilene, the capital, the village of Vrisa, Mithymna and Sigri. Hazard maps are also presented in terms of all three intensity measures, for a mean return period of 475 years (or 10% probability of exceedance in 50 years), assuming a Poisson process. Our results are comparable to the predictions of on-going EU hazard models, but higher than the provisions of the Greek Seismic Code. Finally, we perform disaggregation of hazard to depict the relative contribution of different earthquake sources and magnitudes to the results.

scholarly journals Probabilistic Seismic Hazard Assessment for Amaravathi Region, Andhra Pradesh

2019 ◽  
Vol 8 (6S4) ◽  
pp. 279-283
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Seismic Analysis ◽  
Response Spectrum ◽  
Seismic Hazard Assessment ◽  
Prediction Equation ◽  
Probabilistic Seismic Hazard Assessment ◽  
Ground Acceleration ◽  
Uniform Hazard Response Spectrum ◽  
Seismic Hazard Map

This article explains an analytical attempt that estimates seismic hazard for Amaravathi city. The present study has been carried out contemplating the available faults and epicentral data within a radius of 300km of the Amaravathi region. The homogenous earthquake catalogue has been prepared for Amaravathi region by Steep’s method. The seismic hazard parameters ―a‖ and ―b‖ for Amaravathi city were evaluated by Gutenberg-Ritcher method. The ―a‖ and ―b‖ values obtained as 4.69, 0.6468 respectively. The total 353 epicenters and 31 faults were considered in this seismic analysis for the estimate of PSHA for Amaravathi. The ground motion produced by the faults at this site has been estimated by using the regionspecific Ground Motion Prediction Equation (GMPE) developed by the raghukanth and lyenger (2007). The probability of occurrence of different magnitude classes was estimated. The hazard curves and mean annual rate of exceedance for Peak Ground Acceleration were calculated by using ground motion estimated in this area. The Uniform Hazard Response Spectrum (UHRS) for the ranging time periods between 0.1 – 4 seconds was prepared. PGA values for Amaravati region was found to be in between 0.001g to 0.3g from seismic hazard map that was prepared in this study

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