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.

Months-long seismicity transients preceding the 2023 M 7.8 Kahramanmaraş earthquake, Türkiye.

Short term prediction of earthquake magnitude, time, and location is currently not possible. In some cases, however, documented observations have been retrospectively considered as precursory. Here we present seismicity transients starting approx.

Microearthquakes preceding a M4.2 Earthquake Offshore Istanbul.

A primary hurdle in observing small foreshocks is the detection-limit of most seismic networks, which is typically about magnitude M1-1.5. We show that a start-up test of a borehole-based seismic network with a much lower detection limit overcame this problem for an M4.

Gas and seismicity within the Istanbul seismic gap.

Understanding micro-seismicity is a critical question for earthquake hazard assessment. Since the devastating earthquakes of Izmit and Duzce in 1999, the seismicity along the submerged section of North Anatolian Fault within the Sea of Marmara (comprising the "Istanbul seismic gap") has been extensively studied in order to infer its mechanical behaviour (creeping vs locked). So far, the seismicity has been interpreted only in terms of being tectonic-driven, although the Main Marmara Fault (MMF) is known to strike across multiple hydrocarbon gas sources.

Microseismic monitoring of CO2 injection at the Penn West Enhanced Oil Recovery pilot project, Canada: implications for detection of wellbore leakage.

A passive seismic monitoring campaign was carried out in the frame of a CO2-Enhanced Oil Recovery (EOR) pilot project in Alberta, Canada. Our analysis focuses on a two-week period during which prominent downhole pressure fluctuations in the reservoir were accompanied by a leakage of CO2 and CH4 along the monitoring well equipped with an array of short-period borehole geophones. We applied state of the art seismological processing schemes to the continuous seismic waveform recordings.

An earthquake gap south of Istanbul.

Over the last century the North Anatolian Fault Zone in Turkey has produced a remarkable sequence of large earthquakes. These events have now left an earthquake gap south of Istanbul and beneath the Marmara Sea, a gap that has not been filled for 250 years. Here we investigate the nature of the eastern end of this gap using microearthquakes recorded by seismographs primarily on the Princes Islands offshore Istanbul.

Serovars and serum resistance of Neisseria gonorrhoeae from disseminated and uncomplicated infections.

Two hundred and seventy-four gonococcal strains isolated from patients with either disseminated (DGI) or uncomplicated (UG) infection were examined to determine their serotypes/serovars by two typing systems as well as their resistance to the bactericidal action of normal human serum. The bactericidal assays were performed in particular to determine whether isolates from patients with the clinical syndrome of DGI but negative systemic cultures (suspected DGI) were serum-susceptible. When strains containing protein IA in their outer membranes and having auxotypes other than the arginine-hypoxanthine-uracil requirement were serotyped, a significant difference was found in the distribution of serovars among strains from DGI and suspected DGI compared with UG.

Auxotypes, penicillin susceptibility, and serogroups of Neisseria gonorrhoeae from disseminated and uncomplicated infections.

We examined auxotypes, penicillin susceptibility, and outer membrane serogroups of 137 strains of Neisseria gonorrhoeae isolated from patients with disseminated gonococcal infection (DGI) and 137 control strains from patients with uncomplicated gonorrhea. We analyzed separately the data for strains isolated from systemic sites in patients with DGI and for strains from local sites in patients with the clinical syndrome of DGI (SDGI) who had negative systemic cultures. We found the nutritional requirement for arginine, hypoxanthine, and uracil (AHU auxotype) significantly more often among DGI strains than among SDGI strains.

Evaluation of the RIM-N, Gonochek II, and Phadebact systems for the identification of pathogenic Neisseria spp. and Branhamella catarrhalis.

Methods for identifying Neisseria spp. include conventional and modified carbohydrate degradation procedures, chromogenic enzyme substrate tests, and immunologic coagglutination tests for Neisseria gonorrhoeae. In this study, we evaluated the abilities of the RIM-N carbohydrate degradation system (American MicroScan, Campbell, Calif.

Use of the API NeIdent system for identification of pathogenic Neisseria spp. and Branhamella catarrhalis.

The API NeIdent system (Analytab Products, Plainview, N.Y.) was evaluated for identifying Neisseria spp.

Characteristics of pathogenic Neisseria spp. isolated from homosexual men.

Oropharyngeal, urethral, and rectal cultures for pathogenic Neisseria spp. were collected from 815 homosexual men attending a community clinic in Chicago. Meningococci were characterized by serogrouping and antimicrobial susceptibility testing.

Susceptibility of Neisseria meningitidis and Neisseria gonorrhoeae isolates to N-formimidoyl thienamycin.

A diverse collection of 123 meningococcal and 126 gonococcal isolates was tested for susceptibility to N-formimidoyl thienamycin (N-F-thienamycin; MK0787) and to penicillin G (PEN). All of the meningococci were susceptible to both of these, as well as to rifampin. Among gonococci, beta-lactamase-producing strains, which were resistant to PEN, were susceptible to N-F-thienamycin.

Absence of acetohydroxy acid synthetase in a clinical isolate of Neisseria gonorrhoeae requiring isoleucine and valine.

A clinical isolate of Neisseria gonorrhoeae with an unusual growth requirement for isoleucine and valine lacked the activity of acetohydroxy acid synthetase, one of the enzymes required for the biosynthesis of these amino acids. A spontaneous mutant which no longer required isoleucine and valine had acquired this enzymatic activity.

Characteristics of atypical Neisseria gonorrhoeae from disseminated and localized infections.

Approximately 6% of 1,200 clinical isolates of Neisseria gonorrhoeae were atypical because they produced smaller than normal colonies on conventioal chocolate agar and fermented glucose weakly. Auxotyping studies indicated that these atypical strains required for growth arginine, uracil, and, in most instances, hypoxanthine. In addition, all of them were susceptible to 0.

Plasmid deoxyribonucleic acid in clinical isolates of Neisseria gonorrhoeae.

Two different sizes of circular covalently closed deoxyribonucleic acid plasmids have been identified in four independent clinical isolates of Neisseria gonorrhoeae. All four strains contained a small plasmid with a molecular weight of 2.8 X 10-6 and two of the four stains also contained a large plasmid with a molecular weight of 24.

Experimental infection with parent and L-phase variants of Neisseria meningitidis.

Thirty-six strains of Neisseria meningitidis, including groups A, B, and C, produced L forms in vitro in the presence of an osmotic stabilizer and high concentrations of horse serum using penicillin as the transforming agent. Transformation to L growth occurred most readily among strains recently isolated from patients, and an unusually high rate of transformation was observed in 7 of the 36 strains. Revertant L strains developed diplococcal colonies on blood-agar and L colonies on sucrose-serum-penicillin-agar-always in a ratio of approximately 10 to 100 diplococcal colonies to 1 L colony.

RESISTANCE OF THE MOUSE'S INTESTINAL TRACT TO EXPERIMENTAL SALMONELLA INFECTION. II. FACTORS RESPONSIBLE FOR ITS LOSS FOLLOWING STREPTOMYCIN TREATMENT.

Determinations of pH, Eh, and concentrations of acetic, butyric and lactic acids were made on the content of cecum and transverse colon of groups of mice killed 1, 3, and 5 days after oral administration of 50 mg streptomycin. Control observations on untreated mice are reported in the preceding communication. Heat-killed supenatants of suspensions of bowel content were tested in vitro for their ability to inhibit multiplication of our standard streptomycin-resistant strain of Salmonella enteritidis during aerobic and anaerobic incubation.

RESISTANCE OF THE MOUSE'S INTESTINAL TRACT TO EXPERIMENTAL SALMONELLA INFECTION. I. FACTORS WHICH INTERFERE WITH THE INITIATION OF INFECTION BY ORAL INOCULATION.

Multiplication of Salmonella enteritidis was inhibited in vitro by buffered suspensions of fecal material freshly removed from the large intestine of normal mice. Most effective was material obtained from cecum and transverse colon. Inhibitory activity was not impaired by sterilization by heat or filtration.