Seismic hazard

About: Seismic hazard is a research topic. Over the lifetime, 8462 publications have been published within this topic receiving 165830 citations.

Engineering seismic risk analysis

Abstract: This paper introduces a method for the evaluation of the seismic risk at the site of an engineering project. The results are in terms of a ground motion parameter (such as peak acceleration) versus average return period. The method incorporates the influence of all potential sources of earthquakes and the average activity rates assigned to them. Arbitrary geographical relationships between the site and potential point, line, or areal sources can be modeled with computational ease. In the range of interest, the derived distributions of maximum annual ground motions are in the form of Type I or Type II extreme value distributions, if the more commonly assumed magnitude distribution and attenuation laws are used.

Injection-Induced Earthquakes

Abstract: Background Human-induced earthquakes have become an important topic of political and scientific discussion, owing to the concern that these events may be responsible for widespread damage and an overall increase in seismicity. It has long been known that impoundment of reservoirs, surface and underground mining, withdrawal of fluids and gas from the subsurface, and injection of fluids into underground formations are capable of inducing earthquakes. In particular, earthquakes caused by injection have become a focal point, as new drilling and well-completion technologies enable the extraction of oil and gas from previously unproductive formations. Earthquakes with magnitude (M) ≥ 3 in the U.S. midcontinent, 1967–2012. After decades of a steady earthquake rate (average of 21 events/year), activity increased starting in 2001 and peaked at 188 earthquakes in 2011. Human-induced earthquakes are suspected to be partially responsible for the increase. Advances Microearthquakes (that is, those with magnitudes below 2) are routinely produced as part of the hydraulic fracturing (or “fracking”) process used to stimulate the production of oil, but the process as currently practiced appears to pose a low risk of inducing destructive earthquakes. More than 100,000 wells have been subjected to fracking in recent years, and the largest induced earthquake was magnitude 3.6, which is too small to pose a serious risk. Yet, wastewater disposal by injection into deep wells poses a higher risk, because this practice can induce larger earthquakes. For example, several of the largest earthquakes in the U.S. midcontinent in 2011 and 2012 may have been triggered by nearby disposal wells. The largest of these was a magnitude 5.6 event in central Oklahoma that destroyed 14 homes and injured two people. The mechanism responsible for inducing these events appears to be the well-understood process of weakening a preexisting fault by elevating the fluid pressure. However, only a small fraction of the more than 30,000 wastewater disposal wells appears to be problematic—typically those that dispose of very large volumes of water and/or communicate pressure perturbations directly into basement faults. Outlook Injection-induced earthquakes, such as those that struck in 2011, clearly contribute to the seismic hazard. Quantifying their contribution presents difficult challenges that will require new research into the physics of induced earthquakes and the potential for inducing large-magnitude events. The petroleum industry needs clear requirements for operation, regulators must have a solid scientific basis for those requirements, and the public needs assurance that the regulations are sufficient and are being followed. The current regulatory frameworks for wastewater disposal wells were designed to protect potable water sources from contamination and do not address seismic safety. One consequence is that both the quantity and timeliness of information on injection volumes and pressures reported to regulatory agencies are far from ideal for managing earthquake risk from injection activities. In addition, seismic monitoring capabilities in many of the areas in which wastewater injection activities have increased are not capable of detecting small earthquake activity that may presage larger seismic events.

The role of stress transfer in earthquake occurrence

Abstract: An earthquake alters the shear and normal stress on surrounding faults. New evidence strengthens the hypothesis that such small, sudden stress changes cause large changes in seismicity rate. Rates climb where the stress increases (aftershocks) and fall where the stress drops. Both increases and decreases in seismicity rate are followed by a time-dependent recovery. When stress change is translated into probability change, seismic hazard is seen to be strongly influenced by earthquake interaction.

Designer's guide to EN 1998-1 and en 1998-5 Eurocode 8: Design of structures for earthquake resistance; general rules, seismic actions, design rules for buildings, foundations and retaining structures/ M.Fardis[et al.]

Abstract: Chapter 1. Introduction Chapter 2. Performance requirements and compliance criteria, 2.1 Performance requirements for new designs in Eurocode 8 and associated seismic hazard levels, 2.2 Compliance criteria for the performance requirements and their implementation, 2.3 Exemption from the application of Eurocode 8 Chapter 3. Seismic Actions, 3.1 Ground conditions, 3.2 Seismic action,3.3 Displacement Response Spectra Chapter 4. Design of Buildings, 4.1 Scope, 4.2 Conception of structures for earthquake resistant buildings, 4.3 Structural regularity and implications for the design, 4.4 Combination of gravity loads and other actions with the design seismic action, 4.5 Methods of analysis, 4.6 Modeling of buildings for linear analysis, 4.7 Modeling of buildings for nonlinear analysis, 4.8 Analysis for accidental torsional effects, 4.9 Combination of the effects of the components of the seismic action, 4.10 "Primary" vs. "secondary" seismic elements, 4.11 Verifications, 4.12 Special rules for frame systems with masonry infills Chapter 5. Design and detailing rules for concrete buildings, 5.1 Scope, 5.2 Types of concrete elements-Definition of their "critical regions", 5.3 Types of structural systems for earthquake resistance of concrete buildings, 5.4 Design concepts: Design for strength or for ductility and energy dissipation-Ductility Classes, 5.5 Behaviour factor q of concrete buildings designed for energy dissipation, 5.6 Design strategy for energy dissipation, 5.7 Detailing rules for local ductility of concrete members, 5.8 Special rules for large walls in structural systems of large lightly reinforced walls, 5.9 Special rules for concrete systems with masonry or concrete infills, 5.10 Design and detailing of foundation elements Chapter 6. Design and detailing rules for steel buildings, 6.1 Scope, 6.2 Dissipative versus low dissipative structures, 6.3 Capacity design principle, 6.4 Design for local energy dissipation in the elements and their connections, 6.5 Design rules aiming at the realisation of dissipative zones, 6.6 Background of the deformation capacity required by Eurocode 8, 6.7 Design against localization of strains, 6.8 Design for global dissipative behaviour of structures, 6.9 Moment resisting frames, 6.10 Frames with concentric bracings, 6.11 Frames with eccentric bracings, 6.12 Moment resisting frames with infills, 6.13 Control of design and construction Chapter 7. Design and detailing of composite steel-concrete buildings, 7.1 Introductory remark, 7.2 Degree of composite character, 7.3 Materials, 7.4 Design for local energy dissipation in the elements and their connections, 7.5 Design for global dissipative behaviour of structures, 7.6 Properties of composite sections for analysis of structures and for resistance checks, 7.7 Composite connections in dissipative zones, 7.8 Rules for members, 7.9 Design of columns, 7.10 Steel beams composite with slab, 7.11 Design and detailing rules for moment frames, 7.12 Composite concentrically braced frames, 7.13 Composite eccentrically braced frames, 7.14 Reinforced concrete shear walls composite with structural steel elements, 7.15 Composite or concrete shear walls coupled by steel or composite beams, 7.16 Composite steel plates shear walls Chapter 8. Design and detailing rules for timber buildings, 8.1 Scope, 8.2 General concepts in earthquake resistant timber buildings, 8.3 Materials and properties of dissipative zones, 8.4 Ductility classes and behaviour factors, 8.5 Detailing, 8.6 Safety verifications Chapter 9. Seismic design with base isolation, 9.1 Introduction, 9.2 Dynamics of seismic isolation, 9.3 Design criteria, 9.4 Seismic isolation systems and devices, 9.5 Modelling and analysis procedures, 9.6 Safety criteria and verifications, 9.7 Design seismic action effects on fixed base and isolated buildings Chapter 10. Foundations, retaining structures and geotechnical aspects, 10.1 Introduction, 10.2 Seismic action, 10.3 Ground properties, 10.4 Requ

Introduction to Special Section: Stress Triggers, Stress Shadows, and Implications for Seismic Hazard

Abstract: Many aspects of earthquake mechanics remain an enigma as we enter the closing years of the twentieth century. One potential bright spot is the realization that simple calculations of stress changes may explain some earthquake interactions, just as previous and on going studies of stress changes have begun to explain human-induced seismicity. This paper, which introduces the special section “Stress Triggers, Stress Shadows, and Implications for Seismic Hazard,” reviews many published works and presents a compilation of quantitative earthquake interaction studies from a stress change perspective. This synthesis supplies some clues about certain aspects of earthquake mechanics. It also demonstrates that much work remains before we can understand the complete story of how earthquakes work.