Seismology (Engineering)

Στη σημερινή εποχή ο σχεδιασμός και προγραμματισμός ενός ηλεκτρονικού συστήματος που διευκολύνει τον άνθρωπο σε κάποια από τις δραστηριότητές του αποτελεί  το επόμενο μεγάλο βήμα στον χώρο της τεχνολογίας. Προφασιζόμενοι τα διάφορα συστήματα διαχείρισης δεδομένων, αποφασίσαμε να δημιουργήσουμε ένα τέτοιο σύστημα για τα δεδομένα που παράγουν οι σεισμογράφοι. Στη εργασία αυτή δόθηκε το όνομα: eSeismographos Project. Σκοπός της εργασίας είναι η διευκόλυνση της διανομής και επεξεργασίας των σεισμολογικών μετρήσεων, καθώς και τον σχεδιασμό ενός σεισμογράφου ανοιχτού κώδικα. Καταφέραμε έτσι να δημιουργήσουμε έναν σεισμογράφο, ο οποίος συνδέεται με μια λειτουργική ιστοσελίδα που βασίζεται σε μια βάση δεδομένων.

We review site parameters used in ground motion prediction equations (GMPEs) for various tectonic regimes and describe procedures for estimation of site parameters in the absence of site-specific data. Most modern GMPEs take as the principal site parameter the average shear wave velocity in the upper 30 m of the site (Vs30) either directly or as the basis for site classification into categories. Three GMPEs developed for active regions also use basin depth parameters. We review estimation procedures for Vs30 that utilize surface geology, terrain-based site categories, ground slope, or combinations of these. We analyze the relative efficacy of those procedures using a profile data set from California assembled in a recent NGA project. The results indicate that no single procedure is most effective and that prediction dispersion is lower for young sediments than for stiff soils or rock.

Archaeoseismology of the A.D. 1545 earthquake in Chiang Mai, northern Thailand): The A.D. 1545 Chiang Mai earthquake in northern Thailand was studied by historical and archaeological sources.The temple Wat Chedi Luang has lost about half of the original 80-metres height due to southward-directed collapse. Twenty-one temple sites -out of 74 visited -has tilted pagodas, up to 5° in various directions, dominated by a SE trend. All damaged temples were built before the 1545 earthquake. We suggest that a city-wide liquefaction event caused tilting. The responsible earthquake possibly occurred along the Doi Suthep Fault within city limits. Possible activity of distant faults is assessed.

In the present study, we have estimated the coda Q (Q C) and the geometrical spreading factor (gamma) for the Saurashtra region that is located in the western part of the Deccan Volcanic Province, Gujarat, India. The waveform data from the seismic network operated by the Institute of Seismological Research, Gandhinagar, are used for the analysis. We have used records of a total of 221 local earthquakes with epicentral distances less than 70 km from the seismic stations. The moment magnitude range of the earthquakes is 2.5-5.3, and the depth range is 1-22 km. The Q C has been estimated at five central frequencies (1.5, 3, 6, 12, and 20 Hz) using 20, 30, and 40 s window lengths for vertical, north-south, and eastwest components, respectively. The obtained Q C values show that the attenuation in the region has a strong dependence on frequency and points toward a heterogeneous medium. The geometrical spreading factors are also estimated for two cases, that is, with and without Q at the same central frequencies and window lengths. The average geometrical spreading factors with

Similar to Båth’s law, which points that the difference in magnitude between the main shock and its largest aftershock is generally about 1.2, the Panza- Rugarli law states that for MCE, the design magnitude Mdesign, can be set, given the current state of knowledge, equal to the sum of Mmax and 0.7, and it is an intriguing topic for further discussion.

We computed broadband (0-5 Hz) ground motions from large earthquakes (magnitudes M 6.5 and 7.0) in the near-fault region (< 50 km) for engineering applications. Simulations were run with SW4, a summation-by-parts finite difference code, and included three-dimensional (3D) Earth structure. In order to run large domains (100 x 50 km) and accurately model high frequencies (up to 5-10 Hz), we ran on state-of-the-art high-performance computing (HPC) platforms at Lawrence Livermore and Lawrence Berkeley National Laboratories. Earthquake rupture models were based on pseudodynamic kinematic methods and include stochastic slip distributions and scaling between slip, rise time and variable rake. Earth models include simple plane-layered (onedimensional, 1D) average crustal models, as well as models with sedimentary basins and stochastic heterogeneity. We obtained good agreement between simulated motions and Ground Motion Prediction Equations (GMPE’s). Seismograms computed in this study are...

Author(s): Ibrahim, Ahmed Mokhtar Nagy | Advisor(s): Eltawil, Ahmed | Abstract: Smart phones are an indispensable tool in modern day-to-day life. Their widespread use has spawned numerous applications targeting diverse domains such as bio-medical, environment sensing and infrastructure monitoring. In such applications, the accuracy of the sensors at the core of the system is still questionable, since these devices are not originally designed for high accuracy sensing purposes. In this thesis, we investigate the accuracy limits of one of the commonly used sensors, namely, a smart phone accelerometer. As a use case, we focus on utilizing smart phone accelerometers in structural health monitoring (SHM). Using the already deployed network of distributed citizen-owned sensors is considered a cheap alternative to standalone sensors. These devices can capture floors vibration during disasters, and consequently compute the instantaneous displacement of each floor. Hence, damage indicators d...

Pengumpulan data intensitas gempa bumi di indonesia telah dilakukan sejak tahun 1821 pada zaman pemerintahan kolonial Hindia-belanda hingga sekarang. Seiring kemajuan teknologi pengumpulan data intensitas telah berkembang menjadi sistem pelaporan intensitas gempa secara online yang telah dilakukan oleh beberapa negara maju seperti Amerika dan Eropa. Laporan bersumber dari masyarakat yang terdampak gempa bumi. Untuk memperoleh informasi intensitas yang dapat dipercaya dibutuhkan kuesioner survei makroseismik yang standar dan mudah diaplikasikan ke masyarakat. Penelitian ini bertujuan untuk mendapatkan kuesioner survei makroseismik yang layak untuk digunakan dalam pengumpulan data intensitas gempa bumi. Uji validitas dan uji reliabilitas dilakukan untuk mengetahui kelayakan kuesioner. Hasil pengujian menunjukkan bahwa kuesioner valid dan reliabel. Dilakukan survei makroseismik menggunakan kuesioner yang dibuat untuk kejadian gempa bumi yang dipilih. Peta guncangan dibuat dengan menambahkan data MMI yang diperoleh dan membandingkan dengan peta guncangan BMKG. Hasil menunjukkan bahwa informasi MMI yang diperoleh cukup merepresentasikan peta guncangan BMKG.

Nowadays, low-cost accelerometers are getting more attention from civil engineers to make Structural Health Monitoring (SHM) applications affordable and applicable to a broader range of structures. The present accelerometers based on Arduino or Raspberry Pi technologies in the literature share some of the following drawbacks: (1) high Noise Density (ND), (2) low sampling frequency, (3) not having the Internet’s timestamp with microsecond resolution, (4) not being used in experimental eigenfrequency analysis of a flexible and a less-flexible bridge, and (5) synchronization issues. To solve these problems, a new low-cost triaxial accelerometer based on Arduino technology is presented in this work (Low-cost Adaptable Reliable Accelerometer—LARA). Laboratory test results show that LARA has a ND of 51 µg/√Hz, and a frequency sampling speed of 333 Hz. In addition, LARA has been applied to the eigenfrequency analysis of a short-span footbridge and its results are compared with those of a h...

The implementation of systems for Structural Health Monitoring and Earthquake Observation is increasing in the last years owing to the development of new technologies which enable low-cost and small-size devices to be installed in large-scale or high-density applications. This paper introduces the implementation of monitoring systems, either for structural health assessment and earthquake observation. The applications are based in Sicily (Italy), a region characterized by a high seismic hazard and where the buildings are often old and vulnerable. The system relies on a MEMS (Micro Electro-Mechanical Systems) sensor, a 3-axial accelerometer which has been specifically selected in order to ensure the suitability for the specific applications: accelerations from 10 0 to 10 2 Hz. We present the details of the designed monitoring station, of the network architecture, and some of the recorded data.

A multiscale approach to the monitoring of earthquakes and their effects can represent an effective tool for the reduction of seismic risk. Devoted monitoring networks are essential to cope with the seismic emergency in urban areas, to assess the damage scenarios, which are useful for the preservation of the strategic functions and services and to improve the community resilience to earthquakes. The National Earthquake Observatory, Italian Institute for Geophysics and Volcanology (ONT-INGV, Italy), has been recently involved in several projects devoted to the reduction of seismic risk by means of the implementation of urban-scale and building-scale monitoring networks. Such systems represent a necessary support for the well-established national seismic network. All these approaches (country, urban, and building scale) could be framed within of a unique system in which each part holds different tasks, with the common final objective of the earthquake risk reduction. In this paper different approaches, experiences and potential capabilities on urban seismic networks, structural health and cultural heritage monitoring implemented in Italy by the ONT-INGV will be presented, with the ultimate goal of achieving an effective integrated multi-scale system.

In this paper, we introduce a project for the realization of the first European real-time urban seismic network based on Micro Electro-Mechanical Systems (MEMS) technology. MEMS accelerometers are a highly enabling technology, and nowadays, the sensitivity and the dynamic range of these sensors are such as to allow the recording of earthquakes of moderate magnitude even at a distance of several tens of kilometers. Moreover, thanks to their low cost and smaller size, MEMS accelerometers can be easily installed in urban areas in order to achieve an urban seismic network constituted by high density of observation points. The network is being implemented in the Acireale Municipality (Sicily, Italy), an area among those with the highest hazard, vulnerability and exposure to the earthquake of the Italian territory. The main objective of the implemented urban network will be to achieve an effective system for post-earthquake rapid disaster assessment. The earthquake recorded, also that with moderate magnitude will be used for the effective seismic microzonation of the area covered by the network. The implemented system will be also used to realize a site-specific earthquakes early warning system.

Banat region is one of the most active zones in terms of crustal seismicity in Romania. Even though the active seismic monitoring started from early XXth century, the data sets got more performant with the development and expansion of the seismic network monitoring in the late 1970’s. One particularity regarding seismic data acquisition is that in many cases anthropic activity, such as mining and quarry exploitation, interferes with natural seismicity. Our aim is to bring forward a series of data extracted from the ROMPLUS catalogue to identify the anthropic interference. To this we propose a method based on multiple discrimination criteria, such as local time of event occurrence, magnitude, location in respect with the nearest exploitation site, depth and P-wave input analysis (polarity and waveform). Identifying and filtering the anthropic events from the catalogue will result in a better imaging and characterizing of the natural seismic phenomenon in Banat region improving this w...

Evidence of ancient seisms in Cusco, Peru and Tzintzuntzan, Mexico and their cultural relations) At first sight the ancient pre-Columbian cultures seem to have had no awareness of seisms. Purhepecha and Andean cultures nevertheless not only show awareness of these, but also similitude between their anti seismic building techniques. This work exposes clear evidence of coseismic ruptures found In Cusco and in Tzintzuntzan-Patzcuaro. More profound research could nevertheless be helpful to reveal sceneries which are for their most part unknown to current generations.

Earthquake Early Warning (EEW) network performance improves with the number and density of sensing stations, quality of the sites and of strong-motion instrumentation, degree of coverage near at-risk populated areas and potential fault zones, and minimizing latency of signal processing and transmission. Seismic research tends to emphasize competing requirements: low-noise sites, high-performance broadband seismic instrumentation, and high-quality signal processing without regard for latency. Recent advances in instrumentation and processing techniques have made feasible the concept of a multi-use seismic station in which strongand weak-motion seismometry are both cost-effectively served without compromising the performance demands of either.

In seismic applications, the molecular-electronic transfer (MET) sensors are considered as ones of the most promising instruments for the measurements of seismic-associated signals. The subject of the presented study is the MET (molecular-electronic transfer) angular motion sensor self-noise dependence on the area of the electrodes of the electrochemical signal converting cell. Sensors with different area of the signal conditional cell electrodes have been produced and their self-noise at frequencies <100 Hz has been studied. The results show that sensors with a larger area of electrodes have lower self-noise at low frequencies and larger self-noise at high frequencies. It agrees with the assumption that uncorrelated small-scale hydrodynamic velocity fluctuations are responsible for the sensors convective noise. The results of the study allowed to refine the MET sensors self-noise model and refined and revealed the directions of further improvement of the MET angular sensors performance.

The possibility to obtain a more complete and unbiased long-term history of seismic shakings over large territories than is explicitly reported from inhabited localities is discussed in the paper. An approach proposed for this purpose consists in complementing the spatial distribution of the macroseismic effect of earthquakes by calculated intensities at localities where information on felt shakings is absent. The calculated intensity is obtained on the basis of data on the epicentral intensity and location of epicenters provided by earthquake catalogs. This approach is applied to the analysis of the history of seismic shaking in Spain. The calculated intensities are shown to be comparable in accuracy with the ordinary practice of intensity determinations at national seismological centers.

This paper presents findings from ongoing research that explores the ability to use Micro-Electromechanical Systems (MEMS)-based technologies and various digital communication protocols for earthquake early warning (EEW). The paper proposes a step-by-step guide to developing a unique EEW network architecture driven by a Software-Defined Wide Area Network (SD-WAN)-based hole-punching technology consisting of MEMS-based, low-cost accelerometers hosted by the general public. In contrast with most centralised cloud-based approaches, a node-level decentralised data-processing is used to generate warnings with the support of a modified Propagation of Local Undamped Motion (PLUM)-based EEW algorithm. With several hypothetical earthquake scenarios, experiments were conducted to evaluate the system latencies of the proposed decentralised EEW architecture and its performance was compared with traditional centralised EEW architecture. The results from sixty simulations show that the SD-WAN-bas...

Telah dilakukan perhitungan nilai percepatan tanah Pulau Lombok yang divalidasi dengan nilai percepatan tanah di Stasiun Mataram.  Percepatan tanah dihitung dengan beberapa rumusan empiris, yaitu Mc. Guire, Fukushima-Tanaka, Esteva dan Donovan.  Data gempa yang digunakan adalah data gempa bumi di Pulau Lombok dan sekitarnya pada periode 1979-2018.  Hasil validasi menunjukkan rumusan Fukushima adalah rumusan terbaik untuk menghitung percepatan tanah di Pulau Lombok dengan persentase kesalahan rata-rata terendah 220%, sedangkan rumusan lainnya memiliki persentase kesalahan rata-rata Mc. Guire 2.586%, Esteva 614%, dan Donovan 3.906%.  Berdasarkan hasil yang diperoleh maka rumusan Fukushima-Tanaka adalah rumusan yang paling cocok untuk menghitung nilai percepatan tanah di Pulau Lombok. The calculation of Lombok Island ground acceleration values which are validated with the value of acceleration of the land at Mataram Stationhas been carried out.  Land accelerationis calculated by severa...

The August 19, 1977 earthquake was one of the major earthquakes that ever occurred in the Nusa Tenggara region with an impact on the island of Lombok, one of which was in Kuta Village. The purpose of this research is to determine the empirical equation that is suitable for use in Kuta Village to calculate the Peak Ground Acceleration (PGA) value in the form of a distribution map. The PGA value can provide an overview of the damage to buildings caused by the earthquake. The PGA calculation uses several empirical equations of Donovan, M.C.Guirre, Esteva and Oliviera. Earthquake data obtained through data released from the USGS and the destructive earthquake catalog. The PGA value obtained with the Donovan empirical equation is a PGA value that is close to the value from the results of the BMKG Shakemap scenario with the MMI III scale. This earthquake did not cause damage to the Kuta Village area but damage was caused by the tsunami after the earthquake occurred.

This document represents a compilation of recommendations for the USGS component of the Earthquake Hazard Reduction Program (EHRP) to be conducted during the next five years. These recommendations represent the proceedings of a workshop entitled "Earthquake Engineering and Risk" organized to review the 5 Year EHRP Plan of the USGS. The workshop focused on products and issues important for Earthquake Engineering, which as a profession requires information from all major components of the EHRP. Workshop discussion also emphasized the importance of these products for earthquake insurance, emergency management, and disaster recovery. Recommendations of the working groups focused on the overall USGS EHRP, the National Seismic Hazard Mapping Project, and the National Strong-Motion Program. Written recommendations of the working groups, participants and invitees are provided in detail. A brief, but limited summary is presented here. Two types of products were identified by the workshop participants, basic or foundation products and high-level integrative products. Basic or foundation products identified to be of highest priority are: National earthquake catalog (incl. historic events) with consistent moment magnitudes for Mw > 3. Digital active fault data base (fault traces, recurrence times, slip rates, magnitudes ...) Strong motion recordings of all major damaging US earthquakes in densely urbanized areas Rapid dissemination of strong motion recordings via Internet, ftp, ... for disaster response, engineering, and research. Regionally-specific attenuation relationships Surficial geology and shallow Vs data bases and maps for urban areas

Three-component digital datafrom a 12-station seismological network in the Garhwal Himalaya have been used estimate the site effectsfrom S-wave componentsof eight local earthquakes and microtremors. These earthquakes (2.0 ≤ M L ≤2.92) have been occurred at epicentral distances between 100 km to 200 km from the center of the network with focal depths ranging from 2.5 km to 22.7 km. S-wave spectral ratios were computed from 273 waveforms in frequency range from 1 to 12 Hz considering PRT as a reference site. H/V spectral ratios in frequency range from 1 Hz to 25 Hz have been estimated from 117 samples of microtremors with duration ranging from 30 seconds to 280 seconds. From S-wave spectral ratios, higher amplifications have been brought out at sites located nearest to the epicenters of the earthquakes as compared to sites located away from the epicenters. Almost similar frequency dependent trends in the S-wave site amplifications in the radial and transverse components have been brought out at the majority of sites.High amplificationaround 10 Hz at CHN site seems to be due to topographic effect as the site is located on 2244 m high mountain peak. At most of the sites, the vertical components show consistently low site amplifications as compared to horizontal components particularly at frequencies above 4 Hz to 5 Hz. H/V spectral ratios from the microtremorsof morning hours have showndominant broad peaks between 3 Hz and 4 Hz at CNT, PRT, NTT and RAJ sites, whereas at all sites microtremors recorded in the afternoon show maximum peaks between 2 Hz and 4 Hz, and beyond 4 Hz the amplifications decreases. An interesting feature at NTT and AYR sites, is a sharp peak embedded in a broad peak around 4 Hz. This response seems to be due to the vibrations generated by the operation of turbines which are within the radius of 2 km to 3 km from the sites.

A single-axis Microelectromechanical system gravimeter has recently been developed at the University of Glasgow. The sensitivity and stability of this device was demonstrated by measuring the Earth tides. The success of this device was enabled in part by its extremely low resonant frequency. This low frequency was achieved with a geometric anti-spring design, fabricated using well-established photolithography and dry etch techniques. Analytical models can be used to calculate the results of these non-linear oscillating systems, but the power of finite element analysis has not been fully utilised to explore the parameter space before now. In this article, the results of previous analytical solutions are replicated using finite element models, before applying the same techniques to optimise the design of the gravimeter. These computer models provide the ability to investigate the effect of the fabrication material of the device: anisotropic <100> crystalline silicon. This is a parameter that is difficult to investigate analytically, but finite element modelling is demonstrated here to provide accurate predictions of real gravimeter behaviour by taking anisotropy into account. The finite element models are then used to demonstrate the design of a three-axis gravimeter enabling the gravity tensor to be measured-a significantly more powerful surveying tool than the original single-axis device.

In this paper we look at an issue rarely approached: the economic efficiency of earthquake risk mitigation. The urban scale at which a natural hazard can impact leads to the importance of urban planning strategy in risk management. However, usually natural, engineering, and social sciences deal with it, and the role of architecture and urban planning is neglected. We look at the way ICT can contribute to organize the information from the building survey to economic computations in direct modelling or through games. Also we take into consideration at a rare element, which is the role of landscape planning, through the inclusion of green elements in reconstruction.

The mapping of the seismic ground motion in Bucharest, due to the strong Vrancea earthquakes is carried out using a complex hybrid waveform modeling method which combines the modal summation technique, valid for laterally homogeneous anelastic media, with finite-differences technique, and optimizes the advantages of both methods. For recent earthquakes, it is possible to validate the modeling by comparing the synthetic seismograms with the records. We consider for our computations the frequency range from 0.05 to 1.0 Hz and control the synthetic signals against the accelerograms of the Magurele station, low-pass filtered with a cutoff frequency of 1.0 Hz of the 3 last major strong (M w > 6) Vrancea earthquakes. Using the hybrid method with a double-couple seismic source approximation, scaled for the source dimensions and relatively simple regional (bedrock) and local structure models, we succeeded in reproducing the recorded ground motion in Bucharest at a satisfactory level for seismic engineering. Extending the modeling to the entire territory of the Bucharest area, we construct a new seismic microzonation map, where five different zones are identified by their characteristic response spectra.

Objective: To investigate the dependence of maximum direction ground motions on magnitude, distance, and rupture directivity. Specifically, • Develop a non-parametric model of the ratio of the maximum direction (MD) to geometric mean (GMRotI50) motions using the Relevance Vector Machine. • Estimate the expected value of ln(MD/GMRotI50) and its standard deviation for different sets of predictors, and compare the results to those from the existing parametric models. Background: • MD motions define the design levels of ground motions in 2009 NEHRP Provisions. • Current seismic design maps are based on empirical models for a rotated geometric mean (GMRotI50). • The 2009 Provision maps assume MD/GMRotI50=1.1 for short periods and 1.3 for mid-periods. A more detailed investigation of the ratio, and its variability is needed. • Using a parametric model may introduce subjective bias into the predictions due to insufficient knowledge of earthquake processes.

A method is derived for the calculation of ground acceleration from geophone data using a frequency-domain inverse filter and an empirical scaling constant. Acceleration-domain spectra from geophones and MEMS accelerometers from an oilfield survey at Violet Grove, Alberta, Canada are compared. We find that the geophone and accelerometer data, over a band of 5-200 Hz, are very similar. The accelerometer amplitudes are larger than the geophones' below 5 Hz and there are some differences at very high freqencies. Significant events related to the first breaks are not observed on the accelerometer records at some stations.

Earthquake Early Warning Systems (EEWS) are often challenged when the earthquakes occur outside the seismic network or where the station density is sparse. In these situations, poor locations and large alert delays are more common because of the limited azimuthal coverage and the time required for the wavefield to reach the minimum number of seismic stations to issue an alert. Seismic arrays can be used to derive the directivity of the wavefield and obtain better location. However, they are uncommon because of the prohibitive cost of the sensors. Here, we propose the development of an array-based approach using mini-arrays of low-cost Microelectromechanical Systems (MEMS) accelerometers and show how they can be used to improve EEWS. In this paper, we demonstrate this approach using data from two MEMS Accelerometer Mini-Arrays (MAMA) deployed at University of California Berkeley and Humboldt State University. We use a new low-cost (

Digital Twins (DT) models are gaining special attention in the management and maintenance of facilities. The quality of data contained in these models may be enhanced by the use of processed information coming from long-term Structural Health Monitoring (SHM). In this case real time processing and updating in systems using sensor networks for SHM need low latency and reliable communication. This paper presents a solution for exploiting DT models for SHM and early warning solutions improvement. The case study scenario resides within the 5G experimentation in the city of L’Aquila and it exploits a highly adaptable sensor board and a 5G Multi-Access Edge Computing architecture.

The paper presents (i) historical earthquake damage and lessons learned (ii) how to strengthen tall reinforced concrete fragile buildings in central Bucharest, (iii) international projects for seismic risk reduction in Romania and (iv) the current challenges involved in conserving historical buildings in the center of Bucharest.

Pulau Lombok berada di antara dua lempeng besar yaitu lempeng Asia dan lempeng Australia sehingga Pulau Lombok sangat rawan terhadap guncangan gempa bumi dan pergeseran tanah. Faktor yang mempengaruhi nilai percepatan tanah maksimum yaitu kondisi geologi dan karakteristik wilayah tersebut. Penelitian ini dilakukan untuk menganalisis nilai percepatan tanah maksimum menggunakan rumus empiris Donovan, Guirre, dan Mickey di Pulau Lombok dengan data sekunder gempa bumi Lombok dari Juli September 2018. Hasil analisis menunjukkan bahwa nilai percepatan tanah maksimum paling tinggi sebesar 0,11191 gal yang terjadi di daerah Lombok Utara yang setelah kejadian gempa termasuk kategori mengalami kerusakan berat. Nilai percepatan tanah maksimum terkecil terjadi didearah Lombok Tengah dengan besar 0,03441 gal dan termasuk kategori sangat ringan. Dari ketiga rumusan, yang mendekati nilai percepatan tanah maksimum berdasarkan peta Shakemap yaitu rumusan Guirre.

Three-component digital datafrom a 12-station seismological network in the Garhwal Himalaya have been used estimate the site effectsfrom S-wave componentsof eight local earthquakes and microtremors. These earthquakes (2.0 ≤ M L ≤2.92) have been occurred at epicentral distances between 100 km to 200 km from the center of the network with focal depths ranging from 2.5 km to 22.7 km. S-wave spectral ratios were computed from 273 waveforms in frequency range from 1 to 12 Hz considering PRT as a reference site. H/V spectral ratios in frequency range from 1 Hz to 25 Hz have been estimated from 117 samples of microtremors with duration ranging from 30 seconds to 280 seconds. From S-wave spectral ratios, higher amplifications have been brought out at sites located nearest to the epicenters of the earthquakes as compared to sites located away from the epicenters. Almost similar frequency dependent trends in the S-wave site amplifications in the radial and transverse components have been brought out at the majority of sites.High amplificationaround 10 Hz at CHN site seems to be due to topographic effect as the site is located on 2244 m high mountain peak. At most of the sites, the vertical components show consistently low site amplifications as compared to horizontal components particularly at frequencies above 4 Hz to 5 Hz. H/V spectral ratios from the microtremorsof morning hours have showndominant broad peaks between 3 Hz and 4 Hz at CNT, PRT, NTT and RAJ sites, whereas at all sites microtremors recorded in the afternoon show maximum peaks between 2 Hz and 4 Hz, and beyond 4 Hz the amplifications decreases. An interesting feature at NTT and AYR sites, is a sharp peak embedded in a broad peak around 4 Hz. This response seems to be due to the vibrations generated by the operation of turbines which are within the radius of 2 km to 3 km from the sites.

ABSTRACTSince its deployment at the surface of Mars, the Seismic Experiment for Interior Structure (SEIS) instrument of the InSight mission has detected hundreds of small-magnitude seismic events. In this work, we highlight some features of two specific families: high-frequency (HF) and very-high-frequency (VF) events. We characterize the shape of the energy envelopes of HF and VF events with two parameters: (1) the delay time td between the onset and the peak of the dominant arrival; and (2) the quality factor Qc, which quantifies the energy decay rate in the coda. We observe that the envelope of HF and VF events is frequency independent. As a consequence, a single delay time suffices to characterize envelope broadening in the 2.5–7.5 Hz band. The typical coda decay time is also frequency independent, as attested by the close to linear increase of Qc with frequency. Finally, we use elastic radiative transfer theory to perform a series of inversion of seismogram envelopes for the at...

In this paper, we have studied the seismic activity in relation with geology, and tectonics in order to highlight seismogenic processes recorded in Danubian area and Hateg-Strei Basin. The Danubian seismogene area presents a complex geological structure, being characterized by the following tectonic units: Median Dacides (Getic and Supra-Getic nappes), Marginal Dacides (Danubian Unit) and External Dacides (Severin nappe). The recent seismic activity in this area, starting from 1990 until present, is described by the seismic sequence from 2002, in the Moldova Noua area, in connection to Oravita-Moldova Noua fault and by the seismic sequence from 1991, in the Baile Herculane area, belonging to the Cerna-Jiu fault system. Also, the Teregova area is present with the seismic sequence from 2014 and another two smaller sequences. From a statistical point of view, the seismicity is mainly described by the b-value coefficients from the empirical relation between the frequencies and magnitude...

This case study is about the foundation and the site geotechnical potential evaluation for the rehabilitation of an emergency hospital building, placed in Bucharest. This building was strongly damaged by the main earthquakes that occurred in Romania, within the last 30 years (March 4 th , 1977, August 30 th , 1986 and May 30 th , 1990). The building had, from the beginning, an unfavorable structural concept, in what concerns its shape in plane. The paper presents the methods used for the rehabilitation of the existing building foundation, together with the integration of a new foundation for a new building, that appeared necessary to be built, as a single solution for the strengthening of the old one. Important additional loads were considered for the proposed solution and thus an extensive study on the foundation and geotechnical aspects of the project were carried out, including a site geotechnical study, evaluation of bearing capacity and settlement, evaluation of safety factors on bearing capacity, before and after the strengthening. The paper also presents some considerations on the peculiarities of the seismic events that occur in Romania.

The SM-ROM-GL database includes data obtained by the processing of records performed at ground level by the Romanian seismic networks, namely INCERC, NIEP, NCSRR and ISPH-GEOTEC, during recent seismic events with moment magnitude Mw ≥ 5 and epicenters located in Romania. All the available seismic records were re-processed using the same basic software (from Kinemetrics, Inc.) and the same procedures and options (filtering and baseline correction), in order to obtain a consistent dataset. The database stores computed parameters of seismic motions, i.e. peak values: PGA, PGV, PGD, effective peak values: EPA, EPV, EPD, control periods: TB, TC, TD, spectral values of absolute acceleration, relative velocity and relative displacement, as well as of instrumental intensity (as defined in Sandi and Borcia, 2011a). The fields in the database include: coding of seismic events, stations and records, a number of associated fields (seismic event source parameters, geographical coordinates of sei...

A high-precision angular accelerometer based on molecular-electronic transfer (MET) technology with a high dynamic range and a low level of self-noise has been developed. Its difference from the analogues is in the use of liquid (electrolyte) as the inertial mass and the use of negative feedback based on the magnetohydrodynamic effect. This article reports on the development of the angular molecular-electronic accelerometer with a magnetohydrodynamic cell for the creation of negative feedback, and the optimization of electronics for the creation of a feedback signal. The main characteristics of the angular accelerometer, such as amplitude-frequency characteristics, self-noise and Allan variance were experimentally measured. The obtained output parameters were compared to its analogues and it showed perspectives for further development in this field.

Abstract. Bucharest is one of the most affected cities by earthquakes in Europe. Situated at 150–170 km distance from the Vrancea epicentral zone, Bucharest has suffered many damages due to high energy Vrancea intermediate-depth earthquakes. For example, the 4 March ...

Structural engineering involves clear understanding of characteristics of ground motion used in the design of structures to identify the critical aspects of their behavior. Peak amplitude of response (a, v, or d), predominant frequency and duration of strong ground motion are the most important parameters of ground motion that are required for this purpose. These parameters are influenced by the source, path and site conditions. However, it is also found that for the same distance these characteristics are highly sensitive to the fault direction and the side on which the site lies i.e., hanging wall or foot wall. In this paper, a case study is performed to understand the influence of fault direction and location of site on the characteristics of the ground motion. For this purpose, 371 ground motions recorded during 1999 Chi-Chi, Taiwan earthquake are selected. Initially, these ground motions were arranged in terms of fault parallel and fault normal direction and also according to d...

During 2017–2018, the National Seismic Hazard Model for the conterminous United States was updated as follows: (1) an updated seismicity catalog was incorporated, which includes new earthquakes that occurred from 2013 to 2017; (2) in the central and eastern United States (CEUS), new ground motion models were updated that incorporate updated median estimates, modified assessments of the associated epistemic uncertainties and aleatory variabilities, and new soil amplification factors; (3) in the western United States (WUS), amplified shaking estimates of long-period ground motions at sites overlying deep sedimentary basins in the Los Angeles, San Francisco, Seattle, and Salt Lake City areas were incorporated; and (4) in the conterminous United States, seismic hazard is calculated for 22 periods (from 0.01 to 10 s) and 8 uniform VS30 maps (ranging from 1500 to 150 m/s). We also include a description of updated computer codes and modeling details. Results show increased ground shaking i...

ANALISIS PERCEPATAN TANAH MAKSIMUM DENGAN MENGGUNAKAN RUMUSAN ESTEVA DAN DONOVAN (Studi Kasus Pada Semenanjung Utara Pulau Sulawesi) ABSTRAK Telah dilakukan analisis percepatan tanah maksimum di semenanjung utara Pulau Sulawesi dengan menggunakan rumusan Esteva dan rumusan Donovan. Data yang digunakan adalah data gempa bumi tektonik yang terjadi di sekitar semenanjung utara Pulau Sulawesi pada periode tahun 2008 – 2014. Hasil analisis menunjukkan bahwa perubahan nilai percepatan tanah dari rumusan Esteva dan rumusan Donovan memiliki pola perubahan yang sama terhadap jarak. Nilai percepatan tanah menurut rumusan Donovan lebih tinggi dibandingkan dari rumusan Esteva. Perbandingan dengan data akselerograf mengindikasikan bahwa rumusan Esteva lebih cocok digunakan dalam mengestimasi percepatan tanah maksimum di semenanjung utara Pulau Sulawesi. Hasil pemetaan sebaran percepatan tanah maksimum menunjukkan bahwa wilayah Kabupaten Minahasa Utara berada pada zona dengan resiko yang lebih ti...

Structural engineering involves clear understanding of characteristics of ground motion used in the design of structures to identify the critical aspects of their behavior. Peak amplitude of response (a, v, or d), predominant frequency and duration of strong ground motion are the most important parameters of ground motion that are required for this purpose. These parameters are influenced by the source, path and site conditions. However, it is also found that for the same distance these characteristics are highly sensitive to the fault direction and the side on which the site lies i.e., hanging wall or foot wall. In this paper, a case study is performed to understand the influence of fault direction and location of site on the characteristics of the ground motion. For this purpose, 371 ground motions recorded during 1999 Chi-Chi, Taiwan earthquake are selected. Initially, these ground motions were arranged in terms of fault parallel and fault normal direction and also according to d...

We describe the first dense real-time urban seismic–accelerometric network in Italy, named OSU-CT, located in the historic center of Catania. The city lies in the region with the greatest danger, vulnerability, and earthquake exposure in the entire Italian territory. OSU-CT was planned and realized within the project called EWAS “an Early WArning System for cultural heritage”, aimed at the rapid assessment of earthquake-induced damage and the testing of an on-site earthquake early warning system. OSU-CT is mainly based on low-cost instrumentation realized ad hoc by using cutting-edge technologies and digital MEMS (micro-electro-mechanical systems) triaxial accelerometers with excellent resolution and low noise. Twenty of the forty scheduled stations have already been set up on the ground floor of significant historic public buildings. In order to assess the performance of an earthquake early warning (EEW) on-site system, we also installed wide-band velocimeters (ETL3D/5s) in three e...

Based on the earthquake event data accumulated by the Turkish National Seismic Network between 2007 and 2013, the local magnitude (Richter, Ml) scale is calibrated for Turkey and the close neighborhood. A total of 137 earthquakes (Mw > 3.5) are used for the Ml inversion for the whole country. Three Ml scales, whole country, East, and West Turkey, are developed, and the scales also include the station correction terms. Since the scales for the two parts of the country are very similar, it is concluded that a single Ml scale is suitable for the whole country. Available data indicate the new scale to suffer from saturation beyond magnitude 6.5. For this data set, the horizontal amplitudes are on average larger than vertical amplitudes by a factor of 1.8. The recommendation made is to measure Ml amplitudes on the vertical channels and then add the logarithm scale factor to have a measure of maximum amplitude on the horizontal. The new Ml is compared to Mw from EMSC, and there is almost a 1:1 relationship, indicating that the new scale gives reliable magnitudes for Turkey.

The reference rock site condition is defined by the shear (S)-and compression (P)-wave velocities, as well as a site attenuation parameter (0 ). The significance of the reference rock is that it represents the site condition for which ground motions will be estimated using semi-empirical ground motion prediction equations (GMPEs). Moreover, it is the site condition where site amplification are referenced to (i.e., site amplification is unity for reference rock). This paper presents the recommendation of a reference S-wave velocity, a reference P-wave velocity, and S-wave site attenuation parameter, 0  , associated with a reference rock site condition in Central and Eastern North America (CENA), supported by results of a comprehensive literature search and additional studies. The work is part of the Next Generation Attenuation Relationships for Central and Eastern North America (NGA-East) Project. The recommended Sand P-wave velocities are 3,000 and 5,500 m/sec, respectively. Considering a  5% impact on the site amplification, ranges for the reference Sand P-wave velocities of 2,700 to 3,300 m/sec and 5,000 to 6,100 m/sec, respectively, are recommended. The recommended reference rock site kappa is 0.006 sec. The uncertainty in the site kappa is described using a log-normal distribution with an aleatory standard deviation of 0.43, and epistemic standard deviations of 0.12, when uncertainty in source, path, and site-amplification effects are included in simulations used to develop ground motion prediction equations, and 0.20, when they are not.

Three-component digital datafrom a 12-station seismological network in the Garhwal Himalaya have been used estimate the site effectsfrom S-wave componentsof eight local earthquakes and microtremors. These earthquakes (2.0 ≤ M L ≤2.92) have been occurred at epicentral distances between 100 km to 200 km from the center of the network with focal depths ranging from 2.5 km to 22.7 km. S-wave spectral ratios were computed from 273 waveforms in frequency range from 1 to 12 Hz considering PRT as a reference site. H/V spectral ratios in frequency range from 1 Hz to 25 Hz have been estimated from 117 samples of microtremors with duration ranging from 30 seconds to 280 seconds. From S-wave spectral ratios, higher amplifications have been brought out at sites located nearest to the epicenters of the earthquakes as compared to sites located away from the epicenters. Almost similar frequency dependent trends in the S-wave site amplifications in the radial and transverse components have been brought out at the majority of sites.High amplificationaround 10 Hz at CHN site seems to be due to topographic effect as the site is located on 2244 m high mountain peak. At most of the sites, the vertical components show consistently low site amplifications as compared to horizontal components particularly at frequencies above 4 Hz to 5 Hz. H/V spectral ratios from the microtremorsof morning hours have showndominant broad peaks between 3 Hz and 4 Hz at CNT, PRT, NTT and RAJ sites, whereas at all sites microtremors recorded in the afternoon show maximum peaks between 2 Hz and 4 Hz, and beyond 4 Hz the amplifications decreases. An interesting feature at NTT and AYR sites, is a sharp peak embedded in a broad peak around 4 Hz. This response seems to be due to the vibrations generated by the operation of turbines which are within the radius of 2 km to 3 km from the sites.

1992). The 1985 M 6.9 Nahanni earthquake produced horizontal accelerations of 1.2 g and a peak vertical acceleration > 2 g (Weichert et al., 1986). The 1989 M 7.0 Loma Prieta, California, earthquake occurred on an unidentified steeply-dipping fault adjacent to the San Andreas fault, with reverse-slip on half of the fault (Hanks and Krawinkler, 1991), and produced significant damage > 100 km away related to critical reflections of shear-waves off the Moho (Somerville and Yoshimura, 1990; Catchings and Kohler, 1996). The 1992 M 7.0 Petrolia, California, earthquake produced peak horizontal accelerations > 1.4 g (Oglesby and Archuleta, 1997). The 1992 M 7.4 Landers, California, earthquake demonstrated that multisegment fault rupture could occur on fault segments with substantially different orientations that are separated by several km (Li et al., 1994). The 1994 M 6.7 Northridge, California, earthquake produced a then world-record peak horizontal velocity (> 1.8 m/s) associated with rupture directivity (O'Connell, 1999a), widespread nonlinear soil responses (Field et al., 1997; Cultera et al., 1999), and resulted in substantial revision of existing ground motion-attenuation relationships (Abrahamson and Shedlock, 1997). The 1995 M 6.9 Hyogoken Nanbu (Kobe) earthquake revealed that basin-edge generated waves can strongly amplify strong ground motions (Kawase, 1996; Pitarka et al., 1998) and provided ground motion recordings demonstrating time-dependent nonlinear soil responses that amplified and extended the durations of strong ground motions (Archuleta et al., 2000). The 1999 M > 7.5 Izmit, Turkey, earthquakes produced asymmetric rupture velocities, including rupture velocities ~40% faster than shear-wave velocities, which may be associated with a strong velocity contrast across the faults (Bouchon et al., 2001). The 1999 M 7.6 Chi-Chi, Taiwan, earthquake produced a world-record peak velocity > 3 m/s with unusually low peak accelerations (Shin et al., 2000). The 2001 M 7.7 Bhuj India demonstrated that M > 7.5 blind thrust earthquakes can occur in intraplate regions. The M 6.9 2008 Iwate-Miyagi, Japan, earthquake produced a current world-record peak vector acceleration > 4 g, with a vertical acceleration > 3.8 g (Aoi et al., 2008). The 2011 M 9.1 Tohoku, Japan, earthquake had a world-record peak slip on the order of 60 m (Shao et al., 2011) and produced a world-record peak horizontal acceleration of 2.7 g at > 60 km from the fault (NIED, 2011). This progressive sequence of ground motion surprises suggests that the current state of knowledge in strong motion seismology is probably not adequate to make unequivocal strong ground motion predictions. However, with these caveats in mind, strong ground motion estimation provides substantial value by reducing risks associated with earthquakes and engineered structures. We present the current state of earthquake ground motion estimation. We start with seismic source characterization, because this is the most important and challenging part of the problem. To better understand the challenges of developing ground motion prediction equations (GMPE) using strong motion data, we present the physical factors that influence strong ground shaking. New calculations are presented to illustrate potential pitfalls and identify key issues relevant to ground motion estimation and future ground motion research and applications. Particular attention is devoted to probabilistic implications of all aspects of ground motion estimation.

Recent years have shown that all manner of disasters have become increasingly damaging, dangerous and complex. Recent examples include the 2004 South Asian tsunami, Hurricane Katrina in 2005, and the Sichuan earthquake of 2008. Disasters like these have, for years, been understood as neither strictly man-made or strictly natural; most disasters are a complex blend physical forces and social organization. And some disasters, such as the Madrid bombings of 2004 and the London bombings of 2005, are man-made, but their effects are vast, with structural, social, and environmental ramifi cations that reverberate locally, nationally, and globally. We cannot explain the full complexity of these events using singlediscipline approaches. This series will therefore reflect and promote the increasingly interdisciplinary nature of hazards and disaster research. Its reach will be wide because hazards research is very broad, encompassing such varied fields of study as research on industrial accidents, research on public health, biosecurity issues and "homeland security", just to name a few. And its reach will include an wide array of facets because scholars from the social, natural, and behavioral sciences have concluded that we cannot fully understand hazards and disasters without an appreciation for the social, natural and man-made environments involved. In addressing the technical, social and environmental issues of hazards and disasters, this series will include up-to-date, comprehensive texts on key hazards and disasters at the local, regional, national, and global levels. It will cover numerous issues critical to successful research and practice and will consider these issues through an international lens. And it will involve all fi elds connected to the study of hazards and natural disasters, including disciplines found within the natural sciences, physical sciences, social sciences, and engineering. The series' coverage will therefore be broad, but it will be centered on the interactions between society, technology, and the natural environment in the hazards and disasters field.