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1980 Azores Islands Earthquake
Striking the Autonomous Region of Azores on 1 January, the 1980 Azores Island earthquake killed 61 people and injured over 400, causing severe damage on the islands of Terceira and São Jorge. Measuring 6.9 on the moment magnitude scale, it also shook the islands of Pico and Faial, and resulted from a strike slip fracture, typical of other historical Azorean earthquakes. In response to the earthquake, Portuguese president António Ramalho Eanes announced three days of national mourning, while relief efforts, initiated by agents of the local Air Force, were soon accompanied by government-supported agencies. Geology Background In 1950, another strong earthquake had rocked the Azores Islands region, and this was the largest earthquake since.Western Newspapers (2 January 1980) Description Volcanic in origin, the Azores lie in a tectonically complex area on either side of the Mid-Atlantic Ridge, between the European, American and African plate boundaries, forming thei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angra Do Heroísmo
Angra do Heroísmo (), or simply Angra, is a city and municipality on Terceira Island, Portugal, and one of the three capital cities of the Azores. Founded in 1478, Angra was historically the most important city in the Azores, as seat of the Roman Catholic Diocese of Angra, Bishop of the Azores, government entities, and having previously served as the capital city of Portugal during the Liberal Wars. The population in 2011 was 35,402, in an area of 239.00 km². It was classified as a World Heritage Site, World Heritage site by UNESCO in 1983. Name Angra is the Portuguese language, Portuguese word for "inlet", "cove", or "bay". The epithet ' ("of Heroism", "the Heroic") was granted to the city by Maria II of Portugal, Maria II to commemorate its citizens' Battle of Praia da Vitória, successful defense of the island against a Miguelist assault in 1829. History Some claim that Angra was founded by Álvaro Martins, who sailed with Didrik Pining on his expedition to the New W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
European 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 1783 eruptio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Geological Survey
The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization's work spans the disciplines of biology, geography, geology, and hydrology. The USGS is a fact-finding research organization with no regulatory responsibility. The agency was founded on March 3, 1879. The USGS is a bureau of the United States Department of the Interior; it is that department's sole scientific agency. The USGS employs approximately 8,670 people and is headquartered in Reston, Virginia. The USGS also has major offices near Lakewood, Colorado, at the Denver Federal Center, and Menlo Park, California. The current motto of the USGS, in use since August 1997, is "science for a changing world". The agency's previous slogan, adopted on the occasion of its hundredt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Graciosa Island
Graciosa Island () (literally "graceful" or "enchanting" in Portuguese) is referred to as the ''White Island'', the northernmost of the Central Group of islands in the Azores. The ovular Portuguese island has an area of , a length of and a width of . It is a volcanic island, dominated by a central caldera (the Caldeira) located in the southeast. History In addition to the other islands of the Central Group, Graciosa was explored by Portuguese navigators during the first quarter of the 15th century, although there exist no accounts of the first sighting of the island. May 2, 1450 has frequently been referred to as the date of the island's "discovery", although there exists no documentation to support this date. Paradoxically, it is clear that in 1440, by order of Prince Henry the Navigator, cattle and swine were settled on the island in order to facilitate colonization. Similarly, it is unclear the names of the first settlers to colonize the island, although around 1450 t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terceira
Terceira () is a volcanic island in the Azores archipelago, in the middle of the North Atlantic Ocean. It is one of the larger islands of the archipelago, with a population of 53,311 inhabitants in an area of approximately . It is the location of the Azores' oldest city, Angra do Heroísmo, the historical capital of the archipelago and UNESCO World Heritage Site; the seat of the judicial system (Supreme Court); and the main Air Force base, Base Aérea nº 4 at Lajes, with a United States Air Force detachment. The island has two main sea ports, one at Angra do Heroísmo and the other at Praia da Vitória, and a commercial airport integrated with the flight operations at Base Aérea nº 4. The Portuguese bullfight is popular on the island, coming in two variations: the traditional equestrian bullfight (in the ring) and the popular " touradas à corda" that occur in the streets. History In 1439, the first official discovery document appeared, attributing the discovery of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geophysical Research Letters
''Geophysical Research Letters'' is a biweekly peer-reviewed scientific journal of geoscience published by the American Geophysical Union that was established in 1974. The editor-in-chief is Harihar Rajaram. Aims and scope The journal aims for rapid publication of concise research reports on one or more of the disciplines covered by the American Geophysical Union, such as atmospheric sciences, solid Earth, space science, oceanography, hydrology, land surface processes, and the cryosphere. The journal also publishes invited reviews that cover advances achieved during the past two or three years. The target readership is the earth science community, the broader scientific community, and the general public. Abstracting and indexing This journal is abstracted and indexed in: According to the 2020 ''Journal Citation Reports'', the journal has a 2019 impact factor of 4.58. ''Geophysical Research Letters'' was also the 5th most cited publication on climate change between 1999 and 2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dextral
Sinistral and dextral, in some scientific fields, are the two types of chirality ("handedness") or relative direction. The terms are derived from the Latin words for "left" (''sinister'') and "right" (''dexter''). Other disciplines use different terms (such as dextro- and laevo-rotary in chemistry, or clockwise and anticlockwise in physics) or simply use left and right (as in anatomy). Relative direction and chirality are distinct concepts. Relative direction is from the point of view of the observer; a completely symmetric object has a left side and a right side, from the observer's point of view, if the top and bottom and direction of observation are defined. Chirality, however, is observer-independent: no matter how one looks at a right-hand screw thread, it remains different from a left-hand screw thread. Therefore, a symmetric object has sinistral and dextral directions arbitrarily defined by the position of the observer, while an asymmetric object that shows chirality may ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shear (geology)
Boudinaged quartz vein (with strain fringe) showing ''Fault (geology)">sinistral shear sense'', Starlight Pit, Fortnum Gold Mine, Western Australia In geology, shear is the response of a rock to deformation usually by compressive stress and forms particular textures. Shear can be homogeneous or non-homogeneous, and may be pure shear or simple shear. Study of geological shear is related to the study of structural geology, rock microstructure or rock texture and fault mechanics. The process of shearing occurs within brittle, brittle-ductile, and ductile rocks. Within purely brittle rocks, compressive stress results in fracturing and simple faulting. Rocks Rocks typical of shear zones include mylonite, cataclasite, S-tectonite and L-tectonite, pseudotachylite, certain breccias and highly foliated versions of the wall rocks. Shear zone A shear zone is a tabular to sheetlike, planar or curviplanar zone composed of rocks that are more highly strained than rocks adjacent to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nodal Plane (geology)
Nodal homolog is a secretory protein that in humans is encoded by the ''NODAL'' gene which is located on chromosome 10q22.1. It belongs to the transforming growth factor beta superfamily (TGF-β superfamily). Like many other members of this superfamily it is involved in cell differentiation in early embryogenesis, playing a key role in signal transfer from the primitive node, in the anterior primitive streak, to lateral plate mesoderm (LPM). Nodal signaling is important very early in development for mesoderm and endoderm formation and subsequent organization of left-right axial structures. In addition, Nodal seems to have important functions in neural patterning, stem cell maintenance and many other developmental processes, including left/right handedness. Signaling Nodal can bind type I and type II serine/threonine kinase receptors, with Cripto-1 acting as its co-receptor. Signaling through SMAD 2/3 and subsequent translocation of SMAD 4 to the nucleus promotes the expressio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Focal Mechanism
The focal mechanism of an earthquake describes the deformation in the source region that generates the seismic waves. In the case of a fault-related event it refers to the orientation of the fault plane that slipped and the slip vector and is also known as a fault-plane solution. Focal mechanisms are derived from a solution of the moment tensor for the earthquake, which itself is estimated by an analysis of observed seismic waveforms. The focal mechanism can be derived from observing the pattern of "first motions", that is, whether the first arriving P waves break up or down. This method was used before waveforms were recorded and analysed digitally and this method is still used for earthquakes too small for easy moment tensor solution. Focal mechanisms are now mainly derived using semi-automatic analysis of the recorded waveforms. Moment tensor solutions The moment tensor solution is typically displayed graphically using a so-called ''beachball'' diagram. The pattern of en ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aftershock
In seismology, an aftershock is a smaller earthquake that follows a larger earthquake, in the same area of the main shock, caused as the displaced crust adjusts to the effects of the main shock. Large earthquakes can have hundreds to thousands of instrumentally detectable aftershocks, which steadily decrease in magnitude and frequency according to a consistent pattern. In some earthquakes the main rupture happens in two or more steps, resulting in multiple main shocks. These are known as doublet earthquakes, and in general can be distinguished from aftershocks in having similar magnitudes and nearly identical seismic waveforms. Distribution of aftershocks Most aftershocks are located over the full area of fault rupture and either occur along the fault plane itself or along other faults within the volume affected by the strain associated with the main shock. Typically, aftershocks are found up to a distance equal to the rupture length away from the fault plane. The pattern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strike-slip Fault
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] |
