Search results for " Earthquake"

Monochromatic Long-Period Seismicity Prior to the 2012 Earthquake Swarm at Little Sitkin Volcano, Alaska

2021

Detection of the earliest stages of unrest is one of the most challenging and yet critically needed aspects of volcano monitoring. We investigate a sequence of five unusual long-period (LP) earthquakes that occurred in the days prior to the onset of a months-long volcano-tectonic (VT) earthquake swarm beneath Little Sitkin volcano in the Aleutian Islands during late 2012. The long-period earthquakes had two distinctive characteristics: their signals were dominated by a monochromatic spectral peak at approximately 0.57 Hz and they had impulsive P and S-wave arrivals on a seismometer located on Amchitka Island 80 km to the southeast of the volcano. In each case, the monochromatic earthquakes …

Characterization of MEMS accelerometer self-noise by means of PSD and Allan Variance analysis

2017

In this paper, we have studied the sources of error of a low-cost 3-axis MEMS accelerometer by means of Power Spectral Density and Allan Variance techniques. These techniques were applied to the signals acquired from ten identical devices to characterize the variability of the sensor produced by the same manufacturer. Our analysis showed as identically produced accelerometer have somehow variable behavior in particular at low frequency. It is therefore of paramount importance before their use in Inertial Navigation or Earthquakes Monitoring System, a complete characterization of each single sensors.

The tsunami phenomenon

2017

Abstract With human activity increasingly concentrating on coasts, tsunamis (from Japanese tsu = harbour, nami = wave) are a major natural hazard to today’s society. Stimulated by disastrous tsunami impacts in recent years, for instance in south-east Asia (2004) or in Japan (2011), tsunami science has significantly flourished, which has brought great advances in hazard assessment and mitigation plans. Based on tsunami research of the last decades, this paper provides a thorough treatise on the tsunami phenomenon from a geoscientific point of view. Starting with the wave features, tsunamis are introduced as long shallow water waves or wave trains crossing entire oceans without major energy l…

Late Hercynian Plate and Intraplate Processes within Europe

1987

The Hercynian orogenic belt of Europe consists of a central crystalline ridge which is accompanied on both sides by a rather unmetamorphosed foldbelt. It is speculated that the crystalline ridge represents some kind of island arc system underlain by a segment of continental crust. On both sides this island arc system was involved in subduction of oceanic crust, first of the Mideuropean Sea in the North and then of the Paleotethys in the South. When the continental areas to the north and south of the oceanic areas (North America/Northern Europe and Africa) finally got involved in the subduction processes, continent/continent collision took place on both sides of the island arc system. The tw…

The ‘false vaults’ in the architecture of Sicily

2015

Between the end of the 17th century and the first decades of the 18th, Sicily was struck by several violent earthquakes. The total and partial collapse of monumental buildings produced a global debate involving various aspects of construction practice. One of the central topics of discussion was the construction of domes and large vaulted structures. Some architects studied the possibility of using so-called ‘false vaults’, a kind of lightweight structure created with a wooden frame, reed mats, and plaster. The technique was probably known by the 16th century and was used in a few major monuments, such as the dome of the Palermo Cathedral, in the mid-17th century. It was only after the Eart…

An algorithm for earthquakes clustering based on maximum likelihood

2007

In this paper we propose a clustering technique set up to separate and find out the two main components of seismicity: the background seismicity and the triggered one. We suppose that a seismic catalogue is the realization of a non homogeneous space-time Poisson clustered process, with a different parametrization for the intensity function of the Poisson-type component and of the clustered (triggered) component. The method here proposed assigns each earthquake to the cluster of earthquakes, or to the set of independent events, according to the increment to the likelihood function, computed using the conditional intensity function estimated by maximum likelihood methods and iteratively chang…

Innovative connections for steel-concrete-trussed beams: a patented solution

2023

The most recent design strategies welcome the adoption of innovative techniques for seismic energy input mitigation, aiming to achieve high dissipation capacity, prevent the structure from collapse and ensure the serviceability of the construction. Friction damper devices have been widely adopted in framed steel structures for decades, while their introduction in different structural types is still under investigation. This paper presents the outcomes of innovative research supported by the industry and conducted on beam-to-column connections of RC structures in which the beams are Hybrid Steel-Trussed Concrete Beams (HSTCBs) and the columns are classical RC pillars. An innovative solution,…

An Overview of Public Concerns During the Recovery Period after a Major Earthquake: Nepal Twitter Analysis

2016

In responding to disasters, Twitter is extensively used, both for information exchange and mapping the crisis, among citizens, and in relation to national and international humanitarian responders. This paper reports Twitter analysis aimed at identifying the most pressing issues that arose in the short term recovery phase starting about a week after the Nepal earthquake, including the heretofore neglected topic of mismatch between international relief and local cultures. Based on Twitter data collected between April 30th and May 6th 2015. 1,074,864 raw messages apparently related to the Nepal earthquake were retrieved, filtered and analyzed. This exploratory adapts established frameworks fo…

Soft-sediment deformation structures (SSDS) in Pleistocene calcarenites of Favignana island (Sicily, Italy)

2013

(Di)segni contemporanei

2018

Il contributo intende presentare criticamente alcuni interventi di restauro allineati alla più moderna ed evoluta cultura della conservazione. I due interventi sono compiuti in Sicilia sui resti di due monumenti distrutti dal terremoto che danneggiò la vallata del fiume Belice nel 1968. Il tema della reintegrazione della lacuna nei volumi strutturali degli edifici storici è realizzata attraverso il procedimento per "astrazione volumetrica", con esiti sorprendenti e d'elevata qualità conservativa. The contribution intends to critically present some restoration interventions aligned with the most modern and evolved culture of conservation. The two interventions are carried out in Sicily on th…