Fault roughness controls injection-induced seismicity.

Surface roughness ubiquitously prevails in natural faults across various length scales. Despite extensive studies highlighting the important role of fault geometry in the dynamics of tectonic earthquakes, whether and how fault roughness affects fluid-induced seismicity remains elusive. Here, we investigate the effects of fault geometry and stress heterogeneity on fluid-induced fault slip and associated seismicity characteristics using laboratory experiments and numerical modeling. We perform fluid injection experiments on quartz-rich sandstone samples containing either a smooth or a rough fault. We find that geometrical roughness slows down injection-induced fault slip and reduces macroscopic slip velocities and fault slip-weakening rates. Stress heterogeneity and roughness control hypocenter distribution, frequency-magnitude characteristics, and source mechanisms of injection-induced acoustic emissions (AEs) (analogous to natural seismicity). In contrast to smooth faults where injection-induced AEs are uniformly distributed, slip on rough faults produces spatially localized AEs with pronounced non-double-couple source mechanisms. We demonstrate that these clustered AEs occur around highly stressed asperities where induced local slip rates are higher, accompanied by lower Gutenberg-Richter b-values. Our findings suggest that real-time monitoring of induced microseismicity during fluid injection may allow identifying progressive localization of seismic activity and improve forecasting of runaway events.

Slow earthquake scaling reconsidered as a boundary between distinct modes of rupture propagation.

The scaling law for slow earthquakes, which is a linear relationship between seismic moment and duration, was proposed 15 y ago and initiated a debate on the difference in physical processes governing slow vs. fast (ordinary) earthquakes. Based on new observations across a wide period range, we show that linear scaling of slow earthquakes remains valid, but as a well-defined upper bound on moment rate of ~1013 Nm/s. The large gap in moment-rate between the scaling of slow and fast earthquakes remains unfilled. Slow earthquakes occur near the detectability threshold, such that we are unable to detect deformation events with lower moment rates. Observed trends within slow earthquake categories support the idea that this unobservable field is populated with events of lower moment rate. This suggests a change in perspective - that the proposed scaling should be considered as a bound, or speed limit, on slow earthquakes. We propose that slow earthquakes represent diffusional propagation, and that the bound on moment rate reflects an upper limit on the speed of those diffusional processes. Ordinary earthquakes, in contrast, occur as a coupled process between seismic wave propagation and fracture. Thus, even though both phenomena occur as shear slip, the difference of scaling reflects a difference in the physical process governing propagation.

The dynamics of unsteady frictional slip pulses.

Self-healing slip pulses are major spatiotemporal failure modes of frictional systems, featuring a characteristic size [Formula: see text] and a propagation velocity [Formula: see text] ([Formula: see text] is time). Here, we develop a theory of slip pulses in realistic rate- and state-dependent frictional systems. We show that slip pulses are intrinsically unsteady objects-in agreement with previous findings-yet their dynamical evolution is closely related to their unstable steady-state counterparts. In particular, we show that each point along the time-independent [Formula: see text] line, obtained from a family of steady-state pulse solutions parameterized by the driving shear stress [Formula: see text], is unstable. Nevertheless, and remarkably, the [Formula: see text] line is a dynamic attractor such that the unsteady dynamics of slip pulses (when they exist)-whether growing ([Formula: see text]) or decaying ([Formula: see text])-reside on the steady-state line. The unsteady dynamics along the line are controlled by a single slow unstable mode. The slow dynamics of growing pulses, manifested by [Formula: see text], explain the existence of sustained pulses, i.e., pulses that propagate many times their characteristic size without appreciably changing their properties. Our theoretical picture of unsteady frictional slip pulses is quantitatively supported by large-scale, dynamic boundary-integral method simulations.

Carbonates and intermediate-depth seismicity: Stable and unstable shear in altered subducting plates and overlying mantle.

A model for intermediate-depth earthquakes of subduction zones is evaluated based on shear localization, shear heating, and runaway creep within thin carbonate layers in an altered downgoing oceanic plate and the overlying mantle wedge. Thermal shear instabilities in carbonate lenses add to potential mechanisms for intermediate-depth seismicity, which are based on serpentine dehydration and embrittlement of altered slabs or viscous shear instabilities in narrow fine-grained olivine shear zones. Peridotites in subducting plates and the overlying mantle wedge may be altered by reactions with CO2-bearing fluids sourced from seawater or the deep mantle, to form carbonate minerals, in addition to hydrous silicates. Effective viscosities of magnesian carbonates are higher than those for antigorite serpentine and they are markedly lower than those for H2O-saturated olivine. However, magnesian carbonates may extend to greater mantle depths than hydrous silicates at temperatures and pressures of subduction zones. Strain rates within altered downgoing mantle peridotites may be localized within carbonated layers following slab dehydration. A simple model of shear heating and temperature-sensitive creep of carbonate horizons, based on experimentally determined creep laws, predicts conditions of stable and unstable shear with strain rates up to 10/s, comparable to seismic velocities of frictional fault surfaces. Applied to intermediate-depth earthquakes of the Tonga subduction zone and the double Wadati-Benioff zone of NE Japan, this mechanism provides an alternative to the generation of earthquakes by dehydration embrittlement, beyond the stability of antigorite serpentine in subduction zones.

Updated concepts of seismic gaps and asperities to assess great earthquake hazard along South America.

So far in this century, six very large-magnitude earthquakes (MW ≥ 7.8) have ruptured separate portions of the subduction zone plate boundary of western South America along Ecuador, Peru, and Chile. Each source region had last experienced a very large earthquake from 74 to 261 y earlier. This history led to their designation in advance as seismic gaps with potential to host future large earthquakes. Deployments of geodetic and seismic monitoring instruments in several of the seismic gaps enhanced resolution of the subsequent faulting processes, revealing preevent patterns of geodetic slip deficit accumulation and heterogeneous coseismic slip on the megathrust fault. Localized regions of large slip, or asperities, appear to have influenced variability in how each source region ruptured relative to prior events, as repeated ruptures have had similar, but not identical slip distributions. We consider updated perspectives of seismic gaps, asperities, and geodetic locking to assess current very large earthquake hazard along the South American subduction zone, noting regions of particular concern in northern Ecuador and Colombia (1958/1906 rupture zone), southeastern Peru (southeasternmost 1868 rupture zone), north Chile (1877 rupture zone), and north-central Chile (1922 rupture zone) that have large geodetic slip deficit measurements and long intervals (from 64 to 154 y) since prior large events have struck those regions. Expanded geophysical measurements onshore and offshore in these seismic gaps may provide critical information about the strain cycle and fault stress buildup late in the seismic cycle in advance of the future great earthquakes that will eventually strike each region.

Metamorphism-facilitated faulting in deforming orthopyroxene: Implications for global intermediate-depth seismicity.

SignificanceThe exothermic metamorphic reaction in orthopyroxene (Opx), a major component of oceanic lithospheric mantle, is shown to trigger brittle failure in laboratory deformation experiments under conditions where garnet exsolution takes place. The reaction product is an extremely fine-grained material, forming narrow reaction zones that are mechanically weak, thereby facilitating macroscopic faulting. Oceanic subduction zones are characterized by two separate bands of seismicity, known as the double seismic zone. The upper band of seismicity, located in the oceanic crust, is well explained by dehydration-induced mechanical instability. Our newly discovered metamorphism-induced mechanical instability provides an alternative physical mechanism for earthquakes in the lower band of seismicity (located in the oceanic lithospheric mantle), with no requirement of hydration/dehydration processes.

Are maximum magnitudes of induced earthquakes controlled by pressure diffusion?

There is an ongoing discussion about how to forecast the maximum magnitudes of induced earthquakes based on operational parameters, subsurface conditions and physical process understanding. Although the occurrence of damage caused by induced earthquakes is rare, some cases have caused significant economic loss, injuries and even loss of life. We analysed a global compilation of earthquakes induced by hydraulic fracturing, geothermal reservoir stimulation, water disposal, gas storage and reservoir impoundment. Our analysis showed that maximum magnitudes scale with the characteristic length of pressure diffusion in the brittle Earth's crust. We observed an increase in the nucleation potential of larger-magnitude earthquakes with time and explained it by diffusion-controlled growth of the pressure-perturbed part of faults. Numerical and analytical fault size modelling supported our findings. Finally, we derived magnitude scaling laws to manage induced seismic hazard of upcoming energy projects prior to operation. This article is part of the theme issue 'Induced seismicity in coupled subsurface systems'.

Local wisdom in psychosocial handling of women earthquake survivors in Indonesia.

This article highlights local Indonesian wisdom in the psychosocial treatment of female earthquake survivors, including interaction with nature, God and fellow humans, which helps reduce the psychological impact through activities such as reading the Koran, praying and cooking together in the refugee camp's public kitchen.

The impact of earthquakes on women: assessing women's mental health in aftermath of the Kahramanmaras-centred earthquake in Türkiye.

BACKGROUND: Earthquakes disproportionately affect women and exacerbate gender and social inequalities. This study aims to investigate the psychological impact of the earthquake in Türkiye on women and the associated factors. METHODS: This is a survey-based study. We collected data from 498 women residing in cities most affected by the earthquake. RESULTS: Participants' mean age was 27.72 ± 5.4. Over 78% of the participants lost at least one family member, and 43.7% lost at least one child due to the earthquake. The mean average of Brief Symptom Inventory (BSI) scores was 100.8 (SD = 8.37), and the Global Severity Index was 1.9 (SD = 0.16). Regression analysis showed that higher education levels predicted poor outcomes across most BSI dimensions. Losing a family member and shelter and injury status were also predictors for several mental health outcomes of the BSI subscales. CONCLUSIONS: Earthquakes significantly impact women's well-being and may have a broader impact on the whole family. There is an urgent need to provide psycho-social interventions in the response and recovery phases of the crisis to meet the affected women's needs. This includes providing basic needs with attention to women-specific needs, restoring social networks, addressing gender-based violence and providing gender-sensitive specialized interventions for those who need further support.

Base excess is superior to creatinine in predicting haemodialysis: A multicenter study conducted Kahramanmaras earthquake victims.

PURPOSE: This study had two main goals: to determine which rhabdomyolysis patients need haemodialysis; and to highlight the significance of blood gas parameters, particularly base excess, as predictors of the need for haemodialysis. METHOD: A total of 270 patients were included in this multicentre, retrospective study. Among the patients who were transferred in from the earthquake region and developed rhabdomyolysis, those with creatine kinase (CK) values >1000 U/L were included in our study. The need for renal replacement in these patients was determined via laboratory tests, urine output monitoring and clinical follow-up. FINDINGS: A total of 270 patients were included in our study. Univariate and multivariate regression analyses of laboratory parameters were performed to identify predictors of HD treatment. According to the univariate regression analysis, BE, HCO3, creatinine, CK, lactate, alanine transaminase (ALT) and aspartate transaminase (AST) levels were found to be significantly associated with receiving HD treatment. According to multivariate regression analysis, only BE (p = 0.003) was found to be a significant predictor of HD treatment. ROC analysis revealed that the optimal cutoff value for BE was -2.6; at this value, the sensitivity and specificity of BE for predicting HD treatment were 89% and 77.1%, respectively (AUC: 0.912; 95% CI: 0.872-0.943; p < 0.001). CONCLUSION: Base excess is an effective predictor of the need for haemodialysis in patients with crush-related injuries that cause rhabdomyolysis and in patients who develop acute renal failure due to elevated CK.

The effect of earthquake on fibromyalgia: a comparison of patients on medication and without medication.

INTRODUCTION / OBJECTIVES: Stressful events like earthquakes might worsen the symptoms of fibromyalgia, although the influence of medications on these consequences is yet uncertain. The objective of this study was to examine the influence of an earthquake on the symptoms of fibromyalgia and evaluate the impacts of medications used to treat fibromyalgia on the clinical picture. METHOD: Ninety-five fibromyalgia patients were enrolled in a comparative study and divided into two groups: medication and non-medication. Three subcategories of medication groups were established: selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), and gabapentinoid drugs (GDs). Before and after the earthquake, clinical evaluations were conducted using the Fibromyalgia Impact Questionnaire (FIQ), Hospital Anxiety and Depression Scale (HADS), and Jenkins Sleep Rating Scale (JSS). Statistical analyses were conducted to compare the scores before and after the earthquake and evaluate the differences between the groups. RESULTS: Statistically significant increases were observed in FIQ, HADS-anxiety, HADS-depression, and JSS scores in the medication and non-medication groups before and after the earthquake comparisons (p < 0.05). Non-medication group reported significantly higher post-earthquake changes in FIQ, HADS-anxiety, HADS-depression, and JSS compared to the medication group (p < 0.05). While HADS-anxiety, HADS-depression, and JSS changes after the earthquake differed according to the drug subgroups (p < 0.05), no statistically significant difference was observed in FIQ values (p > 0.05). The highest scores were detected in the GD subgroup. CONCLUSIONS: This study highlights the substantial impact of earthquakes on fibromyalgia patients. Medication use may assist in reducing the detrimental effects of stresses like earthquakes on fibromyalgia symptomatology. Future research with larger sample sizes and more extended follow-up periods is needed to explain these findings and optimize treatment regimens for fibromyalgia patients experiencing significant stressors.

A scoping review of post-earthquake healthcare for vulnerable groups of the 2023 Turkey-Syria earthquakes.

BACKGROUND: Identifying healthcare services and also strengthening the healthcare systems to effectively deliver them in the aftermath of large-scale disasters like the 2023 Turkey-Syria earthquakes, especially for vulnerable groups cannot be emphasized enough. This study aimed at identifying the interventions undertaken or proposed for addressing the health needs or challenges of vulnerable groups immediately after the occurrence of the 2023 Turkey-Syria earthquakes, as well as for prioritizing their healthcare service delivery in the post-Turkey-Syria earthquake. METHODS: In this scoping review compiled with the five steps of the Arksey and O'Malley framework, five databases, including PubMed, Science Direct, Web of Science, OVID, and Google Scholar, were searched for studies published between March and April 2023 in line with the eligibility criteria. Interventions for enhancing post-earthquake healthcare services (PEHS) were grouped into seven (7) categories, adopted from previous guidelines and studies. Each one was assigned a default score of a value equal to one (1), which, in the end, was summed up. RESULTS: Of the 115 total records initially screened, 29 articles were eligible for review. Different interventions they reported either undertaken or proposed to address the healthcare needs and challenges, especially faced by the most vulnerable groups in the aftermath of the Turkey-Syria earthquakes, were categorized into 7 PEHS. They were ranked with their scores as follows: humanitarian health relief (25); medical care (17); mental health and psychosocial support (10); health promotion, education, and awareness (9); disease surveillance and prevention (7); disability rehabilitation (7); and sexual and reproductive health (5). CONCLUSION: Since there are no proper guidelines or recommendations about the specific or most significant PEHS to prioritize for vulnerable groups after the occurrence of large-scale earthquakes, this scoping review provides some insights that can help inform healthcare service delivery and prioritization for vulnerable groups in the post-2023 Turkey-Syria earthquakes and other similar disasters.

Dynamic rupture initiation and propagation in a fluid-injection laboratory setup with diagnostics across multiple temporal scales.

Fluids are known to trigger a broad range of slip events, from slow, creeping transients to dynamic earthquake ruptures. Yet, the detailed mechanics underlying these processes and the conditions leading to different rupture behaviors are not well understood. Here, we use a laboratory earthquake setup, capable of injecting pressurized fluids, to compare the rupture behavior for different rates of fluid injection, slow (megapascals per hour) versus fast (megapascals per second). We find that for the fast injection rates, dynamic ruptures are triggered at lower pressure levels and over spatial scales much smaller than the quasistatic theoretical estimates of nucleation sizes, suggesting that such fast injection rates constitute dynamic loading. In contrast, the relatively slow injection rates result in gradual nucleation processes, with the fluid spreading along the interface and causing stress changes consistent with gradually accelerating slow slip. The resulting dynamic ruptures propagating over wetted interfaces exhibit dynamic stress drops almost twice as large as those over the dry interfaces. These results suggest the need to take into account the rate of the pore-pressure increase when considering nucleation processes and motivate further investigation on how friction properties depend on the presence of fluids.

Laboratory earthquake forecasting: A machine learning competition.

Earthquake prediction, the long-sought holy grail of earthquake science, continues to confound Earth scientists. Could we make advances by crowdsourcing, drawing from the vast knowledge and creativity of the machine learning (ML) community? We used Google's ML competition platform, Kaggle, to engage the worldwide ML community with a competition to develop and improve data analysis approaches on a forecasting problem that uses laboratory earthquake data. The competitors were tasked with predicting the time remaining before the next earthquake of successive laboratory quake events, based on only a small portion of the laboratory seismic data. The more than 4,500 participating teams created and shared more than 400 computer programs in openly accessible notebooks. Complementing the now well-known features of seismic data that map to fault criticality in the laboratory, the winning teams employed unexpected strategies based on rescaling failure times as a fraction of the seismic cycle and comparing input distribution of training and testing data. In addition to yielding scientific insights into fault processes in the laboratory and their relation with the evolution of the statistical properties of the associated seismic data, the competition serves as a pedagogical tool for teaching ML in geophysics. The approach may provide a model for other competitions in geosciences or other domains of study to help engage the ML community on problems of significance.

The Impact of Major Earthquakes on Students' Emotional Distress and Internalizing Symptoms, Externalizing Behaviors, and Coping During the Implementation of keepin' it REAL-Mexico.

This article reports on effects of two earthquakes in Mexico on adolescents attending middle school. The earthquakes struck in close succession during the implementation of a school-based prevention program, providing an opportunity to assess emotional distress due to the earthquakes and whether the life skills taught in the program affected how students coped with the natural disaster. The objectives were to (1) evaluate the earthquakes' impact on students' distress; (2) assess if distress is associated with internalizing symptomology and externalizing behaviors; and (3) investigate if students receiving the original and adapted versions of the intervention coped better with the events. A Mexico-US research team culturally adapted keepin' it REAL to address connections between substance use among early adolescents in Mexico and exposure to violence. A random sample of public middle schools from three cities (Mexico City, Guadalajara, and Monterrey), stratified by whether they held morning or afternoon sessions, was selected. A total of 5522 7th grade students from 36 schools participated in the study. Students answered pretest and posttest questionnaires; the latter assessed earthquake-related distress and coping strategies. Earthquake-related distress was associated with all measures of undesired internalizing symptomology and externalizing behaviors. Compared to controls, students in the adapted intervention reported less aggressive and rule-breaking externalizing behavior and less violence perpetration. However, these intervention effects were not moderated by the level of earthquake-related distress, and they were not mediated by positive or negative coping. The findings have implications for prevention intervention research and policy as natural and human-made disasters occur more often.

Natural disasters: a comprehensive study using EMDAT database 1995-2022.

INTRODUCTION: The frequency, intensity, and geographical reach of natural disasters, fueled in part by factors such as climate change, population growth, and urbanization, have undeniably been escalating concerns around the world. DESIGN AND METHODS: This is a retrospective analysis of natural disasters recorded in the Emergency Events Database from 1995 to 2022. RESULTS: Between 1995 and 2022, 11,360 natural disasters occurred, with a mean of 398 per year. Asia experienced the most disasters (4390) and the highest number of casualties (918,198). Hydrological disasters were the most common subgroup (4969), while geophysical disasters led in terms of deaths (770,644). Biological disasters caused the most injuries (2544), particularly in Africa. CONCLUSION: Recognizing the historical impacts of the various subtypes of natural disasters may help different regions better risk analyze and mitigate the unique risks associated with such events.

Nutritional status among earthquake survivors: a systematic review and meta-analysis.

OBJECTIVE: Earthquakes, as one of the most devastating natural disasters, have many consequences, including the collapse of buildings where food is produced, stored, and distributed, which can ensue with numerous nutritional problems. This study was to investigate the nutritional status of earthquake survivors. STUDY DESIGN: This was a systematic review and meta-analysis study. METHODS: The present review was conducted according to the PRISMA guideline. The data were collected by searching the data resources of PubMed, Scopus, Web of Science, Science Direct, Google Scholar, MagIran, and Scientific Information Database. Meta-analysis was conducted using the random effects model, and the I2 index was used to assess heterogeneity among studies. Publication bias was assessed using Begg's test. RESULTS: In this study, 342 studies were identified in the primary literature search, and after removing duplicates, 14 of which were finally selected for meta-analysis. Based on the results of the meta-analysis, the overall prevalence was obtained: 4.19% for wasting, 16.78% for stunting, 12.59% for underweight, and 28.06% for anemia after the earthquake. CONCLUSION: The results indicated that earthquake survivors are exposed to malnutrition. Therefore, it is recommended that adequate food and nutritional supplements are provided to all earthquake survivors.

Recovering the status quo: tipping points and earthquake aftermaths in colonial India.

Scholars of disaster politics debate how far natural hazards cause or catalyse political change. This paper builds on recent scholarship on tipping points and social contracts to argue that two case studies of historical earthquakes in 1930s British-colonised India invite a focus on the dynamics of cooperation and conflict between state and non-state actors. Officials of the colonial state and its nationalist rivals cooperated after one earthquake even though they otherwise bitterly opposed each other. Cooperation broke down after the second event, just one year later. Yet, in both cases, officials and nationalist leaders shared a broad vision for Indian society, which pushed both sides actively to seek to recover the social and economic status quo ante, preventing potential tipping points from crystallising. These case studies reveal how and why highly fraught social contracts can survive major disasters. The colonial state's transient and reactive approach to disaster governance continued to impact on post-independence India.

Source Models of the 2016 and 2022 Menyuan Earthquakes and Their Tectonic Implications Revealed by InSAR.

The Haiyuan fault system plays a crucial role in accommodating the eastward expansion of the Tibetan Plateau (TP) and is currently slipping at a rate of several centimeters per year. However, limited seismic activities have been observed using geodetic techniques in this area, impeding the comprehensive investigation into regional tectonics. In this study, the geometric structure and source models of the 2022 Mw 6.7 and the 2016 Mw 5.9 Menyuan earthquakes were investigated using Sentinel-1A SAR images. By implementing an atmospheric error correction method, the signal-to-noise ratio of the 2016 interferometric synthetic aperture radar (InSAR) coseismic deformation field was significantly improved, enabling InSAR observations with higher accuracy. The results showed that the reliability of the source models for those events was improved following the reduction in observation errors. The Coulomb stress resulting from the 2016 event may have promoted the strike-slip movement of the western segment of the Lenglongling fault zone, potentially expediting the occurrence of the 2022 earthquake. The coseismic slip distribution and the spatial distribution of aftershocks of the 2022 event suggested that the seismogenic fault may connect the western segment of the Lenglongling fault (LLLF) and the eastern segment of the Tuolaishan fault (TLSF). Additionally, the western segment of the surface rupture zone of the northern branch may terminate in the secondary branch close to the Sunan-Qilian fault (SN-QL) strike direction, and the earthquake may have triggered deep aftershocks and accelerated stress release within the deep seismogenic fault.

Environmental Surveillance through Machine Learning-Empowered Utilization of Optical Networks.

We present the use of interconnected optical mesh networks for early earthquake detection and localization, exploiting the existing terrestrial fiber infrastructure. Employing a waveplate model, we integrate real ground displacement data from seven earthquakes with magnitudes ranging from four to six to simulate the strains within fiber cables and collect a large set of light polarization evolution data. These simulations help to enhance a machine learning model that is trained and validated to detect primary wave arrivals that precede earthquakes' destructive surface waves. The validation results show that the model achieves over 95% accuracy. The machine learning model is then tested against an M4.3 earthquake, exploiting three interconnected mesh networks as a smart sensing grid. Each network is equipped with a sensing fiber placed to correspond with three distinct seismic stations. The objective is to confirm earthquake detection across the interconnected networks, localize the epicenter coordinates via a triangulation method and calculate the fiber-to-epicenter distance. This setup allows early warning generation for municipalities close to the epicenter location, progressing to those further away. The model testing shows a 98% accuracy in detecting primary waves and a one second detection time, affording nearby areas 21 s to take countermeasures, which extends to 57 s in more distant areas.