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2009 L'Aquila Earthquake
The 2009 L'Aquila earthquake occurred in the region of Abruzzo, in central Italy. The main shock occurred at 03:32 CEST (01:32 UTC) on 6 April 2009, and was rated 5.8 or 5.9 on the Richter magnitude scale and 6.3 on the moment magnitude scale; its epicentre was near L'Aquila, the capital of Abruzzo, which together with surrounding villages suffered the most damage. There have been several thousand foreshocks and aftershocks since December 2008, more than thirty of which had a Richter magnitude greater than 3.5. The earthquake was felt throughout central Italy; 308 people are known to have died, making this the deadliest earthquake to hit Italy since the 1980 Irpinia earthquake. In a subsequent inquiry of the handling of the disaster, seven members of the Italian National Commission for the Forecast and Prevention of Major Risks were accused of giving "inexact, incomplete and contradictory" information about the danger of the tremors prior to the main quake. On 22 October 201 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Central European Time
Central European Time (CET) is a standard time which is 1 hour ahead of Coordinated Universal Time (UTC). The time offset from UTC can be written as UTC+01:00. It is used in most parts of Europe and in a few North African countries. CET is also known as Middle European Time (MET, German: MEZ) and by colloquial names such as Amsterdam Time, Berlin Time, Brussels Time, Madrid Time, Paris Time, Rome Time, Warsaw Time or even Romance Standard Time (RST). The 15th meridian east is the central axis for UTC+01:00 in the world system of time zones. As of 2011, all member states of the European Union observe summer time ( daylight saving time), from the last Sunday in March to the last Sunday in October. States within the CET area switch to Central European Summer Time (CEST, UTC+02:00) for the summer. In Africa, UTC+01:00 is called West Africa Time (WAT), where it is used by several countries, year round. Algeria, Morocco, and Tunisia also refer to it as ''Central Euro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dip-slip Faults
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 geologic 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] |
1706 Abruzzo Earthquake
The 1706 Abruzzo earthquake, also known as the Maiella earthquake, occurred on November 3 at 13:00 CEST. The earthquake with a possible epicenter in the Central Apennine Mountains (Maiella), Abruzzo had an estimated moment magnitude of 6.6–6.84 . It was assigned a maximum Mercalli intensity of XI (''Extreme''), causing tremendous destruction in Valle Peligna. At least 2,400 people were killed. Tectonic setting The central Italian Peninsula is dominated by active extensional tectonics, forming the Apennine Mountains. The mountain range formed during the Miocene and Pliocene due to the subduction of the Adriatic Plate beneath the Eurasian Plate. The resulting subduction formed a fold and thrust belt. During the Quaternary, thrust tectonics gave way to extensional tectonics, with the development of a zone of normal faulting running along the crest of the mountain range. One possible explanation for the change in the tectonic regime is slab rollback occurring within the Adr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Structure
Soil structure describes the arrangement or the way of soil in the solid parts of the soil and of the pore space located between them. It is determined by how individual soil granules clump, bind together, and aggregate, resulting in the arrangement of soil pores between them. Soil has a major influence on water and air movement, biological activity, root growth and seedling emergence. There are several different types of soil structure. It is inherently a dynamic and complex system that is affected by different factors. Overview Soil structure describes the arrangement of the solid parts of the soil and of the pore spaces located between them (Marshall & Holmes, 1979). Aggregation is the result of the interaction of soil particles through rearrangement, flocculation and cementation. It is enhanced by: the precipitation of oxides, hydroxides, carbonates and silicates; the products of biological activity (such as biofilms, fungal hyphae and glycoproteins); ionic bridging betwe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eurasian Plate
The Eurasian Plate is a tectonic plate that includes most of the continent of Eurasia (a landmass consisting of the traditional continents of Europe and Asia), with the notable exceptions of the Indian subcontinent, the Arabian subcontinent and the area east of the Chersky Range in eastern Siberia. It also includes oceanic crust extending westward to the Mid-Atlantic Ridge and northward to the Gakkel Ridge. The eastern edge is a boundary with the North American Plate to the north and a boundary with the Philippine Sea Plate to the south and possibly with the Okhotsk Plate and the Amurian Plate. The southern edge is a boundary with the African Plate to the west, the Arabian Plate in the middle and the Indo-Australian Plate to the east. The western edge is a divergent boundary with the North American Plate forming the northernmost part of the Mid-Atlantic Ridge, which is straddled by Iceland. All volcanic eruptions in Iceland, such as the 1973 eruption of Eldfell, the 17 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Continental Collision
In geology, continental collision is a phenomenon of plate tectonics that occurs at convergent boundaries. Continental collision is a variation on the fundamental process of subduction, whereby the subduction zone is destroyed, mountains produced, and two continents sutured together. Continental collision is only known to occur on Earth. Continental collision is not an instantaneous event, but may take several tens of millions of years before the faulting and folding caused by collisions stops. The collision between India and Asia has been going on for about 50 million years already and shows no signs of abating. Collision between East and West Gondwana to form the East African Orogen took about 100 million years from beginning (610 Ma) to end (510 Ma). The collision between Gondwana and Laurasia to form Pangea occurred in a relatively brief interval, about 50 million years long. Subduction zone: the collision site The process begins as two cont ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
African Plate
The African Plate is a major tectonic plate that includes much of the continent of Africa (except for its easternmost part) and the adjacent oceanic crust to the west and south. It is bounded by the North American Plate and South American Plate to the west (separated by the Mid-Atlantic Ridge); the Arabian Plate and Somali Plate to the east; the Eurasian Plate, Aegean Sea Plate and Anatolian Plate to the north; and the Antarctic Plate to the south. Between and , the Somali Plate began rifting from the African Plate along the East African Rift. Since the continent of Africa consists of crust from both the African and the Somali plates, some literature refers to the African Plate as the Nubian Plate to distinguish it from the continent as a whole. Boundaries The western edge of the African Plate is a divergent boundary with the North American Plate to the north and the South American Plate to the south which forms the central and southern part of the Mid-Atlantic Ridge. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tyrrhenian Sea
The Tyrrhenian Sea (; it, Mar Tirreno , french: Mer Tyrrhénienne , sc, Mare Tirrenu, co, Mari Tirrenu, scn, Mari Tirrenu, nap, Mare Tirreno) is part of the Mediterranean Sea off the western coast of Italy. It is named for the Tyrrhenian people identified with the Etruscans of Italy. Geography The sea is bounded by the islands of Corsica and Sardinia (to the west), the Italian Peninsula (regions of Tuscany, Lazio, Campania, Basilicata, and Calabria) to the north and east, and the island of Sicily (to the south). The Tyrrhenian Sea also includes a number of smaller islands like Capri, Elba, Ischia, and Ustica. The maximum depth of the sea is . The Tyrrhenian Sea is situated near where the African and Eurasian Plates meet; therefore mountain chains and active volcanoes such as Mount Marsili are found in its depths. The eight Aeolian Islands and Ustica are located in the southern part of the sea, north of Sicily. Extent The International Hydrographic Organization defin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Back-arc Basin
A back-arc basin is a type of geologic basin, found at some convergent plate boundaries. Presently all back-arc basins are submarine features associated with island arcs and subduction zones, with many found in the western Pacific Ocean. Most of them result from tensional forces, caused by a process known as oceanic trench rollback, where a subduction zone moves towards the subducting plate. Back-arc basins were initially an unexpected phenomenon in plate tectonics, as convergent boundaries were expected to universally be zones of compression. However, in 1970, Dan Karig published a model of back-arc basins consistent with plate tectonics. Structural characteristics Back-arc basins are typically very long and relatively narrow, often thousands of kilometers long while only being a few hundred kilometers wide at most. For back-arc extension to form, a subduction zone is required, but not all subduction zones have a back-arc extension feature. Back-arc basins are found in ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Active Fault
An active fault is a fault that is likely to become the source of another earthquake sometime in the future. Geologists commonly consider faults to be active if there has been movement observed or evidence of seismic activity during the last 10,000 years. * Active faulting is considered to be a geologic hazard - one related to earthquakes as a cause. Effects of movement on an active fault include strong ground motion, surface faulting, tectonic deformation, landslides and rockfalls, liquefaction, tsunamis, and seiches. Quaternary faults are those active faults that have been recognized at the surface and which have evidence of movement during the Quaternary Period. Related geological disciplines for ''active-fault'' studies include geomorphology, seismology, reflection seismology, plate tectonics, geodetics and remote sensing, risk analysis, and others. Location Active faults tend to occur in the vicinity of tectonic plate boundaries, and active fault research has foc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58See the 2014 version of the ICS geologic time scale million years ago. It is the second and most recent epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Epoch and is followed by the Epoch. Prior to the 2009 revision of the geologic time sca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extensional Tectonics
Extensional tectonics is concerned with the structures formed by, and the tectonic processes associated with, the stretching of a planetary body's crust or lithosphere. Deformation styles The types of structure and the geometries formed depend on the amount of stretching involved. Stretching is generally measured using the parameter ''β'', known as the ''beta factor'', where : \beta = \frac \,, ''t''0 is the initial crustal thickness and ''t''1 is the final crustal thickness. It is also the equivalent of the strain parameter ''stretch''. Low beta factor In areas of relatively low crustal stretching, the dominant structures are high to moderate angle normal faults, with associated half grabens and tilted fault blocks. High beta factor In areas of high crustal stretching, individual extensional faults may become rotated to too low a dip to remain active and a new set of faults may be generated. Large displacements may juxtapose syntectonic sediments against metamorphic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
