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EN
In September 2017, in only 17 days, two enormous earthquakes triggered Mexico’s earthquake early warning system (EEWS) in a unique sequence of events that tested its capabilities. Through a series of unforeseen circumstances, including a test and an accident, during those two and a half weeks the EEWS was also activated three additional times. The EEWS presents several remarkable strengths. Mexico’s entire emergency management system is relatively well resourced and has helped produce a more resilient culture that appreciates the alert system. Public agencies in all levels of government work in close coordination. However, the system has not been able to overcome continual political expediency and general public distrust of some of its components. The consequence is an alert system that is relatively strong in Mexico City but leaves much of the rest of the country unprotected. But even in Mexico City, the system suffers from extensive concealed vulnerabilities that put the population and the city’s infrastructure at risk. In this paper, two specific weaknesses are analysed. The first is a result of weak regulations and inappropriate business models, which impacts the country as a whole. The second is essentially a local complication resulting from the increased risk generated by the excessive trust of the population in the sirens that are so characteristic of the system. The data were collected during a reconnaissance trip organized by the Earthquake Engineering Research Institute (EERI) in October 2017.
PL
We wrześniu 2017 r., w ciągu jedynie 17 dni, dwa potężne trzęsienia ziemi uruchomiły system wczesnego ostrzegania przed trzęsieniami ziemi w Meksyku (EEWS) w unikalnej sekwencji wypadkow, które poddały probie jego możliwości. W wyniku szeregu nieprzewidzianych okoliczności, w tym przeprowadzonego testu oraz wypadku, w tym 2-tygodniowym okresie EEWS został dodatkowo aktywowany trzykrotnie. System EEWS oferuje szereg niezwykłych zalet. Cały system zarządzania kryzysowego Meksyku jest stosunkowo dobrze wyposażony, dzięki czemu sprzyjał stworzeniu bardziej odpornej kultury, ktora docenia system ostrzegania. Agencje publiczne na wszystkich poziomach funkcjonowania rządu ściśle wspołpracują. Niestety system nie był w stanie pokonać ciągłej zależności politycznej oraz ogolnego braku zaufania publicznego w stosunku do niektorych elementow składowych. Konsekwencją jest system ostrzegania, ktory jest stosunkowo niezawodny w Meksyku, lecz jednocześnie nie zapewnia odpowiedniej ochrony reszcie kraju. Jednak nawet w samym mieście Meksyk system cierpi z powodu pewnych szeroko rozumianych ukrytych słabości, które narażają na ryzyko ludność miasta i jego infrastrukturę. W niniejszym artykule autor analizuje dwie słabe strony. Pierwsza z nich wynika ze słabych regulacji i niewłaściwych modeli biznesowych, co wywiera wpływ na kraj. Druga natomiast stanowi lokalny problem wynikający ze zwiększonego ryzyka generowanego przez nadmierne zaufanie ludności do syren, które są charakterystyczną cechą systemu. Dane zostały pozyskane w czasie wyprawy badawczej zorganizowanej przez instytut Earthquake Engineering Research Institute (EERI) w październiku 2017 r.
EN
This paper presents the seismic hazard assessment for Thuong Tan-Tan My quarries in Di An commune, Binh Duong province, Vietnam. Combination methods of gravity and magneto-telluric were used to estimate the dip angle and the width of the seismic source. The highest water column of 160 m will cause direct stress on the reservoir bottom with a maximum value of 1535.600 kPa and Coulomb stress of 68.693 kPa (at a depth of 2 km). The typical components of natural earthquake hazard (Mn.max = 5.0, depth of 10 km) in Thuong Tan - Tan My reservoir have the following values: peak ground acceleration PGA = 0.073 g ÷ 0.212 g; peak ground velocity PGV = 2.662 cm/s ÷ 7.984 cm/s; peak ground displacement PGD = 0.706 cm ÷ 1.918 cm at 10% probability of exceedance in 50 years. The typical components of triggered earthquake hazard (Mtr.max = 3.5, depth of 6 km) in Thuong Tan - Tan My reservoir have the following values: peak ground acceleration PGA = 0.024 g ÷ 0.172 g; peak ground velocity PGV = 0 ÷ 5.484 cm/s; peak ground displacement PGD = 0.061 cm ÷ 0.461 cm at 10% probability of exceedance in 50 years.
PL
W artykule przedstawiono ocenę zagrożenia sejsmicznego dla kamieniołomów na rejonie Thuong Tan-Tan My w gminie Di An w prowincji Binh Duong, Wietnamie. Do oszacowania kąta upadu i szerokości źródła sejsmicznego wykorzystano kombinację metod grawitacyjnych i magneto-tellurycznych. Najwyższy słup wody 160 m spowoduje bezpośrednie naprężenia na dnie zbiornika o maksymalnej wartości 1535,600 kPa i naprężeniu kulombowskim 68,693 kPa (na głębokości 2 km). Typowe składowe naturalnego zagrożenia trzęsieniem ziemi (Mn.max = 5,0, głębokość 10 km) w zbiorniku Thuong Tan-Tan My mają następujące wartości: szczytowe przyspieszenie gruntu PGA = 0,073 g ÷ 0,212 g; szczytowa prędkość gruntu PGV = 2,662 cm / s ÷ 7,984 cm / s; szczytowe przemieszczenie gruntu PGD = 0,706 cm ÷ 1,918 cm przy 10% prawdopodo-bieństwie przekroczenia za 50 lat. Typowe składowe wywołanego zagrożenia trzęsieniem ziemi (Mtr.max = 3,5, głębokość 6 km) w zbiorniku Thuong Tan-Tan My mają następujące wartości: szczytowe przyspieszenie ziemi PGA = 0,024 g ÷ 0,172 g; szczytowa prędkość gruntu PGV = 0 ÷ 5,484 cm / s; szczytowe przemieszczenie ziemi PGD = 0,061 cm ÷ 0,461 cm przy 10% prawdopodobieństwie za 50 lat.
EN
The purpose of entity resolution (ER) is to identify records that refer to the same real-world entity from diferent sources. Most traditional ER studies identify records based on string-based data, so the ER problem relies mostly on string comparison techniques. There is little research on numeric-based data. Traditional ER approaches are widely used in many domains, such as papers, gene sequencing and restaurants, but they have not been used in an earthquake disaster. In this paper, earthquake disaster event information that was collected from diferent websites is denoted with numeric data. To solve the problem of ER in numeric data, we use the following methods to conduct experiments. First, we treat numbers as strings and use string-based approaches. Second, we use the Euclidean distance to measure the diference between two records. Third, we combine the above two strategies and use a comprehensive approach to measure the distance between the two records. We experimentally evaluate our methods on real datasets that represent earthquake disaster event information. The experimental results show that a comprehensive approach can achieve high performance.
EN
The seismic elastomeric bearings reinforced with fibre is considered as a new technology in comparison to other conventional isolator systems in civil engineering. In this type of bearing, recycled fibres replaced traditional steel plates used in common bearings. Therefore, this type of bearing has been studied in recent years due to both environmental and cost-saving advantages. The shortage of references about the application of this type of bearing in the bridge industry, and particularly the continuous-span bridges, prompted the researchers in this study to investigate the performance of the isolated reinforced concrete box girder bridges with continuous spans. Reducing the acceleration transmission from the substructure to the superstructure is one of the main advantages of using seismic bearings. Based on the study of the structural models, it was found that, in most cases, elastomeric bearings reinforced with fibres showed a suitable performance and reduced the acceleration applied to the superstructure by absorbing the earthquake energy.
PL
Nowozelandzki teatr „Isaac Theatre Royal” to duchowe serce sceny artystycznej miasta Christchurch i całego regionu Canterbury. W teatrze tym od ponad wieku odbywają się widowiskowe spektakle cenionych na całym świecie artystów. W 2011 roku podczas bardzo poważnego trzęsienia ziemi obiekt poniósł znaczne szkody, a audytorium i foyer zostały uznane za nienaprawialne w ich pierwotnej formie, głównie ze względu na niebezpieczeństwo zawalenia. Podczas kilku lat prac budowlanych i renowacyjnych prawie wszystkie elementy obiektu i jego wyposażenia o znacznej wartości kulturowej udało się uratować i wybudować ponownie. Projekt odbudowy umożliwił przebudowanie teatru zgodnie z najnowszymi wymogami technicznymi oraz bieżącą najlepszą praktyką teatralną, przy jednoczesnym zachowaniu wartości kulturowej i niewątpliwego uroku. W artykule przedstawiono historię obiektu, przyczyny i skutki katastrofy oraz proces odbudowy i efekt końcowy.
EN
The New Zealand theatre “Isaac Theatre Royal” is the spiritual heart of the art scene of the city of Christchurch and the entire Canterbury region. In this theatre, spectacular performances of artists valued all over the world have been taking place for over a century. In 2011, during a very serious earthquake, the facility suffered considerable damage, and the auditorium and foyer were considered irreparable in their original form, mainly due to the danger of collapse. During several years of construction and renovation work, almost all elements of the facility and its equipment of considerable cultural value were saved and rebuilt. The reconstruction project made it possible to rebuild the theatre in accordance with the latest technical requirements and current best theatre practice, while maintaining cultural value and undoubted charm. The article presents the history of the object, causes and effects of the disaster as well as the reconstruction process and the final effect.
EN
Cel: Celem artykułu jest przedstawienie przeszkód składających się na tzw. „efekt bariery” podczas rozpoznawania terenu w ramach działań grup poszukiwawczo-ratowniczych w pierwszej dobie po trzęsieniach ziemi. Artykuł przedstawia także wstępne wyniki badań i dotychczasowe prace eksperckie związane z projektem wdrożeniowym „EASeR”, w ramach którego opracowane zostaną procedury i rekomendacje dla włoskich strażaków służące minimalizowaniu wspomnianego „efektu bariery”. Procedury te mogą stanowić także wsparcie dla innych krajów. Wprowadzenie: We wstępie autorzy przedstawiają okoliczności utworzenia przy ONZ Międzynarodowej Grupy Doradczej ds. Poszukiwań i Ratownictwa INSARAG oraz jej europejskiego odpowiednika posiadającego szerszy zakres odpowiedzialności (Unijny Mechanizm Ochrony Ludności), podstawy prawne funkcjonowania tej organizacji. Przywołują także międzynarodowe wytyczne określające standardy i metodologię w zakresie grup poszukiwawczoratowniczych (GPR). Mechanizm odpowiada nie tylko za zakres modułów GPR, lecz też za ok. 20 typów rożnych zasobów ochrony ludności. Autorzy przywołują również cały cykl trwania misji GPR oraz przykładowe katastrofy naturalne i okoliczności, które doprowadziły do projektu EASeR. Przedstawione zostały założenia projektu i jego partnerzy. Metodologia: Wyjściowy materiał badawczy związany z problematyką stanowiły międzynarodowe dokumenty normatywne ONZ i UE ustanawiające standardy organizacyjne i operacyjne dla działania akcji i grup poszukiwawczo-ratowniczych (GPR) oraz przykładowe zrealizowane unijne projekty wdrożeniowe związane z problematyką projektu. Identyfikacja wstępnych „przeszkód” ograniczających prowadzenie rozpoznania wstępnego (ASR 1–3) na miejscu akcji, określona przez strażaków włoskich z miasta Pisa jako „efekt bariery”, była punktem wyjścia do dokonania szerszej analizy stanu faktycznego, opracowania kwestionariusza ankiety i przeprowadzenia międzynarodowych badań metodą sondażu diagnostycznego w kilkunastu krajach na całym świecie. Wnioski: Uzyskane w badaniu sondażowym dane ilościowe oraz opinie na temat głównych przeszkód podczas rozpoznania po katastrofie pozwoliły ekspertom projektu potwierdzić lub odrzucić przyjęte wstępnie założenia do projektowanych treści końcowych dokumentów projektowych, a w czasie dalszych spotkań umożliwiły opracowanie końcowych wersji indeksów procedur operacyjnych dla służb ratowniczych we Włoszech, a także indeksu wytycznych dla międzynarodowych GPR w zakresie prowadzenia rozpoznania we wstępnej fazie (tzw. ASR 1–3).
EN
Given that more than 90% of earthquake fatalities occur in rural environments, one has to rethink how to protect the population. With most rural buildings being one- and two-story dwellings, the earthquake closet (EC) offers an affordable solution as a protection unit. Two recent earthquakes with nearly 100,000 fatalities each are used for estimating the lives that could be saved and how much this would cost. The cost of constructing an EC in a single-family home is taken to be $500–$600 in developing countries. For the “statistical value of life” $1 million is used, a minimum amount given in the literature. The cost of hospitalization is derived from reports after an earthquake. The number of fatalities and injured avoided is estimated for an example earthquake each in China and Pakistan. The estimated dollar savings resulting in large earthquakes reach $18.3 billion at a cost of $1.3 billion, and $10 billion at a cost of $0.5 billion, respectively, in the two examples.
EN
The complexity of seismogenesis tantalizes the scientific community for understanding the earthquake process and its underlying mechanisms and consequently, precise earthquake forecasting, although a realistic target, is yet far from being a practice. Therefore, seismic hazard assessment studies are focused on estimating the probabilities of earthquake occurrence. For a more precise representation of seismicity-regarding time, space and magnitude stochastic modeling is engaged. The candidate models deal with either a single fault or fault segment, or a broader area, leading to fault-based or seismicitybased models, respectively. One important factor in stochastic model development is the time scale, depending upon the target earthquakes. In the case of strong earthquakes, the interevent times between successive events are relatively large, whereas, if we are interested in triggering and the probability of an event to occur in a small time increment then a family of short-term models is available. The basic time-dependent models that can be applied toward earthquake forecasting are briefly described in this review paper.
EN
The work is aimed at revealing a possible connection between seismic activity and cosmic-ray muon fuxes capable of penetrating into the Earth’s crust and generating a nuclear electromagnetic cascade in a tense seismically active medium, leading to the formation of microcracks, the opening of which is accompanied by the generation of acoustic and, under certain conditions, seismic energy as predicted by Tsarev and Chechin (Atmospheric muons and high-frequency seismic noise. In: Preprint of the FIAN, vol 179, 1988). The data of the underground installation (in a well at a depth of 52 m) for monitoring geoacoustic signals correlated in time with the fow of high-energy cosmic-ray muons generated in extensive atmospheric showers implemented on the basis of the experimental complex “ATHLET” in the Tien Shan High-Altitude Scientifc Station of the Physical Institute of the Russian Academy of Sciences were used. It is found that the daily number of acoustic pulses increases signifcantly before and during appreciable regional earthquakes. The most pronounced pulsed emissions of acoustic energy, correlated in time with the fow of high-energy cosmic-ray muons generated in extensive atmospheric showers, are followed by an increasing seismic activity in the region, that support idea that penetrating into Earth’s crust the fux of cosmic-ray muons may become a “trigger” of earthquake.
EN
The aim of this paper was to analyze the hydroseismic response of water level in boreholes during the passage of wave trains of remote strong earthquakes and the pattern of local seismic events, dynamically triggered by these earthquakes. As the exact type of forcing (certain phase of wave train) can be identified, the interpretation of hydroseismic effects is more straightforward and could render new important information on hydroseismic processes and, possibly, on the local stress state in a given block of the Earth crust. We tried to find out which parameter of the teleseismic wave dominates the hydroseismic response (susceptibility)—epicentral distance or velocity.
EN
The 2015 M7.8 Gorkha earthquake has moved the upper, unbroken, part of the Main Himalayan Thrust (MHT) and the neighboring sections of this fault closer to failure. Using the program and data set of QLARM, which has been correct in fatality estimates of past Himalayan earthquakes, we estimate quantitatively the numbers of fatalities, injured and strongly affected people when assumed ruptures along these two sections will happen. In the Kathmandu up-dip scenario with M8.1, we estimate that more than 100,000 people may perish, about half a million may be injured, and 19 million are likely to be affected strongly, if we assume the high virtual attenuation observed for the 2015 Gorkha earthquake exists here also. Likewise, if the 100 km underthrusting segment west of Gorkha ruptures, we quantitatively estimate that 12,000–62,000 people may perish and 4 million to 8 million will be strongly affected, in a down-dip (lower half of the thrust plane) and an up-dip rupture (upper half) scenario, respectively. If the up-dip part of the MHT cannot rupture by itself, and greater earthquakes are required to generate the several meters of displacement observed in trenches across the MHT, then our estimates are minima.
12
Content available remote Geologiczne uwarunkowania rozwoju osuwisk w rejonie Krynicy-Zdroju
EN
The paper presents the final results of mapping work of the Polish Geological Institute - National Research Institute, carried out in the Krynica-Zdrój area in 2010-2012. In the Beskid Niski and Sądecki there are numerous landslides of surface sediments. They also occur in the spa zone of Krynica-Zdrój, posing a threat to its functioning. The basic problem is to recognise the nature of these geohazards and their occurrence in this region. For these reasons, a landslide inventory map was constructed for the whole study area (urban-rural commune). As a result of the analysis, a large variation in the distribution, type and range of landslides has been documented. The landslide surface index and the landslide density index were calculated, concluding that the two indexes differ from each other depending on the geographical position of the analysed area. Both indicators are 2.5-3 times higher for the Krynica-Zdrój town area than for the rural commune area. This variability is associated with different lithologies, tectonics, and geomorphologic features in the area. Krynica-Zdrój lies in the area predisposed to the development of landslides, where the overlapping effects of several passive factors causes mass movements. The Krynica-Zdrój area is composed of thick-bedded sandstones of the Krynica Sandstone Member and the Piwniczna Sandstone Member. They are underlain by variegated shales and thin-bedded turbidites of the Zarzecze Formation. In addition, tectonics of the deep basement is very important. Under the town, there is a deep Krynica fault zone additionally cut by sets of strike-slip faults that altogether cause severe disintegration of the subsurface material and the weakening of cohesive force. The area with the dense sets of faults is an active stress zone. Epicentres of earthquakes probably clustered along all these faults, causing the development and rejuvenation of many landslides in the Krynica-Zdrój area.
13
PL
Struktura materiałowa przewodów wodociągowych została opisana w Japonii w porównaniu ze strukturą stosowaną w Polsce. Opisano w jaki sposób bardzo wysokie straty wody, zaraz po drugiej wojnie światowej, były stopniowo ograniczane i jaka jest współczesna polityka w tym zakresie.
EN
The structure of materials applied to water supply systems construction in Japan has been compared with Poland. It has been described how large water losses just after the second world war has been reduced step by step and what is the Japan strategy of water losses control now.
PL
Cel: Autorzy artykułu, uczestnicy akcji Ciężkiej Grupy Poszukiwawczo-Ratowniczej Państwowej Straży Pożarnej (HUSAR Poland) po trzęsieniu ziemi w Nepalu w 2015 r. na podstawie prezentowanego studium przypadku dokonali próby przybliżenia czytelnikom specyfiki działań komponentu medycznego tej specjalistycznej formacji. Wprowadzenie: We wstępie wyliczono główne jednostki organizacyjne PSP, z których pochodzą ratownicy Grupy, doprecyzowano okoliczności jej formalnego utworzenia, w tym powołanie pierwszego Zespołu Komendanta Głównego PSP ds. specjalizacji poszukiwawczo-ratowniczej. Następnie opisano rolę ustandaryzowanych zasad poszukiwawczo-ratowniczych w Krajowym Systemie Ratowniczo-Gaśniczym oraz przedstawiono dotychczasowe międzynarodowe akcje po trzęsieniach ziemi, w których brali udział polscy strażacy. Następnie, po wyjaśnieniu mandatu prawnego Międzynarodowej Grupy Doradczej ds. Poszukiwań i Ratownictwa (INSARAG) oraz roli jej wytycznych w określaniu minimalnych międzynarodowych standardów, autorzy doprecyzowali skład wszystkich komponentów HUSAR Poland. Celem badań było znalezienie odpowiedzi na pytanie dotyczące optymalnego sposobu wykorzystania potencjału komponentu medycznego HUSAR Poland podczas zagranicznych akcji poszukiwawczo-ratowniczych. Metody: Materiał badawczy stanowiły międzynarodowe i krajowe dokumenty normatywne regulujące zasady funkcjonowania HUSAR Poland i określające minimalne standardy dla grup poszukiwawczo-ratowniczych i zagranicznych zespołów medycznych. Wykorzystano analizę akcji HUSAR Poland w Nepalu w 2015 r. oraz wnioski z akcji na Haiti w 2010 r. Główną metodą badawczą była analiza dokumentów oraz statystyk. W tekście przekrojowo przedstawiono zadania komponentu medycznego USAR Poland w różnych fazach tzw. „cyklu misji” i używane w praktyce dokumenty. Szczególną uwagę, zgodnie z tytułem artykułu, poświęcono ukazaniu zadań medycznych zrealizowanych podczas akcji w Nepalu. Autorzy nie tylko przedstawili przykładowe statystyki z działań komponentu medycznego Grupy w Nepalu, ale odnieśli się też do zakresu analogicznych działań z akcji na Haiti w 2010 r. Podsumowanie: W podsumowaniu i wnioskach autorzy podjęli się próby wskazania najefektywniejszego wykorzystania komponentu medycznego HUSAR Poland w działaniach międzynarodowych, tuż po zakończeniu fazy poszukiwawczo-ratowniczej związanej z wydobywaniem poszkodowanych spod gruzów (tzw. koncepcja działania poza gruzami), tak aby jego możliwości były wykorzystane optymalnie i w pełni komplementarnie do oczekiwań społeczności poszkodowanej oraz zarządzających katastrofą instytucji. Sformułowano wnioski, zgodnie z którymi sugerowaną rolą mogłaby być realizacja zadań zbieżnych do przewidzianych wg Światowej Organizacji Zdrowia dla zagranicznego zespołu medycznego typu pierwszego „Foreign Medical Team type 1”.
EN
Purpose: Based on a case study, the authors, members of a heavy urban search and rescue unit (HUSAR Poland) of the State Fire Service (SFS), who participated in relief operations in the aftermath of the 2015 Nepal earthquake, try to describe the roles of medical teams within this specialist organisation. Introduction: The article starts by enumerating the key organisational bodies of the State Fire Service where the Unit’s members normally work, and proceeds to outline the history of its formal establishment, including the appointment of the first SFS Chief Commander Team for Search & Rescue. Then it describes the role of the uniform search and rescue procedures within the State Rescue and Fire-Fighting System, and presents previous international operations following earthquakes, in which Polish firefighters participated. Finally, the paper explains the legal basis for the International Search and Rescue Advisory Group (INSARAG) and the importance of its guidelines for specifying minimum international standards, and lists all the components of HUSAR Poland. The purpose of this paper was to address the question concerning the best way to utilise the potential of HUSAR Poland’s medical component during foreign search & rescue operations. Methods: Research material comprised international and domestic standards which govern the functioning of HUSAR Poland and which define the minimum standards for search and rescue groups and foreign medical teams. The paper analyses HUSAR Poland’s involvement in the 2015 Nepal operation, and conclusions drawn from the 2010 Haiti operation. Its primary research method was the analysis of documents and statistical data. The article provides an overview of USAR Poland’s medical team at different phases of the Response Cycle, and documents used in practice. As shown in the title, special attention was given to describing medical roles and responsibilities fulfilled during the Nepal operation. The authors not only present some statistical examples for the Unit’s medical team involvement in Nepal, but also refer to some similar activities carried out during the 2010 Haiti operation. Summary: In the Summary and conclusions section, the authors tried to identify the most effective ways of utilising HUSAR Poland’s medical component in international operations, immediately after the search & rescue phase involving the recovery of victims from the rubble (known as beyond the rubble) is completed, so that its potential can be used in full to meet the expectations of the affected communities and the local emergency services. These conclusions suggest that a possible role could be to serve the functions similar to those defined by the World Health Organisation for Foreign Medical Teams Type 1.
15
Content available remote Effects of staircase on the seismic behavior of RC moment frame buildings
EN
Staircase has a potential to change the seismic behavior of structures, but it is often neglected during design. In this research, effects of staircase in 5 groups including 27 models have been studied. Results show that staircase constructed with the use of RC slab, performs as a K-shaped bracing in longitudinal direction and as an inclined shear wall in transverse direction, so in both directions structural stiffness increases, period and lateral displacement of structure decrease, but staircase constructed by means of stringer beam only acts as a bracing in longitudinal direction. Stiffness caused by small span, inclined RC slabs and perimeter infill walls of staircase, based on the staircase location and the number of structural bays could change mode shape and lead to torsion. Along ladder running, staircase leads shear force and bending moment of columns adjacent to the landing to increase, while the internal forces of others to decrease. The majority of adverse effects of the staircases can be prevented by isolating the staircase from master structure. In this case, only the changes in geometry of the structure due to location and dimension of staircase and arrangement of infill walls should be studied.
EN
The Alborz is one of the most important seismotectonic provinces in Iran. Furthermore, emplacement of Tehran as a mega city in southern part of the Alborz intensifies the seismic vulnerability in this area. In this study, the focal mechanism data from teleseismic and local seismic networks are used for stress tensor inversion. The earthquake focal mechanisms in the Central Alborz are divided into several groups with respect to their location. Two different stress tensor inversions, linear and nonlinear, are used for obtaining the principal stress orientations. The results show spatial variations in tectonic stress field, consistent with fault orientations and faulting mechanisms. The maximum compressional stress directions obtained in this study are confirmed by fast S-wave polarization axes reported by a previous shear wave splitting study. The maximum horizontal stress directions are also compared with GPS strain rates. The results indicate a partitioning of deformation in the area due to regional stresses along preexisting faults.
EN
Many precursor-like anomaly observations prior to the Wenchuan earthquake were reported and analyzed, especially the abnormal strain pulses observed at the Guza station, but there are few discussions of the causes. Stick–slip motion is the basis for description of a great variety of phenomena characterized by the presence of sliding friction. In this article, perturbed Sine–Gordon (SG) equation is established from Bykov’s unsteady-state slip model. Stable solitary solutions of displacement and strain dimension are obtained and nonlinear pulse propagation is simulated using finite-difference modeling, while numerical stability is obtained by the flux-corrected transport method. Considering the solution of SG equation as initial source, a comparison between the modeling results and actual data at the Guza station gives one possible interpretation for this anomaly. During the seismogenic process of the Wenchuan earthquake, faults may likely occur as stick–slip tectonic movements which might be described by SG equation and would generate solitary wave signal. This kind of pulse experiences a forward tilting distortion due to nonlinear effect of the Earth and is received by the borehole strainmeter. Two kinds of nonlinear effects could lead to these special pulses. One is the nonlinear effects in the wave propagation process, and the other is effects of friction and stress in the process of unsteady-state slip. Because of the convergence effect of pulse, the wave would be collapsed at a certain time due to an excessive increase in the tilt angle. Hence, this kind of pulse cannot propagate for a long distance.
EN
Located within a basin structure, at the conjunction of North East Anatolian, North Anatolian and Ovacik Faults, Erzincan city center (Turkey) is one of the most hazardous regions in the world. Combination of the seismotectonic and geological settings of the region has resulted in series of significant seismic activities including the 1939 (Ms~7.8) as well as the 1992 (Mw = 6.6) earthquakes. The devastative 1939 earthquake occurred in the pre-instrumental era in the region with no available local seismograms. Thus, a limited number of studies exist on that earthquake. However, the 1992 event, despite the sparse local network at that time, has been studied extensively. This study aims to simulate the 1939 Erzincan earthquake using available regional seismic and geological parameters. Despite several uncertainties involved, such an effort to quantitatively model the 1939 earthquake is promising, given the historical reports of extensive damage and fatalities in the area. The results of this study are expressed in terms of anticipated acceleration time histories at certain locations, spatial distribution of selected ground motion parameters and felt intensity maps in the region. Simulated motions are first compared against empirical ground motion prediction equations derived with both local and global datasets. Next, anticipated intensity maps of the 1939 earthquake are obtained using local correlations between peak ground motion parameters and felt intensity values. Comparisons of the estimated intensity distributions with the corresponding observed intensities indicate a reasonable modeling of the 1939 earthquake.
EN
The main goal of this article is to decluster Iranian plateau seismic catalog by the epidemic-type aftershock sequence (ETAS) model and compare the results with some older methods. For this purpose, Iranian plateau bounded in 24°–42°N and 43°–66°E is subdivided into three major tectonic zones: (1) North of Iran (2) Zagros (3) East of Iran. The extracted earthquake catalog had a total of 6034 earthquakes (Mw > 4) in the time span 1983–2017. The ETAS model is an accepted stochastic approach for seismic evaluation and declustering earthquake catalogs. However, this model has not yet been used to decluster the seismic catalog of Iran. Until now, traditional methods like the Gardner and Knopoff space–time window method and the Reasenberg link-based method have been used in most studies for declustering Iran earthquake catalog. Finally, the results of declustering by the ETAS model are compared with result of Gardner and Knopoff (Bull Seismol Soc Am 64(5):1363–1367, 1974), Uhrhammer (Earthq Notes 57(1):21, 1986), Gruenthal (pers. comm.) and Reasenberg (Geophys Res 90:5479–5495, 1985) declustering methods. The overall conclusion is difficult, but the results confirm the high ability of the ETAS model for declustering Iranian earthquake catalog. Use of the ETAS model is still in its early steps in Iranian seismological researches, and more parametric studies are needed.
EN
The Sakarya prefecture is an interesting area with various seismicity types. This activity comes from earthquakes occurring at the North Anatolian Fault Zone and from a few quarry blast areas in the region. These quarry blast recordings produce errors in the determination of active faults and mapping of the microearthquake activity. Therefore, to recognize the tectonic activity in the region, we need to be able to discriminate between earthquakes and quarry blasts in the catalogues. In this study, a statistical analysis method (linear discriminant function) has been applied to classify seismic events occurring in the Sakarya region. We used 110 seismic events that were recorded by Sakarya University Seismic Station between 2012 and 2014. Time and frequency variant parameters, maximum S wave and maximum P wave amplitude ratio (S/P), the spectral ratio (Sr), maximum frequency (fmax), and total signal duration of the waveform were used for discrimination analyses. The maximum frequency (fmax) versus time duration of the seismic signal gives a higher classification percentage (94%) than the other discriminants. At the end of this study, 41 out of 110 events (44%) are determined as quarry blasts, and 62 (56%) are considered as earthquakes.
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