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1997 Assisi Earthquake
The 1997 Umbria and Marche earthquakes occurred in the regions of Umbria and Marche, central Italy over a period of several months from September 1997 to April 1998. It consisted of eight earthquakes with magnitudes greater than . The first of the larger shocks, which measured , occurred at 02:33 CEST (00:33 UTC) on 26 September 1997. It was preceded by several foreshocks, beginning with a event on 3 September. A second and slightly larger shock occurred about nine hours later at 11:40 CEST (09:40 UTC), rated . The epicentres of first two larger earthquakes were in Annifo. The shaking associated with first two larger shocks was estimated at VIII (''Severe'') and X (''Extreme'') on the Mercalli intensity scale, respectively. There were several thousands of foreshocks and aftershocks from May 1997 to April 1998, more than thirty of which had a magnitude more than 3.5. Eleven people died and approximately 100 were injured, with significant damage to buildings including the par ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basilica Of Saint Francis Of Assisi
The Basilica of Saint Francis of Assisi (; ) is the mother church of the Roman Catholic Order of Friars Minor Conventual in Assisi, a town in the Umbria region in central Italy, where Saint Francis was born and died. It is a papal minor basilica and one of the most important places of Christian pilgrimage in Italy. With its accompanying friary, Sacro Convento, the basilica is a distinctive landmark to those approaching Assisi. It has been a UNESCO World Heritage Site since 2000. The basilica, which was begun in 1228, is built into the side of a hill and comprises two churches (known as the Upper Church and the Lower Church) and a crypt, where the remains of the saint are interred. The interior of the Upper Church is an important early example of the Gothic style in Italy. The Upper and Lower Churches are decorated with frescoes by numerous late medieval painters from the Roman and Tuscan schools, and include works by Cimabue, Giotto, Simone Martini, Pietro Lorenzetti, and pos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58See the 2014 version of the ICS geologic time scale million years ago (Ma). It is the second and most recent epoch of the Neogene Period in the Cenozoic, Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch. Prior to the 2009 revision of the geologic time scale, which placed the four most recent major glaciations entirely within the Pleistocene, the Pliocene also included the Gelasian Stage, which lasted from 2.59 to 1.81 Ma, and is now included in the Pleistocene. As with other older geologic periods, the Stratum, geological strata that define the start and end are well-identified but the exact dates of the start a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shear Stress
Shear stress (often denoted by , Greek alphabet, Greek: tau) is the component of stress (physics), stress coplanar with a material cross section. It arises from the shear force, the component of force vector parallel to the material cross section. ''Normal stress'', on the other hand, arises from the force vector component perpendicular to the material cross section on which it acts. General shear stress The formula to calculate average shear stress or force per unit area is: \tau = ,where is the force applied and is the cross-sectional area. The area involved corresponds to the material face (geometry), face parallel to the applied force vector, i.e., with surface normal vector perpendicular to the force. Other forms Wall shear stress Wall shear stress expresses the retarding force (per unit area) from a wall in the layers of a fluid flowing next to the wall. It is defined as:\tau_w := \mu\left.\frac\_,where is the dynamic viscosity, is the flow velocity, and is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coulomb Stress Transfer
Coulomb stress transfer is a Seismology, seismic-related geology, geological process of Stress (mechanics), stress changes to surrounding material caused by local discrete deformation events. Using mapped displacements of the Earth's surface during earthquakes, the computed Coulomb stress changes suggest that the stress relieved during an earthquake not only dissipates but can also move up and down Fault (geology), fault segments, concentrating and promoting subsequent tremors. Importantly, Coulomb stress changes have been applied to earthquake-forecasting models that have been used to assess potential Seismic hazard, hazards related to earthquake activity. Coulomb stress change The Mohr–Coulomb theory, Coulomb failure criterion requires that the Coulomb stress exceeds a value σf defined by the shear stress τB, normal stress σB, pore pressure p, and coefficient of friction μ of a failure plane, such that It is also often assumed that changes in pore fluid pressure induced b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Longitude
Longitude (, ) is a geographic coordinate that specifies the east- west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek letter lambda (λ). Meridians are imaginary semicircular lines running from pole to pole that connect points with the same longitude. The prime meridian defines 0° longitude; by convention the International Reference Meridian for the Earth passes near the Royal Observatory in Greenwich, south-east London on the island of Great Britain. Positive longitudes are east of the prime meridian, and negative ones are west. Because of the Earth's rotation, there is a close connection between longitude and time measurement. Scientifically precise local time varies with longitude: a difference of 15° longitude corresponds to a one-hour difference in local time, due to the differing position in relation to the Sun. Comparing local time to an absol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Latitude
In geography, latitude is a geographic coordinate system, geographic coordinate that specifies the north-south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from −90° at the south pole to 90° at the north pole, with 0° at the Equator. Parallel (latitude), Lines of constant latitude, or ''parallels'', run east-west as circles parallel to the equator. Latitude and longitude are used together as a coordinate pair to specify a location on the surface of the Earth. On its own, the term "latitude" normally refers to the ''geodetic latitude'' as defined below. Briefly, the geodetic latitude of a point is the angle formed between the vector perpendicular (or ''Normal (geometry), normal'') to the ellipsoidal surface from the point, and the equatorial plane, plane of the equator. Background Two levels of abstraction are employed in the definitions of latitude and longitude. In the first step the physical surface i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fault Zone
In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as the megathrust faults of subduction zones or transform faults. Energy release associated with rapid movement on active faults is the cause of most earthquakes. Faults may also displace slowly, by aseismic creep. A ''fault plane'' is the plane that represents the fracture surface of a fault. A ''fault trace'' or ''fault line'' is a place where the fault can be seen or mapped on the surface. A fault trace is also the line commonly plotted on geological maps to represent a fault. A ''fault zone'' is a cluster of parallel faults. However, the term is also used for the zone of crushed rock along a single fault. Prolonged motion along closely spaced faults can blur the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thrust Fault
A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. If the angle of the fault plane is lower (often less than 15 degrees from the horizontal) and the displacement of the overlying block is large (often in the kilometer range) the fault is called an ''overthrust'' or ''overthrust fault''. Erosion can remove part of the overlying block, creating a ''fenster'' (or ''window'') – when the underlying block is exposed only in a relatively small area. When erosion removes most of the overlying block, leaving island-like remnants resting on the lower block, the remnants are called ''klippen'' (singular '' klippe''). Blind thrust faults If the fault plane terminates before it reaches the Earth's surface, it is called a ''blind thrust'' fault. Because of the lack of surface evidence, blind thrust fa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trench Rollback
Oceanic trenches are prominent, long, narrow topographic depressions of the ocean floor. They are typically wide and below the level of the surrounding oceanic floor, but can be thousands of kilometers in length. There are about of oceanic trenches worldwide, mostly around the Pacific Ocean, but also in the eastern Indian Ocean and a few other locations. The greatest ocean depth measured is in the Challenger Deep of the Mariana Trench, at a depth of below sea level. Oceanic trenches are a feature of the Earth's distinctive plate tectonics. They mark the locations of convergent plate boundaries, along which lithospheric plates move towards each other at rates that vary from a few millimeters to over ten centimeters per year. Oceanic lithosphere moves into trenches at a global rate of about per year. A trench marks the position at which the flexed, subducting slab begins to descend beneath another lithospheric slab. Trenches are generally parallel to and about from a volcani ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adriatic Plate
The Adriatic or Apulian plate is a small list of tectonic plates, tectonic plate carrying primarily continental crust that broke away from the African plate along a large transform fault in the Cretaceous period. The name Adriatic plate is usually used when referring to the northern part of the plate. This part of the plate was Deformation (engineering), deformed during the Alpine orogeny, when the Adriatic/Apulian plate continental collision, collided with the Eurasian plate. The Adriatic/Apulian plate is thought to still move independently of the Eurasian plate in NNE direction with a small component of counter-clockwise rotation. The fault (geology), fault zone that separates the two is the Periadriatic Seam that runs through the Alps. Studies indicate that in addition to deforming, the Eurasian continental crust has actually subducted to some extent below the Adriatic/Apulian plate, an unusual circumstance in plate tectonics. Oceanic crust of the African plate is also subd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
