Jiri Malek

Jiri Malek
The Czech Academy of Sciences | AVCR · Institute of Rock Structure and Mechanics

RNDr. Ph.D
Local seismic network REYKJANET, SW Iceland Seismic hazard at nuclear power plants Geothermal energy Seismic Beacon

About

114
Publications
21,137
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Introduction
Skills and Expertise
Additional affiliations
January 2003 - December 2013
The Czech Academy of Sciences
Position
  • Head of Department

Publications

Publications (114)
Article
Full-text available
The broader region of the Czech Republic in Central Europe experiences moderate seismicity. However, determination of seismic hazard is significant due to its dense population, large cities, and developed industrial infrastructure, including nuclear power plants. A new catalogue of historical earthquakes has been compiled for the Czech Republic and...
Article
Full-text available
A new model of the Rotaphone-D short-period seismic sensor with six degrees of freedom is introduced. The basis of the instrument is horizontal and vertical geophones in a special paired arrangement. The instrument is designed for simultaneous and collocated measurements of rotational and translational components of ground motion. The basic princip...
Article
The accuracy of the focal mechanism solution mainly depends on the number of stations used and becomes problematic especially in the case of weak earthquakes and sparse networks. In our study, we retrieve the seismic moment tensor of the M=5 earthquake on 9 October 2023 (18:23:09 UTC, 21.783°E, 49.086°N, depth 11.5 km) in Eastern Slovakia from its...
Article
Full-text available
The present study addresses verification of average seismic shear-wave velocity from the surface to a depth of 30 m (VS30) as a suitable proxy for a seismic amplification. For this purpose, we used instrumentally homogeneous and spatially dense seismic network WEBNET (West Bohemia Seismic Network), designed to monitor an intraplate earthquake swarm...
Article
Full-text available
The seismic beacon is a new instrument that allows for the measurement of changes in a rock massif with high sensitivity. It is based on effects, which affect the propagation of harmonic seismic waves generated continuously with stable and precise frequency and amplitude. These seismic waves are registered by a system of seismic stations. The ampli...
Article
Full-text available
The intraplate West Bohemia region is characterized by relatively frequent earthquake swarms mostly concentrated in the vicinity of the Nový Kostel village. Records of selected microearthquakes of the 2008 seismic swarm from a small circular area around Nový Kostel with a radius of 11 km are processed with focus on availability of precise onset rea...
Article
Full-text available
Ground fissures, especially if they open due to a sudden collapse of the surface, is a serious risk for populated areas. Their common occurrence in unconsolidated sediments of the Main Ethiopian Rift was found to be mostly a result of piping. The fissures start by piping in linear sub-horizontal underground voids, which often propagate upwards resu...
Article
West Bohemia is a region with a lot of mineral springs and gas outflows, which seems to be related to the remains of Quaternary volcanism in Central Europe. Earthquake swarms in shallow depths (less than 15 km) are very frequent there. We focused on the strongest earthquake over the past 30 yr (31 May, 2014 Mw∼3.8) and on two smaller ones (Mw∼2.9 a...
Article
Full-text available
Rotaphone-CY is a six-component short-period seismograph that is capable of the co-located recording of three translational (ground velocity) components along three orthogonal axes and three rotational (rotation rate) components around the three axes in one device. It is a mechanical sensor system utilizing records from elemental sensors (geophones...
Article
Full-text available
Interest in measuring displacement gradients, such as rotation and strain, is growing in many areas of geophysical research. This results in an urgent demand for reliable and field-deployable instruments measuring these quantities. In order to further establish a high-quality standard for rotation and strain measurements in seismology, we organized...
Article
Bosnia and Herzegovina is located in the center of the Western Balkans. Until 2018 Bosnia and Herzegovina used the hazard maps based on the macroseismic intensity. The first generation of probabilistic seismic hazard maps of Bosnia and Herzegovina is compiled and presented. Two seismotectonic models were created, the areal and linear (fault) togeth...
Article
Full-text available
A comparative active experiment that is aimed at collocated measurement of seismic rotation rates along three orthogonal axes by means of three different methods is described. The rotation rates in a short-period range of 6-20 Hz were obtained using three different methods: the 6C Rotaphone sensor system developed by the authors, the commercial R-1...
Article
Full-text available
Stability of precariously balanced rocks is employed in seismic hazard estimates. Standard toppling models of these rocks are based on a rigid body motion, i.e., this approximation assumes that their eigenfrequencies are infinite in any position of a rock. This assumption is, however, questionable in the case of rocking stones oscillating with lowe...
Article
Full-text available
Prague is the capital of the Czech Republic with 1.3 million inhabitants. It is situated in an intraplate region with low seismicity. The seismic hazard is low, but not negligible. In its evaluation, we face the following challenging issues: (1) there have been no M > 6 events during the period covered by historical catalog (Giardini et al. 2013) a...
Article
Full-text available
The aim is to obtain a site-specific S-wave structure beneath the Reykjanes Peninsula, southwest Iceland. Nine broadband stations of the Reykjanet network are used to find Rayleigh-wave phase velocity dispersion in a relatively wide range of periods (from 3 to 50 s). The records analyzed were made in the years 2013 to 2015 and concern fourteen sele...
Article
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We used the 2008 West Bohemia (WB) swarm earthquakes to characterize the seismic attenuation in the region. We found effective attenuation factors QP ranging between 150 and 175 and QS between 125 and 165 for most of the stations. We developed an innovative differential attenuation measurement method that shows significantly lower values in the sou...
Article
Macroseismic studies of various historical earthquakes with epicenters in the Eastern Alps region have shown a significant elongation of isoseismals in the North-West direction. Such an anomalous attenuation of seismic waves in Central Europe is investigated on the basis of instrumental records of two moderate-size earthquakes in the Vienna Basin,...
Article
Full-text available
The resolution of a source mechanism is investigated in terms of three differently constrained source models: the moment tensor, the shear-tensile crack source model, and the double-couple source model. The moment tensor (MT) is an unconstrained description of a general dipole source; the shear-tensile crack (STC) represents a slip along a fault wi...
Article
We present the seismic rotation rate due to the earthquake of Mw 6.7 at the Jan Mayen island, obtained from broad-band seismograms at a distance of about 2740 km. The order of magnitude of the rotation rate amplitude is only 10-9 rad/s in this case. It is studied with a focus on rotation-to-translation relations. A joint analysis of the rotational...
Article
The ratio of P- to S-wave velocities, VP/VS, is an important parameter characterizing rock composition and fluid saturation. We have studied properties of the ratio in the West-Bohemian seismically active region, using data from the earthquake swarm which occurred here in 2008. The earthquake swarm was well recorded by 23 seismic stations from epic...
Article
Full-text available
Extension of permanent seismic networks is usually governed by a number of technical, economic, logistic, and other factors. Planned upgrade of the network can be justified by theoretical assessment of the network capability in terms of reliable estimation of the key earthquake parameters (e.g., location and focal mechanisms). It could be useful no...
Conference Paper
Full-text available
We compare two independent methods of determining phase velocity of body and surface waves. The first method is based on matching the waveforms of relevant acceleration and rotation rate components derived from a small aperture seismic array (ADR method). The second method utilizes time delays of corresponding wave phases across the small-aperture...
Article
Full-text available
The paper deals with theoretical aspects of rotation-to-translation relations in six-degree-of-freedom short-period seismic records at close hypocentral distances. Rotation-to-translation ratios are introduced as the ratios relating peak amplitudes of the relevant rotational and translational components. Their frequency dependence is analyzed in si...
Article
Full-text available
Near-source records obtained by the mechanical seismic sensor Rotaphone are presented. The Rotaphone can measure six components of seismic movements, three translational and three rotational. The apparent S-wave phase velocity is determined and the possibility to obtain the wavepath S-wave velocity directly under the receiver is discussed. Rotation...
Article
Full-text available
An analysis of fault-slip data from the Lusatian Fault Belt, limiting the Lusatian Block of the Bohemian Massif in the SW, yielded parameters of eight successive paleostress patterns, Late Cretaceous to Plio-Pleistocene in age. These patterns were linked with specific stages in fault kinematics and fault-belt deformation. They include (1) α1, NE- t...
Article
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The presented study is a part of the passive seismic experiment PASSEQ 2006–2008, which took place around the Trans-European Suture Zone (TESZ) from May 2006 to June 2008. The data set of 4195 manually picked arrivals of teleseismic P waves of 101 earthquakes (EQs) recorded in the seismic stations deployed to the east of the TESZ was inverted using...
Article
Full-text available
The Lusatian Fault in the northern Bohemian Massif is one of the most prominent products of the latest Cretaceous to Paleogene thrusting in the Alpine foreland in Europe. Its fault plane dips to the N to NE, typically separating crystalline units in the N from Upper Paleozoic and Cretaceous units in the south. Crystalline units in Lusatia consist o...
Article
The Hronov-Poříčí Fault Zone (HPFZ) is an active tectonic area with regularly occurring shallow earthquakes up to magnitude 5. For their exact locations, at least an average velocity model of the area is needed. A method of measuring local phase velocities of surface waves using the array of stations deployed permanently in the HPFZ is introduced....
Article
Full-text available
The Mohorovicic discontinuity, Moho for short, which marks the boundary between crust and mantle, is the main first-order structure within the lithosphere. Geodynamics and tectonic evolution determine its depth level and properties. Here, we present a map of the Moho in central Europe across the Teisseyre-Tornquist Zone, a region for which a number...
Book
Full-text available
The Radioactive Waste Repository Authority (SÚRAO) in the Czech Republic is a state institution responsible for safe disposal of all present and future radioactive waste produced in the Czech Republic. Among main responsibilities, except radioactive waste management (RWM) in general, belongs the coordination of the research and development in the f...
Article
Full-text available
Rotational seismology is attracting attention in the seismological community including seismic engineers interested in possible damages to man‐made constructions due to strong rotational ground motions. Mathematically, seismic rotation represents the curl of the seismic displacement u , ![Graphic][1] , with Cartesian components: ![Graphic][2] (1)...
Conference Paper
Full-text available
Comparative experiment of three different methods of measuring rotation rates was provided. Array of twelve 3C geophones was used to compute ADR (array derived rotations). In the center of the array, two types of point rotation rate instruments were installed: Rotaphone and R-1. Thus, the experiment provided both the comparison of the two independe...
Article
Full-text available
We analyze refraction measurements along a short profile in western Krušné hory crystalline unit. The profile passed close to the seismically active zone of Nový Kostel. The measurements were carried out to distances of about 15 km using quarry blasts near the village of Horní Rozmyšl, located at the eastern margin of the crystalline unit. Smoothed...
Article
Full-text available
The territory of Lithuania and adjacent areas of the East European Craton have always been considered a region of low seismicity. Two recent earthquakes with magnitudes of more than 5 in the Kaliningrad District (Russian Federation) on 21 September 2004 motivated re-evaluation of the seismic hazard in Lithuania and adjacent territories. A new oppor...
Article
Cratons with their thick lithospheric roots can influence the thermal structure, and thus the convective flow, in the surrounding mantle. As mantle temperatures are hard to measure directly, depth variations in the mantle transition zone (MTZ) discontinuities are often employed as a proxy. Here, we use a large new data set of P-receiver functions t...
Article
Full-text available
A newly developed mechanical sensor system, called a Rotaphone, for recording rotation rate components is described. The sensor system is based on measurements of the differential motions between paired low-frequency geophones attached to a rigid skeleton. The same differential velocity (and, consequently, the same rotation rate component) is obtai...
Article
Broadband data from the Příbram seismological network was used to investigate the source of two earthquakes, with magnitudes M w = 0.2 and 0.4 respectively, occurring in the period of October–November 2009 in the Háje natural gas storage area (Czech Republic). Both events were located inside the limits of the storage area and at depths similar to t...
Article
Full-text available
We have developed and tested (calibration, linearity, and cross-axis errors) a new six-degree-of-freedom mechanical seismic sensor for collocated measurements of three translational and three rotational ground motion velocity components. The device consists of standard geophones arranged in parallel pairs to detect spatial gradients. The instrument...
Article
Full ground motion description, including both translational and rotational components, attracts still more attention in modern seismology. There is a need for portable rotational sensors, easily installed and operated in the field, sensitive enough to provide 6DOF records in a wide range of amplitudes excited not only by strong but also weak motio...
Conference Paper
Full-text available
Full ground motion description, including both translational and rotational components, attracts still more attention in modern seismology. There is a need for portable rotational sensors, easily installed and operated in the field, sensitive enough to provide 6DOF records in a wide range of amplitudes excited not only by strong but also weak motio...
Conference Paper
Full-text available
Rotational seismic motions can be generated together with S waves by anthropogenic sources. However, traditional sources of seismic energy as shots or vibrators radiate mainly P waves. Examples of rotational records near quarry blasts are presented and rotation to translation ratio (RTR) is calculated. Even if conversion P to S near the source is s...
Book
Full-text available
Read more about the monograph and the related research in supplementary material. Contents: 1. INTRODUCTION 2. EARTHQUAKE PREDICTABILITY / ACCIDENTALITY (Kalenda) 3. THEORY OF EXTERNAL FORCES (Neumann, Kalenda, Skalský, Kopf, Wandrol) 4. EXPERIMENTS WITH SEISMICITY AND TESTS OF EFFECTS (Kalenda, Málek, Skalský, Ostřihanský) 5. VERTICAL STATIC PEND...
Book
Ukázka z úvodní kapitoly: "V této knížce chceme ukázat, že predikce zemětřesení je možná, budeme prezentovat vlastní výsledky měření mikrodeformací masívu pomocí vertikálních statických kyvadel a na jejich základě ukážeme, jak by bylo možno predikovat místo, čas a magnitudo budoucího zemětřesení. Následující kapitoly proto budou na sebe volně nava...
Article
Full-text available
We propose a new quantitative determination of shear wave velocities for distinct geological units in the Bohemian Massif, Czech Republic (Central Europe). The phase velocities of fundamental Love wave modes are measured along two long profiles (~200km) crossing three major geological units and one rift-like structure of the studied region. We have...
Article
Full-text available
The Doupovské Hory Volcanic Complex (DHVC) is the best-preserved large volcanic suite of the Cenozoic intraplate volcanism in the Bohemian Massif. However, many uncertainties remain in the geological setting of its basement. In summer 2008, two seismic refraction profiles ran across this area to reveal the depth of the volcanic rocks and the underl...
Conference Paper
Full-text available
Rotaphone is a newly developed mechanical sensor system for recording seismic rotation rate components. It is based on measurements of differential motions between paired sensors (low-frequency geophones) attached to a rigid (undeformable) skeleton. The same differential velocity (and, consequently, the same rotation rate component) is obtained fro...
Article
Full-text available
The western part of the Bohemian Massif (Vogtland/West-Bohemia region at the Czech-German border) is characterized by relatively frequent intraplate earthquake swarms and by other manifestations of current geodynamic activity, such as mofettes, mineral and thermal springs. In this study we analyze variations of groundwater level in four hydrologica...
Article
Full-text available
The Variscan orogeny is the major Middle to Late Palaeozoic tectonometamorphic event in central Europe, and the Bohemian Massif is the largest exposure of rocks deformed during this orogeny. The Bohemian Massif consists of the Saxothuringian, Barrandian and Moldanubian units. Adjacent to this massif in the southeast, the Western Carpathians form an...
Conference Paper
Full-text available
We present an effective in situ calibration of paired sensor records used to determine differential seismic motions. The calibration is of extreme importance when small differential motions are to be recorded, which requires the paired sensors to be 'identical' in terms of their frequency characteristics. These differential motions are subsequently...
Conference Paper
Full-text available
A new mechanical sensor system for recording the rotational components of ground velocity in a horizontal plane has been constructed. It was tested both in a laboratory and in a field experiment. The sensor system is based on measurements of differential motions between paired sensors mounted along the perimeter of a rigid (undeformable) disc. The...
Conference Paper
Full-text available
Typically, only direct P and direct S waves are picked in local seismograms from Western Bohemia seismoactive region. Many records, however, show systematically certain other important phases, which can be detected using new observational techniques. For instance, small-aperture arrays are useful to observe converted S to P waves transmitted throug...
Conference Paper
Full-text available
A newly developed mechanical sensor system, shortly called Rotaphone, for recording the rotation rate components is described. The sensor system is based on measurements of differential motions between paired sensors (low-frequency geophones) attached to a rigid (undeformable) skeleton. The same differential velocity (and, consequently, the same ro...
Article
Full-text available
A new mechanical sensor system for recording the rotation of ground velocity has been constructed. It is based on measurements of differential motions between paired sensors mounted along the perimeter of a rigid (undeformable) disk. The elementary sensors creating the pairs are sensitive low-frequency geophones currently used in seismic exploratio...
Article
Full-text available
The Orlík water reservoir was built on the Vltava River in the places where the river crosses the geological unit called the Central Bohemian Pluton. Previous geological studies have disclosed no significant lateral inhomogeneity or fault zone in the close vicinity of the reservoir. However, repeated levellings, performed there in the 1950s and 196...
Article
We present an effective in situ calibration of paired sensor records used to determine differential seismic motions. The calibration is of extreme importance when small differential motions are to be recorded, which requires the paired sensors to be 'identical' in terms of their frequency characteristics. These differential motions are subsequently...
Conference Paper
Full-text available
We present an effective in situ calibration of paired sensor records used to determine differential seismic motions. The calibration is of extreme importance when small differential motions are to be recorded, which requires the paired sensors to be ‘identical’ in terms of their frequency characteristics. These differential motions are subsequently...
Conference Paper
Full-text available
A new mechanical sensor system for recording the rotational components of ground velocity in a horizontal plane has been constructed. It was tested both in a laboratory and in a field experiment. The sensor system is based on measurements of differential motions between paired sensors mounted along the perimeter of a rigid (undeformable) disc. The...
Article
Full-text available
The western part of the Bohemian Massif (West-Bohemia/Vogtland region at the Czech-German border) is characterized by relatively frequent intraplate earthquake swarms and by other manifestations of present-day geodynamic activity. During the strong earthquake swarm at the turn of the years 1985 and 1986, significant changes in mineral spring parame...
Article
Full-text available
The Bohemian Massif is one of the largest outcrops of Precambrian rocks in Central and Western Europe. As the SE limits of stable Hercynian Europe it has played an important role during Alpine-Carpathian orogeny and it has been subjected to Tertiary rifting processes. The area has been under controlled source seismology (CSS) investigation for a lo...
Article
The western part of the Bohemian Massif (West-Bohemia/Vogtland region at the Czech-German border) is characterized by relatively frequent intraplate earthquake swarms and by other manifestations of present-day geodynamic activity. During the strong earthquake swarm at the turn of the years 1985 and 1986, significant co-seismic changes were observed...
Article
Full-text available
Since 1998, a seismic network has been monitoring the underground gas storage located near the town of Příbram in the Central Bohemian Pluton, Czech Republic. Hundreds of weak induced seismic events have been recorded there. Moreover, several weak earthquakes have also been recorded from the vicinity of the nearby Orlík water reservoir. To improve...
Conference Paper
Full-text available
Oblique reflectors represent significant structure features influencing measured seismic data for various data gathering geometries. For example, in shallow seismic refraction experiments the presence of an inclined reflector causes significant differences in data collected on both sides of such an reflector. Similarly, in cross-well surveys, an ob...
Conference Paper
Full-text available
Abstrakt "Časové změny rychlosti rotace Slunce jsou způsobeny gravitačními silami planet. Rychlost rotace Slunce může ovlivňovat sluneční aktivitu." Pokud bychom prokázali tuto spojitost, mohli bychom předpovídat sluneční aktivitu z postavení planet, jak se o to pokoušela v minulosti řada autorů. Sluneční soustava představuje s vysokou přesností iz...
Article
Full-text available
In October 2005 local seismic monitoring started in the area of the Hronov-Poříčí Fault Zone. In the present paper we summarize seismic measurements using a small-aperture seismic array Ostaš. Parameters of the array and methodology of the data registration and processing are described. The list of local microearthquakes during two years of registr...
Article
Rayleigh waves in the period range 0.2 - 3.0 s from eight quarry blasts are analyzed to obtain S-wave velocity model beneath the Příbram seven-station array in the Czech Republic. Locations and origin times of blasts are estimated using P- and S-wave onsets and then verified at the quarry in the vicinity of the location. This blind test confirms a...
Article
Full-text available
A novel method called Generalized Average of Signals (GAS) was developed and tested during the last two years (Málek et al., in press). This method is designed for processing of seismograms from dense seismic arrays and is convenient mainly for denoising and weak phase detection. The main idea of the GAS method is based on non-linear stacking of se...
Article
Two strong earthquakes of M8.3 and M8.1 occurred near Kurile Islands in December 2006 and January 2007. Broadband surface wave records were obtained at many stations in Central Europe in the epicentral distance of about 8500 km. We have analyzed broadband seismograms from the Czech Regional Seismic Network together with twelve temporary stations of...
Article
Full-text available
A novel algorithm called Isometric Method (IM) for solving smooth real-valued non-linear inverse problems has been developed. Model and data spaces are represented by using m + 1 corresponding vectors at a time (m is the dimension of model space). Relations among vectors in the data space are set up and then transferred into the model space thus ge...
Article
The SUDETES 2003 wide-angle refraction/reflection experiment covered the area of the south-western Poland and the northern Bohemian Massif. The good quality data that were gathered combined with the data from previous experiments (POLONAISE'97, CELEBRATION 2000) allowed us to prepare a 3D seismic model of the crust and uppermost mantle for this are...
Article
Full-text available
A novel method called Generalized Average of Signals (GAS) for detection of very weak waves in seismograms is described and tested. The general principle of the GAS method is to take advantage of the coherency of the signal, which is extracted. The signals are shaped with moving window and converted to the frequency domain. Then they are non-linear...