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1946 Aleutian Islands Earthquake
The 1946 Aleutian Islands earthquake occurred near the Aleutian Islands, Alaska on April 1, 1946. The shock had a moment magnitude () of 8.6, a tsunami magnitude of 9.3, and a surface-wave magnitude () of only 7.4, and a maximum Mercalli intensity of VI (''Strong''). It resulted in 165–173 casualties and over $26 million in damage. The seafloor along the fault was elevated, triggering a Pacific-wide tsunami with multiple destructive waves at heights ranging from . The tsunami obliterated the Scotch Cap Lighthouse on Unimak Island, Alaska among others, and killed all five lighthouse keepers. Despite the destruction to the Aleutian Island Unimak, the tsunami had almost an imperceptible effect on the Alaskan mainland. Tectonic setting The Aleutian Islands are a group of 14 large and 55 smaller volcanic islands situated between mainland Alaska and Kamchatka. They are situated along the Aleutian Trench as they were formed by the active subduction of the oceanic Pacific plate unde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hilo, Hawaii
Hilo () is a census-designated place (CDP) and the largest settlement in Hawaii County, Hawaii, United States, which encompasses the Island of Hawaii. The population was 44,186 according to the 2020 census. It is the fourth-largest settlement in the state of Hawaii and largest settlement in the state outside of Oahu. Hilo is the county seat of the County of Hawaii and is in the District of South Hilo. The city overlooks Hilo Bay and has views of two shield volcanoes, Mauna Loa, an active volcano, and Mauna Kea, a dormant volcano. Mauna Kea is the site of some of the world's most important ground-based astronomical observatories. The Hilo bay-front has been destroyed by tsunamis twice. The majority of human settlement in Hilo stretches from Hilo Bay to Waiākea-Uka, on the flanks of the volcanoes. Hilo is home to the University of Hawaii at Hilo, ʻImiloa Astronomy Center, as well as the Merrie Monarch Festival, a week-long celebration, including three nights of competition, of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North American Plate
The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Pacific Plate (which borders the plate to the west). It extends eastward to the Mid-Atlantic Ridge and westward to the Chersky Range in eastern Siberia. The plate includes both continental and oceanic crust. The interior of the main continental landmass includes an extensive granitic core called a craton. Along most of the edges of this craton are fragments of crustal material called terranes, which are accreted to the craton by tectonic actions over a long span of time. It is thought that much of North America west of the Rocky Mountains is composed of such terranes. Boundaries The southern boundary with the Cocos Plate to the west and the Caribbean Plate to the east is a transform fault, represented by the Swan Islands Transform Fault unde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
P Wave
A P wave (primary wave or pressure wave) is one of the two main types of elastic body waves, called seismic waves in seismology. P waves travel faster than other seismic waves and hence are the first signal from an earthquake to arrive at any affected location or at a seismograph. P waves may be transmitted through gases, liquids, or solids. Nomenclature The name ''P wave'' can stand for either pressure wave (as it is formed from alternating compressions and rarefactions) or primary wave (as it has high velocity and is therefore the first wave to be recorded by a seismograph). The name ''S wave'' represents another seismic wave propagation mode, standing for secondary or shear wave. Seismic waves in the Earth Primary and secondary waves are body waves that travel within the Earth. The motion and behavior of both P and S waves in the Earth are monitored to probe the interior structure of the Earth. Discontinuities in velocity as a function of depth are indicative of change ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
S Wave
__NOTOC__ In seismology and other areas involving elastic waves, S waves, secondary waves, or shear waves (sometimes called elastic S waves) are a type of elastic wave and are one of the two main types of elastic body waves, so named because they move through the body of an object, unlike surface waves. S waves are transverse waves, meaning that the direction of particle motion of a S wave is perpendicular to the direction of wave propagation, and the main restoring force comes from shear stress. Therefore, S waves cannot propagate in liquids with zero (or very low) viscosity; however, they may propagate in liquids with high viscosity. The name ''secondary wave'' comes from the fact that they are the second type of wave to be detected by an earthquake seismograph, after the compressional primary wave, or P wave, because S waves travel more slowly in solids. Unlike P waves, S waves cannot travel through the molten outer core of the Earth, and this causes a shadow zone for S ... [...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] |
Honolulu
Honolulu (; ) is the capital and largest city of the U.S. state of Hawaii, which is in the Pacific Ocean. It is an unincorporated county seat of the consolidated City and County of Honolulu, situated along the southeast coast of the island of Oahu, and is the westernmost and southernmost major U.S. city. Honolulu is Hawaii's main gateway to the world. It is also a major hub for business, finance, hospitality, and military defense in both the state and Oceania. The city is characterized by a mix of various Asian, Western, and Pacific cultures, reflected in its diverse demography, cuisine, and traditions. ''Honolulu'' means "sheltered harbor" or "calm port" in Hawaiian; its old name, ''Kou'', roughly encompasses the area from Nuuanu Avenue to Alakea Street and from Hotel Street to Queen Street, which is the heart of the present downtown district. The city's desirability as a port accounts for its historical growth and importance in the Hawaiian archipelago and the broader P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tsunami Earthquake
In seismology, a tsunami earthquake is an earthquake which triggers a tsunami of significantly greater magnitude, as measured by shorter-period seismic waves. The term was introduced by Japanese seismologist Hiroo Kanamori in 1972. Such events are a result of relatively slow rupture velocities. They are particularly dangerous as a large tsunami may arrive at a coastline with little or no warning. Characteristics The distinguishing feature for a tsunami earthquake is that the release of seismic energy occurs at long periods (low frequencies) relative to typical tsunamigenic earthquakes. Earthquakes of this type do not generally show the peaks of seismic wave activity associated with ordinary events. A tsunami earthquake can be defined as an undersea earthquake for which the surface wave magnitude Ms differs markedly from the moment magnitude Mw, because the former is calculated from surface waves with a period of about 20 seconds, whereas the latter is a measure of the total ene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1585 Aleutian Islands Earthquake
The 1585 Aleutian Islands earthquake is the source of a vaguely–described tsunami along the Sanriku coast of Japan on June 11, 1585. The event was misdated to 1586 and thought to be generated by the 1586 Lima–Callao earthquake. The misdating also led to it being attributed with the deadly 1586 Tenshō earthquake ( ja). The source earthquake is now determined to be along the Aleutian Islands. Evidence from tsunami deposit and coral rocks in Hawaii led to the inference that this was a large megathrust earthquake occurring on the Aleutian subduction zone with a moment magnitude () as large as 9.25. Background In 1586, a legend describing a wave, measuring up to two meters, struck near Tokura village in the Motoyoshi District of Miyagi Prefecture. The tsunami is also dubbed the "orphan tsunami" or "ghost tsunami" due to the uncertainties regarding the tsunami event. Tsunami event According to Kenji Satake, a Japanese seismologist, the legend of the 1586 tsunami should be disr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Queen Charlotte Fault
The Queen Charlotte Fault is an active transform fault that marks the boundary of the North American plate and the Pacific plate. It is Canada's right-lateral strike-slip equivalent to the San Andreas Fault to the south in California. The Queen Charlotte Fault forms a triple junction south with the Cascadia subduction zone and the Explorer Ridge (the Queen Charlotte Triple Junction). The Queen Charlotte Fault (QCF) forms a transpressional plate boundary, and is as active as other major transform fault systems (i.e. San Andreas, Alpine) in terms of slip rates and seismogenic potential. It sustains the highest known deformation rates among continental or continent-ocean transform systems globally, accommodating greater than 50mm/yr dextral offset. The entire approximately 900 km offshore length has ruptured in seven greater than magnitude 7 events during the last century, making the cumulative historical seismic moment release higher than any other modern transform plate bound ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cape Yakataga, Alaska
Cape Yakataga is a community in the City and Borough of Yakutat of the U.S. state of Alaska. Also known as Yakataga, its coordinates are and its elevation is . Yakataga is a Native American name meaning "canoe road", a reference to two reefs which form a canoe passage to the village. A United States Post Office was established at Cape Yakataga in 1935. Cape Yakataga is served by the Yakataga Airport, which until 2012 had scheduled passenger service subsidized by the U.S. Essential Air Service program. Air service was withdrawn when, in consultation with the United States Department of Labor and examination of State of Alaska Permanent Fund Division records, it was determined that the location no longer had permanent residents. Demographics Yakataga appeared once on the 1960 U.S. Census as an unincorporated village. It is now located within the City and Borough of Yakutat. Climate Cape Yakataga has a subarctic climate (Köppen Köppen is a German surname. Notable people wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
