Clues for a relation between rotational effects induced by the Mw6.3 2009 L’Aquila (Central Italy) earthquake and site and source effects

The Mw6.3 2009 L’Aquila earthquake produced an impressive number of rotational effects on vertically organized objects such as chimneys, pillars, capitals and gravestones. We present the dataset of such effects, that consists of 105 observations at 37 different sites and represents a compendium of earthquake-induced istances of rotational effects that is unprecedented in recent times. We find that the absolute majority of the reported effects was observed in the epicentral zone and that most of the observations are located where the MCS intensity is between 7 and 8-9. The evident asymmetry in the distribution of the rotational effects resembles the southeastward directivity of the macroseismic effects and highlights a significant convergence between rotations and damage. Finally, we perform some qualitative analyses to recognize and evaluate which *Manuscript Click here to download Manuscript: revised_text.doc 2 geological and seismological parameters can be significant contributors to local rotations. We find that surface geology and amplification of the seismic motion at each reported location strongly influence the occurrence and the nature of the earthquake-induced rotational effects. Conversely, the contribution of the pattern of slip distribution on the fault plane plays only a secondary role in enhancing the rotational motion at each site

Clues to the identification of a seismogenic source from environmental effects. The case of the 1905 Calabria (southern Italy) earthquake

The 8 September 1905 Calabria (Southern Italy) earthquake belongs to a peculiar family of highly destructive (I0=XI) seismic events, occurred at the dawning of the instrumental seismology, for which the location, geometry and size of the causative source are still substantially unconstrained. During the century elapsed since the earthquake, previous Authors identified three different epicenters that are more than 50 km apart and proposed magnitudes ranging from M≤6.2 to M=7.9. Even larger uncertainties were found when the geometry of the earthquake source was estimated. In this study, we constrain the magnitude, location and kinematics of the 1905 earthquake through the analysis of the remarkable environmental effects produced by the event (117 reviewed observations at 73 different localities throughout Calabria). The data used in our analysis include ground effects (landslides, rock falls and lateral spreads) and hydrological changes (streamflow variations, liquefaction, rise of water temperature and turbidity). To better define the magnitude of the event we use a number of empirical relations between seismic source parameters and distribution of ground effects and hydrological changes. In order to provide constraints to the location of the event and to the geometry of the source, we reproduce the coseismic static strain associated with different possible 1905 causative faults and compare its pattern to the documented streamflow changes. From the analysis of the seismically-induced environmental changes we find that: 1) the 1905 earthquake had a minimum magnitude M=6.7; 2) the event occurred in an offshore area west of the epicenters proposed by the historical seismic Catalogs; 3) it most likely occurred along a 100° N oriented normal fault with a left-lateral component, consistently with the seismotectonic setting of the area

I terrazzi marini nell'area di Capo Vaticano (Arco Calabro): solo un record di sollevamento regionale o anche di deformazione cosismica?

In questo lavoro presentiamo uno studio di dettaglio dei terrazzi nell’area di Capo Vaticano (Calabria tirrenica), insieme ad una revisione del piano quotato del terremoto del 1905. Il campo macrosismico rivisitato conferma che le massime intensità sono state raggiunte in un’area estesa fra Vibo Valentia e Capo Vaticano per un evento di magnitudo M=6.8±0.2; la più probabile struttura sismogenetica responsabile dell’evento è una faglia di dimensioni 36x14 km e direzione 80° (faglia “macrosismica”). Lo studio dei terrazzi ha invece messo in evidenza che l’area in studio è in sollevamento attivo da almeno 700.000 anni, che tale processo è in lieve ma progressivo aumento nel tempo, con tassi negli ultimi 124.000 leggermente inferiori a ~1 mm/anno, e che a settentrione di Capo Vaticano i terrazzi sono chiaramente tiltati verso Nord. Inoltre, le variazioni di quota osservate nelle paleolinee di riva a cavallo di una struttura tettonica ad andamento ONO-ESE indicano che tale struttura (faglia “geologica”) è attiva da almeno 330.000 anni, con tassi verticali medi che variano negli ultimi 215.000 anni fra 0,12 e 0,16 mm/anno. Per verificare quanto ognuna di queste due strutture fosse congruente con gli elementi geologici, topografici e macrosismici a disposizione, abbiamo calcolato il campo di deformazione indotto in superficie dall’azione della faglia “macrosismica” rispetto a quello della faglia “geologica”. Il confronto qualitativo fra le deformazioni aspettate evidenzia una buona congruenza nella risposta della faglia “geologica” e rafforza l’ipotesi che a tale struttura possa essere associato l’evento del 1905, anche alla luce di recenti localizzazioni ipocentrali ottenute da inversione di registrazioni storiche. The area of Capo Vaticano in western Calabria displays a well-developed suite of marine terraces. This same region was hit in 1905 by one of the strongest – and still poorly cleared – earthquakes of the instrumental era. Our revision of the intensity map of the event confirms the location of the most damaged area (between Vibo Valentia and Capo Vaticano) and indicates that the most likely source is a N80°-trending, 36(L) x 14(W) km structure with a macroseismic magnitude M=6.8±0.2. A detailed study of the marine terraces shows that sustained uplift has been the long-term dominant process of tectonic deformation in this area over the past 700 kyr, with an average long-term uplift rate slightly less than 1.0 mm/yr, and that terraces are tilted northward. Moreover, the four lowest paleoshorelines are displaced by a WNW-ESE trending fault, that indicates that the fault is active in the last 215,000 years with mean vertical slip rates of 0.12-0.16 mm/yr. Finally, we perform a qualitative comparison between the set of geological, topographic and macroseismic data available and the expected deformation fileds induced by each of the afore-mentioned faults. It is therefore suggested that the good response of the WNW-trending fault strenghtens the hypothesis of this structure as the source of the 1905 earthquake

The 1762 October 6 earthquake in the Middle Aterno Valley (L'Aquila, Central Italy): new constraints and new insights

The effort for reducing the uncertainties in the location and size of historical earthquakes, even moderate-size ones, is not a peripheral issue, as it plays a major role in the distribution of earthquake recurrence times that can affect the maps of seismic hazard of a territory. The L‟Aquila area (Abruzzo, Central Italy) struck by the April 6, 2009 Mw 6.3 seismic event is a typical example of an earthquake-prone region the location of whose historical seismicity needs to be better located. Thanks to a large body of geological, seismological and geodetic evidence the deep source of the 2009 mainshock has been imaged as a ~15 km-long, NW-trending, SWdipping, almost pure normal fault coinciding with the Paganica Fault accepted_Manuscript Click here to download Manuscript: accepted_source_file.doc 2 System at the surface (Fig. 1). Conversely, very few papers have addressed so far the issue of reconstructing the seismic history of the Paganica Fault, charting the relationships between this fault and the adjacent ones, and finding out the causative source for each of the earthquakes listed in the Italian earthquake Catalog (CPTI Working Group, 2004; Rovida et al., 2011)

Rotational Effects associated with ground motion during the Mw 6.3 2009 L’Aquila (Central Italy) Earthquake

The Mw 6.3 2009 L’Aquila (Central Italy) earthquake produced more than one hundred rotational effects on chimneys, pillars, capitals and gravestones. In this paper we focus on the 37 objects that can be more reliably considered as representative of pure rotational ground motion, and find a relation between the distribution of the observed rotations, the epicentral distance, the macroseismic intensities and the directivity effects that characterize the L’Aquila event. We also find sound relationships between the type of observed rotations and the geophysical, geotechnical and geomorphological characteristics of the site of observation. In downtown L’Aquila we find 1) a remarkable convergence between distribution of the rotations and of the damage; 2) 100% of the rotations occurred at sites characterized by high factors of amplification and poor geological setting; 3) the ground rotations are not strongly dependent on topographic effects. Finally, from quantitative analyses of GPS data we find that the effect of the seismic arrival on an individual vertical object retrieved rotated is an overall rotation with a substantially unpredictable directio

Accurate Optical Target Pose Determination For Applications In Aerial Photogrammetry

We propose a new design for an optical coded target based on concentric circles and a position and orientation determination algorithm optimized for high distances compared to the target size. If two ellipses are fitted on the edge pixels corresponding to the outer and inner circles, quasi-analytical methods are known to obtain the coordinates of the projection of the circles center. We show the limits of these methods for quasi-frontal target orientations and in presence of noise and we propose an iterative refinement algorithm based on a geometric invariant. Next, we introduce a closed form, computationally inexpensive, solution to obtain the target position and orientation given the projected circle center and the parameters of the outer circle projection. The viability of the approach is demonstrated based on aerial pictures taken by an UAV from elevations between 10 to 100 m. We obtain a distance RMS below 0.25 % under 50 m and below 1 % under 100 m with a target size of 90 cm, part of which is a deterministic bias introduced by image exposure

Performances of the Italian Seismic Network, 1985-2002: the hidden thing

Abstract Seismic data users and people managing a seismic network take a great interest in the potentiality of the data, with the difference that the former look at stability, the latter at improvements. In this work, we measure the performances of the Italian Telemetered Seismic Network in the years 1985-2002 by defining basic significant parameters and studying their evolution during those years. Then, we deal with the geological methods used to characterise or to plan seismic station deployments in a few cases. Last, we define the gain of the network as the percentage of well-located earthquakes with respect to the total recorded earthquakes. By analysing the distribution of non-located (“missed”) earthquakes, we suggest possible actions to take in order to increase the gain. Results show that completeness magnitude is 2.4 in the average over the analysed period, and it can be as low as 2.2 when we consider non-located earthquakes as well. Parameters such as the minimum recording distance and the RMS of the location decrease with time, reflecting improvements in the location quality. Methods for geologic and seismological characterisation of a possible station site also resulted to be effective. Finally, we represent the number of missed earthquakes at each station, showing that nine stations control more than 50% of all missed earthquakes, and suggesting areas in Italy where the network might be easily improved

A Deep Learning Approach to Ancient Egyptian Hieroglyphs Classification

Nowadays, advances in Artificial Intelligence (AI), especially in machine and deep learning, present new opportunities to build tools that support the work of specialists in areas apparently far from the information technology field. One example of such areas is that of ancient Egyptian hieroglyphic writing. In this study, we explore the ability of different convolutional neural networks (CNNs) to classify pictures of ancient Egyptian hieroglyphs coming from two different datasets of images. Three well-known CNN architectures (ResNet-50, Inception-v3 and Xception) were taken into consideration and trained on the available images. The paradigm of transfer learning was tested as well. In addition, modifying the architecture of one of the previous networks, we developed a specifically dedicated CNN, named Glyphnet, tailoring its complexity to our classification task. Performance comparison tests were carried out and Glyphnet showed the best performances with respect to the other CNNs. In conclusion, this work shows how the ancient Egyptian hieroglyphs identification task can be supported by the deep learning paradigm, laying the foundation for information tools supporting automatic documents recognition, classification and, most importantly, the language translation task

ON RAW INERTIAL MEASUREMENTS IN DYNAMIC NETWORKS

Dynamic Networks have been introduced in the literature to solve multi-sensor fusion problems for navigation and mapping. They have been shown to outperform conventional methods in challenging scenarios, such as corridor mapping or self-calibration. In this work we investigate the problem of how raw inertial readings can be fused with GNSS position observations in Dynamic Networks (DN) with the goal of i) limiting the number of unknowns in the estimation problem and ii) improving the conditioning of the normal equations arising in least-squares adjustments in the absence of spatial constraints (e.g., image observations). For that we propose a modified version of the well known IMU-preintegration method, accounting for a non-constant gravity model, the Earth rotation and the apparent Coriolis force, and we compare it with the conventional DN formulation in a emulated scenario. This consists of a fixed-wing UAV flying four times over a 2 km long corridor

The Generalized Method of Wavelet Moments with Exogenous Inputs: a Fast Approach for the Analysis of GNSS Position Time Series

The Global Navigation Satellite System (GNSS) daily position time series are often described as the sum of stochastic processes and geophysical signals which allow studying global and local geodynamical effects such as plate tectonics, earthquakes, or ground water variations. In this work we propose to extend the Generalized Method of Wavelet Moments (GMWM) to estimate the parameters of linear models with correlated residuals. This statistical inferential framework is applied to GNSS daily position time series data to jointly estimate functional (geophysical) as well as stochastic noise models. Our method is called GMWMX, with X standing for eXogeneous variable: it is semi-parametric, computationally efficient and scalable. Unlike standard methods such as the widely used Maximum Likelihood Estimator (MLE), our methodology offers statistical guarantees, such as consistency and asymptotic normality, without relying on strong parametric assumptions. At the Gaussian model, our results show that the estimated parameters are similar to the ones obtained with the MLE. The computational performances of our approach has important practical implications. Indeed, the estimation of the parameters of large networks of thousands of GNSS stations quickly becomes computationally prohibitive. Compared to standard methods, the processing time of the GMWMX is over $1000$ times faster and allows the estimation of large scale problems within minutes on a standard computer. We validate the performances of our method via Monte-Carlo simulations by generating GNSS daily position time series with missing observations and we consider composite stochastic noise models including processes presenting long-range dependence such as power-law or Mat\'ern processes. The advantages of our method are also illustrated using real time series from GNSS stations located in the Eastern part of the USA.Comment: 30 pages, 11 figures, 3 table