Determining the surface fault-rupture hazard zone for the Pazarcık segment of the East Anatolian fault zone through comprehensive analysis of surface rupture from the February 6,2023,Earthquake(Mw 7.7)

Following surface rupture observations in populated areas affected by the KahramanmaraşEarthquake(Mw 7.7)on February 6th,2023,along the Pazarcık segment of the East Anatolian Fault Zone(EAFZ),this study presents novel insights into physical criteria for delineating surface fault-rupture hazard zones(SRHZs)along ruptured strike-slip faults.To achieve this objective,three trench studies across the surface rupture were conducted on the Pazarcık segment of the EAFZ to collect field data,and earthquake recurrence intervals were interpreted using Bayesian statistics from previously conducted paleoseismological trenchings.The results of the proposed model indicate that the Pazarcık segment produced five significant surface-rupturing earthquakes in the last∼11 kyr:E1:11.13±1.74 kyr,E2:7.62±1.20 kyr,E3:5.34±1.05 kyr,E4:1.82±0.93 kyr,and E5:0.35±0.11 kyr.In addition,the recurrence intervals of destructive earthquakes on the subject in question range from 0.6 kyr to 4.8 kyr.Considering that the last significant earthquake occurred in 1513,the longest time since the most recent surface fault rupturing earthquake on this particular segment was 511 years.These results indicate that,in terms of the theoretical recurrence interval of earthquakes that can create surface ruptures on the Pazarcık segment,the period in which the February 6,2023,earthquake occurred was within the end of the expected return period.As a result,the potential for a devastating earthquake in the near future is not foreseen on the same fault.Finally,the SRHZ proposed for the Pazarcık section of Gölbaşıvillage was calculated as a 61-meter-wide offset on the fault lineament to reduce the negativities that may occur in the ruptured area in the future.It is recommended to take into account this width in the settlement of this area and nearby areas.

Overcoming obstacles to implementation: addressing political,institutional and behavioral problems in earthquake hazard mitigation policies

This project is aimed at bridging the three planes,from basic research,through enabling processes,to engineered systems.At the basic research plane,we have been working to improve our collective understanding about obstacles to implementing mitigation practices,owner decision processes (in connection with other MCEER projects),and public policy processes.At the level of enabling processes,we have been seeking to develop an understanding of how obstacles to greater mitigation can be overcome by improved policy design and processes.At the engineered systems plane, our work is intended to result in practical guidelines for devising policies and programs with appropriate motivation and incentives for implementing policies and programs once adopted.This phase of the research has been aimed,first,at a thorough,multidisciplinary review of the literature concerning obstacles to implementation.Second,the research has focused on advancing the state of the art by developing means for integrating the insights offered by diverse perspectives on the implementation process from the several social,behavioral,and decision sciences.The research establishes a basis for testing our understanding of these processes in the case of hospital retrofit decisions.

Earthquake vulnerability disaster in the Lembang district of West Bandung Regency, Indonesia

This research is concerned with an analysis of the level of vulnerability for an earthquake disaster in Lembang district,an area in West Java that includes the Bandung basin and has a high potential for earthquake disaster.The Lembang district is close to the active Lembang fault whose movement can cause earthquakes of magnitude 7 on the Richter scale(Tempo Interaktif,May 11,2010).The research method used to assess the level of vulnerability is essentially a descriptive approach.The data analysis is based on calculating an earthquake disaster risk index(EDRI),which is in turn based on assessment of the region's social,physical and economic vulnerabilities.The vulnerability level for earthquake disaster in the Lembang is ranked as medium category.The social vulnerability of the population is the major contributing factor given the high population density and growth rate for the region.The physical characteristics of the district,which includes mild temperatures and attractive scenery,make many people want to stay in and visit Lembang.The construction quality of buildings is so bad that they are not designed to withstand earthquakes,so improvement of building infrastructure is an alternative to reducing the various physical vulnerabilities.

Research status of earthquake forecasting in hydraulicfracturing induced earthquakes

In the new types of industrial activities including unconventional energy extraction associated with shale gas and hot dry rock,gas reservoir operations,CO2 geological storage,undergoing research on induced earthquake forecasting has become one of the forward positions of current seismology.As for the intense actual demand,the immature research on induced earthquake forecasting has already been applied in pre-assessment of site safety and seismic hazard and risk management.This work will review systematically recent advances in earthquake forecasting induced by hydraulic fracturing during industrial production from four aspects:earthquake occurrence probability,maximum expected magnitude forecasting,seismic risk analysis for engineering and social applications and key scientific problems.In terms of earthquake occurrence probability,we introduce statistical forecasting models such as an improved ETAS and non-stationary ETAS and physical forecasting models such as Seismogenic Index(SI)and hydro-mechanism nucleation.Research on maximum expected magnitude forecasting has experienced four stages of linear relationship with net injection volume of fluid,power exponential relationship and physical forecasting regarding fault parameters.For seismic risk analysis,we focus on probabilistic seismic hazard assessment and quantitative geological susceptibility model.Furthermore,this review is extended to key scientific problems that contain obtaining accurate fault scale and environmental stress state of reservoir,critical physical process of runaway rupture,complex mechanism of fault activation as well as physical mechanism and modeling of trailing effect.This work in understanding induced earthquake forecasting may contribute to unconventional energy development and production,seismic hazard mitigation,emergency management and scientific research as a reference.

Large, moderate, small earthquakes and seismic fortification criterion

This paper discusses the relation between two-step seismic design and the standard of probability of exceedance, and the relation of three-levels seismic ground motion parameters given by probability method and comprehensive probability method. The relative size relations of the ground motions with 2%, 10%, 63% probability of exceedance in 50 years, namely large earthquake, moderate earthquake, and small earthquake, are discussed through a practical example of seismic hazard analysis. The methods to determine seismic fortification criterion are discussed.

Study on optimum arrangement of hysteretic dampers in frame structure

The earthquake mitigation effect of hysteretic dampers is not only related to the number, stiffness, strength, deformation ability of dampers but also to the strength and stiffness of the structure. This paper studied the condition that structures should be in when the hysteretic dampers mitigated seismic action most effectively and made appropriate numerical analysis to verify the effectiveness of theory derivation. The inelastic seismic responses were analyzed for the SDOF system that the shear strength ratio of the damper system was taken differently and the result showed that when the ratio was in the vicinity of the optimum strength ratio of the damper system, the displacement of the structure was minimum and the energy dissipation of dampers was maximum, which indicated that the dampers mitigated seismic action most effectively. The result also indicated that the hysteretic dampers had significant earthquake mitigation effect when the strength ratio β changed in a relatively wide range.

Seismic pattern treatment method through calculation of seismic density at grid nodes

Analysis of seismic data and seismicity characteristics in China, we gave a method to deal with seismic patterns by calculating density at grid nodes. Number of earthquakes and epicenter distribution are considered comprehensively in this method. Effect of datum accuracy is stressed on parameter confirmation. Seismic patterns from this method are stable and can reflect seismic characteristics reliably. These seismic patterns are the base of quantitative analysis of seismicity. It can be applied in seismic tendency analysis and medium-long term earthquake prediction, earthquake countermeasure and risk mitigation.

Fluid injection-induced fault slip during unconventional energy development:A review

An unusual increase in seismicity rate near the development and production sites of unconventional energy(e.g.,natural gas and geothermal fluids)has been attributed to subsurface fluid injection.Damaging and hazardous earthquakes in many countries(e.g.,China,South Korea,and the United States)have motivated tremendous effort to understand the complexity of fault slip behaviors in response to fluid pressurization.This study reviews key characteristics of injection-induced fault slip and highlights prediction and mitigation strategies relevant to unconventional energy projects.This capability relies on adequate understanding and characterization of first-and second-order friction and stability behaviors of faults as well as impacts of fluid pressurization and its role in triggering aseismic,seismic,and transitional slip behaviors.Suitable methods of investigation and characterization are noted together with typical examples together with scientific advances in our understanding towards forewarning and mitigation.Present challenges are addressed relating to the understanding of complex secondorder friction behaviors and the location and characterization of blind faults.These needs are aided in the integration of multi-scale and multi-physical data obtained from laboratory,numerical,and field studies to offer crucial information for induced hazard preparedness and rapid run-up assessment.Finally,emerging technologies contributing to an improved understanding,such as data analytics and machine learning,are discussed in heralding the next frontier for injection-induced seismicity research.