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2022 Fukushima Earthquake
On March 16, 2022, at 23:36 JST, a strong earthquake struck off the coast of Fukushima, Japan. The earthquake had a magnitude of 7.4 according to the Japanese Meteorological Agency (JMA), while the United States Geological Survey (USGS) gave an estimate of 7.3. Immediately after the event a 30cm tsunami was reported. The event is known in Japanese as . As a result of this natural disaster, three people died and 247 were injured. Tectonic setting The Pacific Plate, made of oceanic lithosphere, subducts beneath the Okhotsk Plate along a convergent boundary located off the east coast of the northern half of Japan. It runs from the Boso Triple Junction and ends near Hokkaido, where it joins the Kuril–Kamchatka Trench. At this location, the Pacific Plate moves approximately westward relative to the North American Plate at a velocity of 70 mm/yr, subducting beneath Japan at the Japan Trench. This subduction zone can produce megathrust earthquakes with magnitudes greater th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Tsunami Warning Center
The National Tsunami Warning Center (NTWC) forms part of an international tsunami warning system (TWS). It serves as the operations center for all coastal regions of Canada and the United States, except Hawaii, the Caribbean, and the Gulf of Mexico. Headquartered in Palmer, Alaska, it is operated by the National Oceanic and Atmospheric Administration, National Oceanic and Atmospheric Administration (NOAA). The NTWC detects and analyzes earthquakes worldwide, issuing warnings to local officials in the hazard zones about the advisability of evacuating low-lying coastal areas and moving ships to deep water. History Following the March 27, 1964 Alaska earthquake and tsunami, the NTWC (formerly known as The Palmer Observatory) was established in 1967 in Palmer, Alaska, under the auspices of the U.S. National Geodetic Survey, Coast and Geodetic Survey. This earthquake alerted State and Federal officials that a facility was necessary to provide timely and effective tsunami warnings and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Japan Trench
The Japan Trench is an oceanic trench part of the Pacific Ring of Fire off northeast Japan. It extends from the Kuril Islands to the northern end of the Izu Islands, and is at its deepest. It links the Kuril–Kamchatka Trench to the north and the Izu–Ogasawara Trench to its south with a length of . This trench is created as the oceanic Pacific plate subducts beneath the continental Okhotsk Plate (a microplate formerly a part of the North American Plate). The subduction process causes bending of the down going plate, creating a deep trench. Continuing movement on the subduction zone associated with the Japan Trench is one of the main causes of tsunamis and earthquakes in northern Japan, including the megathrust Tōhoku earthquake and resulting tsunami that occurred on 11 March 2011. The rate of subduction associated with the Japan Trench has been recorded at about /yr. Tectonic history During the late Neogene period (23.03-2.58 million years ago), the Japan Trench underwent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earthquake Rupture
In seismology, an earthquake rupture is the extent of slip that occurs during an earthquake in the Earth's crust. Earthquakes occur for many reasons that include: landslides, movement of magma in a volcano, the formation of a new fault, or, most commonly of all, a slip on an existing fault. Nucleation A tectonic earthquake begins by an initial rupture at a point on the fault surface, a process known as nucleation. The scale of the nucleation zone is uncertain, with some evidence, such as the rupture dimensions of the smallest earthquakes, suggesting that it is smaller than 100 m while other evidence, such as a slow component revealed by low-frequency spectra of some earthquakes, suggest that it is larger. The possibility that the nucleation involves some sort of preparation process is supported by the observation that about 40% of earthquakes are preceded by foreshocks. However, some large earthquakes, such as the M8.6 1950 India - China earthquake., have no foreshocks and it re ... [...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] |
Reverse 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] |
Foreshock
A foreshock is an earthquake that occurs before a larger seismic event (the mainshock) and is related to it in both time and space. The designation of an earthquake as ''foreshock'', ''mainshock'' or aftershock is only possible after the full sequence of events has happened. Occurrence Foreshock activity has been detected for about 40% of all moderate to large earthquakes, and about 70% for events of M>7.0. They occur from a matter of minutes to days or even longer before the main shock; for example, the 2002 Sumatra earthquake is regarded as a foreshock of the 2004 Indian Ocean earthquake with a delay of more than two years between the two events. Some great earthquakes (M>8.0) show no foreshock activity at all, such as the M8.6 1950 India–China earthquake. The increase in foreshock activity is difficult to quantify for individual earthquakes but becomes apparent when combining the results of many different events. From such combined observations, the increase before the mai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
March 2021 Miyagi Earthquake
On March 20, 2021 at 18:09 JST (09:09 UTC). The magnitude 6.9 or 7.0 earthquake struck offshore east of Tōhoku, Japan at a depth of to . It had a maximum JMA intensity of ''Shindo'' 5+ while on the Mercalli intensity scale, it earned a rating of VII (''Very strong''). Power outages and some slight damage in Miyagi was reported. A press release by the Japan Meteorological Agency stated that the earthquake was an aftershock of the 2011 Tōhoku earthquake and tsunami from ten years prior. Earthquake The earthquake occurred as the result of thrust faulting near the subduction zone interface plate boundary between the Pacific and North America plates. Moment tensor solutions indicate that slip occurred either on a moderately dipping fault striking to the south, or a moderately dipping fault striking to the north-northeast, consistent with the east-west oriented compression expected in this region. At the location of this earthquake, the Pacific plate moves approximately ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2021 Fukushima Earthquake
An intense and deadly seismic event struck offshore east of Tōhoku, Japan. The 7.3 or 7.1 earthquake occurred on a Saturday night at 23:07 JST (14:07 UTC) on 13 February at a focal depth of . It had a maximum JMA intensity of ''Shindo'' 6+ to ''Shindo'' 7 while on the Mercalli intensity scale, earned a rating of VIII (''Severe''). The earthquake was followed by multiple aftershocks within less than an hour, three of which registering magnitude 5.3. The earthquake itself has been considered an aftershock of the 2011 Tōhoku earthquake which had occurred almost ten years prior. The earthquake left three people dead, and at least 186 injured. It also inflicted significant structural damage across the Tōhoku and Kanto regions. This earthquake resulted in both insurance claims and losses exceeding ¥138billion (US$1.3billion). Small tsunami waves were also observed without any damage. Because of its proximity to the Fukushima Daiichi Nuclear Power Plant, the event provoked ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2011 Tōhoku Earthquake And Tsunami
The occurred at 14:46 JST (05:46 UTC) on 11 March. The magnitude 9.0–9.1 (M) undersea megathrust earthquake had an epicenter in the Pacific Ocean, east of the Oshika Peninsula of the Tōhoku region, and lasted approximately six minutes, causing a tsunami. It is sometimes known in Japan as the , among other names. The disaster is often referred to in both Japanese and English as simply 3.11 (read in Japanese). It was the most powerful earthquake ever recorded in Japan, and the fourth most powerful earthquake in the world since modern record-keeping began in 1900. The earthquake triggered powerful tsunami waves that may have reached heights of up to in Miyako in Tōhoku's Iwate Prefecture,Yomiuri Shimbun evening edition 2-11-04-15 page 15, nearby Aneyoshi fishery port (姉吉漁港)(Google map E39 31 57.8, N 142 3 7.6) 2011-04-15大震災の津波、宮古で38.9 m…明治三陸上回るby okayasu Akio (岡安 章夫) and which, in the Sendai area, traveled at a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kuril–Kamchatka Trench
The Kuril–Kamchatka Trench or Kuril Trench (russian: Курило-Камчатский жёлоб, ''Kurilo-Kamchatskii Zhyolob'') is an oceanic trench in the northwest Pacific Ocean. It lies off the southeast coast of Kamchatka and parallels the Kuril Island chain to meet the Japan Trench east of Hokkaido. It extends from a triple junction with the Ulakhan Fault and the Aleutian Trench near the Commander Islands, Russia, in the northeast, to the intersection with the Japan Trench in the southwest. The trench formed as a result of the subduction zone, which formed in the late Cretaceous, that created the Kuril island arc as well as the Kamchatka volcanic arc. The Pacific Plate is being subducted beneath the Okhotsk Plate along the trench, resulting in intense volcanism. Tectonics At the Kuril-Kamchatka Trench, the Pacific Plate is subducting beneath the Okhotsk Plate, a microplate formerly considered to be part of the North American Plate. The convergence rate ranges f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hokkaido
is Japan's second largest island and comprises the largest and northernmost prefecture, making up its own region. The Tsugaru Strait separates Hokkaidō from Honshu; the two islands are connected by the undersea railway Seikan Tunnel. The largest city on Hokkaidō is its capital, Sapporo, which is also its only ordinance-designated city. Sakhalin lies about 43 kilometers (26 mi) to the north of Hokkaidō, and to the east and northeast are the Kuril Islands, which are administered by Russia, though the four most southerly are claimed by Japan. Hokkaidō was formerly known as ''Ezo'', ''Yezo'', ''Yeso'', or ''Yesso''. Nussbaum, Louis-Frédéric. (2005). "Hokkaidō" in Although there were Japanese settlers who ruled the southern tip of the island since the 16th century, Hokkaido was considered foreign territory that was inhabited by the indigenous people of the island, known as the Ainu people. While geographers such as Mogami Tokunai and Mamiya Rinzō explored the isla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
