Earthquake Period Research Articles

Seismic Safety Evaluation of Mechanically Stabilized Earth (MSE) Wall for Highway Construction

The usage of Mechanically Stabilized Earth (MSE) Walls has grown in popularity over the last few decades and has been widely used in many countries for highway construction, including Indonesia. As a country with a high risk against seismic hazards, a considerable stability analysis against earthquakes for construction must be conducted. This paper is directed to evaluate the static and seismic stability of MSE wall by adopting design criteria from SNI 8460:2017 using the pseudo-static approach with Limit Equilibrium Method (LEM) which modelling earthquake as a seismic coefficient, a one-way constant load and dynamic response approach with Finite Element Method (FEM) which modelling earthquake as ground motion, a fluctuating load which varies in time. The stability analysis is performed by considering three failure mechanisms that mostly occurred in MSE Walls; base sliding, tensile overstress, and slope failure. The earthquake load is modelled based 1000-year return period earthquake. Based on the analysis result, the most potential failure mechanism that may occur in the MSE wall is tensile overstress, while the least potential failure is base sliding. The analysis result also shows that the finite element method obtained higher safety factors compared to limit equilibrium, while on the other hand, the remaining two failure mechanisms shows the different result, with the finite element method obtaining lower safety factors than limit equilibrium. Modelling seismic load as an accelerogram indicates that earthquakes have higher impacts on structure stability compared to seismic coefficient, based on seismic safety factor reduction of each method. Although show differences in the value of the safety factor, the minimum safety factor required still complies with both methods.

Deep Learning Forecasts Caldera Collapse Events at Kı̄lauea Volcano

AbstractDuring the 3 month long eruption of Kı̄lauea volcano, Hawaii in 2018, the pre‐existing summit caldera collapsed in over 60 quasi‐periodic failure events. The last 40 of these events, which generated Mw > 5 very long period (VLP) earthquakes, had inter‐event times between 0.8 and 2.2 days. These failure events offer a unique data set for testing methods for predicting earthquake recurrence based on locally recorded GPS, tilt, and seismicity data. In this work, we train a deep learning graph neural network (GNN) to predict the time‐to‐failure of the caldera collapse events using only a fraction of the data recorded at the start of each cycle. We find that the GNN generalizes to unseen data and can predict the time‐to‐failure to within a few hours using only 0.5 days of data, substantially improving upon a null model based only on inter‐event statistics. Predictions improve with increasing input data length, and are most accurate when using high‐SNR tilt‐meter data. Applying the trained GNN to synthetic data with different magma‐chamber pressure decay times predicts failure at a nearly constant stress threshold, revealing that the GNN is sensing the underling physics of caldera collapse. These findings demonstrate the predictability of caldera collapse sequences under well monitored conditions, and highlight the potential of machine learning methods for forecasting real world catastrophic events with limited training data.

Friction models of one-dimensional earthquakes

A number of fundamental characteristics of earthquake physics are reproduced by simple stick-slip friction models. These include creep motion, stick/slip periodic earthquakes, reduced frequency of occurrence for more energetic quakes, ground velocity proportional to slip duration, and ground displacement proportional to fault length. By confining attention to one dimension, these results are obtained analytically. Though many earthquake characteristics cannot be reproduced in a one-dimensional model, our simple approach nevertheless has pedagogical value in providing insight into some of the complicated dynamics of earthquakes.

Dynamic Response of Sand Cushion Layer Isolation Concrete Liquid Storage Structure with X-Type Soft Steel-SMA Shock Absorber Considering Long (Short) Period Earthquake

Dynamic Response of Sand Cushion Layer Isolation Concrete Liquid Storage Structure with X-Type Soft Steel-SMA Shock Absorber Considering Long (Short) Period Earthquake

Seismic evaluation and retrofit of a typical reinforced concrete hospital building in Indonesia with DCFP isolation system

In this paper, a study on seismic evaluation and retrofit of a typical reinforced concrete (RC) hospital building in Indonesia is presented. Seismic evaluation is performed against basic structural performance objectives outlined in the current code for structural seismic evaluation. The target building is a typical 5-story RC building designed by the 1970s Indonesia seismic and building codes, which imposed lower seismic demand and were not as strict as the current codes in the requirements for strength and ductility. The first part of the paper describes a seismic evaluation procedure against specific target performance levels. Nonlinear time history analysis (NLTHA) is conducted and structural performances were evaluated against structural responses (base shear force and inter-story drift ratio) and acceptance of seismic performance level for local (element rotational limit) and global (roof drift ratio) performance criteria under 225, 975, and 2475-year return period earthquake scenarios. Results reveal that seismic performances of some structural elements are unsatisfactory and under the acceptable performance level, especially for 2475-year return period (BSE-2 N/MCER) earthquake scenario. Seismic retrofit is thus recommended and the use of double-concave friction pendulum (DCFP) base-isolation system as a retrofit strategy is explored. The seismic performance of DCFP-retrofitted building is examined by NLTHA, where effectiveness of DCFP base-isolation system in improving seismic performance is confirmed by comparing structural responses, local and global structural performance of the existing building and the DCFP-retrofitted building under 2475-year return period earthquake scenario. Results of NLTHA demonstrate that local structural performance level has improved from Collapse Prevention to Immediate Occupancy level, whereas the global structural performance has improved from Limited Safety level to Operational level.

Potential deformation assessment of Semantok Main Dam in North Nganjuk Region at East Java Indonesia

Semantok Dam was constructed using a zone l embankment type and required safety measures for deformation control. This study aims to understand material specifications, geological conditions, and deformation behavior. The results of the material specifications indicate that the core material and fine filter material meet the design criteria. The geological conditions comprise sand, sandstone, and claystone. The rock’s bearing capacity and settlement in the core zone are considered safe. The elastic vertical deformation of the foundation, analyzed using a flexible foundation approach by Lord, is estimated to be between 4.36 and 6.10 cm. Dynamic analysis is also performed using the Plaxis 8.6 version software to estimate deformation. The software input includes soil properties from the borrow and quarry areas surrounding the dam site. Earthquake design criteria are based on the Operating Basis Earthquake (OBE) with a 100-year return period and the Maximum Design Earthquake (MDE) with a 10,000-year return period. The dynamic analysis results indicate that the maximum deformation during a 100-year return period earthquake is 7.37 cm (horizontal deformation) and 12.68 cm (vertical deformation). In the case of a 10,000-year return period earthquake, the maximum deformation is 83.41 cm (horizontal deformation) and 175 cm (vertical deformation) during rapid drawdown.

Islands of chaos in a sea of periodic earthquakes

Long paleoseismic records on mature faults suggest potentially chaotic recurrence patterns with cycles of strain accumulation and release that challenge simple slip- or time-predictable recurrence models. In apparent contradiction, the relatively small variability of earthquake recurrence times on these faults is often characterized as quasi-periodic, implying much regularity in the underlying mechanics. To reconcile these observations, we simulate one of the longest paleoearthquake records – the 24-event record from the Hokuri Creek site on the Alpine fault in New Zealand – using a physical model of rate- and state-dependent friction. In a parameter space formed by three non-dimensional parameters, a sea of parameters produces periodic earthquake recurrence behavior. Only a few models are characterized by fundamentally aperiodic recurrence patterns, in parametric islands of chaos. Complex models that produce partial and full ruptures of the Alpine fault can explain the earthquake recurrence behavior of the Alpine fault, reproducing up to 11 consecutive events of the Hokuri Creek paleoseismic record within uncertainties. The breakdown of the slip- and time-predictable recurrence patterns occurs for faults that are much longer than the characteristic nucleation size. The quasi-periodicity of seismic cycles is compatible with the nonlinear and potentially chaotic underlying mechanical system, posing an inherent challenge to long-term earthquake prediction.

Can Plate Bending Explain the Observed Faster Landward Motion of Lateral Regions of the Subduction Zone After Major Megathrust Earthquakes?

AbstractGreater landward velocities were recorded after six megathrust earthquakes in subduction zone regions adjacent to the ruptured portion. Previous explanations invoked either increased slip deficit accumulation or plate bending during postseismic relaxation, with different implications for seismic hazard. We investigate whether bending can be expected to reproduce this observed enhanced landward motion (ELM). We use 3D quasi‐dynamic finite element models with periodic earthquakes. We find that afterslip downdip of the brittle megathrust exclusively produces enhanced trenchward surface motion in the overriding plate. Viscous relaxation produces ELM when a depth limit is imposed on afterslip. This landward motion results primarily from in‐plane elastic bending of the overriding plate due to trenchward viscous flow in the mantle wedge near the rupture. Modeled ELM is, however, incompatible with the observations, which are an order of magnitude greater and last longer after the earthquake. This conclusion does not significantly change when varying mantle viscosity, plate elasticity, maximum afterslip depth, earthquake size, megathrust locking outside of the rupture, or nature and location of relevant model boundaries. The observed ELM consequently appears to reflect faster slip deficit accumulation, implying a greater seismic hazard in lateral segments of the subduction zone.

Quantitative evaluation of source parameters of historical earthquakes in southern Africa

Macroseismic intensity information is an important instrument in the evaluation of historical seismicity. In an effort to improve the current South African earthquake catalogue, available macroseismic information of historical and early instrumental period earthquakes were used to determine source parameters (epicentre and magnitude of events). Forty-six earthquakes with more than eight Intensity Data Points (IDPs) each were analysed. Of these earthquakes, 16 had 20 or more IDPs and three had more than 80. The IDPs were dominated by relatively low intensity values, mostly determined from human perception of shaking, rather than structural damage, which is consistent with a stable continental region. The source parameters of these earthquakes were computed using a suite of state-of-the-art 3rd generation techniques. The quality of obtained solutions was greatly influenced by the spatial distribution of the IDPs, which was not uniform for all the events, with some events having clustered IDPs whilst others were linearly distributed. As a result, a quality ranking system of the results was developed to give an indication of the confidence in the results. Of the 46 earthquakes analysed, 36 had good quality results. Twelve events analysed in this study are new events that were not in previous catalogues. The results obtained help in improving the earthquake catalogue of the region, as there is an increase in the number of events recoded in the historical and early-instrument period. This kind of work and results obtained highlight the value of seeking out additional contemporary sources in order to revise the source parameters of earthquakes for which no or only very limited instrumental information is available.

Liquefaction Potential Assessment for the City of Mamuju Sulawesi by using N-SPT based methods

Mamuju is the capital city of West Sulawesi Province which has experienced severe damages along its infrastructures due to Majene Earthquake Mw. 6.2 on January 15th 2021. On that event, liquefaction phenomenon has been found on several places, triggering foundation settlements of buildings. Unfortunately, information on Mamuju’s earthquake hazard is still inadequate, while earthquake hazard assessment is urgently needed. Therefore, this study aims to assess liquefaction potential for the city of Mamuju. Serial geotechnical investigations were undertaken through a number of boreholes and N-SPT measurements. For liquefaction assessment, methods of estimating CRRM=7.5 were used including NCEER (1996), Vancouver Task Force (2007), Chinese Code, Japanese Highway Bridge Code, Shibata (1981), Boulanger & Idriss (2014), Cetin et al. (2004), Seed et al. (1983), Tokimatsu & Yoshimi (1983), and Kokusho et al. (1983), while estimation of CSR, the Simplified method (Seed, 1974) was employed. The results show that the coastal areas in the city has a high level of susceptibility to liquefaction. The liquefaction thickness of the ground would be 8 m deep for a 0.367g seismic acceleration (200 years return period earthquake), and 10 – 16 m for 0.414g seismic acceleration (deterministic Mw 7.0 of Fault Mamuju). Ground settlement induced by liquefaction was computed based on Ishihara & Yoshimi (1992) method. It was found that the ground settlement could be 18 – 50 cm, and 31 – 71 cm for each assumed seismic acceleration. The validity of the method used in this study was examined through the comparation of predictive liquefaction thickness and ground settlement based on the empiric methods with the measured ones in the field.

Evidence of the climate control of strong seismicity in the Italian Apennines through groundwater recharge

This work explores the possibility that the destructive earthquakes occurring along the Apennine Chain in Italy are systematically triggered by groundwater recharge. The focus is on multi-year transitions toward phases of wet climate rather than on short-term heavy rainfall occurring in a few days or seasonally. The analysis takes into consideration the earthquakes with a moment magnitude of Mw ≥5.8 that have occurred since 1901. Their time distribution is compared with the fluctuations of the self-calibrated Palmer Drought Severity Index (scPDSI), an indicator of soil moisture, here assumed to be a proxy for groundwater recharge. It is found that the scPDSI evolved through six main oscillations lasting from 11 to 25 years, and that, with one exception, the strongest earthquake in each phase is placed within 2 years from the maximum of soil moisture. Based on a statistical test for pairs of point processes, such a coincidence indicates a significant synchrony between the two phenomena. In particular, the two strongest earthquakes of the study period (the 1915 Marsica earthquake and the 1980 Irpinia–Basilicata earthquake, with moment magnitudes of Mw 7.1 and 6.8, respectively) occurred exactly in the year of two of the largest peaks of scPDSI. The connection between wet climate conditions and the occurrence of strong earthquakes is further investigated by comparing the time distribution of Mw ≥6.1 historical earthquakes that have occurred since 1200 AD with the evolution of the Great Aletsch Glacier in Switzerland, representative of water accumulation at the continental level. Even in this case, the earthquakes clustered during time periods of increased precipitation and lower water evaporation, corresponding to the extreme phases of the Little Ice Age. The agreement of the results at different time scales and using different climate indexes leads to postulate a significant and systematic role of groundwater recharge in the triggering of large earthquakes along the Apennines. It is also suggested that the earthquakes might be triggered by pore-pressure propagation, where the necessary hydraulic continuity is made possible by the intersection of the shallow karst structures with the seismogenic faults.

Assessment of Seismic Loss in Surakarta School Buildings

Surakarta is a relatively small yet is categorized as a densely populated city. There are a lot of types of public buildings, such as hospitals, supermarkets, government infrastructures, and school buildings. The city has more than 1100 school buildings threatened by many potential earthquakes. The possibility of an earthquake hitting Surakarta may be fatal and cause significant losses of buildings. However, studies on seismic hazard of the city are still very rare and need more attention. This paper presents a recent study on the seismic loss assessment of school building in Surakarta. The survey has been conducted by a team to visit, check, record and document all the required information to obtain exposure, combined with the information from google map application, while the seismic hazard analysis was carried out using the event-based stochastic method. An open-source application, OpenQuake, was utilized to assess the seismic loss and the results were presented here. The elaborated analysis is presented concluding that the exposure and vulnerability of school buildings are very important factors to determine a risk of loss. It indicates that the wooden school building contributes a highest risk of loss, whereas the confined masonry ones give a lowest risk. Among the whole sub districts in Surakarta, it is assessed that Laweyan suffers the biggest seismic loss of 2.36 million USD due to 500 years return period earthquake and 5.39 million USD due to 2500 years return period earthquake. These results of this study are valuable information for government in order to overcome disaster mitigation policy of Surakarta.

Physics‐Based Model Reconciles Caldera Collapse Induced Static and Dynamic Ground Motion: Application to Kīlauea 2018

AbstractInflationary deformation and very long period (VLP) earthquakes frequently accompany basaltic caldera collapses, yet current interpretations do not reflect physically consistent mechanisms. We present a lumped parameter model accounting for caldera block/magma momentum change, magma chamber pressurization, and ring fault (assumed vertical) shear stress drop. Pressurization of the underlying magma chamber is represented by a tri‐axial expansion source, and the combined caldera block/magma momentum change by a vertical single force. The model is applied to Kīlauea 2018 caldera collapse events, accurately predicting near field static/dynamic ground motions. In addition to the tri‐axial expansion source, the single force contributes significantly to the VLP waveforms. For an average collapse event with fully developed ring fault, Bayesian inversion constrains ring fault stress drop to ∼0.4 MPa and the pressure increase to ∼1.9 MPa. That the predictions fit both geodetic and seismic observations confirms that the model captures the dominant caldera collapse mechanisms.

Identification of Paleoearthquakes and Coseismic Slips on a Normal Fault Using High-Precision Quantitative Morphology: Application to the Jiaocheng Fault in the Shanxi Rift, China

AbstractThe quantitative morphology of bedrock fault surfaces combined with aerial surveys and field identification is a useful approach to identify paleoearthquakes, obtain coseismic slips, and evaluate the seismogenic capacity of active faults in bedrock areas where traditional trenching methods are not applicable. Here, we report a case study of the Jiaocheng Fault (JCF) in the Shanxi Rift, China. Although several studies have been conducted on the JCF, its coseismic slip history and seismogenic capacity are still unclear. To address these problems, we investigated two bedrock fault surfaces, Sixicun (SXC) and Shanglanzhen (SLZ), on the JCF’s northern segment using quantitative morphological analysis together with aerial and field surveys. Quantitative fractal analysis based on the isotropic empirical variogram and moving window shows that both bedrock fault surfaces have the characteristics of vertical segmentation, which is likely due to periodic earthquakes, the coseismic slip of which can be determined by the height of the segments. Three seismic events at SXC, with a coseismic vertical slip of 1.74, 1.65, and 1.99 m, and three seismic events at SLZ, with a coseismic vertical slip of 1.32, 2.35, and 1.88 m, are identified. Compared with the previous studies, these three seismic events may occur in the Holocene, but it requires absolute dating ages to support, which is also the focus of our future work. Considering the seismologic capability (M>7.5) and the relationship between the recurrence interval of ~2.6 kyr and elapsed time of more than 3 kyr, the seismic hazard of the northern and middle segments of the JCF requires immediate attention.

Probabilistic Seismic Assessment of RC Tall Regular Buildings Having Special Moment Frames Subjected to Long-period Earthquakes

Numerous tall buildings in the world are located in cities near active faults. Generally, past near-fault earthquakes had predominant period greater than 1 sec. so called as long-period earthquakes. In such earthquakes, tall building having great natural period seems to be more vulnerable. In this research, seismic performance of RC tall buildings having special moment frames subjected to long-period earthquakes are assessed via fragility curves. Subsequently, three models of 15, 25 and 35 story buildings are modelled in OpenSEES and IDA analysis is performed under long and short period earthquakes. Considering maximum nonlinear drifts as engineering demand parameter, seismic fragility curves at different performance levels are developed. By comparing the fragility curves and their median values, the effect of earthquake predominant period on the seismic performance of high-rise buildings are discussed. It is concluded that, the RC tall buildings, are more vulnerable in Long-period earthquakes compared with short period ones. At low damage levels such as slight and moderate, this difference seems to be small but for extensive and complete damage levels the considered models are much more fragile in long period records. So that the average values of seismic fragility for 35 story building model Subjected to short-period earthquakes at partial, medium, wide and complete damage levels are equal to the values of 0.084g, 0.16g, 0.44g and 0.95g, respectively. However, these values are equal to 0.032g, 0.065g, 0.175g and 0.39g, respectively, for earth motion with high period. As in complete damage level the seismic median fragility decreased 60 % for long- period earthquakes.

Repeating caldera collapse events constrain fault friction at the kilometer scale

Fault friction is central to understanding earthquakes, yet laboratory rock mechanics experiments are restricted to, at most, meter scale. Questions thus remain as to the applicability of measured frictional properties to faulting in situ. In particular, the slip-weakening distance [Formula: see text] strongly influences precursory slip during earthquake nucleation, but scales with fault roughness and is challenging to extrapolate to nature. The 2018 eruption of K̄ılauea volcano, Hawaii, caused 62 repeatable collapse events in which the summit caldera dropped several meters, accompanied by [Formula: see text] 4.7 to 5.4 very long period (VLP) earthquakes. Collapses were exceptionally well recorded by global positioning system (GPS) and tilt instruments and represent unique natural kilometer-scale friction experiments. We model a piston collapsing into a magma reservoir. Pressure at the piston base and shear stress on its margin, governed by rate and state friction, balance its weight. Downward motion of the piston compresses the underlying magma, driving flow to the eruption. Monte Carlo estimation of unknowns validates laboratory friction parameters at the kilometer scale, including the magnitude of steady-state velocity weakening. The absence of accelerating precollapse deformation constrains [Formula: see text] to be [Formula: see text] mm, potentially much less. These results support the use of laboratory friction laws and parameters for modeling earthquakes. We identify initial conditions and material and magma-system parameters that lead to episodic caldera collapse, revealing that small differences in eruptive vent elevation can lead to major differences in eruption volume and duration. Most historical basaltic caldera collapses were, at least partly, episodic, implying that the conditions for stick-slip derived here are commonly met in nature.

DYNAMIC RESPONSE ANALYSIS AND PRELIMINARY VERIFICATION OF HYBRID TEST OF WIND POWER TOWER UNDER THE COUPLING OF LONG PERIOD GROUND MOTION AND FLUCTUATING WIND

With the increasing demand of green energy, the location of wind farms has gradually developed towards to the earthquake-prone zones in China, causing wind turbines to face severe earthquake threats. Therefore, it is necessary to involve the case of coupled-earthquake-wind loads in the design of wind turbines. The horizontal-axis wind turbines with three blades are the most widely used, which are tall and flexural with a long nature period of vibration. This kind of wind turbines are more sensitive to long period earthquakes. It focus on the dynamic responses of the operating wind turbines under long period earthquakes. Taking a 1.5 MW wind turbine as the prototype, a finite element model was built in ABAQUS firstly using shell elements to simulate the seismic behavior. Then, the fluctuating wind loads were generated based on Kaimal spectrum and the dynamic response of the wind turbine is analyzed under coupled-earthquake-wind loads. Results show that the maximum displacement of tower top provided by long-period earthquakes is significantly amplified. The long-period earthquakes should be taken as one of the dominant loads for wind turbines. Finally, a software platform of hybrid simulation for wind turbines under wind-earthquake loads is developed to solve the problems of the complex loads and the small-scale specimens of wind turbines. The results provided by the numerical hybrid simulation are compared to those provide by ABAQUS model. The consistent results indicate the feasibility of the hybrid simulation.

Analysis of Basic Hazard Parameters Before and After the February 6, 2017 Ayvacik Earthquake (Mw=5.4)

Kuzeybatı Ege bölgesinin en karmaşık tektonik unsurlarını barındıran Biga Yarımadası oldukça yoğun bir dep-remsellik gösterir. Bu yarımada ve yakın çevresi için farklı dönemlerde meydana gelen orta ve büyük depremlerin deprem tehlikesi analizi, çalışmanın temelini oluşturmaktadır. Temel deprem parametreleri olarak da bilinen a ve b-değerleri bu çalışmanın veri tabanı olan aletsel dönem deprem kataloğundaki M>2 için belirlenmiş ve değerlendi-rilmiştir. Bu çalışmada, ÇOMÜ) ve KRDAE tarafından işletilen deprem istasyonları ve buna bağlı yüksek kaliteli faz okumaları sonucuna dayalı ortak bir deprem kataloğu kullanılmıştır. Ayvacık başta olmak üzere ve yakın çevresinde 6 Şubat 2017’de meydana gelen Mw=5.4 büyüklüğündeki deprem ile başlayan ve süreklilik gösteren deprem sonrası aktivitenin Tuzla deformasyon zonu çevresinde yaklaşık 25x10 km’lik bir alanda kümelendiği gözlenmiştir. Bu deprem öncesi ve sonrası yerel tektonik yapılar ve gerilme durumları ile ilişkilendirilebilecek başta b-değeri olmak üzere olasılıksal parametreler de değerlendirilmiştir. Kısa ve uzun dönemde bu parametrelerin ana deprem öncesi ve sonrası azalım ve artış eğilimleri yerel ve bölgesel hâkim gerilmelerin yanında üst kabuktaki heterojenite ve jeotermal kaynaklar da göz önünde bulundurularak sismisite ve sismotektonik yapıya katkısı ve ilişkisi uzaysal ve zamansal olarak incelenmiştir. Saroz-Ayvacık-Edremit doğrultusunda alansal olarak deprem verisi yoğunluğu dikkate alındığında b-değerlerinin gerilmelerle ters orantılı olarak deprem öncesi artışı ve akabin-de de bu davranış azalımı 2014 ve 2017 depremleri ile kendisini göstermiştir.

Active Tectonics of the Frontal Himalayas: An Example from the Manzai Ranges in the Recess Setting, Western Pakistan

The Himalayan main frontal thrust (MFT) accommodates most of the present-day Indo–Asia convergence with related periodic earthquakes. The seismicity and deformation mechanism varies considerably across the frontal Himalayas. We mapped a segment (Manzai Ranges) of the MFT at the western margin of the Himalayas and analyzed its deformation mechanism and active tectonics using geomorphic indices and the Interferometric Synthetic Aperture Radar (InSAR) Small Baseline Subset (SBAS) technique. Two frontal thrust faults (Khirgi and Jandola) were mapped using Sentinel-2B band ratios in the study area. Water gaps were present in the form of deflected streams at the tip of the growing anticlines. The C-band RADAR interferometry (Sentinel-1A) showed an average uplift of 5–9 mm/year in the satellite line of sight (LOS) from May 2018 to October 2019. The velocity profiles show an uplift variation across the anticlines and may be related to the displacement transfer from the zone of compression in the Manzai Ranges to the zone of transpression in the Pezu–Bhittani Ranges. Four types of morphometric analyses were carried out to assess the relative tectonic activity, namely mountain front sinuosity index (Smf), valley floor width to height ratio (Vf), normalized longitudinal river profile, and normalized channel steepness index (Ksn). The landscape response to active tectonics in the study area was recorded as a deep fluvial incision in V-shaped valleys, convex river profiles, topographic breaks as knickpoints, and a high Ksn index. The geomorphic parameters show a relative increase in tectonic uplift and deformation from the Kundi anticline to the Khirgi and Manzai anticline. We concluded that the frontal structures in the western Himalayas are still going through an active phase of deformation and landscape development with both seismic and aseismic creep.

Vibration-based structural health monitoring of a RC-masonry tower equipped with non-conventional TMD

This article presents the development and the results of three years of implementation of an automated vibration-based structural health monitoring system for modal tracking the dynamic characteristics of a concrete-masonry Civic Tower in Rieti (Italy) equipped with a passive vibration control system, a Non-Conventional Tuned Mass Damper. The system is based on the data recorded by a small number of high-sensitivity accelerometers set on remote automated modal parameters tracking. The analysis of monitoring data highlights the main characteristics of the response of the tower to operational vibrations and low-return period earthquakes. Despite the low levels of vibration in operational conditions, the system can track the evolution of the structural frequencies along time and successfully capture their dependence from temperature, both daily and seasonally. Moreover, the robustness of the modal identification procedure allowed the detection of anomalous variation from the validated reference dynamics of the structure.