Analysis of an earthquake based on extensometric and seismological measurements

The rock-deformation data series collected by extensometers provide an opportunity for studying various changes in the geological, rock-physical environment, caused by earthquakes (e.g.,displacement, deformation of rock mass). Hereby further information can be achieved about the nature of these effects, complementing the analysis of seismograms (as e.g. the frequency range embraced by extensometers can record changes with much higher time of periods). In order to investigate the appearance of effects of earthquakes in extensometric data, authors chose a registratum which was collected in the Matyashegy Gravity and Geodynamical Observatory in Budapest in the time of a significant M7.2 earthquake occurred in Turkey, and started its spectral analysis. Results of the examinations were compared to the spectrum of records of a typical, undisturbed lapse of time, as well as to the spectrum calculated from seismogram of Kövesligethy Radó Seismological Observatory in Budapest, nearby the gravity observatory

Politische Dimensionen von Militärübungen und Manövern – ein Projektbericht

Die virtuellen Kriege und Operationen, die in Militärübungen gespielt und geprobt werden, können entweder der Abschreckung dienen oder aber Angriffe vorbereiten bzw. zur Maskierung tatsächlicher Angriffe dienen. Für Beobachter ist es vielfach nicht offensichtlich, um welche Art von Militärübung es sich handelt. Die Ergebnisse eines vierjährigen internationalen Projektes zu politischen Dimensionen von Militärübungen richten das Schlaglicht insbesondere auf Missverständnisse und deren ungewollte politische Auswirkungen, die im Extremfall unbeabsichtigt zum Krieg führen können

Earthquake source parameters and scaling relationships in Hungary (central Pannonian basin)

Abstract Fifty earthquakes that occurred in Hungary (central part of the Pannonian basin) with local magnitude ML ranging from 0.8 to 4.5 have been analyzed. The digital seismograms used in this study were recorded by six permanent broad-band stations and twenty short-period ones at hypocentral distances between 10 and 327 km. The displacement spectra for P- and SH-waves were analyzed according to Brune’s source model. Observed spectra were corrected for path-dependent attenuation effects using an independent regional estimate of the quality factor QS. To correct spectra for near-surface attenuation, the k parameterwas calculated, obtaining it fromwaveforms recorded at short epicentral distances. The values of the k parameter vary between 0.01 to 0.06 s with a mean of 0.03 s for P-waves and between 0.01 to 0.09 s with a mean of 0.04 s for SH-waves. After correction for attenuation effects, spectral parameters (corner frequency and low-frequency spectral level) were estimated by a grid search algorithm. The obtained seismic moments range from4.21×1011 to 3.41×1015 Nm (1.7≤Mw ≤4.3). The source radii are between 125 and 1343 m. Stress drop values vary between 0.14 and 32.4 bars with a logarithmic mean of 2.59 bars (1 bar = 105 Pa). From the results, a linear relationship between local andmomentmagnitudes has been established. The obtained scaling relations show slight evidence of self-similarity violation. However, due to the high scatter of our data, the existence of self-similarity cannot be excluded

Rehabilitation versus surgical reconstruction for non-acute anterior cruciate ligament injury (ACL SNNAP): a pragmatic randomised controlled trial

Background: Anterior cruciate ligament (ACL) rupture is a common debilitating injury that can cause instability of the knee. We aimed to investigate the best management strategy between reconstructive surgery and non-surgical treatment for patients with a non-acute ACL injury and persistent symptoms of instability. Methods: We did a pragmatic, multicentre, superiority, randomised controlled trial in 29 secondary care National Health Service orthopaedic units in the UK. Patients with symptomatic knee problems (instability) consistent with an ACL injury were eligible. We excluded patients with meniscal pathology with characteristics that indicate immediate surgery. Patients were randomly assigned (1:1) by computer to either surgery (reconstruction) or rehabilitation (physiotherapy but with subsequent reconstruction permitted if instability persisted after treatment), stratified by site and baseline Knee Injury and Osteoarthritis Outcome Score—4 domain version (KOOS4). This management design represented normal practice. The primary outcome was KOOS4 at 18 months after randomisation. The principal analyses were intention-to-treat based, with KOOS4 results analysed using linear regression. This trial is registered with ISRCTN, ISRCTN10110685, and ClinicalTrials.gov, NCT02980367. Findings: Between Feb 1, 2017, and April 12, 2020, we recruited 316 patients. 156 (49%) participants were randomly assigned to the surgical reconstruction group and 160 (51%) to the rehabilitation group. Mean KOOS4 at 18 months was 73·0 (SD 18·3) in the surgical group and 64·6 (21·6) in the rehabilitation group. The adjusted mean difference was 7·9 (95% CI 2·5–13·2; p=0·0053) in favour of surgical management. 65 (41%) of 160 patients allocated to rehabilitation underwent subsequent surgery according to protocol within 18 months. 43 (28%) of 156 patients allocated to surgery did not receive their allocated treatment. We found no differences between groups in the proportion of intervention-related complications. Interpretation: Surgical reconstruction as a management strategy for patients with non-acute ACL injury with persistent symptoms of instability was clinically superior and more cost-effective in comparison with rehabilitation management. Funding: The UK National Institute for Health Research Health Technology Assessment Programme

Discrimination of quarry-blasts from earthquakes using spectral analysis and coda waves in Hungary

In the seismological research it is very important to use a correct earthquake catalogue that provides a strong basis for indicating seismic sources and for developing seismotectonic models. Homogeneity is expected from the catalogue and desirable to indicate data that are derived from explosions. The spectral analysis provides means to discriminate explosions from earthquakes. The quarry-blasts have simpler spectra than earthquakes. We estimate coda attenuation Qc for quarry-blasts that occurred in Vértes mountains. It has been found that the coda decay rate Qc is significantly lower for quarry-blasts than for earthquakes. At 6 Hz and 10 Hz there are great differences between explosions and earthquakes

Statistical investigations of local earthquakes in the Carpathian Basin and surrounding area

The Carpathian Basin is situated in the territory between the Mediterranean area, which is seismically one of the active regions and the Carpathian Mountains belt. The temporal variation of seismicity is investigated on the example of three seismo-tectonically different regions: the Carpathian Basin, the Vrancea region and the Dinarides. The seismicity is analyzed since 1900 in order to investigate the existence of diurnal periodicities using hodographs. There are two different diurnal distributions opposing each other: maximum early morning dominates until the year 1963, followed by a period of time when earthquakes seem to occur more often around 13h local time mainly concerning the weak ML < 3.2 events. The midday maximum in the number of minor events may be caused by the inclusion of quarry blasts, but the diurnal geomagnetic variations correlate well with diurnal changes in earthquake activity. Duma and Rhuzin (2003) suppose that the current vortices induced by Sq variations in the lithospheric layer, flowing across the horizontal component of the geomagnetic field generate a torque which can be added to the tectonic loading stress (which have a maximum about noon) and may help trigger instability in a fault approaching the failure threshold. The spatial and temporal fractal structures of earthquakes were analyzed using the box counting method. The regions were divided into different size r of a square box and were counted the minimum number N(r) of boxes necessary to cover all the data. The recurrence times of earthquakes are shown to be a clustering process and are much higher in the Carpathian Basin. The earthquakes in these regions have self-similar structures. The slope of log N − log r function for Carpathian Basin breaks at about 20 km, which divides the range into two bands. This breaking at about 20 km maybe connected to the intrinsic weakness of the Carpathian Basin lithosphere

Discrimination of small earthquakes from quarry blasts in the Vértes Hills, Hungary using complex analysis

The Vértes Hills are interesting region in Hungary where small earthquakes with magnitude 2–3 exist among small quarry blasts in a noisy background. A seismological station PKSG (Gánt) works in the middle of Vértes Hills. The main purpose of this paper is to test the different discriminatory elements using the registrations of this single station.The diurnal discrimination of quarry blasts shows a peak time. My purpose is to focus onto these questionable earthquakes — happened in the peak time of the blasts — and be able to identify them.Every discriminant gave “1” if the event was considered to be a blast, and “0” if the event was considered to be an earthquake. The sum of these values shows the level of the separation. The classification of fifteen events was wrong. This is approximately 7 percentage of the dataset.It has been found that the spectral analysis and the correlation of spectra proved to be successful in the discrimination. One type of blast and five types of earthquakes are identified based on the correlation analysis of spectra of S-phases on the horizontal component. The result of the correlation analysis is that most of the spectrum of the blasts were very similar to each others. Correlation analysis has also showed that the big part of earthquakes could be classified into 5 groups. Earthquakes of each group concentrated on different places on the map. The maximum frequency and cepstrum analysis failed

Annual, monthly, weekly and diurnal distribution of Carpathian (1964–2004) and M>7 earthquakes worldwide (1900–2004) and seeking for the effect of the Moon

The annual, monthly, weekly and diurnal distribution of Carpathian and M> 7 earthquakes through out the world have been investigated together with the effect of the Moon. The annual distribution of the M> 7 earthquakes shows long-term stability. The monthly variation of seismic activity in case of Hungarian seismic events over the period from 1964 to 2004 shows remarkable maximum between May and October and a minimum between January and April. In the Carpathian dataset for 1964–2004 characteristic peak were found in the daily distribution around 13h and minimum at 8h and 18h (local time). There was no statistically significant lunar influence detected

Study of the temporal variation in seismic activity within the Pannonian Basin

The spatio-temporal patterns of the seismicity are shown. The earthquake occurrence is connected to the strain rate on the basis of Kostrov (1974) equation. It is shown that in the Pannonian Basin the seismic rates are 10-7-10-6. This values were derived from the local earthquake catalogues of the area of Komárom, Dunaharaszti (near Budapest) and Kecskemét.  It is shown that the earthquake occurrence in Hungary  has a well expressed diurnal periodicity.  Similar phenomenon was detected in the case of earthquakes of all Europe and in Turkey in case of weak (ML = 3.0) seismic events