CU-PSHA: A MATLAB Software for Probabilistic Seismic Hazard Analysis

2014 ◽  
Vol 08 (04) ◽  
pp. 1450008 ◽  
Author(s):  
Santi Pailoplee ◽  
Chitti Palasri
Keyword(s):  
Seismic Hazard ◽  
Hazard Analysis ◽  
Earthquake Hazard ◽  
Hazard Mapping ◽  
Earthquake Hazards ◽  
Flexible Tool ◽  
Matlab Software ◽  
Ground Shaking ◽  
Magnitude Distribution ◽  
Ground Motion Attenuation

In this study, an open source MATLAB software, called CU-PSHA, is developed in order to analyze probabilistic earthquake hazards. This software aims to provide a user friendly and flexible tool for evaluating reliable earthquake hazard estimates. With the CU-PSHA, the probability of distances between the earthquake sources and the study site can be estimated. Two choices for the estimation of earthquake frequency–magnitude distribution, the exponential magnitude distribution and the characteristic earthquake models, are provided. Some strong ground–motion attenuation models are available for both shallow crustal and subduction zone earthquakes. The probability of exceedance of any individual given ground shaking value can be obtained, allowing the display of a seismic hazard curve. In addition with the supplementary MATLAB scripts, this CU-PSHA software can be employed in general seismic hazard mapping, for both ground shaking level and probability of occurrence, in any specific given time span.

SEISMIC HAZARD ANALYSIS FOR MYANMAR

2013 ◽  
Vol 07 (04) ◽  
pp. 1350029
Author(s):  
NANTHAPORN SOMSA-ARD ◽  
SANTI PAILOPLEE
Keyword(s):  
Seismic Hazard ◽  
Hazard Analysis ◽  
Earthquake Hazard ◽  
Seismic Hazards ◽  
Seismic Hazard Analysis ◽  
Ground Acceleration ◽  
Earthquake Parameters ◽  
Ground Shaking ◽  
Earthquake Sources ◽  
Attenuation Models

In this study, the seismic hazards of Myanmar are analyzed based on both deterministic and probabilistic scenarios. The area of the Sumatra–Andaman Subduction Zone is newly defined and the lines of faults proposed previously are grouped into nine earthquake sources that might affect the Myanmar region. The earthquake parameters required for the seismic hazard analysis (SHA) were determined from seismicity data including paleoseismological information. Using previously determined suitable attenuation models, SHA maps were developed. For the deterministic SHA, the earthquake hazard in Myanmar varies between 0.1 g in the Eastern part up to 0.45 g along the Western part (Arakan Yoma Thrust Range). Moreover, probabilistic SHA revealed that for a 2% probability of exceedance in 50 and 100 years, the levels of ground shaking along the remote area of the Arakan Yoma Thrust Range are 0.35 and 0.45 g, respectively. Meanwhile, the main cities of Myanmar located nearby the Sagaing Fault Zone, such as Mandalay, Yangon, and Naypyidaw, may be subjected to peak horizontal ground acceleration levels of around 0.25 g.

Effects of temporal variations in seismicity on seismic hazard

1981 ◽  
Vol 71 (1) ◽  
pp. 321-334
Author(s):  
Robin K. McGuire ◽  
Theodore P. Barnhard
Keyword(s):  
United States ◽  
Seismic Hazard ◽  
Seismic Activity ◽  
Time Window ◽  
Hazard Analysis ◽  
The United States ◽  
Temporal Variations ◽  
Seismogenic Zone ◽  
Eastern United States ◽  
Ground Shaking

abstract The accuracy of stationary mathematical models of seismicity for calculating probabilities of damaging shaking is examined using the history of earthquakes in China from 1350 A.D. to 1949 A.D. During this time, rates of seismic activity varied periodically by a factor of 10. Probabilities of damaging shaking are calculated in 62 cities in North China using 50 yr of earthquake data to estimate seismicity parameters; the probabilities are compared to statistics of damaging shaking in the same cities for 50 yr following the data window. These comparisons indicate that the seismic hazard analysis is accurate if: (1) the maximum possible earthquake size in each seismogenic zone is determined from the entire seismic history rather than from a short-time window; and (2) the future seismic activity can be estimated accurately. The first condition emphasizes the importance of realistically estimating the maximum possible size of earthquakes on faults. The second indicates the need to understand possible trends in seismic activity where these exist, or to develop an earthquake prediction capability with which to estimate future activity. Without the capability of estimating future seismicity, stationary models provide less accurate but generally conservative indications of seismic ground-shaking hazard. In the United States, the available earthquake history is brief but gives no indication of changing rates of activity. The rate of seismic strain release in the Central and Eastern United States has been constant over the last 180 yr, and the geological record of earthquakes on the southern San Andreas Fault indicates no temporal trend for large shocks over the last 15 centuries. Both observations imply that seismic activity is either stationary or of such a long period that it may be treated as stationary for seismic hazard analyses in the United States.

Large Uncertainties in Earthquake Stress-Drop Estimates and Their Tectonic Consequences

2020 ◽  
Vol 91 (4) ◽  
pp. 2320-2329 ◽  
Author(s):  
James S. Neely ◽  
Seth Stein ◽  
Bruce D. Spencer
Keyword(s):  
Seismic Hazard ◽  
Stress Drop ◽  
Hazard Analysis ◽  
Earthquake Hazards ◽  
Teleseismic Data ◽  
Tectonic Environment ◽  
Zero Correlation ◽  
Environment Stress ◽  
Stress Drops ◽  
Erroneous Inferences

Abstract Earthquake stress drop, the stress change on a fault due to an earthquake, is important for seismic hazard analysis because it controls the level of high-frequency ground motions that damage structures. Numerous studies report that stress drops vary by tectonic environment, providing insight into a region’s seismic hazard. Here, we show that teleseismic stress-drop estimates have large uncertainties that make it challenging to distinguish differences between the stress drops of different earthquakes. We compared stress drops for ∼900 earthquakes derived from two independent studies using teleseismic data and found practically zero correlation. Estimates for the same earthquake can differ by orders of magnitude. Therefore, reported stress-drop differences between earthquakes may not reflect true differences. As a result of these larger uncertainties, some tectonic environment stress-drop patterns that appear in one study do not appear in the other analysis of the same earthquakes. These large uncertainties in teleseismic estimates might lead to erroneous inferences about earthquake hazards. In many applications, it may be more appropriate to assume that earthquakes in different regions have approximately the same average stress drop.

scholarly journals Uncertainties in attenuation relations for New Zealand seismic hazard analysis

1986 ◽  
Vol 19 (1) ◽  
pp. 28-39 ◽  
Author(s):  
G. H. McVerry
Keyword(s):  
New Zealand ◽  
Seismic Hazard ◽  
Hazard Analysis ◽  
Response Spectrum ◽  
Strong Motion ◽  
Seismic Hazard Analysis ◽  
Ground Acceleration ◽  
Attenuation Relations ◽  
Ground Shaking ◽  
Acceleration Data

Probabilistic techniques for seismic hazard analysis have
come into vogue in New Zealand for both the assessment of major projects and the development and review of seismic design codes. However, there are considerable uncertainties in the modelling
 of the strong-motion attenuation, which is necessarily based largely on overseas data. An excellent agreement is obtained between an average 5% damped response spectrum for New Zealand alluvial sites in the 20 to 59 km distance range and 5.4 to 6.0 magnitude class and that given by a Japanese model. Unfortunately, this corresponds to only about half the amplitude levels of 150 year spectra relevant to code design. The much more rapid decay
of ground shaking with distance in New Zealand has led to a considerable modification based on maximum ground acceleration
data from the Inangahua earthquake of the distance-dependence
of the Japanese response spectra model. Less scatter in New Zealand data has resulted in adopting a lower standard deviation for the attenuation model, which is important in reducing the considerable "probabilistic enhancement" of the hazard estimates. Regional differences in attenuation shown by intensities are difficult to resolve from the strong-motion acceleration data, apart from lower accelerations in Fiordland.

scholarly journals SEISMIC HAZARD ESTIMATION IN STABLE CONTINENTAL REGIONS: DOES PSHA MEET THE NEEDS FOR MODERN ENGINEERING DESIGN IN AUSTRALIA?

2020 ◽  
Vol 53 (1) ◽  
pp. 22-36 ◽  
Author(s):  
Trevor I. Allen
Keyword(s):  
Seismic Hazard ◽  
Hazard Analysis ◽  
Ground Motions ◽  
Seismic Hazard Assessment ◽  
Earthquake Hazard ◽  
Exceedance Probability ◽  
Earthquake Catalogues ◽  
Seismic Safety ◽  
Seismic Demands ◽  
Almost All

Damaging earthquakes in Australia and other regions characterised by low seismicity are considered low probability but high consequence events. Uncertainties in modelling earthquake occurrence rates and ground motions for damaging earthquakes in these regions pose unique challenges to forecasting seismic hazard, including the use of this information as a reliable benchmark to improve seismic safety within our communities. Key challenges for assessing seismic hazards in these regions are explored, including: the completeness and continuity of earthquake catalogues; the identification and characterisation of neotectonic faults; the difficulties in characterising earthquake ground motions; the uncertainties in earthquake source modelling, and; the use of modern earthquake hazard information to support the development of future building provisions. Geoscience Australia recently released its 2018 National Seismic Hazard Assessment (NSHA18). Results from the NSHA18 indicate significantly lower seismic hazard across almost all Australian localities at the 1/500 annual exceedance probability level relative to the factors adopted for the current Australian Standard AS1170.4–2007 (R2018). These new hazard estimates have challenged notions of seismic hazard in Australia in terms of the recurrence of damaging ground motions. This raises the question of whether current practices in probabilistic seismic hazard analysis (PSHA) deliver the outcomes required to protect communities and infrastructure assets in low-seismicity regions, such as Australia. This manuscript explores a range of measures that could be undertaken to update and modernise the Australian earthquake loading standard, in the context of these modern seismic hazard estimates, including the use of alternate ground-motion exceedance probabilities for assigning seismic demands for ordinary-use structures. The estimation of seismic hazard at any location is an uncertain science, particularly in low-seismicity regions. However, as our knowledge of the physical characteristics of earthquakes improve, our estimates of the hazard will converge more closely to the actual – but unknowable – (time independent) hazard. Understanding the uncertainties in the estimation of seismic hazard is also of key importance, and new software and approaches allow hazard modellers to better understand and quantify this uncertainty. It is therefore prudent to regularly update the estimates of the seismic demands in our building codes using the best available evidence-based methods and models.

scholarly journals Mapping of PGA Value Using PSA Method in West Halmahera Nort Maluku

2020 ◽  
Vol 9 (2) ◽  
pp. 116
Author(s):  
Rohima Wahyu Ningrum ◽  
Wiwit Suryanto ◽  
Hendra Fauzi ◽  
Estuning Tyas Wulan Mei
Keyword(s):  
Seismic Hazard ◽  
Return Period ◽  
Peak Ground Acceleration ◽  
Hazard Analysis ◽  
Seismic Hazard Analysis ◽  
Earthquake Hazards ◽  
The West ◽  
Ground Acceleration ◽  
Soil Movement ◽  
Megathrust Earthquakes

The earthquake that occurred in the West Halmahera region was very detrimental, even though the human casualties were not very significant. But it will affect the stability and capacity of a region in terms of regional development. The mapping of earthquake-prone areas is carried out by a probabilistic seismic hazard analysis (PSHA) method to analyze soil movement parameters, namely Peak Ground Acceleration so that it can determine earthquake-prone areas in West Halmahera. The results of seismic hazard analysis show that the West Halmahera area is an area that is relatively prone to earthquake hazards because it is still strongly influenced by subduction (megathrust) earthquakes from the Philippine plate, Maluku sea and Sangihe. This is indicated by the value of earthquake acceleration on the Peak Ground Acceleration for the 500 year return period of around 0.38 - 3.69 g and 0.30 - 3.69 g for the 2500 year return period.

Probabilistic seismic hazard analysis and design earthquakes: Closing the loop

1995 ◽  
Vol 85 (5) ◽  
pp. 1275-1284 ◽  
Author(s):  
Robin K. McGuire
Keyword(s):  
Seismic Hazard ◽  
Hazard Analysis ◽  
Large Earthquake ◽  
Probabilistic Seismic Hazard Analysis ◽  
Seismic Hazard Analysis ◽  
Probabilistic Seismic Hazard ◽  
Ground Shaking ◽  
Uniform Hazard Spectrum ◽  
Analysis And Design ◽  
Design Earthquake

Abstract Probabilistic seismic hazard analysis (PSHA) is conducted because there is a perceived earthquake threat: active seismic sources in the region may produce a moderate-to-large earthquake. The analysis considers a multitude of earthquake occurrences and ground motions, and produces an integrated description of seismic hazard representing all events. For design, analysis, retrofit, or other seismic risk decisions a single “design earthquake” is often desired wherein the earthquake threat is characterized by a single magnitude, distance, and perhaps other parameters. This allows additional characteristics of the ground shaking to be modeled, such as duration, nonstationarity of motion, and critical pulses. This study describes a method wherein a design earthquake can be obtained that accurately represents the uniform hazard spectrum from a PSHA. There are two key steps in the derivation. First, the contribution to hazard by magnitude M, distance R, and ɛ must be maintained separately for each attenuation equation used in the analysis. Here, ɛ is the number of standard deviations that the target ground motion is above or below the median predicted motion for that equation. Second, the hazard for two natural frequencies (herein taken to be 10 and 1 Hz) must be examined by seismic source to see if one source dominates the hazard at both frequencies. This allows us to determine whether it is reasonable to represent the hazard with a single design earthquake, and if so to select the most-likely combination of M, R, and ɛ (herein called the “beta earthquake”) to accurately replicate the uniform hazard spectrum. This closes the loop between the original perception of the earthquake threat, the consideration of all possible seismic events that might contribute to that threat, and the representation of the threat with a single (or few) set of parameters for design or analysis.

A Methodology for Probabilistic Fault Displacement Hazard Analysis (PFDHA)

2003 ◽  
Vol 19 (1) ◽  
pp. 191-219 ◽  
Author(s):  
Robert R. Youngs ◽  
Walter J. Arabasz ◽  
R. Ernest Anderson ◽  
Alan R. Ramelli ◽  
Jon P. Ake ◽  
...  
Keyword(s):  
Hazard Analysis ◽  
Probability Distributions ◽  
Ground Surface ◽  
Normal Faulting ◽  
General Application ◽  
Ground Shaking ◽  
Attenuation Function ◽  
Ground Motion Attenuation ◽  
A Site ◽  
Fault Displacement

We present a methodology for conducting a site-specific probabilistic analysis of fault displacement hazard. Two approaches are outlined. The first relates the occurrence of fault displacement at or near the ground surface to the occurrence of earthquakes in the same manner as is done in a standard probabilistic seismic hazard analysis (PSHA) for ground shaking. The methodology for this approach is taken directly from PSHA methodology with the ground-motion attenuation function replaced by a fault displacement attenuation function. In the second approach, the rate of displacement events and the distribution for fault displacement are derived directly from the characteristics of the faults or geologic features at the site of interest. The methodology for probabilistic fault displacement hazard analysis (PFDHA) was developed for a normal faulting environment and the probability distributions we present may have general application in similar tectonic regions. In addition, the general methodology is applicable to any region and we indicate the type of data needed to apply the methodology elsewhere.

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