A fault that shows signs of slipping between the two volumes of rock/ground in the past 40,000 years, leading to presume that they may slip some more.
Numerical parameter describing the amplification of the seismic motion in a given point compared with one measured in a reference site (bedrock), represented by hard (rock) or level ground. Amplification may be linked to the lithological and morphological features of the evaluated area. The amplification factor may be expressed in acceleration (Fa) and/or speed (Fv) terms.
Active fault deemed capable of producing surface faulting, in other words instantaneous vertical and/or horizontal – coseismic – vdislocation of the ground along one or more shear planes.
Phenomena that occur after an earthquake. Direct phenomena are permanent deformation of the topographic surface; indirect phenomena due to shaking and the entity of the shift on the fault plane are: landslides, ground splitting and liquefaction, variations in the flow of rivers, the generation of tsunamis.
A structure that guides the magma towards the surface. The fissure may be caused by magma pressure, or may be a reactivated pre-existing structure. Volcanic activity may be distributed evenly right along the fissure, or more frequently, be concentrated in certain points, leading to alignment of volcanic buildings, typically cones.
The movement of the lithospheric plates ithat make up the earth’s crust causes great pressure on rocks deep down, leading to their breakage along fracture surfaces called faults. Rocks near the fault planes (the slip surface) are often intensely fragmented due to friction between the blocks of rock in relative motion. The fault may be:
- reverse, if the motion of the blocks of rock that touch along the break surface is compressive – the blocks overlap each other;
- normal or extensional faults, if the blocks move apart;
- strike-slip, if the motion of the blocks in mainly horizontal – the blocks slip sideways.
FEMA - Federal Emergency Management Agency
The structure belongs of the US Department of Homeland Security, Dhs – US Department of Homeland Securitysince 2003. It has the task of coordinating the Governement activities of preventing, mitigating, fighting disaster effects, both natural and man-made - including terrorist acts - and protecting, rescuing and granting safety measures for the population.
Variations in the physical and chemical parameters of a volcano system that indicate possible repeat eruptions. Some of these can only be detected by instruments, while others, such as for example more severe earthquakes, visible ground deformation, the appearance of the new fumaroles or the opening of fissures, can be recognised by people.
A cloud denser than air made up of fragments of rocks and gas, characterised by high temperature and speed. It is generated by the collapse of an eruption plume supported either by a dome or by a lateral blast. It tends to flow to the ground under the force of gravity, to channel into valleys and fill depressions and some have enough energy to make their way over even tall morphological barriers. Their distribution in the area will therefore depend on morphology.
Natural emission of gaseous mixtures prevalently made up of water vapour. Dry fumaroles can reach a temperature of several hundred degrees centigrade. Whereas saturated steam fumaroles have a temperature close to the boiling point of water.
They constitute the basic organisational structure of the operations centres and represent the different emergency management activity sectors. Each Function is made up of representatives from the units that cooperate, with professions and resources, in a specific sector, and whose coordination is entrusted to a person in charge. The support functions are activated in emergencies, in a flexible way, in relation to possible requirements and based on emergency planning.