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Earthquake Cycle
The earthquake cycle refers to the phenomenon that earthquakes repeatedly occur on the same fault as the result of continual stress accumulation and periodic stress release. Earthquake cycles can occur on a variety of faults including subduction zones and continental faults. Depending on the size of the earthquake, an earthquake cycle can last decades, centuries, or longer. The Parkfield portion of the San Andreas fault is a well-known example where similarly located M6.0 earthquakes have been instrumentally recorded every 30–40 years. Theory After Harry F. Reid proposed the elastic-rebound theory in 1910 based on the surface rupture record from the 1906 San Francisco earthquake, and accumulated geodetic data demonstrated continual stress loading from the plate motion, a theory of the "cyclic" earthquake re-occurrence began to form in the late twentieth century. Stress accumulation and elastic rebound Earthquake-cycle theory combines the stress-accumulation hypothesis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earthquake Cycle For Megathrust Earthquake
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from those that are so weak that they cannot be felt, to those violent enough to propel objects and people into the air, damage critical infrastructure, and wreak destruction across entire cities. The seismic activity of an area is the frequency, type, and size of earthquakes experienced over a particular time period. The seismicity at a particular location in the Earth is the average rate of seismic energy release per unit volume. The word ''tremor'' is also used for non-earthquake seismic rumbling. At the Earth's surface, earthquakes manifest themselves by shaking and displacing or disrupting the ground. When the epicenter of a large earthquake is located offshore, the seabed may be displaced sufficiently to cause a tsunami. Earthquakes c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gutenberg–Richter Law
In seismology, the Gutenberg–Richter law (GR law) expresses the relationship between the magnitude and total number of earthquakes in any given region and time period of ''at least'' that magnitude. : \!\,\log_ N = a - b M or : \!\,N = 10^ where * \!\, N is the number of events having a magnitude \!\, \ge M , * \!\, a and \!\, b are constants, i.e. they are the same for all values of ''N'' and ''M''. Since magnitude is logarithmic, this is an instance of the Pareto distribution. The Gutenberg–Richter law is also widely used for acoustic emission analysis due to a close resemblance of acoustic emission phenomenon to seismogenesis. Background The relationship between earthquake magnitude and frequency was first proposed by Charles Francis Richter and Beno Gutenberg in a 1944 paper studying earthquakes in California, and generalised in a worldwide study in 1949. This relationship between event magnitude and frequency of occurrence is remarkably common, although the v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sediment
Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand and silt can be carried in suspension in river water and on reaching the sea bed deposited by sedimentation; if buried, they may eventually become sandstone and siltstone ( sedimentary rocks) through lithification. Sediments are most often transported by water ( fluvial processes), but also wind (aeolian processes) and glaciers. Beach sands and river channel deposits are examples of fluvial transport and deposition, though sediment also often settles out of slow-moving or standing water in lakes and oceans. Desert sand dunes and loess are examples of aeolian transport and deposition. Glacial moraine deposits and till are ice-transported sediments. Classification Sediment can be classified based on its grain size, grain s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geological Survey
A geological survey is the systematic investigation of the geology beneath a given piece of ground for the purpose of creating a geological map or model. Geological surveying employs techniques from the traditional walk-over survey, studying outcrops and landforms, to intrusive methods, such as hand augering and machine-driven boreholes, to the use of geophysical techniques and remote sensing methods, such as aerial photography and satellite imagery. Such surveys may be undertaken by state, province, or national geological survey organizations to maintain the geological inventory and advance the knowledge of geosciences for the benefit of the nation. A geological survey map typically superimposes the surveyed extent and boundaries of geological units on a topographic map, together with information at points (such as measurements of orientation of bedding planes) and lines (such as the intersection of faults with the land surface). The maps and reports created by geological surv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wallace Creek Offset Across The San Andreas Fault
Wallace may refer to: People * Clan Wallace in Scotland * Wallace (given name) * Wallace (surname) * Wallace (footballer, born 1986), full name Wallace Fernando Pereira, Brazilian football left-back * Wallace (footballer, born 1987), full name Wallace Reis da Silva, Brazilian football centre-back * Wallace (footballer, born May 1994), full name Wallace Oliveira dos Santos, Brazilian football full-back * Wallace (footballer, born October 1994), full name Wallace Fortuna dos Santos, Brazilian football centre-back * Wallace (footballer, born 1998), full name Wallace Menezes dos Santos, Brazilian football midfielder Fictional characters * Wallace, from ''Wallace and Gromit'' * Wallace (''Pokémon'') * Wallace (''Sin City'') * Wallace (''The Wire'') * Wallace Breen, from ''Half-Life 2'' * Wallace Fennel, from ''Veronica Mars'' * Wallace Footrot, from ''Footrot Flats'' * Eli Wallace, from ''Stargate Universe'' * Wallace, from "The Hangover Part III" * Wallace the Brave, from the c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Creep (deformation)
In materials science, creep (sometimes called cold flow) is the tendency of a solid material to move slowly or deform permanently under the influence of persistent mechanical stresses. It can occur as a result of long-term exposure to high levels of stress that are still below the yield strength of the material. Creep is more severe in materials that are subjected to heat for long periods and generally increases as they near their melting point. The rate of deformation is a function of the material's properties, exposure time, exposure temperature and the applied structural load. Depending on the magnitude of the applied stress and its duration, the deformation may become so large that a component can no longer perform its function – for example creep of a turbine blade could cause the blade to contact the casing, resulting in the failure of the blade. Creep is usually of concern to engineers and metallurgists when evaluating components that operate under high stresses or hig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interferometric Synthetic-aperture Radar
Interferometric synthetic aperture radar, abbreviated InSAR (or deprecated IfSAR), is a radar technique used in geodesy and remote sensing. This geodetic method uses two or more synthetic aperture radar (SAR) images to generate maps of surface deformation or digital elevation, using differences in the phase of the waves returning to the satellite or aircraft. The technique can potentially measure millimetre-scale changes in deformation over spans of days to years. It has applications for geophysical monitoring of natural hazards, for example earthquakes, volcanoes and landslides, and in structural engineering, in particular monitoring of subsidence and structural stability. Technique Synthetic aperture radar Synthetic aperture radar (SAR) is a form of radar in which sophisticated processing of radar data is used to produce a very narrow effective beam. It can be used to form images of relatively immobile targets; moving targets can be blurred or displaced in the formed ima ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nankai Trough
The is a submarine trough located south of the Nankaidō region of Japan's island of Honshu, extending approximately offshore. The underlying fault, the ''Nankai megathrust,'' is the source of the devastating Nankai megathrust earthquakes, while the trough itself is potentially a major source of hydrocarbon fuel, in the form of methane clathrate. In plate tectonics, the Nankai Trough marks a subduction zone that is caused by subduction of the Philippine Sea Plate beneath Japan, part of the Eurasian plate (Kanda et al., 2004). This plate boundary would be an oceanic trench except for a high flux of sediments that fills the trench. Within the Nankai Trough there is a large amount of deformed trench sediments (Ike, 2004), making one of Earth's best examples of accretionary prism. Furthermore, seismic reflection studies have revealed the presence of basement highs that are interpreted as seamounts that are covered in sediments (Ike, 2004). The northern part of the trough is known ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Global Positioning System
The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite systems (GNSS) that provides geolocation and time information to a GPS receiver anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites. It does not require the user to transmit any data, and operates independently of any telephonic or Internet reception, though these technologies can enhance the usefulness of the GPS positioning information. It provides critical positioning capabilities to military, civil, and commercial users around the world. Although the United States government created, controls and maintains the GPS system, it is freely accessible to anyone with a GPS receiver. The GPS project was started by the U.S. Department of Defense in 1973. The first prototype spacecraft was lau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geodetic
Geodesy ( ) is the Earth science of accurately measuring and understanding Earth's figure (geometric shape and size), orientation in space, and gravity. The field also incorporates studies of how these properties change over time and equivalent measurements for other planets (known as '' planetary geodesy''). Geodynamical phenomena, including crustal motion, tides and polar motion, can be studied by designing global and national control networks, applying space geodesy and terrestrial geodetic techniques and relying on datums and coordinate systems. The job title is geodesist or geodetic surveyor. History Definition The word geodesy comes from the Ancient Greek word ''geodaisia'' (literally, "division of Earth"). It is primarily concerned with positioning within the temporally varying gravitational field. Geodesy in the German-speaking world is divided into "higher geodesy" ( or ), which is concerned with measuring Earth on the global scale, and "practical geodes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology
Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth sciences, including hydrology, and so is treated as one major aspect of integrated Earth system science and planetary science. Geology describes the structure of the Earth on and beneath its surface, and the processes that have shaped that structure. It also provides tools to determine the relative and absolute ages of rocks found in a given location, and also to describe the histories of those rocks. By combining these tools, geologists are able to chronicle the geological history of the Earth as a whole, and also to demonstrate the age of the Earth. Geology provides the primary evidence for plate tectonics, the evolutionary history of life, and the Earth's past climates. Geologists broadly study the properties and processes of E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earthquake Swarm
In seismology, an earthquake swarm is a sequence of seismic events occurring in a local area within a relatively short period. The time span used to define a swarm varies, but may be days, months, or years. Such an energy release is different from the situation when a major earthquake (main shock) is followed by a series of aftershocks: in earthquake swarms, no single earthquake in the sequence is obviously the main shock. In particular, a cluster of aftershocks occurring after a mainshock ''is not'' a swarm. History and generalities In the Ore Mountains (Erzgebirge), which form the border between the Czech Republic and Germany, western Bohemia and the Vogtland region, have been known since the 16th century as prone to frequent earthquake swarms, which typically last a few weeks to a few months. Austrian geologist Josef Knett, while studying in 1899 a swarm of about a hundred events felt in western Bohemia/Vogtland in January-February 1824, coined the noun ''Schwarmbeben'', ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
