Human-induced Earthquakes Research Articles

Technique for studying in high resolution poromechanical deformation of a rocklike medium.

Pressurized fluid injection into underground rocks occurs in applications like carbon sequestration, hydraulic fracturing, and wastewater disposal and may lead to human-induced earthquakes and surface uplift. The fluid injection raises the pore pressure within the porous rocks, while deforming them, yet this coupling is rarely captured by experiments. Moreover, experimental studies of rocks are usually limited to postmortem inspection and cannot capture the complete deformation process in time and space. In this Letter we will present a unique experimental system that can capture the spatial distribution of poromechanical effects in real time by using an artificial rocklike transparent medium mimicking the deformation of sandstone. We will demonstrate the system abilities through a fluid injection experiment, showing the nonuniform poroelastic expansion of the medium and the corresponding poroelastic model that captures completely the results without any fitting parameters. Moreover, our results demonstrate and validate the underlying assumptions of the poroelastic theory for fluid injection in rocklike materials, which are relevant for understanding human-induced earthquakes and injection induced surface uplift.

Human-induced earthquakes: E-PIE—a generic tool for Evaluating Proposals of Induced Earthquakes

The HiQuake database documents all cases of earthquake sequences proposed on scientific grounds to have been induced by anthropogenic industrial activity. Because these cases range from being highly plausible to unpersuasive, stakeholders have requested cases to be allocated plausibility grades. Since no questionnaire scheme existed that was sufficiently generalized to be applied to the diverse cases in HiQuake, we developed a new scheme for the task. Our scheme for Evaluating Proposals of Induced Earthquakes (E-PIE) comprises nine generalized questions with a simple weighting system to adjust for the variable diagnostic strength of different observations. Results are illustrated using a simple colored pie chart. We describe the E-PIE scheme and illustrate its application in detail using the example cases of the Groningen gas field in the Netherlands, the November 2017 M5.4 Pohang Enhanced Geothermal Systems-related earthquake sequence in South Korea, and the 2001 deep-penetrating bombing of Tora Bora, Afghanistan. To test the performance of E-PIE, five analysts independently applied it to a suite of 23 diverse cases from HiQuake. By far the most diagnostic questions are those concerning spatial and temporal correlations with industrial effects. Other data are diagnostically subsidiary. For individual cases, the agreement between analysts correlated positively with the strength of evidence for human induction. E-PIE results agree well with those from a specialist scheme tailored to fluid-injection cases. Its strong performance confirms its suitability to apply to the entire HiQuake database.

Experimental characterisation of as-built and retrofitted timber-masonry connections under monotonic, cyclic and dynamic loading

In the province of Groningen (NL), where human-induced earthquakes take place due to gas extraction, a large part of the building stock is composed of brick masonry walls and timber diaphragms. In this framework, timber-masonry connections play a crucial role in the global seismic response of the buildings, but their properties and structural behaviour have not been investigated yet for the Dutch context. This work describes the experimental campaign conducted at Delft University of Technology to characterize as-built and strengthened timber-masonry connections. The joints were tested under either quasi-static monotonic, cyclic or dynamic loading, to analyse the effect of an induced earthquake signal on the connections’ response in terms of strength, stiffness and damage evolution. The obtained test results provided more insight into the capacity and properties of existing connections, and useful knowledge on the effectiveness of the tested retrofitting methods.

Human-Induced Earthquakes: The Performance of Questionnaire Schemes

ABSTRACT Questionnaire schemes are commonly used to investigate whether or not certain earthquakes were induced by industrial activity. Such schemes are subjective and cannot be assumed to give the “right” answer in a scientifically rigorous sense. They only yield current expert opinion on how strongly existing data support an induced or natural cause. Work to optimize a standard generic questionnaire is ongoing. To this end, we designed and compared three schemes that produce measures of data quality and support for human induction. One scheme is a generalization of an existing questionnaire for assessing fluid-injection-associated earthquakes. A second scheme is purely subjective, and a third scheme is purely objective. Because questionnaires are opinion-dependent, different analysts produce different results. We tested the three schemes on 55 diverse cases from the Human-Induced Earthquake Database with the maximum magnitude earthquakes M 4.1–7.9. The results of three analysts correlate with each other at the r ∼ 0.4–0.9 level. Higher correlations were found between schemes than between analysts. A simple, rapid, five-question Likert scale correlated well (r = 0.79) with results from a sophisticated, time-consuming scheme. Measures of data quality were uncorrelated with Mmax, and support for human induction correlated weakly negatively with Mmax. One scheme identified an earthquake sequence not proposed to have been human-induced but that has induced characteristics. New mechanisms of induction are still being recognized, and it is important that questionnaire schemes do not preclude new developments in future.

Seismicity of the repeating earthquake clusters in the northern Xiaojiang fault zone and its implications

The Xiaojiang fault zone (XJF), located at the southeastern margin of the Tibetan plateau, has been frequently struck by destructive earthquakes throughout history. Some studies showed that repeating earthquakes may be used to estimate fault slip rates and even to monitor the pre-slip prior to large asperity. This study focuses on the repeating earthquakes recorded by a high-density seismic array in the northern section of the XJF, a segment ruptured by the 1733 Dongchuan M7.8 earthquake. Using the waveform cross-correlation and relocation techniques, we processed the continuous seismic recordings from seismic stations of the array and confirmed 27 clusters of repeating earthquakes. The repeaters are located in three relatively independent sub-areas, areas A, B, and C. Area A is close to the source areas of the 2014 Ludian Ms6.5 and the 2020 Qiaojia Ms5.0 earthquakes; by analyzing the recurrence intervals of repeating clusters, we found that the Ludian earthquake had an insignificant triggering effect on surrounding events, while the triggering effect from the Qiaojia earthquake was obvious. The clusters in area B were located very close to the northernmost tip of the XJF, which should be associated with an asperity preparing for a large earthquake on the northern XJF. Together with a repeating cluster identified in a previous study and the seismicity pattern revealed by our seismic array, we determined the geometry of the asperity and slip rate, which further helps to estimate a potential Mw7.1 earthquake for the asperity, where no M>7 earthquakes have occurred since the 1733 Dongchuan M7.8 earthquake. The clusters in area C are more like human-induced earthquakes because they are concentrated during the daytime when local people are at work, and, thus, they cannot be used for the study of tectonic deformation. This study clearly indicates that the repeating earthquakes can be triggered by a moderate earthquake nearby and also that repeating earthquakes can be used to estimate fault slip rates and outline locked asperities.

The need for a more integrated approach between human and physical geography at university-level education in the Netherlands

In this paper, we deconstruct how geography is organized as an academic study in the Netherlands. We consider how human and physical foci in geography are included in undergraduate and graduate curricula. As a country with a long academic history and renowned geography programmes, the minimal integration between human and physical geography that we identified is remarkable. We reflect on one high-profile societal debate to illustrate the limitations of the current way of conceptualizing geography as a degree programme: the case of human-induced earthquakes in the Dutch province of Groningen due to gas extraction. We argue that countries with academic geography education similar to the Netherlands stand to gain from embracing the integrative aspects to the field of geography. This is particularly the case when considering processes of global change that rapidly and, arguably, increasingly influence socio-spatial inequalities and livelihoods from global to local levels.

Friction during earthquakes: 25 years of experimental studies

Dynamic fault strength τ (rock friction in the broad sense) and its evolution with seismic slip and slip rate are among the most relevant parameters in earthquake mechanics. Given the large slip rate (1 m s−1 on average), displacement (up to tens of meters), effective stress (tens of MPa), typical of seismic faulting at depth, thermo-mechanical effects become outstanding: dynamic fault strength is severely affected by fluid and rock phase changes, extreme grain size reduction, and the production of amorphous and unstable materials in the slipping zone. Here, first we will summarize the most relevant findings about dynamic fault strength during seismic slip mainly obtained thanks to the exploitation of dedicated experimental machines (i.e., rotary shear apparatus). However, the interpretation of this experimental dataset remains debated because of technical limitations which impede us to measure fundamental parameters such as temperature, strain rate, pore fluid pressure and grain size in the slipping zone. Without a sound estimate of these physical parameters, any constitutive law proposed to describe the evolution of dynamic fault strength during simulated seismic slip remains speculative. Then, we will discuss the results of some recent experiments which exploit new technical approaches to overcome the main limitations of the previous studies. The experimental approach, together with field studies of the geometry and architecture of exhumed faults and modelling, remains our most powerful tool to investigate seismic-related deformation mechanisms in both natural and human-induced earthquakes.

Inversion for the static friction coefficient of seismogenic faults: Application to induced seismicity of the Basel Enhanced Geothermal System, Switzerland

The static coefficient of friction describes the strength of faults and is considered to vary in nature between typical laboratory values measured on a large variety of rocks (0.6-0.85) and very low values for fault rocks containing talc, chlorite and kaolinite (<0.3). The effective frictional strength of a seismically active fault is the result of a combination of frictional properties of the fault rocks and the prevailing pore fluid pressures, which can reach supra-hydrostatic values permitting unfavourably oriented faults to slip. Here, we present an iterative inversion procedure to obtain the average static friction coefficient of a population of seismic faults, provided that stress tensor, geometry of faults and fluid pressures are adequately constrained. The application to a dataset of 48 seismically activated faults (earthquake moment magnitude, MW≤3.0) by fluid injection in crystalline basement in the Basel Enhanced Geothermal System (Switzerland) yields an average coefficient of friction of 0.66±0.11. The inversion results, which are well constrained by high-quality focal mechanisms and robust above-hydrostatic fluid pressure estimations, have uncertainty primarily dependent on the principal stress and fault plane orientations. Values of the friction coefficient in crystalline rocks in the continental basement are compatible with experimentally determined values but require supra-hydrostatic fluid pressures. A comprehensive characterization of all the frictional parameters should be required to better assess rheological and stability fault models, both for natural and human induced earthquakes.

Aandacht voor zingeving

Abstract Attention for Meaning-Making Processes: Context and Practice of Spiritual Care in the Earthquake Area of Groningen In the North of the Netherlands spiritual caregivers have been employed to respond to the social and personal needs resulting from human induced earthquakes. In the Netherlands knowledge on spiritual care in times of disasters is limited. Central to the present study are two questions: How is spiritual care being put into practice in Groningen? And how do the spiritual caregivers cooperate with others in psychosocial care and in the social domain? This article describes the context, the reasons spiritual care came to be provided and the primary activities of the spiritual caregivers during their initial year of practice.

Human-induced earthquakes, risk salience, and housing values

Oklahoma’s households have recently faced several thousand higher-probability but low-impact earthquakes induced by nearby shale gas development. This type of seismic activity is different from natural-occurring earthquakes, which are generally constituted by one, high-loss event. We investigate the mechanisms through which earthquakes may influence household perceptions of risk by modeling changes to property values in and out of seismically-active zones. We estimate that the induced earthquakes are spatially concentrated, which is partially influenced by governmental limits placed on natural gas production and wastewater injections. Additionally, we explore the underlying measure of earthquake intensity and identify its importance in modeling seismic impacts. Controlling for the stock-flow dynamics of seismicity through time, we estimate that Oklahoma County’s cumulative experience of earthquakes led to a diminution of property values. The impacts are further exacerbated by risk-saliency effects, as reflected in declining values associated with nearby wastewater injections and natural gas production.

Experimental characterization of the axial behavior of traditional masonry wall metal tie connections in cavity walls

In recent years, the number of human-induced earthquakes in Groningen, a large gas field in the north of the Netherlands, has increased. The majority of the buildings are built by using unreinforced masonry (URM), most of which consists of cavity (i.e. two-leaf) walls, and were not designed to withstand earthquakes. Efforts to define, test and standardize the metal ties, which do play an important role, are valuable also from the wider construction industry point of view. The presented study exhibits findings on the behavior of the metal tie connections between the masonry leaves often used in Dutch construction practice, but also elsewhere around the world. An experimental campaign has been carried out at Delft University of Technology to provide a complete characterization of the axial behavior of traditional connections in cavity walls. A large number of variations was considered in this research: two embedment lengths, four pre-compression levels, two different tie geometries, and five different testing protocols, including monotonic and cyclic loading. The experimental results showed that the capacity of the connection was strongly influenced by the embedment length and the geometry of the tie, whereas the applied pre-compression and the loading rate did not have a significant influence.

Experimental and analytical evaluation of the in-plane behaviour of as-built and strengthened traditional wooden floors

Traditional timber floors cannot normally withstand horizontal seismic loads without large deformations. This may lead to a corresponding out-of-plane collapse of masonry walls in existing buildings. This situation is even more critical in the Netherlands, around the city of Groningen, where human-induced earthquakes started to take place. Since no seismic events have been experienced until recently, none of the existing buildings was designed with seismic events in mind, with no exception for the timber floors: therefore, it was necessary to characterize their in-plane response. To obtain representative results, firstly floor and roof samples were extracted from existing buildings. The relevant material properties were determined, together with the plank-joist connections behaviour. Replicas were then built with new material and tested to confirm the similarity in response compared to extracted samples. Based on these results, full-scale replicated diaphragms were constructed, and tested quasi-static reversed-cyclic in their plane, either parallel or perpendicular to the joists. Besides characterizing as-built diaphragms, a simple strengthening technique with plywood panels was applied as well, improving their in-plane response in terms of strength, stiffness and energy dissipation, as test results confirm. This study is concluded with an analytical characterization of the diaphragms’ in-plane response, for as-built and strengthened configurations.

Can scientists forecast human-induced earthquakes?

Can scientists forecast human-induced earthquakes?

Fragility of masonry veneers to human-induced Central U.S. earthquakes using neural network models

Since 2008, an increase in human-induced seismic activity related to natural gas production and petroleum activities has resulted in millions of dollars of damage in the Central United States, primarily to residential buildings including chimneys and masonry veneers. This study aims to better understand and evaluate the impacts of such seismic hazards on masonry veneers. To do so, a probabilistic framework is proposed in which fragility curves representing the probability of cracking and collapse damage states for masonry veneers are developed. In the proposed framework, Artificial Neural Networks are adopted to develop probabilistic seismic demand models from experimentally-validated finite element analyses of non-seismically detailed masonry veneers. The framework utilizes a suite of 200 ground motions largely believed to be from human-induced earthquakes with magnitudes of 3.6–5.8 recorded in the Central U.S. since 2008. Fragility curves are produced for masonry veneers with code compliant corrugated brick ties and those with thinner brick ties that are commonly employed in residential construction in the Central U.S. Additionally, the proposed fragilities developed for human-induced earthquakes are compared to those from the literature, which were developed for the New Madrid seismic hazard and are commonly used for seismic vulnerability assessments of infrastructure in the Central U.S. The results indicate that for a given PGA level, induced earthquakes may be more likely to produce damage compared to earthquakes representing the New Madrid hazard. Finally, the regional extents of damage from a recent induced seismic event are estimated using the newly developed and existing fragility functions to evaluate the implications of using these models for regional vulnerability assessments.

Numerical assessment of the dynamic response of a URM terraced house exposed to induced seismicity

This paper presents the results of a numerical study aimed at extending the utility of a shake-table test on an unreinforced masonry building prototype for the seismic assessment of terraced houses in the Groningen region of the Netherlands. The area, with no recorded tectonic activity to date, has recently experienced ground shakings induced by natural-gas production. Local buildings are mostly made of unreinforced masonry, often built with cavity walls, which were not specifically conceived for earthquake resilience; hence, they do not exhibit any seismic-resistant detailing. Numerical models were first generated and fine-tuned based on data obtained from incremental unidirectional dynamic tests on a full-scale building specimen, performed up to near-collapse conditions. The structure represented the end-unit of a typical Dutch terraced building with cavity walls and a flexible timber roof. Several issues concerning the numerical simulation of the dynamic response of unreinforced cavity-wall systems were addressed in the context of employing an equivalent-frame modelling approach. Analyses were conducted also considering the effect of the nonlinear out-of-plane response of walls. The calibrated single-unit model was then enlarged to numerically assess the effects of human-induced earthquakes on an entire row of terraced houses. A cloud method was selected to establish the probabilistic relationship between ground-motion intensity and nonlinear structural response, using a large suite of records characteristic of induced-seismicity earthquakes. The question of selecting an appropriate and comprehensive measure of shaking intensity for correlation with structural performance is also discussed.

Induced Seismicity

The ability of fluid-generated subsurface stress changes to trigger earthquakes has long been recognized. However, the dramatic rise in the rate of human-induced earthquakes in the past decade has created abundant opportunities to study induced earthquakes and triggering processes. This review briefly summarizes early studies but focuses on results from induced earthquakes during the past 10 years related to fluid injection in petroleum fields. Study of these earthquakes has resulted in insights into physical processes and has identified knowledge gaps and future research directions. Induced earthquakes are challenging to identify using seismological methods, and faults and reefs strongly modulate spatial and temporal patterns of induced seismicity. However, the similarity of induced and natural seismicity provides an effective tool for studying earthquake processes. With continuing development of energy resources, increased interest in carbon sequestration, and construction of large dams, induced seismicity will continue to pose a hazard in coming years.

Maturity of nearby faults influences seismic hazard from hydraulic fracturing

Understanding the causes of human-induced earthquakes is paramount to reducing societal risk. We investigated five cases of seismicity associated with hydraulic fracturing (HF) in Ohio since 2013 that, because of their isolation from other injection activities, provide an ideal setting for studying the relations between high-pressure injection and earthquakes. Our analysis revealed two distinct groups: (i) deeper earthquakes in the Precambrian basement, with larger magnitudes (M > 2), b-values < 1, and many post-shut-in earthquakes, versus (ii) shallower earthquakes in Paleozoic rocks ∼400 m below HF, with smaller magnitudes (M < 1), b-values > 1.5, and few post-shut-in earthquakes. Based on geologic history, laboratory experiments, and fault modeling, we interpret the deep seismicity as slip on more mature faults in older crystalline rocks and the shallow seismicity as slip on immature faults in younger sedimentary rocks. This suggests that HF inducing deeper seismicity may pose higher seismic hazards. Wells inducing deeper seismicity produced more water than wells with shallow seismicity, indicating more extensive hydrologic connections outside the target formation, consistent with pore pressure diffusion influencing seismicity. However, for both groups, the 2 to 3 h between onset of HF and seismicity is too short for typical fluid pressure diffusion rates across distances of ∼1 km and argues for poroelastic stress transfer also having a primary influence on seismicity.

Risk remains high for damage from human-induced earthquakes

Oklahoma’s record earthquakes last year fell within the zone that was forecast by the USGS to have the highest hazard.

Man-Made Solutions for Man-Made Quakes.

The article examines human-induced earthquakes. Particular focus is given to man-made solutions for these quakes. Additional topics discussed include the frequency of quakes in states including Oklahoma, Texas, and Kansas, how the quakes are caused by oil and gas production, and research from Stanford University.

River’s Rise Linked to Oklahoma’s Largest Earthquake

As human-induced earthquakes increase in frequency and magnitude, researchers race to uncover their effects on surface water and groundwater.