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Regular monitoring of the seismicity in north-eastern Italy began in 1977, one year after the strong earthquake that caused about 1000 victims in Friuli. Over the years, the monitoring network operated by OGS has increased, today reaching a consolidated level in terms of geometry and number of stations. Furthermore, the entire data acquisition and processing system, which has changed over the years, is currently also highly robust. After the huge number of studies on the 1976 seismic sequence and on the regional seismicity developed in the 1970s and 1980s, the present paper illustrates a comprehensive work on the subject since the beginning of the 21st century. With this work, we take up the thread and analyse the evolution of seismicity in the first two decades of the 21st century (2000-2021). As part of the study, we took a retrospective look at the qualitative development of the data provided by OGS over time, basically focusing on the earthquake catalogue obtained by the network recordings and developing a new relation for calculating the duration magnitude. [ABSTRACT FROM AUTHOR]

In the framework of a scientific collaboration with the National Society for Earthquake Technology, Nepal, after the M7.8 Gorkha earthquake on 25 April 2015, the National Institute of Oceanography and Experimental Geophysics, Italy, organised a geophysical survey at Kathmandu, in order to have a better understanding of the seismic response of the valley in which the city is located. The main goal was to improve the knowledge of the spectral amplification of the ground motion, due to the fluvio-lacustrine sediments that constitute the Kathmandu basin, by combining the noise ratio H/V technique and velocity dispersion curve analysis. Ambient noise recordings were performed mostly in the Lalitpur area as a single station, and also by an array using ReMi measurement. This study mainly investigates the southern part of the city that was not covered by previous studies. In order to assess the resonant conditions of the soil foundation, microtremor measurements were also performed at Swayambhunath (Monkey Temple) hill and a site close to Boudhanath Stupa, the two prominent Buddhist temples-cummonasteries that had suffered significant damage during the Gorkha earthquake. The results show that the frequencies at the bottom of the basin are apparently lower than previous surveys and consequently also its depth would be greater. [ABSTRACT FROM AUTHOR]

The article provides a comprehensive earthquake catalogue for the eastern Alps from 1977 to 2022, focusing on seismic activity in NE Italy. The National Institute of Oceanography and Applied Geophysics manages the Monitoring System for NE Italy, which monitors and researches earthquakes in the region. The catalogue includes earthquake locations and magnitudes, and the article explains the data sources and methods used. It also discusses the reliability of earthquake solutions and the selection process for creating the final catalog. The document is a list of references and citations for scientific papers and reports on earthquake monitoring, location determination, magnitude calculation, and historical analysis in northeastern Italy. These sources are valuable for researchers studying earthquakes in the region. [Extracted from the article]

The duration magnitudes in the North-Eastern Italy Seismic Network (OX) catalogue have been thoroughly revised. Historically, but also today for homogeneous continuity with the past, this catalogue, released yearly by the National Institute for Oceanography and Experimental Geophysics, provides local magnitudes in terms of duration magnitude (MD). Unfortunately, the earthquake total durations were calibrated on a local Richter magnitude (ML) data set characterized by a demonstrated small bias. In this work, based on a revised and corrected ML catalogue of the Trieste seismological station, computed in accordance with the original Wood Anderson requirements and validated in turn with the available moment magnitude estimates, new linear empirical regressions between ML and earthquake total duration have been performed, aimed at producing a homogeneous catalogue of locations and MD for the eastern Southern Alps. [ABSTRACT FROM AUTHOR]

North-eastern Italy is one of the most seismically active areas of Italy, being affected in the past by eight destructive earthquakes. This area is densely populated and heavily industrialized, hence its seismic monitoring is crucial for Civil Defense purposes. This task is managed by the Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), through its Centro Ricerche Sismologiche (CRS), that performs the automatic real-time locations through the Antelope® BRTT software package. An accurate choice of the Antelope® setting parameters is necessary to ensure the best performance of the real-time system, that means the most accurate location for the earthquakes with magnitude ML=2.5 (the alarm threshold), avoiding any false event. This goal was pursued by testing different parameters on a data set built with 295 earthquakes representative of the local seismicity. The tuned parameters were then validated on the earthquakes which occurred in the monitored area in 2011: all events with MML=2.5 were correctly detected and located with a median epicentral distance difference of 2 km with respect to the OGS catalogue. The OGS real-time system was tuned with these parameters that have been operating successfully since 2012. [ABSTRACT FROM AUTHOR]

Three hundred and seventy-five earthquakes recorded by the Trieste station in the eastern Alps in the early instrumental period, i.e., before the occurrence of the destructive event of May 6, 1976, have been located after painstaking gathering of seismograms and bulletins. Analysis of the statistical parameters of the locations, together with comparisons with other instrumental and macroseismic locations, have allowed us to assess the quality of the results obtained, taking into account the often limited nature of the data. Using a process of digitization and the study of seismograms, focal parameters, particularly the magnitude MW, have been recovered for three earthquakes of the 1950s and 1960s. [ABSTRACT FROM AUTHOR]

We present a case history of the complicated strong-motion responses at a site with an almost 1D structure (Buia) in the near field of four Mw 5.2-6.0 earthquakes in the Friuli Plain of Italy. In one case (15 September 1976, 09:21 UTC, Mw 6.0), the 47-rn alluvial cover of Buia experienced spectral amplitudes lower than its reference site on rock due to the different back azimuths from the source. The largest peaks at Buia occurred during an Mw 5.6 event. For practical purposes, we tested (1) subjectivity when preparing the 1D models (using a blind test with three experts); (2) 1D linear, linear-equivalent, or nonlinear modeling in common practice; and (3) the current seismic regulations. We also used noise recordings and the weakmotion velocities recorded for local events (with digital triplets on the top and the bottom of the alluvial cover). Buia's response to weak events was more stable than its response to strong ones. A simple ID model (five-layer) under linear conditions with good knowledge of the propagation velocities was able to reproduce the frequencies of the two relative strong-motion maxima with an average amplitude underestimation of 1.5. The nonlinear approach simulated the two recorded maxima with slight shifts in frequency. Because the disaggregation of the seismic hazard showed that the four destructive shocks studied represent the magnitude and distance ranges that dominate the hazard of Buia, we can conclude that the response spectra of the new Italian (and European) rules were sufficiently preventive, notwithstanding the aforementioned complications in the near field. [ABSTRACT FROM AUTHOR]

Thirty-three cases of sarcoidosis (4.4% of 746 patients) showed an alveolar radiological pattern. A study of pulmonary function was carried out in 25 patients and compared with that of 46 patients with the interstitial radiological type of sarcoidosis. Twenty-two cases have been followed up from one to six years after the initial examination. The radiographic lesions were most often bilateral and included nodules greater than 15 mm with ill-defined margins or diffuse, infiltrative, non-retractile opacities with fluffy margins. Bilateral mediastinal lymph nodes were present in 27 patients. In 20 patients an associated reticulation was found on radiography. In four patients an open lung biopsy was done. The granulomatous nodules were identical to those found in other forms of sarcoidosis, although they were more confluent in the affected areas. Clinical and functional findings did not differ from those in the more common forms of sarcoidosis. Alveolar sarcoidosis has a sudden course. The alveolar radiological patterns always disappeared, with or without steroid treatment, while reticular patterns persisted in four patients. Rapid radiological changes were observed. Some functional abnormalities persisted in cases that were followed. It is concluded that alveolar sarcoidosis is a distinct acute form of sarcoidosis. [ABSTRACT FROM AUTHOR]

We used all the macroseismic data of the Friuli, 6 May 1976 earthquake to: i) retrieve geometric and kinematic information on the source, by doing automatic nonlinear geophysical inversions; ii) to analyse site effects. The inversions were performed with the KF model of radiation of S body waves in the 10- to 100-km distance range from the source, using a genetic algorithm with niching (NGA). A solution with a N-dipping fault was obtained, with strike angle 266°±10°, dip angle 53°±8°, rake angle 71°±11°. For the site effects we used the type of soil, the depth of the bedrock, the simplified impedance classes and the NEHRP classification. A detailed analysis on the Gemona fan in the epicentral area was also done using intensities from 69 districts of the town. The general analysis confirms amplification on soft soils at great epicentral distances. The analysis of Gemona showed a striking correlation between the trend of macroseismic data and the contour lines of the topography of the fan, with maximum intensity (X-XI, i.e. 10.5) toward the apex of the fan and minimum intensity (VI-VII, i.e. 6.5) in the Friulian Plain beneath it. [ABSTRACT FROM AUTHOR]