Mihaela Popa

National Institute for Earth Physics · National Data Center

The seismograms are obtained as part of the collaborations carried out through the participation of the main author, Eugen Oros, as a representative from Romania in the EUROSEISMOS 2002-2007 project of the European Seismological Commission. The participation situation is highlighted in the following links: https://storing.ingv.it/es_web/Data/Collec...

The database contains macroseismic intensities obtained for two groups of earthquakes used for the calibration of the Bakun-Wentworth method of localization and estimation of the Mw magnitude using macroseismic data, respectively the group of earthquakes used to calibrate the attenuation relationship and the group of earthquakes used for its valida...

"The main purpose of this study is to create a database that correlates the data from the current catalogue of Romanian earthquakes (ROMPLUS) with the information from other available catalogues, research studies for the events produced between 984 and 1899, historical documents, and mentions in archives or historical papers. The database will cont...

An intense seismic sequence occurred in 2023 in Gorj area (Romania), part of the Central Southern Carpathians seismic zone, having a doublet as main shocks. The first one, with a local magnitude of 5.2, was recorded on February 13 at 14:58:09 UTC, and the second one, with a local magnitude of 5.7, was recorded the next day at 13:16:52 UTC. The data...

We present a refined and the most complete catalogue of the focal mechanisms for the Intra-Carpathian region of Romania. It contains the high-quality solutions computed for 1217 earthquakes recorded between 1909 and 2018. Primary data gathered from the original seismograms and seismic bulletins have been used to compute the source parameters and fo...

Seismic activity is a permanent threat to human communities located in tectonically active areas through its major impact upon their existence. Since hundreds of years, major earthquakes and observations of their effects have marked the memory of mankind. Seismology as a science, had a fast evolution, with remarkable breakthroughs in a relative sho...

At the beginning of the XXth century, the scientific community, worldwide, awarded much more attention to the understanding of geological peculiarities that influences earthquake occurrence and the development of seismological instruments. Romania was among the first countries in the world that had a seismological service in the late 1890s at...

Earthquakes are natural phenomena that occur suddenly and unexpectedly, representing a real threat in many areas of the world, with destructive potential to both the natural environment and the built one, as well as significant loss of life. Over time, people looked for ways to understand the earthquakes, to identify the places where they occur, wh...

The earthquake catalog is the basis of numerous studies of seismicity, seismic source, tomography, hazard, and seismic risk. That is why it is necessary to complete and update it with as much information as possible regarding the events it contains or which can be added based on studies subsequent to the moment when the catalog was created. The mai...

This database was published in two papers: 1. E. OROS, M. POPA, I. A. MOLDOVAN (2008). SEISMOLOGICAL DATABASE FOR BANAT SEISMIC REGION (ROMANIA) - PART 1: THE PARAMETRIC EARTHQUAKE CATALOG. Romanian Journal of Physics 53 (7-8): 955-964 2. E. OROS, M. POPA, E. POPESCU, I. A. MOLDOVAN (2008). SEISMOLOGICAL DATABASE FOR BANAT SEISMIC REGION (ROMANIA)...

Tectonic stresses in the lithosphere are the key to understanding geodynamic processes in general and seismogenesis in particular, being observed during their release by tectonic earthquakes. The relationships of the stress field with tectonics and the structure of the upper lithosphere are complex and controlled by both regional and local factors....

Modelling the causal relationship between the stress field specific to a complex geological environment as structure and composition and how it reacts and manifests itself through specific, observable and measurable deformations (fracturing and propagation of fractures, seismic faults, seismicity), is the key to understanding seismogenic processes...

Constantin Ionescu, Mihaela Popa, Cristian Neagoe and Daniela Veronica Ghica report on seismic monitorig at the National Institute for Earth Physics in Măgurele, Romania, for the Summary of the Bulletin of the ISC.

The updated Romanian Seismic Catalogue (ROMPLUS, Oncescu et al., 1999) has been contaminated over time by anthropic events, especially in the regions where quarries are exploited. This contamination can affect the interpreting and modelling of seismicity and geodynamics in specific areas. Therefore, a procedure to discriminate between tectonic eart...

The Trans-European Suture Zone (TESZ) is the most important and extensive continental suture in Europe, marking the edge of the East European Craton (EEC), from the North Sea to the Black Sea. It corresponds to significant changes in surface geology and deep crustal structure, evident in seismic, gravitational and magnetic studies. However, the TES...

The paper represents a multidisciplinary investigation of the relation between seismicity, active stress field and geological structure for the West of Romania. The study is based on revised and updated catalogues of earthquakes (3572 events) and focal mechanisms (89 solutions). The large spatio-temporal variations of the stress tensor parameters,...

The purpose of the present study is to elaborate a new model of the macroseismic intensity attenuation using all observed intensities data for the crustal earthquakes in Romania and then, based on this relationship, to calibrate the Bakun-Wentworth method, one of the modern methods most used to estimate the parameters of the historical earthquakes...

We present a study of the strongest historical earthquakes (Mw > 5.0) occurred in West Romania between 1900 and 1980 conducted to review and homogenize the Romanian Earthquakes and Focal Mechanisms Catalogues on instrumental data basis. New hypocenters relocation, moment magnitudes, Mw and focal mechanisms solutions are obtained on historical instr...

Intra-Carpathian Region of Romania experienced strong earthquakes as it is mentioned in the national and international databases, e.g. November 26, 1829 (Ms = 6.4), October 10, 1834 (Ms = 6.3), January 26, 1916 (Ms = 6.4), July 12, 1991 (Mw = 5.7). The paper focuses on calibration and validation of MEEP method (Macroseismic Estimation of Earthquake...

Active tectonic deformation is continuously shaping the landscape in the Alpine Orogenic system. Earthquakes are clear proves of neotectonic deformation process. In the Romanian Carpathians the most active deformation is recorded in the South Eastern Carpathian Bend Zone. Nevertheless, seismicity associated to latest orogenic stage of active deform...

The paper presents a detailed analysis of the seismic activity recorded in the Banloc-Voiteg seismogenic structure (Romania) located on the southeastern border of the Pannonian Depression which is characterized by pre-Alpine and Alpine structures belonging to Tisa-Dacia Microplate and, particularly by the tectonic contact between two main geodynami...

The study region is the most important seismic region of Romania when we refer to the crustal seismicity as a source of seismic hazard. So far there have been recorded 91 seismic events that produced significant effect in buildings (Io ≥ 6 EMS), some of them resulting in severe damage and even casualties (Io ≥ 7 EMS). In this paper we modelled the...

The main task of the presented study is to elaborate a set of relations of mutual conversion macroseismic intensity - magnitude, necessary for the calibration of the historical crustal earthquakes produced in the Intra - Carpathian region of Romania, as a prerequisite for homogenization of the parametric catalogue of Romanian earthquakes. To achiev...

The inner part of the Carpathians in Romania belongs to the Carpathians-Pannonian system bordered by the Eastern Carpathians to the north and east, Southern Carpathians to the south and Pannonian Basin to the west. It is a complex tectonic region with differential folding mechanisms, post-collisional kinematics, rheology and thermal properties, inc...

The active stress pattern in the Apuseni Mts area is investigated and studied in relation to the local seismicity and geology. Our analysis is based on several high quality and resolution data bases obtained recently in the context of national and international projects and which refers to digital seismograms recorded by dense networks, parametric...

Besides the intermediate depth earthquakes (Mw>7.0), in the SE Carpathians and its foreland a crustal seismicity (Mw<=5.6) is as well present. A correlation of the crustal hypocenter distribution with the deep structure displayed by the deep seismic lines is done. Some deep crustal faults extended down to the upper mantle are found out both in the...

The Romanian Intra-Carpathian Region is located on the eastern half of Tisa-Dacia geodynamic block from the Neogene Carpathian-Pannonian Basin. The distribution of seismicity displays clear clusters and narrower zones with seismogenic potential confirmed by the damaging earthquakes recoded in the region, e.g. July 01, 1829 (Mw=6.2), October 10, 183...

The Vrancea region, located at the southeastern edge of the Carpathians arc bend, is a region of intense seismicity, whose major earthquakes produce hazard in southeastern Europe. Despite the consequent focus of the geophysical and geological community on providing accurate structural and dynamical models of Vrancea, these are still subject to nume...

The seismic activity in the Eastern Carpathians area is poorly recorded (a few hundreds of small-to-moderate earthquakes in the Romanian catalogue over the last century). The installation in 2002 of the high-performance Bucovina (BURAR) array in the Eastern Carpathians area contributed to a significant growth of the capacity to monitor local seismi...

The aim of this paper is to describe a managing system for a unique Romanian database of historical seismograms and complementary documentation (metadata) and its dissemination and analysis procedure. For this study, 5188 historical seismograms recorded between 1903 and 1957 by the Romanian seismological observatories (Bucharest-Filaret, Focşani, B...

In order to improve the monitoring of seismic activities in the border regions and to enhance the collaboration between countries and seismological institutions in Central Europe, the Slovenian Environment Agency (ARSO), the Italian National Institute for Oceanography and Experimental Geophysics (OGS), the University of Trieste (UniTS) and the Aust...

An earthquake swarm of 940 events with ML magnitude between 0.1 and 4.0 and the depth no more than 25 km occurred during three months in the SouthEastern Carpathians foredeep, in an area of around 200 km2, at 27 km northeast of the Galati city. JHD relocation highlights a rupture area steeply dipping down to 15 km depth along a NE­SW alignment. Alt...

An earthquake swarm of 940 events with ML magnitude between 0.1 and 4.0 and the depth no more than 25 km occurred during three months in the South-Eastern Carpathians foredeep, in an area of around 200 km2, at 27 km north-east of the Galati city. JHD relocation highlights a rupture area steeply dipping down to 15 km depth along a NE-SW alignment. A...

The papers contained in Part II of this volume are devoted to three main subjects, namely: seismicity of Romania, seismic hazard assessment and the evaluation of local soil conditions. A total of 11 papers authored by researchers from several institutions in Romania, as well as from Bulgaria and which cover all the three above-mentioned subjects we...

During the last decade Romanian Seismic Network has been significantly improved. A total number of 114 3-C seismic stations and the 2 seismic arrays ensure a good coverage of seismically active regions. As a consequence, the detection threshold decreased allowing location with higher accuracy of low magnitude (ML ~1.0) seismic events. This led to a...

The macroseismic effects of three major events recorded in historical time (1738, 1802, 1838) are re-evaluated and compared with three major events recorded in the 20th century in the Vrancea subcrustal source (1940, 1977, 1986). The purpose of the paper is to detect characteristic resemblances and differences in the macroseismic distributions amon...

The crustal seismicity in Romania is concentrated in front of the Carpathians Arc bend (Vrancea region) and at the contact between the extra-Carpathian platform regions and Carpathians orogen. The region investigated in this paper is characterizing the contact of the western side of the South Carpathians with the Tisza-Dacia region. In this area, t...

The Vrancea major earthquake of 10 November 1940 (Mw 7.7) is the largest instrumentally recorded earthquake in Romania. It was preceded and followed by several months of enhanced seismicity with several events of magnitude above 5 and 6. The largest preshock (Mw 6.5) occurred on 22 October 1940, while the largest aftershock (Mw 5.9) occurred one da...

National Institute for Earth Physics is responsible for seismic monitoring of Romania. For this purpose, a dense seismic network is now operating covering almost the entire surface of the country. At present, the Real Time Seismic Network consists of 96 sites with seismic digital equipment, of which 3 in Republic of Moldova, and two seismic arrays:...

Romania is one of the most active seismic countries in Europe, with more than 500 earthquakes occurring every year. The seismic hazard of Romania is relatively high and thus understanding the earthquake phenomena and their effects at the earth surface represents an important step toward the education of population in earthquake affected regions of...

A unique macroseismic data set for the strongest earthquakes occurring since 1940 in the Vrancea region is constructed by a thorough review of all available sources. Inconsistencies and errors in the reported data and in their use are also analysed. The final data set, which is free from inconsistencies, including those at the political borders, co...

The ISOLA iterative deconvolution technique proposed by Sokos and Zahradnik (2008) to retrieve seismic moment tensor and moment magnitude of local and regional events was applied to shallow earthquakes selected as representative in various seismic regions of Romania. Moderate size earthquakes recorded by at least four broad-band stations within 100...

The goal of the paper is to investigate the most recent crustal earthquake sequence (40 earthquakes detected and located in the time interval 30 December 2011- 10 January 2012), generated in the weastern part of the Getic Depression (about 20 km east from the Tg-Jiu city). The main shock, occurred on January 1, 2012, 23:57 (45.04, 23.56, h=14 km, M...

The purpose of this paper is to revise the local magnitude formula for the intermediate-depth Vrancea earthquakes. The new magnitude scale is based on the local magnitude scale defined by [9] and revised by [3]. The coefficients in the magnitude relation are determined through multiple regression method using as reference the duration magnitude sca...

The southern part of the southeastern Carpathians represents the site of the most recent volcanic eruptions of the entire Carpathian-Pannonian region. The products of these eruptions range from 42 to 10 Ka radiocarbon ages in the South Harghita Mountains (high K calc-alkaline rocks with adakite-like features), and at 1.2–0.6 Ma K–Ar ages in the Per...

The BURAR seismic array, located in Northern Romania (Bucovina region), is designed to monitor events located in an area poorly covered by other existing seismic stations. In order to use the BURAR array for single-station locations, it is crucial to calibrate the azimuth and slowness parameters, which are currently used in array techniques to loca...

We determine crust and upper mantle structure in the western part of Romania using regional seismicity recorded on a combined temporary and permanent network (station spacing ∼ 50 km). The area is characterized by shallow seismic activity of moderate magnitude (ML < 6) with frequent clusters of events. Tectonically, the region is divided into block...

The main goal of this study is to investigate the crustal structure in the western part of Romania, in Banat seismic area. The seismicity in this area is characterized by shallow activity of moderate magnitude (magnitude below 6) with frequent multiple sequences. The region is divided in many tectonic blocks bordered by intracrustal faults and with...

The Vrancea seismic region represents a unique case of well-defined and intense intermediate-depth earthquake activity as a consequence of specific geodynamic processes at the continental contact between East-European, Moesian and Intra-Alpine plates. Apart the subcrustal earthquakes generated in the Vrancea slab, the analysis of seismicity puts in...

The Bucovina Romanian Seismic Array (BURAR) was deployed in the northern Romania, under a joint effort of the Air Force Technical Applications Center (AFTAC), USA, and the National Institute for Earth Physics (NIEP), Romania. BURAR consists of 10 seismological stations: 9 sites, vertical-component short-period instruments, and one site, three-compo...

In the last years the National Institute for Earth Physics (NIEP), Romania, has developed its real-time broadband seismic network. At present, NIEP operates 34 stations with both broadband velocity sensors (CMG3ESP, CMG40T, KS2000, STS2) and accelerometer sensors (2gEpi). The data are continuously recorded and transmitted to the Romanian Data Centr...

Vrancea, located at the southeastern Carpathians Arc bend, is one of the areas in the Alpine-Himalayan belt that features strong earthquakes occurring at intermediate depths (60–200 km). In this study we investigated the crustal and lithospheric structure beneath the Vrancea seismic area using a local earthquake tomography approach. We used an upda...

Recently the number and distribution of the Romanian Seismic Network instruments has been improved significantly. Since at present the used magnitude law for Romania crustal events is that determined by Richter for California and leads to large variations among stations, our goal is to calibrate this relation for each station and seismogenic region...

The National Institute for Earth Physics (NIEP, Bucharest) hosts the National Data Centre of Romania (ROM NDC), and operates the auxiliary seismic station Muntele Rosu (AS081, MLR) as part of International Monitoring System (IMS). The paper presents the Romanian contribution in support of verification regime of the Comprehensive Nuclear-Test-Ban Tr...

Vrancea seismic zone is located in Romania at the South-Easter Carpathians bend, where at least three major tectonic units are in contact: East Europen Plate, Intra-Alpine Plate and Moesian Plate. The seismicity of the Vrancea zone consist of both crustal and intermediate-depth earthquakes. The crustal events are moderate (M w ≤ 5.5) and generally...

The main goal of this study is to investigate the lithospheric structure beneath Vrancea seismic area using local earthquakes. Vrancea area, located at the South-Eastern Carpathians Arc bend, is characterized by strong earthquakes generated at intermediate depths (60 - 170 km) in a complex geotectonic system. The tomography image obtained using tel...

Seismicity of the Vrancea region shows characteristic clustering features in space, time and energy that are clearly related to specific physical processes in the subcrustal domain. For the study of the frequency-magnitude distribution and seismic cycle behaviour we use Romanian routine catalogue for a 100-year time interval (6589 events) as well a...

Shear-wave splitting results are presented for the broad-band stations of the Romanian seismic network. For stations BUC1 and CRAR (located in Moesian Platform), IAS (in East-European Platform), TIRR and CVD (in Central Dobrudja–Black Sea microplate), TIM and DRGR (in Dacia-Tisza plate, including Apuseni Mts.), BURAR, BZS and GZR (in, or very close...

The Vrancea region, in the Southeastern Carpathians (Romania), represents a unique case among the seismic areas in the world taking into account the extreme concentration and persistence of seismicity and the tectonic stress field. Subduction in a post-collisional phase is still active in a narrow area located at the sharp bend of the mountain belt...

A high quality Catalogue of Focal Mechanism Solutions of the earthquakes occurred in the Banat Seismic Region (Romania) (CFMSBSR) is presented. It comprises focal mechanism solutions (FMS) for 140 events, spanning 47 years (1959–2006). CFMSB includes three kinds of the FMS: i) collected FMS with their original parameters, ii) compiled FMS with modi...

This paper presents an instrumental review of the strongest crustal Romanian earthquake occurred last Century, namely the M6.4, 26 th January, 1916 event. The earthquake occurred in Fagaras Seismogenic Zone that lies in the central part of South Carpathians. The maximum intensity reported by different authors for this event is Imax=9MM (Atanasiu, 1...

The Vrancea region, in the South-Eastern Carpathians (Romania), represents a unique case among the seismic areas in the world taking into account the extreme concentration and persistence of seismicity and tectonic stress field. Our goal is to show that the particular shape of attenuation and shear wave splitting properties can be interpreted in th...

Notable clustering effects in seismic activity are observed at the sharp bend of the South-Eastern Carpathians both at subcrustal and crustal domains. The seismic energy release is strongly increasing with depth, where apparently the principal source controlling the geodynamics of the entire system is located. New developments of instrumental monit...

We relocated M 6 or larger intermediate-depth earthquakes in Vrancea, Romania that have occurred since 1934. To determine their absolute hypocenters accurately, we combined them with recent (from January 1996 to November 2003) smaller earthquakes recorded by the Romanian local network and then relocated all of them simultaneously using a modified j...

Array processing techniques can characterize the details of arriving seismic waves front for different wave phases. We applied one of these techniques, f-k analysis, to estimate azimuth and slowness systematic deviations specific for Bucovina array (BURAR) and to detect significant lateral variations in the lithosphere structure. BURAR array is a h...