Calibration of Soil Amplification Factors for Real-Time Ground-Motion Scenarios in Italy

This study deals with the calibration of soil amplification factors to be used for generating site-specific, real-time (or quasi real-time) ground-motion scenarios in Italy. To this end, the ground response of 100 soil profiles is studied through 1-dimensional (1D) equivalent-linear numerical simulations. Several real, rock ground-motion time histories, grouped into different peak ground acceleration (PGA) classes, are driven through the models of the soil columns. Soil amplification factors are then calculated using different definitions, either as the ratio of the spectral acceleration at the surface to the spectral acceleration at the rock outcrop or by dividing the (acceleration or pseudo-velocity) response spectrum intensity at the surface to the reference response spectrum intensity. Finally, regression analyses are performed to derive empirical equations that relate the amplification factor to different soil parameters, such as the average shear wave velocity VS,30 in the top 30 m of a soil profile and the soil fundamental frequency, f0. The reliability of the amplification factors here calculated is verified through comparison with experimental data recorded during the April 6, 2009 L’Aquila earthquake (Mw = 6.3)

Detection of Spatial and Temporal Stress Changes During the 2016 Central Italy Seismic Sequence by Monitoring the Evolution of the Energy Index

We consider approximately 23,000 microearthquakes that occurred between 2005 and 2016 in central Italy to investigate the crustal strength before and after the three largest earthquakes of the 2016 seismic sequence (i.e., the Mw 6.2, 24 August 2016 Amatrice, the Mw 6.1, 26 October 2016 Visso, and the Mw 6.5, 30 October 2016 Norcia earthquakes). We monitor the spatiotemporal deviations of observed radiated energy, ES, with respect to theoretical values, ESt, derived from a scaling model between ES and M0 calibrated for background seismicity in central Italy. These deviations, defined here as Energy Index (EI), allow us to identify in the years following the Mw 6.1, 2009 L’Aquila earthquake a progressive evolution of the dynamic properties of microearthquakes and the existence of high EI patches close to the Amatrice earthquake hypocenter. We show the existence of a crustal volume with high EI even before the Mw 6.5 Norcia earthquake. Our results agree with the previously suggested hypothesis that the Norcia earthquake nucleated at the boundary of a large patch, highly stressed by the two previous mainshocks of the sequence. We highlight the mainshocks interaction both in terms of EI and of the mean loading shear stress associated to microearthquakes occurring within the crustal volumes comprising the mainshock hypocenters. Our study shows that the dynamic characteristics of microearthquakes can be exploited as beacons of stress change in the crust and thus be exploited to monitor the seismic hazard of a region and help to intercept the preparation phase of large earthquakes

Long-range dependence in earthquake-moment release and implications for earthquake occurrence probability

Since the beginning of the 1980s, when Mandelbrot observed that earthquakes occur on 'fractal' self-similar sets, many studies have investigated the dynamical mechanisms that lead to self-similarities in the earthquake process. Interpreting seismicity as a self-similar process is undoubtedly convenient to bypass the physical complexities related to the actual process. Self-similar processes are indeed invariant under suitable scaling of space and time. In this study, we show that long-range dependence is an inherent feature of the seismic process, and is universal. Examination of series of cumulative seismic moment both in Italy and worldwide through Hurst's rescaled range analysis shows that seismicity is a memory process with a Hurst exponent H 48 0.87. We observe that H is substantially space-and time-invariant, except in cases of catalog incompleteness. This has implications for earthquake forecasting. Hence, we have developed a probability model for earthquake occurrence that allows for long-range dependence in the seismic process. Unlike the Poisson model, dependent events are allowed. This model can be easily transferred to other disciplines that deal with self-similar processe

Site Amplifications in the epicentral area of the 2016, M 6, Amatrice earthquake (Italy)

The first mainshock (Mw 6.0) of the 2016 Central Italy seismic sequence, severely struck the Amatrice village and the surrounding localities. After a few days, some Italian Institutions, coordinated by the “Center for Seismic Microzonation and its applications”, carried out several preparatory activities for seismic microzonation of the area. A temporary seismic network was installed that monitored about 50 sites in epicentral area. The network produced a huge amount of records in a wide range of magnitude up to Mw 6.5. For about half of the recording stations, detailed site characterization was undertaken, encompassing single station noise measurements and S-wave velocity profiles. The geological and geophysical data together with the collected dataset of seismic signals were exploited to investigate the site response of selected stations. Significant amplifications are found in the correspondence of several sites that experienced a high level of damage (Imcs >IX), mainly at short and intermediate periodsPublishedRoma5T. Sismologia, geofisica e geologia per l'ingegneria sismic

Serum levels of VCAM-1 are associated with survival in patients treated with nivolumab for NSCLC

Background High circulating levels of cellular adhesion molecules (CAMs) in non-small cell lung cancer (NSCLC) have been supposed to act as a negative prognostic factor. Here, we explored the predictive role of pre-treatment levels of CAMs in previously treated patients receiving nivolumab for NSCLC. Materials and methods Seventy one patients with advanced NSCLC, treated with nivolumab at the dose of 3 mg/kg every 14 days, were enrolled. Maximum follow-up time was 3 years. Serum levels of Vascular Cell Adhesion Molecule-1 (VCAM-1) and Intracellular Adhesion Molecule-1 (ICAM-1) were measured at baseline and before each nivolumab administration. Endpoints of the study were a composite outcome of survival >= 2 years or absence of disease progression at the end of the follow-up, and the overall survival. Results Composite outcome and overall survival were positively associated with VCAM-1 baseline levels and with the reduction of VCAM-1 during the treatment. After adjustment for potential confounders, the change in VCAM-1 serum levels during the treatment was an independent predictor of overall survival. Conclusions High baseline serum levels of VCAM-1 are associated with a longer survival in patients treated with nivolumab as second line treatment for NSCLC. Surviving patients experience also a significant reduction in CAMs expression during the treatment. Hence, CAMs might be promising prognostic factors in patients with NSCLC underoing immunotherapy

A comprehensive suite of earthquake catalogues for the 2016-2017 Central Italy seismic sequence

The protracted nature of the 2016-2017 central Italy seismic sequence, with multiple damaging earthquakes spaced over months, presented serious challenges for the duty seismologists and emergency managers as they assimilated the growing sequence to advise the local population. Uncertainty concerning where and when it was safe to occupy vulnerable structures highlighted the need for timely delivery of scientifically based understanding of the evolving hazard and risk. Seismic hazard assessment during complex sequences depends critically on up-to-date earthquake catalogues—i.e., data on locations, magnitudes, and activity of earthquakes—to characterize the ongoing seismicity and fuel earthquake forecasting models. Here we document six earthquake catalogues of this sequence that were developed using a variety of methods. The catalogues possess different levels of resolution and completeness resulting from progressive enhancements in the data availability, detection sensitivity, and hypocentral location accuracy. The catalogues range from real-time to advanced machine-learning procedures and highlight both the promises as well as the challenges of implementing advanced workflows in an operational environment

30 years of seismicity in the south-western Alps and northern Apennines as recorded by the Regional Seismic Network of northwestern Italy

The aim of this work is to describe the seismicity of the South-western Alps and Northern Apennines from the very detailed picture provided by thirty years of operation of the Regional Seismic Network of northwestern Italy .PublishedTeatro Metastasio - Palazzo Vaj, Prato, Italy1.1. TTC - Monitoraggio sismico del territorio nazionaleope

A microseismic study in a low seismicity area of Italy: the Città di Castello 2000-2001 experiment

Recent seismological studies contribute to better understand the first order characteristics of earthquake occurrence in Italy, identifying the potential sites for moderate to large size earthquakes. Ad hoc passive seismic experiments performed in these areas provide information to focus on the location and geometry of the active faults more closely. This information is relevant for assessing seismic hazard and for accurately constraining possible ground shaking scenarios. The area around the Città di Castello Basin, in the Northern Apennines (Central Italy), is characterized by the absence of instrumental seismicity (M > 2.5), it is adjacent to faults ruptured by recent and historical earthquakes. To better understand the tectonics of the area, we installed a dense network of seismic stations equipped with broadband and short period seismometers collecting data continuously for 8 months (October 2000-May 2001). The processing of ~ 900 Gbyte of data revealed a consistent background seismicity consisting of very low magnitude earthquakes (ML < 3.2). Preliminary locations of about 2200 local earthquakes show that the area can be divided into two regions with different seismic behaviour: an area to the NW, in between Sansepolcro and Città di Castello, where seismicity is not present. An area toward the SE, in between Città di Castello, Umbertide and Gubbio, where we detected a high microseismicity activity. These findings suggest a probable different mechanical behaviour of the two regions. In the latter area, the seismicity is confined between 0 and 8 km of depth revealing a rather well defined east-dipping, low angle fault 35 km wide that cuts through the entire upper crust down to 12-15 km depth. Beside an apparent structural complexity, fault plane solutions of background seismicity reveal a homogeneous pattern of deformation with a clear NE-SW extension