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The November 12, 2017, moment magnitude (Mw) 7.3 Sarpol-e Zahab earthquake, which occurred after a seismic quiescence, close to the Iran–Iraq border, is one of the largest events recorded in the Zagros fold and thrust belt. In this study, we analyzed strong-motion data of this event from 38 stations within an epicentral distance of 36 to 200 km. Spectral analysis of strong-motion data resulted in an Mw estimate of 7.34, an average rupture velocity of 3.03 km/s, and a stress drop of 154 bars. We estimated that shear dislocation propagated over a rectangular fault area with a length of ~97 km and width of ~17 km. Comparison of the horizontal peak ground-motions from this earthquake with the ground-motion model for active crustal regions indicated overall good agreement; however, the model underestimates ground-motions at stations within distances of approximately 30 km or less. The model appears to underestimate the observed strong-motion recordings from the Mw7.4 September 16, 1978, Tabas and the Mw7.4 June 20, 1990, Manjil earthquakes as well. Investigation of the observed accelerograms showed that the Sarpol-e Zahab earthquake was nucleated by a sub-event with a local magnitude (ML) of 4.9 which contributed about 0.02% to the total seismic moment. The empirical data indicated multiple arrivals due to the development of the rupture as two major sub-events. The spatial distribution of stations along with the time difference between the sub-events on the recorded time-series implies their occurrence from the hypocenter toward the S-SE direction which is coincident with the principal directions of the majority of damaged buildings. The estimated Mw of these sub-events is 6.79 and 7.08, respectively. The distinctive characteristics of near-field recordings from Sarpol-e Zahab earthquake (e.g., multiple phase arrivals due to complex source process, forward directivity effect, and blind thrust faulting) make these data a valuable supplement to the recorded ground-motion database. The improved strong-motion database plays a fundamental role in calibrating seismological simulation models, developing ground-motion models that capture near-source effects, and performing nonlinear dynamic structural analyses. [ABSTRACT FROM AUTHOR]

Characterizing the ground-motion signature of various event types is important for event discrimination and for the development of reliable earthquake catalogues. Small-magnitude seismic events are often enigmatic and determining their cause can be challenging. This is because there are various sources of energy (e.g., rock bursts, construction blasts, cultural noise, etc.) that generate seismic waves similar to those from small-magnitude earthquakes. A sequence of eight unusual small-magnitude (local magnitude, ML, of −0.17 to 1.39) seismic signals were detected in the area surrounding the Brazeau Reservoir and river (Alberta), beginning in mid-2014. Detailed analyses of the waveforms and spectra for these events, as well as their timing, strongly suggest that at least seven of these events are cryoseismic signals associated with freeze-up on the reservoir and Brazeau River. [ABSTRACT FROM AUTHOR]

Montreal has significant seismic risk due to the combination of moderate seismicity, high population density, and vulnerable infrastructure. An important tool in damage and risk assessment is a scenario shakemap, which shows the expected ground shaking intensity distribution patterns. In this study, we use regional ground motion and site response evaluations to generate scenario shakemaps for Montreal. The impact of event location on expected ground motions and intensities was tested by considering the occurrence of a scenario (a given magnitude event) at various locations, where the scenarios are defined based on an analysis of the most likely future event locations. Variability in near surface geology plays an important role in earthquake ground shaking; we use microzonation information from Montreal to assess the expected site amplification effects. The results of this study may be used as input to seismic risk studies for Montreal. [ABSTRACT FROM AUTHOR]

We compared several different duration measures for the 2011 M9.0 Tohoku earthquake sequence, because empirical duration models are of great interest for purposes of correlation with structural damage, and the Tohoku mainshock was remarkable for its long duration. Among the three considered definitions, RMS duration (McCann and Shah, Bull Seism Soc Am 69: 1253-1265, ) is best able to predict the duration within which pulses or groups of pulses of energy arrive; it is particularly suitable for the Tohoku mainshock, for which source complexity caused time-series with multiple-phase arrivals. Two other considered definitions, both of which tend to underestimate the observed duration, are: (i) duration defined by random vibration theory (RVT); and (ii) the significant duration as defined by the interval between 5 and 75 % or 95 % of the integral of the square of the ground acceleration (known as 'Arias intensity' (Arias )) or velocity (known as 'energy integral' (Anderson )). In the Tohoku mainshock, significant amplitudes precede the 5 % of the Arias intensity marker; we need to use 0.3 % of the maximum of the accumulated energy as the lower bound marker to appropriately estimate the duration using the significant duration definition. The RVT duration (used in stochastic simulations) can be estimated easily from the 5-75 % of the Arias intensity (significant duration) definition as the two measures give very similar durations. Overall, the significant duration of ground motions observed during the 2011 M9.0 Tohoku earthquake increases with distance as 0.19 R for the horizontal components or 0.33 R for the vertical component, where R is the closest distance to the fault plane. By comparison, the duration of four aftershocks ( M4.5-7.7) increases with distance as ~0.10 R where R is the hypocentral distance. For the mainshock, the distance-dependent slope term is greater, presumably due to the large fault plane size. [ABSTRACT FROM AUTHOR]

Ground motion prediction equations (GMPEs) have a major impact on seismic hazard estimates, because they control the predicted amplitudes of ground shaking. The prediction of ground-motion amplitudes due to mega-thrust earthquakes in subduction zones has been hampered by a paucity of empirical ground-motion data for the very large magnitudes (moment magnitude ( M) $$>$$ 7) of most interest to hazard analysis. Recent data from Tohoku M9.0 2011 earthquake are important in this regard, as this is the largest well-recorded subduction event, and the only such event with sufficient data to enable a clear separation of the overall source, path and site effects. In this study, we use strong-ground-motion records from the M9 Tohoku event to derive an event-specific GMPE. We then extend this M9 GMPE to represent the shaking from other M $$>$$ 7 interface events in Japan by adjusting the source term. We focus on events in Japan to reduce ambiguity that results when combining data in different regions having different source, path and site effect attributes. Source levels (adjustment factors) for other Japanese events are determined as the average residuals of ground-motions with respect to the Tohoku GMPE, keeping all other coefficients fixed. The mean residuals (source terms) scale most steeply with magnitude at the lower frequencies; this is in accord with expectations based on overall source-scaling concepts. Interpolating source terms over the magnitude range of 7.0-9.0, we produce a GMPE for large interface events of M7- M9, for NEHRP B/C boundary site conditions (time-averaged shear-wave velocity of 760 m/s over the top 30 m) in both fore-arc and back-arc regions of Japan. We show how these equations may be adjusted to account for the deeper soil profiles (for the same value of $$\hbox {V}_\mathrm{S30})$$ in western North America. The proposed GMPE predicts lower motions at very long periods, higher motions at short periods, and similar motions at intermediate periods, relative to the simulation-based GMPE model of Atkinson and Macias () for the Cascadia subduction zone. [ABSTRACT FROM AUTHOR]

Site response in Japan is characterized using thousands of surface and borehole recordings from events of moment magnitude $$(\mathbf{M}) > 5.5$$ collected by the KiK-net network, including the 2011 M9.0 Tohoku earthquake. Site amplification is defined by the ratio of motions at the surface to those at depth (within the borehole), corrected for the depth effect due to destructive interference using a technique based on cross-spectral ratios between surface and down-hole motions. Site effects were particularly strong at high frequencies, despite the expectation that high-frequency response may be damped by nonlinear effects. In part, the large amplitudes at high frequencies are due to the prevalence of shallow soil conditions in Japan. We searched for typical symptoms for soil nonlinearity, such as a decrease in the predominant frequency and/or amplification, using spectral ratios of weak to strong ground motions. Localized nonlinearity occurred at some recording sites, but was not pervasive. We developed a general empirical model to express site amplification for the KiK-net sites as a function of common site variables, such as the average shear-wave velocity in the uppermost 30 m ( $$\text{ V}_\mathrm{S30})$$ and the horizontal-to-vertical (H/V) spectral ratio. We use the model to estimate site-corrected ground-motions for the Tohoku mainshock for a reference site condition; these motions are in reasonable agreement with the predictions of some of the published ground motion prediction equations for subduction zones. [ABSTRACT FROM AUTHOR]

On December 20, 2017, a light shallow earthquake (M w 4.9) with a purely strike-slip mechanism occurred on a hidden unknown fault, 30 km west of the city of Tehran. The purpose of this study is to determine the causative fault plane based on the directivity effect that was observed during this shallow crustal depth earthquake, referred to as the Malard earthquake. This was achieved by using data from 96 seismic and accelerometer stations, and employing a variety of methods. For the analysis of the directivity effect, we employed methods including empirical Green's function deconvolution in the frequency domain, inversion of corrected ground motions based on empirical models, and comparison of relative peak ground acceleration and velocity between the mainshock and the largest aftershock. All approaches indicate that the Malard earthquake occurred on a previously unknown fault with a strike of 71°, a steep southward dip, and a confirmed left-lateral strike-slip mechanism, as evidenced by the analysis of aftershock distribution. The earthquake exhibited a strong directivity effect, with rupture propagating unilaterally from the hypocenter to the southwest at a velocity of 2.5 km/s. In addition to enhancing our understanding of active earthquake sources in the densely populated areas of Iran, the findings of this study will also contribute to future earthquake risk assessments in the Tehran region. However, it's important to note that Tehran was situated in the backward zone of the Malard earthquake rupture, where the least ground motion was recorded. Future earthquakes on this fault may exhibit different propagation patterns, toward the city. The determination of a preferred propagation direction can only be achieved probabilistically through the study of a substantial number of earthquakes in the region. The absence of recorded ground motion data will lead to significant uncertainty in predicting the propagation direction of future earthquakes, which must be taken into consideration during hazard analysis. [Display omitted] • The Malard earthquake (Mw 4.9, Iran, near Tehran) occurred on a previously unknown fault • The causative fault was recognized using directivity analysis by various methods • This earthquake exhibited a strong directivity effect • The fault is left-lateral strike-slip with the strike of 71° and a steep dip to the south • The rupture propagated unilaterally to SW with the rupture velocity of 2.49 km/s [ABSTRACT FROM AUTHOR]

This study investigates whether real-time strong ground motion data from seismic stations could have been used to provide an accurate estimate of the magnitude of the 2011 Tohoku-Oki earthquake in Japan. Ultimately, such an estimate could be used as input data for a tsunami forecast and would lead to more robust earthquake and tsunami early warning. We collected the strong motion accelerograms recorded by borehole and free-field (surface) Kiban Kyoshin network stations that registered this mega-thrust earthquake in order to perform an off-line test to estimate the magnitude based on ground motion prediction equations (GMPEs). GMPEs for peak ground acceleration and peak ground velocity (PGV) from a previous study by Eshaghi et al. in the Bulletin of the Seismological Society of America 103. () derived using events with moment magnitude ( M) ≥ 5.0, 1998-2010, were used to estimate the magnitude of this event. We developed new GMPEs using a more complete database (1998-2011), which added only 1 year but approximately twice as much data to the initial catalog (including important large events), to improve the determination of attenuation parameters and magnitude scaling. These new GMPEs were used to estimate the magnitude of the Tohoku-Oki event. The estimates obtained were compared with real time magnitude estimates provided by the existing earthquake early warning system in Japan. Unlike the current operational magnitude estimation methods, our method did not saturate and can provide robust estimates of moment magnitude within ~100 s after earthquake onset for both catalogs. It was found that correcting for average shear-wave velocity in the uppermost 30 m ( $$ V_{{{\text{s}}_{30} }} $$ ) improved the accuracy of magnitude estimates from surface recordings, particularly for magnitude estimates of PGV (Mpgv). The new GMPEs also were used to estimate the magnitude of all earthquakes in the new catalog with at least 20 records. Results show that the magnitude estimate from PGV values using borehole recordings had the smallest standard deviation among the estimated magnitudes and produced more stable and robust magnitude estimates. This suggests that incorporating borehole strong ground-motion records immediately available after the occurrence of large earthquakes can provide robust and accurate magnitude estimation. [ABSTRACT FROM AUTHOR]

Laparoscopic cholecystectomy (LC) is one of the most commonly performed surgeries worldwide. Stones can be spilled from the gallbladder during LC. These stones can be left in the peritoneal cavity or trapped at the trocar site. The potential late sequelae and associated morbidity are not well documented. Every effort should be made in order to avoid spillage of stones during dissection of the gallbladder through the abdominal wall. We describe one case that underwent LC and presented with dropped gallstones. [ABSTRACT FROM AUTHOR]

We analysed 478 three-component strong ground motion time-series from 65 events in the moment magnitude (M w) 3–6.5 range recorded at 111 stations at distances up to 150 km from 1997 to 2019 in the Alborz region. Non-parametric spectral functions for seismological source, path and site-effects were derived from Fourier amplitude spectra of observed acceleration time-histories using the generalized inversion technique (GIT) for the Alborz region of Iran. To characterize the spectral models in terms of the anelastic attenuation (Q), geometrical spreading, magnitude and stress parameter (Δ σ), we fitted non-parametric attenuation and source functions (resulted from inversion) with the standard parametric models. The frequency-dependent non-parametric attenuation function shows a rapid decay at close distances (<60 km) and decreases monotonically at larger distances. The frequency-independent geometrical spreading follows a bilinear hinged model with a crossover distance at 70 km. For hypocentral distances R hypo < 70 km, the geometrical spreading is |${R^{ - 1.01}}$|⁠ , and for R hypo > 70 km it is |${R^{ - 1.37}}$|⁠. The corresponding quality factor is |$Q\ (f) = \ 146{f^{0.91}}$|⁠. The non-parametric source spectra were found in a good agreement with Brune's ω -squared model. The stress-parameter (Δ σ) values were found to exhibit large variability from 0.36 to 86.7 MPa with no significant magnitude-dependence. The average Δ σ was found to be 8.6 MPa. The mean value of the estimated near-surface attenuation (κ 0) from high-frequency part of non-parametric source function is 0.032 s (±0.01 s). In general, there is a good agreement between subsoil resonance frequencies and amplification levels estimated from GIT and HVSR (horizontal to vertical spectral ratio). The results of this study provide updated values of seismological source, attenuation and site properties in the Alborz region of northern Iran, which are expected to improve regional seismic hazard analysis studies in the region. [ABSTRACT FROM AUTHOR]

Background/Aim: Endosonography is a distinct method for evaluating the structural lesions of the gastrointestinal (GI) tract, particularly the pancreatobilliary region. This procedure has made a fundamental change in the diagnosis of pancreatic mass lesion through providing fine needle aspiration. This study aims at evaluating the results and efficacy of endoscopic ultrasound fine needle aspiration (EUS-FNA) in patients with pancreatic solid mass. Patients and Methods: The present study is an observational, prospective case series nature, evaluated patients with pancreatic solid mass referred to Imam Khomeini educational hospital in Tehran for a duration of one year since November 2010. In order to determine the false negative cases, the patients were followed-up from 6 to 12 months. Results: EUSFNA was conducted on all 53 patients without any complication. The majority of patients included in the study were males (68%) and 81% of patients had a mass in the head of pancreas. The result of cytopathology revealed 36 adenocarcinomas (68%), 7 other malignancies (13%), benign lesions (6%) and 7 nondiagnostic cases (13%). The frequency of nondiagnostic results was significantly high in masses smaller than 3 cm (6 vs. 1, P < 0.002). Patients with nondiagnostic result were younger than those with malignant cytopathology (52 ± 7.5 vs. 66 ± 7.5 years, P < 0.001). Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of this procedure concerning Adenocarcinoma were 88%, 100%, 100%, 70% and 90%, respectively. Conclusion: EUS--FNA is an effective and safe procedure in histopathologic diagnosis of pancreatic tumors. This procedure is useful in all pancreatic mass cases including resectable and nonresectable ones. [ABSTRACT FROM AUTHOR]

Any process that causes a sudden brittle failure of material has the potential to cause earthquake-like seismic events. Cryoseisms represent an underreported class of seismic event due to their (often) small magnitudes. In this paper, we document the phenomenon of some of the largest magnitude lake-associated icequakes (ML 2.0) yet reported. These events occurred nearly simultaneously (within ∼2 h) on geographically separate lakes in Alberta, Canada, starting 1 January 2018. We conjecture that these events were caused by the sudden brittle failure of lake ice due to thermal expansion; the effects of the thermal expansion were compounded by the lack of insulating snow cover, high lake water levels, and a rapid onset of atmospheric warming. These factors also contributed to ice-jacking — a repeating process in which thermal contraction produces tensile cracks (leads) in lake ice that are then filled with water that is frozen during the cooling cycle. Thus, any subsequent thermal expansion must be accommodated by new deformation or brittle failure. This ice-jacking process caused creeping ground deformation after the initial brittle failure and again two weeks later following a second warming period. In many cases, the resulting ground deformation was significant enough to cause property damage. [ABSTRACT FROM AUTHOR]

Background: Insulin-like growth factor is a polypeptide with endocrine, autocrine and paracrine effects which its structure is similar to the insulin molecule. While various tissues secrete IGF-1, 90% of the circulating IGF-1 is secreted by liver. Cirrhosis of liver is a condition accompanied by decreased level of IGF-1, in which the level of IGF-1 may be further decreased thorough the progression of the disease. Objectives: The aim of the present study was to demonstrate the relation between the IGF-1 levels and severity of liver disease according to Child- Pugh and Model for end stage liver diseases (MELD) Scores. Patients and Method: This was a descriptive-analytic cross sectional study performed on patients with cirrhosis admitted to gastroenterology clinic of Imam Khomeini Hospital in Tehran, Iran during the years 2007-2008. The diagnosis was based on liver biopsy. Initially for all patients, laboratory investigations including IGF-1, CBC, liver Enzymes, Alkaline phosphates, serum Albumin, Creatinine, direct and total Bilirubin were conducted. Also ultrasound and endoscopy were performed for evaluation of ascites and varices. Results: 100 patients with cirrhosis with a male to Female ratio of 63:37 and a mean age of 44.4 ± 15 years were enrolled in the study. Median IGF-1 was 92.95 ± 91.51 ng/mL. 14 patients (14%) had IGF-1 within normal limits while 86 patients (86%) had abnormal IGF-1 levels. In all patients the correlation coefficient between IGF-1 and MELD was -0.317 (P = 0.001) and 0.478 between IGF-1 and Child- Pugh (P < 0.001). Conclusions: Our findings showed that IGF-1 can be used as an index for evaluating the severity of cirrhosis; also it can be used for determining the severity of the disease, when liver biopsy is not possible. [ABSTRACT FROM AUTHOR]

Background: Investigators were suspicious of tyrosine-methionine-aspartate-aspartate (YMDD) mutations occurred only in patients who were treated by lamivudine. However, YMDD mutations of hepatitis B virus gene (HBV DNA) in patients with chronic hepatitis B (CHB) untreated with antiviral medicines was reported in some studies. The aim of this study was to evaluate YMDD mutations in Iranian Patients with chronic hepatitis B (CHB) untreated with antiviral medicines. Methods: In a cross sectional study, 151 adult patients with positive Hepatitis B surface antigen (HBsAg) (78 asymptomatic hepatitis B virus carriers, 73 active chronic hepatitis B patients or cirrhosis patients) were evaluated for YMDD mutants. The patients who were treated with interferon and Lamivudine or Adfovier in one year prior to the study were excluded. YMDD mutations of HBV DNA were detected by PCR-RFLP (PCR Restriction Fragment Length Polymorphism) in a single laboratory. Results: The mean (±SD) age of patients was 37±4 years. Eighty one (54%) cases were male and 70 (46%) were female. Eight cases (5.3%) out of 151 had YMDD mutations. The type of mutation in all of these patients was YSDD. There was no significant relationship between YMDD mutation and viral load and HDV Ab (p>0.05). Conclusions: The mutant strains of the YMDD motif of HBV polymerase can be found in some patients without lamivudine treatment. However, in view of rather clinically insignificant YMDD mutation frequency, routine testing for YMDD mutations prior to antiviral therapy is not recommended in these patients. [ABSTRACT FROM AUTHOR]

Background: The irritable bowel syndrome (IBS) is one of the most common chronic medical conditions. Various mechanisms, including altered gut flora and/or small bowel bacterial overgrowth, have been suggested to play a role in the development of gasrelated symptoms aim of study. The clinical evidence of small intestinal bacterial overgrowth as an important etiology of irritable bowel syndrome continues to accumulate. Clinical symptoms of bacterial overgrowth and irritable bowel syndrome are similar; however, a definitive cause-and-effect relationship remains unproven. It is unclear whether motility dysfunction causes bacterial overgrowth or gas products of enteric bacteria affect intestinal motility in irritable bowel syndrome. Methods: In a randomized double-blind placebo-controlled trial consisting of treatment with bismuth subcitrate. Primary efficacy variable was subjective symptoms; frequency of abdominal pain, Number of bowel movement & Bloating/distension. Results: 119 patients were enrolled (59 bismuth subcitrate and 60 placebo recipients). At the end of phase 2, all symptom scores dropped significantly both in bismuth subcitrate and placebo group (p<0.001). There was not a significant difference in symptom relief with bismuth subcitrate versus placebo administration. Conclusions: There was not a significant difference in symptom relief with bismuth subcitrate versus placebo in IBS patients. Whether antibiotics can improve quality of life in patients with irritable bowel syndrome warrants further research. Interventions: Participants were randomly assigned to receive 120mg bismuth subcitrate four times daily for 14 days (n=59) or placebo (n=60). [ABSTRACT FROM AUTHOR]

Balloon dilatation of stricture is one of the new treatment methods among patients with gastric outlet obstruction (GOO). However, the prevalence and underlying etiologies of GOO in various populations are different. The goal of the present study was to determine the effectiveness of endoscopic balloon dilatation and factors that would affect its success rate patients with benign etiology for GOO. Forty-five patients with the symptoms of benign GOO were randomly selected. Gastric outlet was delineated using double channel videoendoscopy. The information of initial balloon dilation was collected from recorded files. Balloon dilatation was repeated during the mean follow up of 9.9 ± 5.8 months. The severity of gastric pain was measured immediately before balloon dilatation and one month after procedure and was rated on a 10 cm visual analogue scale. The mean age of patients was 43.7 ± 18.1 years and 86.7% of them were men. Furthermore, 71.1% were H pylori positive. Response rate to endoscopic balloon dilatation was 80% and 8 patients underwent surgical resection. Weight loss was more frequent in non-responding group. The pain severity was significantly reduced more in responding subjects. No meaningful relationships were found between the responses to balloon dilatation and positive H pylori and cigarette smoking. Endoscopic balloon dilation is safe and effective for most patients with benign gastric outlet obstruction and has favorable long-term outcome. [ABSTRACT FROM AUTHOR]

A rapid increase of injection‐induced earthquakes (IIE) is often linked to a higher level of seismic hazard. In this study, we compare the geodetically defined moment rate to seismicity distribution in western Canada where significant IIE are observed. The regional seismic pattern is dominated by IIE, both in number and moment, along a 150‐km wide NW‐SE band of moderate strain rate in the easternmost Cordillera and foothills. The observed rate of moment release from local earthquakes is much closer to the tectonic moment rate in the IIE‐dominated areas. We conclude that, on a regional scale, tectonic strain rate is an important control on IIE. Injection in areas with moderate tectonic strain may temporarily increase the local seismic hazard, but widespread IIE over an extended period of time may deplete the available tectonic moment and could, under the right conditions, have a limited long‐term effect of reducing regional seismic hazard. Plain Language Summary: Fluids are commonly injected into oil and gas wells to shutter the reservoir formations of shale gas and tight oil and to increase production. However, not all injections cause induced earthquakes and some areas have more events than others. In this study, we examine the geological controls on where there is greatest susceptibility to induced earthquakes. In western Canada, we find that they are generally associated with the areas of moderate long‐term geological/tectonic deformation rates, as mapped by the relative motion of high‐resolution Global Navigation Satellite System stations. Most induced earthquakes are in a 150‐km‐wide band in the easternmost Canadian Cordillera and foothills. They are much less frequent farther to the east where the geological deformation rates are low. We conclude that the geological deformation rate is an important controlling factor for the occurrence of induced earthquakes. In some areas, the strain rate from induced earthquakes may temporarily exceed the natural geological strain rate. Widespread injections in areas with relatively high geological deformation rate may increase the regional seismic hazard in the short term. But if frequent occurrence of induced earthquakes persists over time, it could lead to a reduction of natural earthquake occurrence in the long term. Key Points: Most induced seismicity in western Canada occurred in regions with relatively higher tectonic strain rateRelease rate of seismic moment in the most active areas of induced seismicity exceeds the corresponding tectonic moment rateInjections may temporarily increase the local seismic hazard, but widespread induced seismicity may have a contrasting long‐term effect [ABSTRACT FROM AUTHOR]