Papers by LALLIANA MUALCHIN
of Mines & Geology Open-File Report 92-01 for use in Caltrans. New technology of mapping, GIS is ... more of Mines & Geology Open-File Report 92-01 for use in Caltrans. New technology of mapping, GIS is used to make the hazard map for wider applications. Caltrans criteria is clearly reflected in this report in that we use late Quarternary faults for our considerations. Also, we proved that the concept of MCE is appropriate for our purpose, considering that we deal about critical facilities for public safety. The author has a long experience in earthquake hazard assessment for critical facilities and has done the previus report for Caltrans while at California Division of Mines & Geology. I know him for more than 18 years. • The new map is to be used for Acceleration factor of the ARS curves which will reflect the MCE and the distance of the fault, in conformity with scientific understanding of earthquake ground motion spectra. A guideline has been provided by the latest ATC-32. • As surface fault rupture is critical, the map will also be used to evaluate fault displacement rupture hazar...
The California Department of Transportation (CALTRANS) considers earthquake effects in planning, ... more The California Department of Transportation (CALTRANS) considers earthquake effects in planning, design, and construction of their structures. Obviously, CALTRANS has to respond to damaging earthquakes. The earthquake effects are primarily caused by strong ground motions and surface fault rupture displacements with possible liquefaction of soils and slope instabilities. CALTRANS estimates expected earthquake effects from the potential of Maximum Credible Earthquakes (MCE's) caused by younger (late Quaternary and younger) earthquake sources or faults in and adjacent to California.
Environmental & Engineering Geoscience, 1985
Siting of Liquefied Natural Gas (LNG) facilities requires seismological investigations to identif... more Siting of Liquefied Natural Gas (LNG) facilities requires seismological investigations to identify the closest capable faults, to estimate the capability of faults in the vicinity of proposed sites to generate earthquakes, and to provide engineers with appropriate ground-motion parameters (peak acceleration, predominant period, and duration of strong ground-motion) for design and construction. These investigations consist of analysis of seismicity data to correlate hypocenters and faults, estimation of the maximum magnitude of an earthquake for particular faults, and calculations of recurrence intervals of earthquakes. The investigation of the proposed Little Cojo Bay LNG Terminal Site, near Point Conception, California, for which a peak acceleration of about 0.65 g appears reasonable, is presented as an example.
Bulletin of the Seismological Society of America, 2002
The M 7.1 Hector Mine earthquake caused little bridge or highway damage. Although it seems reason... more The M 7.1 Hector Mine earthquake caused little bridge or highway damage. Although it seems reasonable to assume that the lack of damage was the result of the earthquake occurring in the middle of the desert, there were several state highways in the area, including Interstate 40 about 10 km north of the fault rupture. Moreover, California's experience has been that enhancements to ground motion have resulted in major damage and collapse of bridges up to 100 km from the epicenter of large earthquakes. It would be of great practical value to bridge owners to understand why large-magnitude events like the Hector Mine earthquake have so little effect on bridges. In this article we describe all of the bridge and highway damage resulting from the Hector Mine earthquake. Most of this damage was the result of long-term problems for these bridges that were exacerbated by the earthquake.
Encyclopedia of Earthquake Engineering, 2013
In earthquake-prone regions of the world, it is a common practice to assess anticipated hazard se... more In earthquake-prone regions of the world, it is a common practice to assess anticipated hazard severity for land-use planning, emergency management, and structural design load considerations for public safety applications. Generally, strong ground motion hazards would impact a large area, and displacement hazards could affect a relatively small area localized along the fault trace of surface-faulting earthquakes. This section will review inputs for obtaining a generic ground motion as the most pervasive earthquake hazard and that without site-specific considerations. Note that soft soil sites are generally more hazardous than stiff soil or rock sites, and such site-specific conditions should be characterized realistically in practice for ground response analysis. Implications of the inputs for seismic hazard assessed results will be discussed. The hazard assessment is accomplished by performing seismic hazard analysis (SHA) procedures using either a deterministic or a probabilistic approach (Reiter 1990). The deterministic results provide hazards anticipated from the largest potential events and the probabilistic from prescribed recurrent event(s). The ground motion hazard is obtained from the mean or a certain level above the mean as applied to the ground motion prediction equations (GMPEs) in both the deterministic and probabilistic approaches according to policy or guidelines.
Earthquakes and Sustainable Infrastructure, 2022
Abstract I entered my profession (1972–2005) in California in seismic hazard determination, which... more Abstract I entered my profession (1972–2005) in California in seismic hazard determination, which started in earnest after the destructive 1971 San Fernando earthquake. I have been fortunate to survive my work of more than 3 decades with the satisfaction of public service as well as passing through the oppositions to making and applying the state seismic hazard map of California twice. Determining the largest earthquakes on seismogenic faults based on its spatial dimension, with no regard to recurrence or probability, and estimating the anticipated ground motion hazard at a site from those largest earthquakes are the two components of seismic hazard determination. The earthquake is called a maximum credible earthquake (MCE) in magnitude. For earthquake-resistant design, the highest ground motion at a site from one or more of the MCEs is used. The ground motion is estimated by using empirical attenuation curves or calculated by using assumed earthquake source representation and seismic waves propagation, such as that applied in Neo-Deterministic Seismic Hazard Analysis (NDSHA). The deterministic approach has been easily understood and well accepted with confidence by engineers in California for decades for almost all applications. It has never been opposed as too extreme, because it is not so, and is reasonable for the intended purposes. Years later, that method has been called the deterministic method by those who promoted the use of likelihood or other probabilistic measure such as in weather forecasting. Failure in weather forecasting is well known but the consequences are not devastating. Failure in earthquakes could be deadly and therefore not acceptable. Likelihood of earthquake will trivialize earthquake hazards. More importantly, buildings based on such likelihood cannot be easily modified if the likelihood becomes known to be higher. Likelihood must not be used for earthquake policy concerning public safety. The hazards of recent destructive earthquakes exceeded those presented in probabilistic hazard maps with deadly consequences but would not exceed deterministic estimates (e.g., International Seismic Safety Organization, 2012). Despite this fact, most people in this field today seem to know only the probabilistic approach as the only way to define seismic hazards. For safety and peace of mind, the profession must know and use deterministic hazards that will not be exceeded by future events. My experience has shown why and how the probabilistic approach has become so dominant despite its continuing failures. Writing this unconventional article forced me to recall my experience about how this had been started in California and was exported out all over the world. I am still in the never-ending discovery stage of what really had happened. It deserves a serious investigation. The deterministic approach would be the best option for seismic hazard definition for public safety policy because it is transparent, easy to understand, economic, and realistic for engineering; and is conservative for public safety as the hazard would not be exceeded. It has a proven track record in California. It can incorporate new information, advanced earthquake source representations, and seismic wave propagation for any applications. With its simple but sound framework and minimum analysis, it has never been proven wrong or inappropriate for the intended purposes.
This is a progress report on the Bay Bridges downhole network. Between 2 and 8 insthments have be... more This is a progress report on the Bay Bridges downhole network. Between 2 and 8 insthments have been spaced along the Dumbarton, San Mateo, Bay, and San Rafael bridges in San Francisco Bay, California. The instruments will provide multiple use data that is important to geotechnical, structural engineering, and seismological studies. The holes are between 100 and 1000 ft deep and were drilled by Caltrans. There are twenty-one sensor packages at fifteen sites. The downhole instrument package contains a three component HS-1 seismometer and three orthogonal Wilcox 731 accelerometers, and is capable of recording a micro g from local M =1.0 earthquakes to 0.5 g strong ground motion form large Bay Area earthquakes. This report list earthquakes and stations where recordings were obtained during the period February 29,2000 to November 11,2000. Also, preliminary results on noise analysis for up and down hole recordings at Yerba Buena Island is presented. This work was pevomzed under the auspices of the US.
Doboku Gakkai Ronbunshu, 1997
A deterministic seismic hazard map of Japan using the concept of maximum credible earthquakes (MC... more A deterministic seismic hazard map of Japan using the concept of maximum credible earthquakes (MCE's) is developed for engineering. Seismogenic mapped faults on land in Japan', which may produce a significant earthquake, are used for seismic sources. An appropriate attenuation relationship of peak rock accelerations (PRA's) for this analysis is selected after comparing five published attenuation studies. The horizontal PRA's are obtained by applying the estimated MCE magnitude to the attenuation relationship. The median PRA contours for 0. 7g, 0. 5g, 0. 3g, and 0.1g (g: acceleration due to gravity) levels are shown in the seismic hazard map.
Eos, Transactions American Geophysical Union, 2013
Pure and Applied Geophysics, 2010
What is the largest earthquake likely to occur, with allowable probability P, on a given fault du... more What is the largest earthquake likely to occur, with allowable probability P, on a given fault during the planned lifetime T of a structure? This question is appropriate for planning because it considers both the time period for which protection is needed, and the importance of that protection through the probability P. We approach this problem by considering the magnitude-frequency distribution of earthquakes on the fault, and solving for that magnitude that corresponds to the specified time and probability requirements. The resulting magnitude, which we call the Functional Evaluation Earthquake (or FEE for short) depends on the moment rate (from the length, width, and slip rate), and maximum magnitude on the fault, as well as the assumed magnitude-frequency distribution. The moment rate is measurable directly, but the maximum magnitude can only be estimated indirectly. Assuming a density-truncated Gutenberg-Richter magnitude-frequency distribution and Poissonian recurrence, we'...
If mx is the largest earthquake magnitude that can occur on a fault, then what is mp, the largest... more If mx is the largest earthquake magnitude that can occur on a fault, then what is mp, the largest magnitude that should be expected during the planned lifetime of a particular structure? Most approaches to these questions rely on an estimate of the Maximum Credible Earthquake, obtained by regression (e.g. Wells and Coppersmith, 1994) of fault length (or area) and magnitude. Our work differs in two ways. First, we modify the traditional approach to measuring fault length, to allow for hidden fault complexity and multi-fault rupture. Second, we use a magnitude-frequency relationship to calculate the largest magnitude expected to occur within a given time interval. Often fault length is poorly defined and multiple faults rupture together in a single event. Therefore, we need to expand the definition of a mapped fault length to obtain a more accurate estimate of the maximum magnitude. In previous work, we compared fault length vs. rupture length for post-1975 earthquakes in Southern Cal...
We estimate the largest magnitude expected with a given probability in a given time interval, for... more We estimate the largest magnitude expected with a given probability in a given time interval, for individual faults in California. We refer to such a quake as the "Functional Evaluation Earthquake, and to its magnitude as MFEE. For selecting scenario earthquakes in engineering studies, our approach provides an alternative to the "maximum credible earthquake" magnitude, MMCE [Mualchin et al., Caltrans Technical Report, 1996]. We assume a truncated Gutenberg-Richter magnitude distribution. We estimate the upper magnitude limit MMCE for each fault segment from the Wells and Coppersmith [1994] empirical relation between magnitude and fault length. We combined fault slip rates from the USGS/CDMG and the CALTRANS fault databases to estimate tectonic moment rate for each fault. We then assume a uniform b-value (1.0) and determine the a-value, which matches the tectonic moment rate for each fault. By definition, the estimated MFEE is lower than MMCE. It depends on the magnitude-frequency distribution, assumed probability level (P), considered time interval (T), and indirectly on the upper magnitude limit. The a-value decreases as the MMCE increases, and for some cases, this causes the MFEE to decrease as well. We summed the magnitude distributions for all faults to obtain a theoretical magnitude distribution for California. This distribution forecasts a significantly higher rate than reported in the Toppozada [2000] catalogue for earthquakes in the magnitude range 6-7. The same discrepancy occurred in the SCEC Phase II model, the 1996 CDMG/USGS hazard model, and others in which the maximum earthquakes size is assumed limited by fault length or area. A better fit would require significantly lower coupling (0.6 to 0.7) and substantially larger MMCE. For example, the theory and observations would agree well if the MMCE for each fault were increased by more than half a unit, or if the MMCE had a uniform value 8 and the coupling coefficient were 0.6. To consider possible effects due to large uncertainties in geologically determined fault slip rates, we are now using optimized estimates of fault slip rate to improve our estimation of MFEE. We estimate optimal slip rates for all faults in California from kinematic modeling (by finite elements) and including geologic slip rates, GPS measurements, and most compressive stress directions. Our final goal is to construct contour maps of MFEE for various P, T in California, compare with other seismic hazard approaches (geodesy, past seismicity), and test our prediction against future earthquakes.
Earthquake Resistant Engineering Structures IX, 2013
We present a detailed discussion on the needs of hazard assessment for different applications of ... more We present a detailed discussion on the needs of hazard assessment for different applications of earthquake engineering and risk assessment. This discussion includes design and risk assessment issues. We define the requested information from seismic hazard analysis as an input to a meaningful and economical engineering analysis. This provides the basis for a detailed review of the main methods of contemporary seismic hazard analysis: (1) traditional Probabilistic Seismic Hazard Analysis (PSHA) as used in building codes of many countries, (2) scenario-based seismic hazard analysis or neo-deterministic seismic hazard analysis (NDSHA) as the principal alternative, and (3) the state of the art physics-based deterministic method. We demonstrate that only the physics-and scenario-based seismic hazard analysis method that combines (a) contemporary seismic waveform modelling, (b) an in-depth geological and seismo-tectonic analysis of the region of interest, and (c) empirical information is able to provide the complete set of input information for economical earthquake engineering analysis that allows to combine improved seismic performance of both the structures and components with reasonable design costs. We show that the scenario-based seismic hazard method can easily be adapted/extended for risk assessment as required in assurance applications by developing state of the art probabilistic data models that are in compliance with observational data assembled in earthquake catalogues. The paper includes a practical example of the scenario-based approach for the development of the design basis of a critical infrastructure and the risk assessment for a seismically induced production loss of a nuclear power plant located in Switzerland. We recommend that DSHA and NDSHA must be used for engineering design. When/if PSHA is required based on national regulations, it is highly Earthquake Resistant Engineering Structures IX 47
Engineering Geology, 2006
A new methodology for seismic risk analysis based on probabilistic interpretation of deterministi... more A new methodology for seismic risk analysis based on probabilistic interpretation of deterministic or scenario-based hazard analysis, in full compliance with the likelihood principle and therefore meeting the requirements of modern risk analysis, has been developed. The proposed methodology can easily be adjusted to deliver its output in a format required for safety analysts and civil engineers. The scenario-based approach allows the incorporation of all available information collected in a geological, seismotectonic and geotechnical database of the site of interest as well as advanced physical modelling techniques to provide a reliable and robust deterministic design basis for civil infrastructures. The robustness of this approach is of special importance for critical infrastructures. At the same time a scenario-based seismic hazard analysis allows the development of the required input for probabilistic risk assessment (PRA) as required by safety analysts and insurance companies. The scenario-based approach removes the ambiguity in the results of probabilistic seismic hazard analysis (PSHA) which relies on the projections of Gutenberg-Richter (G-R) equation. The problems in the validity of G-R projections, because of incomplete to total absence of data for making the projections, are still unresolved. Consequently, the information from G-R must not be used in decisions for design of critical structures or critical elements in a structure. The scenario-based methodology is strictly based on observable facts and data and complemented by physical modelling techniques, which can be submitted to a formalised validation process. By means of sensitivity analysis, knowledge gaps related to lack of data can be dealt with easily, due to the limited amount of scenarios to be investigated. The proposed seismic risk analysis can be used with confidence for planning, insurance and engineering applications.
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Papers by LALLIANA MUALCHIN