|
2002 Bou'in-Zahra Earthquake
The 2002 Bou'in-Zahra earthquake (also known as the 2002 Avaj earthquake or the 2002 Changureh earthquake) occurred on 22 June 2002. The epicenter was near the city of Bou'in-Zahra in Qazvin Province, a region of northwestern Iran which is crossed by several major faults that is known for destructive earthquakes. The shock measured 6.5 on the scale, had a maximum Mercalli intensity of VIII (''Severe''), and was followed by more than 20 aftershocks. At least 230 people were killed and 1,500 more were injured. According to the International Institute of Earthquake Engineering and Seismology ( IIEES), the earthquake was felt as far away as the capital city of Tehran, approximately east of the epicenter, although no damage was reported there. Most houses in the region were single-story masonry buildings, and virtually all of these collapsed. The public became angry due to the slow official response to victims who needed supplies. Residents of the town of Avaj resorted to thro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iran Standard Time
Iran Standard Time (IRST) or Iran Time (IT) is the time zone used in Iran. Iran uses a UTC offset UTC+03:30. IRST is defined by the 52.5 degrees east meridian, the same meridian which defines the Iranian calendar and is the official meridian of Iran. Between 2005 and 2008, by decree of President Mahmoud Ahmadinejad, Iran did not observe daylight saving time (DST) (called ''Iran Daylight Time'' or ''IRDT''). It was reintroduced from 21 March 2008. On 21 September 2022, Iran abolished DST and now observes standard time year-round. Daylight Saving Time transitions The dates of DST transitions in Iran were based on the Solar Hijri calendar, the official calendar of Iran, which is in turn based on the March equinox (Nowruz) as determined by astronomical calculation at the meridian for Iran Standard Time (52.5°E or GMT+3.5h). This resulted in the unique situation wherein the dates of DST transitions didn't fall on the same weekday each year as they do in most other countries. DST st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CBS News
CBS News is the news division of the American television and radio service CBS. CBS News television programs include the ''CBS Evening News'', ''CBS Mornings'', news magazine programs '' CBS News Sunday Morning'', '' 60 Minutes'', and '' 48 Hours'', and Sunday morning political affairs program ''Face the Nation''. CBS News Radio produces hourly newscasts for hundreds of radio stations, and also oversees CBS News podcasts like '' The Takeout Podcast''. CBS News also operates a 24-hour digital news network. Up until April 2021, the president and senior executive producer of CBS News was Susan Zirinsky, who assumed the role on March 1, 2019. Zirinsky, the first female president of the network's news division, was announced as the choice to replace David Rhodes on January 6, 2019. The announcement came amid news that Rhodes would step down as president of CBS News "amid falling ratings and the fallout from revelations from an investigation into sexual misconduct allegations" ag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1990 Manjil–Rudbar Earthquake
The 1990 Manjil–Rudbar earthquake occurred on Thursday, June 21, 1990 at in northern Iran. The shock had a moment magnitude of 7.4 and a Mercalli Intensity of X (''Extreme''). Damage and casualties Widespread damage occurred to the northwest of the capital city of Tehran, including the cities of Rudbar and Manjil. The National Geophysical Data Center estimated that $8 billion in damage occurred in the affected area. Other earthquake catalogs presented estimates of the loss of life in the range of 35,000–50,000, with a further 60,000–105,000 that were injured. Use in media Acclaimed Iranian director Abbas Kiarostami has fictionally incorporated the earthquake and its effects on northern Iran into multiple films of his. In ''And Life Goes On'' (1992), a director and his son search for child actors from a previous Kiarostami film; ''Where Is the Friend's Home?'' (1986), which was shot in a city that, by the time of the second film's production, is recovering from the earthqua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1962 Bou'in-Zahra Earthquake
The 1962 Buin Zahra earthquake occurred on September 1 in the area of Buin Zahra, Qazvin Province, Iran. The shock had a Richter magnitude of 7.1 and resulted in 12,225 fatalities. Qazvin Province lies in an area of Iran that experiences large earthquakes. The 1962 event originated on one of many faults in the area, called the Ipak Fault. The fault is believed to have been reactivated multiple times. Geology Iran is a seismically active zone, lying between the converging Eurasian and Arabian Plates. Because it has both strike-slip and reverse faults, earthquakes often proceed so that if one fault is overwhelmed by movement, the movement will branch off to another fault, creating a separate earthquake. Buin Zahra County lies within a zone of active thrust faults, complemented by folds, that extends south from the Alborz mountains. Despite the presence of faults, Qazvin Province does not regularly experience earthquakes. However, the space between earthquakes allows pressu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neogene
The Neogene ( ), informally Upper Tertiary or Late Tertiary, is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period Mya. The Neogene is sub-divided into two epochs, the earlier Miocene and the later Pliocene. Some geologists assert that the Neogene cannot be clearly delineated from the modern geological period, the Quaternary. The term "Neogene" was coined in 1853 by the Austrian palaeontologist Moritz Hörnes (1815–1868). During this period, mammals and birds continued to evolve into modern forms, while other groups of life remained relatively unchanged. The first humans (''Homo habilis'') appeared in Africa near the end of the period. Some continental movements took place, the most significant event being the connection of North and South America at the Isthmus of Panama, late in the Pliocene. This cut off the warm ocean currents from the Pacific to th ... [...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] |
Centroid
In mathematics and physics, the centroid, also known as geometric center or center of figure, of a plane figure or solid figure is the arithmetic mean position of all the points in the surface of the figure. The same definition extends to any object in ''n''-dimensional Euclidean space. In geometry, one often assumes uniform mass density, in which case the ''barycenter'' or ''center of mass'' coincides with the centroid. Informally, it can be understood as the point at which a cutout of the shape (with uniformly distributed mass) could be perfectly balanced on the tip of a pin. In physics, if variations in gravity are considered, then a ''center of gravity'' can be defined as the weighted mean of all points weighted by their specific weight. In geography, the centroid of a radial projection of a region of the Earth's surface to sea level is the region's geographical center. History The term "centroid" is of recent coinage (1814). It is used as a substitute for the older te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Body-wave Seismograms
A seismic wave is a wave of acoustic energy that travels through the Earth. It can result from an earthquake, volcanic eruption, magma movement, a large landslide, and a large man-made explosion that produces low-frequency acoustic energy. Seismic waves are studied by seismologists, who record the waves using seismometers, hydrophones (in water), or accelerometers. Seismic waves are distinguished from seismic noise (ambient vibration), which is persistent low-amplitude vibration arising from a variety of natural and anthropogenic sources. The propagation velocity of a seismic wave depends on density and elasticity of the medium as well as the type of wave. Velocity tends to increase with depth through Earth's crust and mantle, but drops sharply going from the mantle to Earth's outer core. Earthquakes create distinct types of waves with different velocities. When recorded by a seismic observatory, their different travel times help scientists locate the quake's hypocenter. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linear Seismic Inversion
Inverse modeling is a mathematical technique where the objective is to determine the physical properties of the subsurface of an earth region that has produced a given seismogram. Cooke and Schneider (1983) defined it as calculation of the earth's structure and physical parameters from some set of observed seismic data. The underlying assumption in this method is that the collected seismic data are from an earth structure that matches the cross-section computed from the inversion algorithm. Some common earth properties that are inverted for include acoustic velocity, formation and fluid densities, acoustic impedance, Poisson's ratio, formation compressibility, shear rigidity, porosity, and fluid saturation. The method has long been useful for geophysicists and can be categorized into two broad types: Deterministic and stochastic inversion. Deterministic inversion methods are based on comparison of the output from an earth model with the observed field data and continuously updating ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fold (geology)
In structural geology, a fold is a stack of originally planar surfaces, such as sedimentary strata, that are bent or curved during permanent deformation. Folds in rocks vary in size from microscopic crinkles to mountain-sized folds. They occur as single isolated folds or in periodic sets (known as ''fold trains''). Synsedimentary folds are those formed during sedimentary deposition. Folds form under varied conditions of stress, pore pressure, and temperature gradient, as evidenced by their presence in soft sediments, the full spectrum of metamorphic rocks, and even as primary flow structures in some igneous rocks. A set of folds distributed on a regional scale constitutes a fold belt, a common feature of orogenic zones. Folds are commonly formed by shortening of existing layers, but may also be formed as a result of displacement on a non-planar fault (''fault bend fold''), at the tip of a propagating fault (''fault propagation fold''), by differential compaction or due to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.svg "Click for more on -> CBS News"){kind=logo}
