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1949 Queen Charlotte Earthquake
The 1949 Queen Charlotte Islands earthquake struck Haida Gwaii (at the time known as the Queen Charlotte Islands) and the Pacific Northwest coast at 8:01 p.m. PDT on August 21. The earthquake had a moment magnitude of 8.0 and a surface wave magnitude of 8.1. The maximum Mercalli Intensity in the event was VIII (''Severe''). The interplate earthquake began in the ocean bottom just off the rugged coast of Graham Island. It ruptured along the Queen Charlotte Fault both northward and southward more than . Shaking was felt throughout British Columbia, parts of Washington, Oregon, Alberta, the Yukon, and Alaska. No deaths were reported in this earthquake. Earthquake The 1949 Queen Charlotte Islands earthquake was caused by a rupture on the Queen Charlotte Fault, which forms part of the boundary between the Pacific and North American plates. This fault runs from northern Vancouver Island, west of Haida Gwaii, up to the Gulf of Alaska. The earthquake ruptured the fault for a dista ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fault (geology)
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pacific Plate
The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At , it is the largest tectonic plate. The plate first came into existence 190 million years ago, at the triple junction between the Farallon, Phoenix, and Izanagi Plates. The Pacific Plate subsequently grew to where it underlies most of the Pacific Ocean basin. This reduced the Farallon Plate to a few remnants along the west coast of North America and the Phoenix Plate to a small remnant near the Drake Passage, and destroyed the Izanagi Plate by subduction under Asia. The Pacific Plate contains an interior hot spot forming the Hawaiian Islands. Boundaries The north-eastern side is a divergent boundary with the Explorer Plate, the Juan de Fuca Plate and the Gorda Plate forming respectively the Explorer Ridge, the Juan de Fuca Ridge and the Gorda Ridge. In the middle of the eastern side is a transform boundary with the North American Plate along the San Andreas Fault, and a boundary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terrace, British Columbia
Terrace is a city located near the Skeena River in British Columbia, Canada. The community is the regional retail and service hub for the northwestern portion of British Columbia. With a current population of over 12,000 within municipal boundaries, the city services surrounding communities as well bringing the Greater Terrace Area population to over 18,000 residents. The Kitselas and Kitsumkalum people, tribes of the Tsimshian Nation, have lived in the Terrace area for thousands of years. The individual Indigenous communities neighbour the city with Kitselas to the east and Kitsumkalum to the west. Terrace was originally called Littleton, but this name was rejected by postal authorities because of possible confusion with Lyttleton, a town in New Brunswick. The new name is descriptive of the manner in which the land rises from the river. As northwest British Columbia's main services and transportation hub, Terrace is intersected by the Canadian National Railway as well as Highway ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cumshewa Inlet
Cumshewa Inlet (), also recorded or referred to in exploration logs as Cumchewas Harbour and Tooscondolth Sound, is a large inlet on the east coast of Moresby Island in the Haida Gwaii islands of the North Coast of British Columbia. The inlet was the site of various Haida villages, including Cumshewa (known as ''Thlinul'' or ''Tlkinool'' in the Haida language), Tanu (New Clew) and Djí-gua. The name for the inlet was conferred in the days of the Maritime Fur Trade following a custom whereby captains named locations for the most important local chief, in this case Cumshewa (or G'omshewah), who figures in maritime fur trade The maritime fur trade was a ship-based fur trade system that focused on acquiring furs of sea otters and other animals from the indigenous peoples of the Pacific Northwest Coast and natives of Alaska. The furs were mostly sold in China in exc ... vessel logs from 1787 onwards. In 1794 Cumshewa and his followers massacred the crew of the American trading v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Landslide
Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, deep-seated slope failures, mudflows, and debris flows. Landslides occur in a variety of environments, characterized by either steep or gentle slope gradients, from mountain ranges to coastal cliffs or even underwater, in which case they are called submarine landslides. Gravity is the primary driving force for a landslide to occur, but there are other factors affecting slope stability that produce specific conditions that make a slope prone to failure. In many cases, the landslide is triggered by a specific event (such as a heavy rainfall, an earthquake, a slope cut to build a road, and many others), although this is not always identifiable. Causes Landslides occur when the slope (or a portion of it) undergoes some processes that change its condition from stable to unstable. This is essentially due to a decrease in the shear stren ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Richter Magnitude Scale
The Richter scale —also called the Richter magnitude scale, Richter's magnitude scale, and the Gutenberg–Richter scale—is a measure of the strength of earthquakes, developed by Charles Francis Richter and presented in his landmark 1935 paper, where he called it the "magnitude scale". This was later revised and renamed the local magnitude scale, denoted as ML or . Because of various shortcomings of the original scale, most seismological authorities now use other similar scales such as the moment magnitude scale () to report earthquake magnitudes, but much of the news media still erroneously refers to these as "Richter" magnitudes. All magnitude scales retain the logarithmic character of the original and are scaled to have roughly comparable numeric values (typically in the middle of the scale). Due to the variance in earthquakes, it is essential to understand the Richter scale uses logarithms simply to make the measurements manageable (i.e., a magnitude 3 quake factors ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Northern California
Northern California (colloquially known as NorCal) is a geographic and cultural region that generally comprises the northern portion of the U.S. state of California. Spanning the state's northernmost 48 counties, its main population centers include the San Francisco Bay Area (anchored by the cities of San Jose, San Francisco, and Oakland), the Greater Sacramento area (anchored by the state capital Sacramento), the Redding, California, area south of the Cascade Range, and the Metropolitan Fresno area (anchored by the city of Fresno). Northern California also contains redwood forests, along with most of the Sierra Nevada, including Yosemite Valley and part of Lake Tahoe, Mount Shasta (the second-highest peak in the Cascade Range after Mount Rainier in Washington), and most of the Central Valley, one of the world's most productive agricultural regions. The 48-county definition is not used for the Northern California Megaregion, one of the 11 megaregions of the United St ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megathrust Earthquake
Megathrust earthquakes occur at convergent plate boundaries, where one tectonic plate is forced underneath another. The earthquakes are caused by slip along the thrust fault that forms the contact between the two plates. These interplate earthquakes are the planet's most powerful, with moment magnitudes (''Mw'') that can exceed 9.0. Since 1900, all earthquakes of magnitude 9.0 or greater have been megathrust earthquakes. The thrust faults responsible for megathrust earthquakes often lie at the bottom of oceanic trenches; in such cases, the earthquakes can abruptly displace the sea floor over a large area. As a result, megathrust earthquakes often generate tsunamis that are considerably more destructive than the earthquakes themselves. Teletsunamis can cross ocean basins to devastate areas far from the original earthquake. Terminology and mechanism The term ''megathrust'' refers to an extremely large thrust fault, typically formed at the plate interface along a subduction zon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1700 Cascadia Earthquake
The 1700 Cascadia earthquake occurred along the Cascadia subduction zone on January 26, 1700, with an estimated moment magnitude of 8.7–9.2. The megathrust earthquake involved the Juan de Fuca Plate from mid-Vancouver Island, south along the Pacific Northwest coast as far as northern California. The length of the fault rupture was about , with an average slip of . The earthquake caused a tsunami which struck the west coast of North America and the coast of Japan. Japanese tsunami records, along with reconstructions of the wave moving across the ocean, put the earthquake at about 9pm on the evening of 26 January 1700. Evidence The earthquake took place at about 21:00 Pacific Time on January 26, 1700 ( NS). Although there are no written records for the region from the time, the timing of the earthquake has been inferred from Japanese records of a tsunami that does not correlate with any other Pacific Rim quake. The Japanese records exist primarily in the modern-day Iwate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seismometer
A seismometer is an instrument that responds to ground noises and shaking such as caused by earthquakes, volcanic eruptions, and explosions. They are usually combined with a timing device and a recording device to form a seismograph. The output of such a device—formerly recorded on paper (see picture) or film, now recorded and processed digitally—is a seismogram. Such data is used to locate and characterize earthquakes, and to study the Earth's internal structure. Basic principles A simple seismometer, sensitive to up-down motions of the Earth, is like a weight hanging from a spring, both suspended from a frame that moves along with any motion detected. The relative motion between the weight (called the mass) and the frame provides a measurement of the vertical ground motion. A rotating drum is attached to the frame and a pen is attached to the weight, thus recording any ground motion in a seismogram. Any movement from the ground moves the frame. The mass tends not ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1906 San Francisco Earthquake
At 05:12 Pacific Standard Time on Wednesday, April 18, 1906, the coast of Northern California was struck by a major earthquake with an estimated moment magnitude of 7.9 and a maximum Mercalli intensity of XI (''Extreme''). High-intensity shaking was felt from Eureka on the North Coast to the Salinas Valley, an agricultural region to the south of the San Francisco Bay Area. Devastating fires soon broke out in San Francisco and lasted for several days. More than 3,000 people died, and over 80% of the city was destroyed. The events are remembered as one of the worst and deadliest earthquakes in the history of the United States. The death toll remains the greatest loss of life from a natural disaster in California's history and high on the lists of American disasters. Tectonic setting The San Andreas Fault is a continental transform fault that forms part of the tectonic boundary between the Pacific Plate and the North American Plate. The strike-slip fault is characterize ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2012 Haida Gwaii Earthquake
The 2012 Haida Gwaii earthquake occurred just after . The shock had a moment magnitude of 7.8 and a maximum Mercalli Intensity of V (''Moderate''). The earthquake's epicentre was on Moresby Island of the Haida Gwaii archipelago (formerly known as the Queen Charlotte Islands). This was the second largest Canadian earthquake ever recorded by a seismometer, after the 1949 Queen Charlotte Islands earthquake, about away. One person died due to a car crash related to the tsunami in Oahu, Hawaii. Earthquake Strong shaking was felt throughout Haida Gwaii where residents in Masset, Skidegate, Sandspit, and Queen Charlotte City were evacuated to higher ground. Minor shaking was felt in Prince Rupert and in other cities of the Interior such as Prince George, Quesnel, and as far away as Kamloops. Electricity service was interrupted in Bella Coola. Although the earthquake occurred on the Queen Charlotte Fault, a primarily strike-slip boundary between the Pacific and North Am ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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