It started on the previously unrecognized Susitna Glacier Thrust fault, a splay fault south of the McKinley strand of the Denali fault system (DFS). It is located near the centre of the Alaska Range, with two summits rising above the Denali Fault, in south-central Alaska, U.S. Denali’s official elevation figure of 20,310 feet (6,190 metres), established by the United States Geological Survey in September During the afternoon of November 3, 2002, the water in Seattle’s Lake Union suddenly began sloshing hard enough to knock houseboats off their moorings. It is located near the center of the Alaska Range, with two summits rising above the Denali Fault, in south-central Alaska, U.S. Denali lies about 130 miles (210 km) north-northwest of Anchorage and some 170 miles (275 km) southwest of Fairbanks in Denali National Park and Preserve, which covers six million acres (24,281 square km) of land. The earthquake began at 1:12 p.m. Alaska local time, and was centered approximately 135 kilometers (84 miles) south of Fairbanks and 283 kilometers (176 miles) north of Anchorage. The Muldrow Glacier is the park's longest and it is a great example of the power these behemoth ice masses have on the landscape. The Denali fault is an active intraplate dextral strike-slip fault. Its epicenter was located on the Denali fault 22 km east of the M 7.9 event epicenter. “The less time between repeat orbits, the less chance there is for change on the Earth’s surface,” said Ford. Along the Denali Fault, lateral and vertical offset movement is taking place. Even though the earthquakes occurred in a sparsely populated area, scientists are keeping an eye on the Denali Fault because of its similarities to the San Andreas Fault, located near heavily populated areas in California. When Denali was remeasured in 2015, some believed that the mountain was shrinking due to … Unlike the other national parks in Alaska, Denali existed in a smaller form before the Alaska Native Interests Land Conservation Act in 1980 created the 8 Alaskan national parks. Journal of Geophysical Research. Denali lies about 130 miles (210 km) north-northwest of Anchorage and some 170 miles (275 km) southwest of Fairbanks in Denali National Park and Preserve. (Also an important part of fossil location and evolution, but that’s a whole other story.) [2], Learn how and when to remove this template message, "Distribution, nature, and origin of Neogene–Quaternary magmatism in the northern Cordilleran volcanic province, Canada", 10.1130/0016-7606(2000)112<1280:dnaoon>2.0.co;2, "The 2002 Denali Fault Earthquake, Alaska: A Large Magnitude, Slip-Partitioned Event", https://en.wikipedia.org/w/index.php?title=Denali_Fault&oldid=962479519, Articles that may contain original research from June 2015, All articles that may contain original research, Articles with unsourced statements from September 2015, Alaska articles missing geocoordinate data, Creative Commons Attribution-ShareAlike License, This page was last edited on 14 June 2020, at 09:04. The November 3, 2002, magnitude (M) 7.9 Denali Fault earthquake was the strongest ever recorded in the interior of Alaska. The range is also part of the Pacific Ring of Fire, and the Denali Fault that runs along the southern edge of the range is responsible for a number of earthquakes. Notice it is not a Fitch fault as it does not follow the magmatic arc complex. Because some of the faults in southeast Alaska are heavily glaciated, Ford and his colleagues are also interested in studying the relationship between glaciers and structural geology. Landslide material may insulate glacier ice, raising its temperature towards the melting point. In addition, landslides completely covered parts of several Alaskan glaciers after the November 3 Denali Fault earthquake. It is convenient to view the fault as a single curve, but it is actually comprised of clusters of fault patterns. The Denali fault system is widely recognized as transpressional due to the presence of the Denali fault, a major, active, right-lateral fault, and subparallel zones of thrust faults and fault-related folding along both the north and south flanks of the Alaska Range. “With InSAR, we can capture the whole picture, no matter where the epicenter of an earthquake is,” said Ford. The M W (moment magnitude) 7.9 Denali fault earthquake on 3 November 2002 was associated with 340 kilometers of surface rupture and was the largest strike-slip earthquake in North America in almost 150 years. Kahiltna Glacier is the longest glacier in the park. However, only 13,803 feet (4,207 meters) rise above sea level. Shaking at the epicenter lasted approximately 1.5 to 2 minutes, but in Fairbanks the duration of the earthquake was over 3 minutes. [2] The fault's rate of displacement varies from 1 mm to 35 mm per year.[3]. In that respect, RADARSAT-1 had an advantage over the ERS missions. The middle elevations feature tundra. Measuring 7.9 in magnitude, the earthquake caused ground to shift beneath the pipeline 14 feet horizontally and 2.5 feet vertically. In addition, both of the Denali Fault earthquakes occurred at a depth in the Earth’s crust of 5 kilometers (3.1 miles) or less, which is considered relatively shallow. Both quakes were centered along the Denali Fault. The resulting image, called an interferogram, shows where deformation occurred on the Earth’s surface. Facts about Denali National Park 2: the landscape of Denali National Park. “It’s the first time this has ever been done in earthquake research. Now considered a foreshock of the larger quake, the October earthquake caused no surface ruptures. The lowest elevations of Denali National Park are a combination of forests. The president was, however, from Ohio and never even visited the state of Alaska. Random Facts About Denali Mount McKinley is the highest point on the North American continent, with its peak rising to 20,320 feet. By further studying and understanding the kind of deformation that split open the ground surface in Alaska, scientists hope to glean clues about earthquake damage potential along the San Andreas Fault. Denali, highest peak in North America. Surface changes occurring between orbits (such as excessive rainfall or snowfall, or changes in vegetation) can cause “noise” in interferograms, making them less accurate. ASF’s fortuitous collection of images allowed Ford and his colleagues to make a series of three interferograms: one for each of the earthquakes, and a cumulative interferogram that includes both earthquakes. However, that skin is not all in one piece, it is a… Alaska is the most geologically active part of the United States. USGS Fact Sheet 014-03: Rupture in South-Central Alaska — The Denali Fault Earthquake of 2002. “Usually, the earthquakes that are damaging to populations and structures occur close to the surface, so this is significant,” said Price. Because earthquakes tend to recur along faults, an earthquake that relieves stress on one part of a fault may actually increase stress on other parts of a fault system. USGS Fact Sheet 014-03: Rupture in South-Central Alaska — The Denali Fault Earthquake of 2002, NASA Goddard Space The ability to generate interferograms for each earthquake allowed Ford to investigate how the foreshock focused tectonic stresses and added strength to the mainshock. Bedrock geologic map of the eastern Denali Highway area, Mount Hayes, Healy, and Talkeetna Mountains quadrangles, Alaska - RI 2020-7 New release! The Denali Fault is a major intracontinental dextral (right lateral) strike-slip fault in western North America, extending from northwestern British Columbia, Canada to the central region of the U.S. state of Alaska.[1]. The Denali Fault System. The Denali Fault is located in Alaska's Denali National Park and to the east. This National Park includes part of a massive mountain range more than 600 miles long. According to Ford, “The Denali Fault earthquake was the ‘big one’ for Alaska.” The cracks in the Earth’s surface along parts of the fault were up to 6.7 meters (22 feet) wide, which would have caused considerable damage to a more heavily populated area, such as California. Glaciers tend to flow down fault lines, eroding the ground surface and acting as conveyor belts for rock material. Accessed August 10, 2003. The earthquake began at 1:12 p.m. Alaska local time, and was centered approximately 135 kilometers (84 miles) south of Fairbanks and 283 kilometers (176 miles) north of Anchorage. It began with thrusting on the previously unrecognized Susitna Glacier fault, continued with right-slip … It began with thrusting on the previously unrecognized Susitna Glacier fault, continued with right-slip … 40Ar/39Ar data from the Richardson mining district, Big Delta Quadrangle, Alaska - RDF 2020-11 40Ar/39Ar data from the Richardson mining district, Big Delta Quadrangle, Alaska - RDF 2020-11 The earthquake began at 1:12 p.m. Alaska local time, and was centered approximately 135 kilometers (84 miles) south of Fairbanks and 283 kilometers (176 miles) north of Anchorage. Bedrock geologic map of the eastern Denali Highway area, Mount Hayes, Healy, and Talkeetna Mountains quadrangles, Alaska - RI 2020-7 New release! Then the rupture transferred onto the main strand of the DFS and continued as a right-lateral strike-slip event for ~220 km until it … The Denali Fault System is refereed to as such because there are numerous faults present. As a final tribute to the active tectonics of Alaska, a series of faults have fractured the park and most of the state in the last 100 million years. If that is the case, the longer fault system could produce larger temblors. The Denali Fault and other active faults in Alaska encroach on populated areas and critical infrastructure, including existing and proposed oil and natural gas pipelines. Anchorage is precariously perched 100 miles south of … The surface wave magnitude of this quake was 8.5, with an overall magnitude estimated around 7.0 to 7.9. Evelyn J. Accessed June 26, 2003. Fault creep The resulting surface rupture was approximately 336 kilometers (209 miles) long, and it cut through streams, divided forests, opened chasms in roads, and even generated fault traces visible across several glaciers. Originating on the previously unknown Susitna Glacier Fault, the earthquake shot eastward along the well-known Denali Fault at a speed of over 11,265 kilometers (7,000 miles) per hour before branching southeast onto the Totschunda Fault. Running right by Denali, the Denali Fault triggers around 600 earthquakes a year within the park that are at least a magnitude 1. Denali is a region of great geologic activity and complex-ity, and scientists are only beginning to piece together its puzzling past. Much of the lower reaches of the ice are covered in dirt and rocks that have been scoured off of the neighboring mountains on the slow journey from Denali… In Denali, this group of faults is known as the Denali fault system, which arcs East-West through the park (and most of the state) for 1200 kilometers (720 miles). The Denali Fault is also known as a “strike slip” fault: where two pieces of continent rub against each other as they head in opposite directions. The November 3 Denali Fault earthquake was preceded by the magnitude 6.7 Nenana Mountain earthquake on October 23. It illuminates earthquake mechanics and hazards of large strike-slip faults. Image courtesy of the USGS. Alaska’s Denali Fault was on the move, jostling the state with a magnitude 7.9 earthquake. The Alaska Range is a 600-mile long arc of mountains that stretches from the Alaska-Canada border all the way to the Alaska Peninsula. The Denali-Totschunda fault is a major dextral (right lateral) strike-slip system, similar in scale to the San Andreas fault system. Every pair of SAR images used in the past has straddled both the major foreshocks and the mainshock. The resulting surface rupture was approximately 336 kilometers (209 miles) long, and it cut through streams, divided forests, opened chasms in roads, and even generated fault traces visible across several glaciers. This is the location of the largest earthquake ever recorded in North America. It has rock for-mations that have b… In the two hours since the primary earthquake, nearly half a dozen aftershocks of 4.0 or greater occurred. While the fault rupture lasted for approximately 100 sec from its initiation to the arrest, its distal effects were felt for many days. The principal rupture was a 210-kilometer-long section of the Denali fault, with horizontal shifts of up to nearly 9 meters (26 feet). The top of the mantle makes up a thin skin on the surface of the Earth. It was said that he named it after McKinley because of his support for the gold rush and gold standard. Over the billions of years, the land broke apart and created what we recognize today. Although Alaska’s Denali Fault was home to a network of GPS receivers, earthquakes are unpredictable, and no one knows whether the next one will strike in a location with a GPS receiver to measure it. [4] During the afternoon of November 3, 2002, the water in Seattle's Lake Union suddenly began sloshing hard enough to knock houseboats off their moorings. However, many scientists believe that the Hayward Fault is connected to the Calaveras Fault to the south, the Rodgers Creek Fault to the north and to the Maacama Fault still farther north. Water in pools, ponds, and bayous as far away as Texas and Louisiana splashed for nearly half an hour. This places the rupture in the same class as those that produced the San Andreas fault's two historical great earthquakes in 1906 and 1857. It was the main fault along which the 2002 Denali earthquake occurred, which was measured as a magnitude of 7.9 Mw. It illuminates earthquake mechanics and hazards of large strike-slip faults. The additional weight of rocks and dirt can also cause greater pressure and melting at the base of the glacier, increasing the likelihood that a glacier may surge forward. They also prevent material from filling in faults, which tends to keep faults active. Price and David T. Sandwell. On November 3, 2002, the largest earthquake recorded in the interior of Alaska, at 7.9 magnitude, shook the park from its epicenter along the Denali Fault… Once the satellite acquired the image we needed, ASF downloaded and formatted it, and it was ready for us within hours,” said Ford. Interferometry involves taking Synthetic Aperture Radar (SAR) satellite images from two different dates and precisely calculating the differences between the two. The range is highest at its mid-section, a vast region of towering peaks and massive glaciers that lies within Denali National Park and Preserve. “When the earthquakes occurred, we wanted to see if we could determine how much ground motion there was,” said Ford. The M W (moment magnitude) 7.9 Denali fault earthquake on 3 November 2002 was associated with 340 kilometers of surface rupture and was the largest strike-slip earthquake in North America in almost 150 years. Flight Center. 3. 1998. Shaking at the epicenter lasted approximately 1.5 to 2 minutes, but in Fairbanks the duration of the earthquake was over 3 minutes. “We want to know how earthquakes affect the behavior of these glaciers and how the glaciers are moving and responding,” said Ford. After the November 3 earthquake, Ford and his colleagues contacted the Alaska Satellite Facility (ASF) in Fairbanks. In addition, both of the Denali Fault earthquakes occurred at a depth in the Earth’s crust of 5 kilometers (3.1 miles) or less, which is considered relatively shallow. In 2015, the mountain was officially changed to the name that the locals always referred to it as; Denali. “RADARSAT-1 repeats its orbit every 24 days, whereas ERS-1 and ERS-2 repeated every 35 days,” said Ford. According to Ford, “The Denali Fault earthquake was the ‘big one’ for Alaska.” The cracks in the Earth’s surface along parts of the fault were up to 6.7 meters (22 feet) wide, which would have caused considerable damage to a more heavily populated area, such as California. Because the earthquake released most of its energy on the sparsely populated eastern end of the fault, Alaska’s major cities were spared serious damage. The Denali Fault earthquake will give clues to the behavior of underground layers of rock known as the lower crust and mantle. On November 3, 2002, the Denali Fault ruptured over a distance of 336 km, producing the largest earthquake from a continental strike-slip fault in North America since the 1906 San Francisco earthquake. Like most earthquakes of its size, it was complex, consisting of several subevents. The quake was the largest on the Denali Fault since at least 1912 and among the strongest earthquakes recorded in North America in the last 100 years. One of the biggest challenges with SAR imagery is the infrequency of satellite overpasses. Abstract . 103(B11):27,001-27,016. Note also, that Alaska is not behaving as one rigid plate. “ASF gave us priority. “And you can’t measure ground motion on the scale of millimeters over that kind of area unless you use interferometry.”. Alaska’s Denali Fault was on the move, jostling the state with a magnitude 7.9 earthquake. The M 7.9 Denali Fault event was preceded by the magnitude 6.7 Nenana Mountain event on October 23, 2002. The MW (moment magnitude) 7.9 Denali fault earthquake on 3 November 2002 was associated with 340 kilometers of surface rupture and was the largest strike-slip earthquake in North America in almost 150 years. The InSAR maps of surface deformation near the earthquake epicenters that Ford and his colleagues generated agreed with USGS findings, which included aerial and ground surveys of the fault rupture, as well as Global Positioning System (GPS) measurements. Ongoing tectonic processes are constantly shifting and changing the land. While the November 3 earthquake in Alaska caused few injuries and no deaths, it did cause numerous landslides and damaged roads and bridges at a cost of at least $25 million. In Alaska, moving from east to west, the plate interactions change from a transform boundary between Pacific and North American plates to a collision zone with a microplate, the Yakutat terrane, which is in the process of being accreted to the North American plate, to a destructive … You can also find deciduous taiga here. So Ford and his colleagues turned to SAR imagery from RADARSAT-1 (a satellite managed by the Canadian Space Agency), which had never before been applied in earthquake interferometry. Water in pools, ponds, and bayous as far away as Texas and Louisiana splashed for nearly half an hour.

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