Fujita scale

The Fujita scale (F-Scale), or Fujita–Pearson scale (FPP scale), is a scale for rating tornado intensity, based primarily on the damage tornadoes inflict on human-built structures and vegetation. The official Fujita scale category is determined by meteorologists and engineers after a ground or aerial damage survey, or both; and depending on the circumstances, ground-swirl patterns (cycloidal marks), weather radar data, witness testimonies, media reports and damage imagery, as well as photogrammetry or videogrammetry if motion picture recording is available. The Fujita scale was replaced with the Enhanced Fujita scale (EF-Scale) in the United States in February 2007. In April 2013, Canada adopted the EF-Scale over the Fujita scale along with 31 "Specific Damage Indicators" used by Environment Canada (EC) in their ratings.[1][2]

Fujita scale
F0 40–72 mph Light damage
F1 73–112 mph Moderate damage
F2 113–157 mph Considerable damage
F3 158–206 mph Severe damage
F4 207–260 mph Devastating damage
F5 261–318 mph Incredible damage


The scale was introduced in 1971 by Tetsuya Fujita of the University of Chicago, in collaboration with Allen Pearson, head of the National Severe Storms Forecast Center/NSSFC (currently the Storm Prediction Center/SPC). The scale was updated in 1973, taking into account path length and width. In the United States, starting in 1973, tornadoes were rated soon after occurrence. The Fujita scale was applied retroactively to tornadoes reported between 1950 and 1972 in the National Oceanic and Atmospheric Administration (NOAA) National Tornado Database. Fujita rated tornadoes from 1916–1992 [3][4] and Tom Grazulis of The Tornado Project retroactively rated all known significant tornadoes (F2–F5 or causing a fatality) in the U.S. back to 1880.[5] The Fujita scale was adopted in most areas outside of Great Britain.

In 2007, the Fujita scale was updated, and the Enhanced Fujita Scale was introduced in the United States. The new scale more accurately matches wind speeds to the severity of damage caused by the tornado.

Though each damage level is associated with a wind speed, the Fujita scale is effectively a damage scale, and the wind speeds associated with the damage listed aren't rigorously verified. The Enhanced Fujita Scale was formulated due to research which suggested that the wind speeds required to inflict damage by intense tornadoes on the Fujita scale are greatly overestimated. A process of expert elicitation with top engineers and meteorologists resulted in the EF scale wind speeds, however, these are biased to United States construction practices. The EF scale also improved damage parameter descriptions.


Fujita scale technical

The original scale as derived by Fujita was a theoretical 13-level scale (F0–F12) designed to smoothly connect the Beaufort scale and the Mach number scale. F1 corresponds to the twelfth level of the Beaufort scale, and F12 corresponds to Mach number 1.0. F0 was placed at a position specifying no damage (approximately the eighth level of the Beaufort scale), in analogy to how the Beaufort's zeroth level specifies little to no wind. From these wind speed numbers, qualitative descriptions of damage were made for each category of the Fujita scale, and then these descriptions were used to classify tornadoes.[6] The diagram on the right illustrates the relationship between the Beaufort, Fujita, and Mach number scales.

At the time Fujita derived the scale, little information was available on damage caused by wind, so the original scale presented little more than educated guesses at wind speed ranges for specific tiers of damage. Fujita intended that only F0–F5 be used in practice, as this covered all possible levels of damage to frame homes as well as the expected estimated bounds of wind speeds. He did, however, add a description for F6, which he phrased as "inconceivable tornado", to allow for wind speeds exceeding F5 and for possible future advancements in damage analysis which might show it.[7]

Furthermore, the original wind speed numbers have since been found to be higher than the actual wind speeds required to incur the damage described at each category. The error manifests itself to an increasing degree as the category increases, especially in the range of F3 through F5. NOAA notes that "... precise wind speed numbers are actually guesses and have never been scientifically verified. Different wind speeds may cause similar-looking damage from place to place—even from building to building. Without a thorough engineering analysis of tornado damage in any event, the actual wind speeds needed to cause that damage are unknown."[7] Since then, the Enhanced Fujita Scale has been created using better wind estimates by engineers and meteorologists.

Some sources add level F+", meaning a tornado with winds below 39 mph; on rare occasions tornadoes this weak are observed covering a wide range of path widths and lengths.


The six categories are listed here, in order of increasing intensity.

  • The rating of any given tornado is of the most severe damage to any well-built frame home or comparable level of damage from engineering analysis of other damage.
  • Since the Fujita scale is based on the severity of damage resulting from high winds, an F6 or an F7 tornado is a theoretical construct. Structural damage cannot exceed total destruction, which constitutes F5 damage. A tornado with wind speeds greater than 319 miles per hour (513 km/h) is theoretically possible, and the 1999 Bridge Creek-Moore Tornado may have been such an event. However, no such wind speed has ever been recorded and that measurement was not near ground level.
Scale Wind speed estimate[8] Potential damage[8]
mph km/h
F0 40–72 64–116 Light damage.

Some damage to chimneys; branches broken off trees; shallow-rooted trees pushed over; sign boards damaged.

F0 damage example
F1 73–112 117–180 Moderate damage.

The lower limit is the beginning of hurricane wind speed; peels surface off roofs; mobile homes pushed off foundations or overturned; moving vehicles pushed off the roads; attached garages may be destroyed.

F1 damage example
F2 113–157 181–253 Significant damage.

Roofs torn off frame houses; mobile homes demolished; boxcars overturned; large trees snapped or uprooted; highrise windows broken and blown in; light-object missiles generated.

F2 damage example
F3 158–206 254–332 Severe damage.

Roofs and some walls torn off well-constructed houses; trains overturned; most trees in forest uprooted; heavy cars lifted off the ground and thrown.

F3 damage example
F4 207–260 333–418 Devastating damage.

Well-constructed houses leveled; structures with weak foundations blown away some distance; cars thrown and large missiles generated.

F4 damage example
F5 261–318 419–512 Incredible damage.

Strong frame houses lifted off foundations and carried considerable distances to disintegrate; automobile sized missiles fly through the air farther than 100 meters (110 yards); trees debarked; steel reinforced concrete structures badly damaged and skyscrapers toppled

F5 damage example

Rating classifications

Tornado rating classifications
F0 F1 F2 F3 F4 F5
Weak Strong Violent

For purposes such as tornado climatology studies, Fujita scale ratings may be grouped into classes.[5][9][10]

Decommission in the US

The Fujita scale, introduced in 1971 as a means to differentiate tornado intensity and path area, assigned wind speeds to damage that were, at best, educated guesses.[11] Fujita and others recognized this immediately and intensive engineering analysis was conducted through the rest of the 1970s. This research, as well as subsequent research, showed that tornado wind speeds required to inflict the described damage were actually much lower than the F-scale indicated, particularly for the upper categories. Also, although the scale gave general descriptions for the type of damage a tornado could cause, it gave little leeway for strength of construction and other factors that might cause a building to receive higher damage at lower wind speeds. Fujita tried to address these problems somewhat in 1992 with the Modified Fujita Scale,[12] but by then he was semi-retired and the National Weather Service was not in a position for the undertaking of updating to an entirely new scale, so it went largely unenacted.[13]

In the United States, on February 1, 2007,[1][2] the Fujita scale was decommissioned in favor of what these scientists believe is a more accurate Enhanced Fujita Scale, which replaces it. The meteorologists and engineers who designed the EF Scale believe it an improvement on the F-scale on many counts—it accounts for different degrees of damage that occur with different types of structures, both man-made and natural. The expanded and refined damage indicators and degrees of damage standardize what was somewhat ambiguous. It also is thought to provide a much better estimate for wind speeds, and sets no upper limit on the wind speeds for the strongest level, EF5. Several countries continue to use the original Fujita Scale. Environment Canada has begun using the Enhanced Fujita scale in Canada as of April 18, 2013.[14]

See also



  1. ^ a b "Fujita Tornado Damage Scale". spc.noaa.gov. Retrieved May 27, 2017.
  2. ^ a b "Tornado Scale – The Enhanced Fujita Scale". tornadofacts.net. Retrieved May 27, 2017.
  3. ^ McDonald, James R. (2001). "American Meteorological Society". Bulletin of the American Meteorological Society. 82: 63–72. doi:10.1175/1520-0477(2001)000<0063:TTFHCT>2.3.CO;2.
  4. ^ McCarthy, Daniel. "NWS TORNADO SURVEYS AND THE IMPACT ON THE NATIONAL TORNADO" (PDF). www.spc.noaa.gov.
  5. ^ a b Grazulis, Thomas P. (July 1993). Significant Tornadoes 1680–1991. St. Johnsbury, Vermont: The Tornado Project of Environmental Films. ISBN 978-1-879362-03-1.
  6. ^ "Storm Prediction Center". spc.noaa.gov. Retrieved May 27, 2017.
  7. ^ a b Tornado FAQ. Storm Prediction Center. Site accessed June 27, 2006.
  8. ^ a b Fujita Tornado Damage Scale Storm Prediction Center. Accessed May 20, 2009.
  9. ^ The Fujita Scale of Tornado Intensity, Archived at: Archived December 30, 2011, at the Wayback Machine
  10. ^ Brooks, Harold. "index". nssl.noaa.gov. Retrieved May 27, 2017.
  11. ^ Fujita, Tetsuya Theodore (1971). Proposed characterization of tornadoes and hurricanes by area and intensity. Chicago: University of Chicago.
  12. ^ Center, Storm Prediction. "NOAA's NWS Storm Prediction Center". www.spc.noaa.gov. Retrieved May 27, 2017.
  13. ^ Fujita, Tetsuya Theodore (1992). Memoirs of an Effort to Unlock the Mystery of Severe Storms. Chicago: University of Chicago.
  14. ^ Assessing tornado damage: EF-scale vs. F-scale Archived April 27, 2013, at the Wayback Machine


External links

1865 Viroqua tornado

The 1865 Viroqua tornado moved through western Wisconsin on Thursday, June 29, 1865. With at least 22 fatalities, it was one of the first deadly tornadoes recorded in Wisconsin after it became a state 17 years prior.

1992 Queensland storms

The 1992 Queensland storms were a series of thunderstorms which struck southeastern Queensland, Australia on 29 November 1992. The storms produced strong winds, flash flooding and large hailstones in the region, including the capital city of Brisbane. The storms also spawned two of the most powerful tornadoes recorded in Australia, including the only Australian tornado to be given an official 'F4' classification on the Fujita scale.The meteorological instability in the region resulted in the formation of at least five supercell thunderstorms in the space of around three hours. The storms, which spawned progressively further up the coast from Brisbane to Gladstone as the afternoon progressed, left a trail of damage resulting from hail, rain and wind. The event has been described as "one of the most widespread outbreaks of severe thunderstorms recorded" by veteran meteorologist Richard Whitaker.

2006 London tornado

The 2006 London tornado was a significant United Kingdom tornado spawned from a squall line moving over the city on 7 December 2006 at approximately 11:02 GMT. Its intensity is estimated to have been T4 on the TORRO scale, equating to F2 on the Fujita scale.

2007 Elie, Manitoba tornado

The Elie, Manitoba tornado was an F5 tornado that struck the town of Elie, in the Canadian province of Manitoba (40 kilometres (25 miles) west of Winnipeg), on Friday, June 22, 2007. While several houses were leveled, no one was injured or killed by the tornado. A home in the town was swept clean off of its foundation, justifying the F5 classification. This makes it one of the strongest twisters on record since 1999 and one of only nine to reach F5/EF5 intensity between 1999 and 2011 in North America. This tornado was part of a two-day outbreak of severe weather through June 23, including at least four other tornadoes confirmed in Manitoba and Saskatchewan. Because Environment Canada adopted the Enhanced Fujita scale in 2013, there will be no more tornadoes with an F5 rating, making this tornado the first and last confirmed F5 tornado in Canada.

Birmingham tornado of 2005

The Birmingham tornado of 2005 was one of the strongest tornadoes recorded in the United Kingdom in nearly 30 years, occurring on 28 July 2005 in the suburbs of Birmingham. It formed on a day when strong tornadoes were expected to develop across the Midlands and eastern England. The tornado struck at approximately 2.30pm BST in the Sparkbrook area of the city, also affecting King's Heath, Moseley and Balsall Heath as it carved 7 kilometre-long path through the city. Its main effects were felt in the Ladypool Road which bore the brunt of the damage. Ladypool Primary School was extensively damaged and lost its distinctive Martin & Chamberlain tower. The adjacent St Agatha's Church also suffered some damage. Christ Church (consecrated 1867), on the corner of Dolobran Road and Grantham Road in Sparkbrook was also damaged and has now been demolished.The Met Office and TORRO (The Tornado and Storm Research Organisation) has estimated that the tornado had a general T4 rating on the TORRO scale with a short spell as a T5/6 tornado, which would indicate wind speeds between 137 and 186 mph (220 and 299 km/h), equivalent to an F2 or F3 tornado on the Fujita scale.

There were no fatalities, although there were approximately 19 injuries, three of which were reported to be serious. The tornado uprooted an estimated 1000 trees, removed the roofs of buildings, picked up and deposited cars and caused other damage during its short existence. The total cost of damage has been put at £40 million, making it the most costly tornado in British history.

While the United Kingdom has more reported tornadoes, relative to its land area, than any other country excluding the Netherlands, the vast majority are weak. The strongest recorded tornado in the country struck Portsmouth on 14 December 1810 with a T8 (F4) rating and a top wind speed of 213 to 240 mph (343 to 386 km/h).

Edgewater, Alabama

Edgewater is a census-designated place in Jefferson County, Alabama, United States. It is northeast from the Birmingham suburb of Pleasant Grove. Its population was 883 at the 2010 census. This area was damaged by tornadoes on April 15, 1956 and April 8, 1998. The 1998 tornado was rated an F5 on the Fujita scale.

Enhanced Fujita scale

The Enhanced Fujita scale (EF-Scale) rates the intensity of tornadoes in some countries, including the United States and Canada, based on the damage they cause.

Implemented in place of the Fujita scale introduced in 1971 by Tetsuya Theodore Fujita, it began operational use in the United States on February 1, 2007, followed by Canada on April 1, 2013. It has also been proposed for use in France. The scale has the same basic design as the original Fujita scale—six categories from zero to five, representing increasing degrees of damage. It was revised to reflect better examinations of tornado damage surveys, so as to align wind speeds more closely with associated storm damage. Better standardizing and elucidating what was previously subjective and ambiguous, it also adds more types of structures and vegetation, expands degrees of damage, and better accounts for variables such as differences in construction quality.

The newer scale was publicly unveiled by the National Weather Service at a conference of the American Meteorological Society in Atlanta on February 2, 2006. It was developed from 2000 to 2004 by the Fujita Scale Enhancement Project of the Wind Science and Engineering Research Center at Texas Tech University, which brought together dozens of expert meteorologists and civil engineers in addition to its own resources.

As with the Fujita scale, the Enhanced Fujita scale remains a damage scale and only a proxy for actual wind speeds. While the wind speeds associated with the damage listed have not undergone empirical analysis (such as detailed physical or any numerical modeling) owing to excessive cost, the wind speeds were obtained through a process of expert elicitation based on various engineering studies since the 1970s as well as from field experience of meteorologists and engineers. In addition to damage to structures and vegetation, radar data, photogrammetry, and cycloidal marks (ground swirl patterns) may be utilized when available.

The scale was used for the first time in the United States a year after its public announcement when parts of central Florida were struck by multiple tornadoes, the strongest of which were rated at EF3 on the new scale. It was used for the first time in Canada shortly after its implementation there when a tornado developed near the town on Shelburne, Ontario on April 18, 2013, causing up to EF1 damage.

F scale

F scale may refer to:

F-scale (personality test), a personality test that attempts to quantify authoritarian tendencies

Fujita scale, a rating of a tornado's intensity by its impact on structures and vegetation

F scale (modelling), a 1:20.3 scaled gauge track used with model trains

F Scale, a validity scale of the Minnesota Multiphasic Personality Inventory

the F major scale.

Great Natchez Tornado

The Great Natchez Tornado hit Natchez, Mississippi, on Thursday, May 7, 1840. This tornado was the second deadliest tornado in United States history; at least 317 people were killed and at least 109 were injured.

McDonald Chapel, Alabama

McDonald Chapel is a census-designated place in Jefferson County, Alabama, United States. It is northeast of the Birmingham suburb of Pleasant Grove. At the 2010 census the population was 717. Large portions of this area were damaged by violent tornadoes in 1956, 1998, and 2011. The 1998 tornado was rated an F5 on the Fujita scale.

Northeast Snowfall Impact Scale

The Northeast Snowfall Impact Scale (NESIS) was created to measure snowstorms in the U.S. Northeast in much the same way the Saffir-Simpson Hurricane Scale records hurricane intensity and the Enhanced Fujita Scale with tornadoes.

TORRO scale

The TORRO tornado intensity scale (or T-Scale) is a scale measuring tornado intensity between T0 and T11. It was proposed by Terence Meaden of the Tornado and Storm Research Organisation (TORRO), a meteorological organisation in the United Kingdom, as an extension of the Beaufort scale.

Ted Fujita

Tetsuya Theodore "Ted" Fujita (藤田 哲也, Fujita Tetsuya, October 23, 1920 – November 19, 1998) was a prominent Japanese-American severe storms researcher. His research at the University of Chicago on severe thunderstorms, tornadoes, hurricanes, and typhoons revolutionized the knowledge of each. He is best known for creating the Fujita scale of tornado intensity and damage.

Teton–Yellowstone tornado

The Teton–Yellowstone tornado was a rare high-altitude tornado which occurred on July 21, 1987 in the U.S. State of Wyoming. Rated at F4 on the Fujita scale, it was the strongest tornado ever recorded in the state. It was also the only recorded F4 tornado in Wyoming history. The tornado cut through a 24-mile (39 km) long, 1.5-mile (2.4 km) wide swath of the Teton Wilderness and Yellowstone National Park, and even crossed the Continental Divide. The damage occurred at elevations ranging from 8,500 to 10,000 feet (2,600 to 3,000 m), making it the highest altitude violent tornado recorded in the United States. No human fatalities or injuries were recorded, but up to 1,000,000 trees were uprooted by the storm. The F4 rating was based on the severity of the tree damage in the worst affected areas. Huge swaths of trees were flattened, and many were stripped of leaves and limbs, with the trunks debarked. Topsoil was picked up and spattered against the bare trunks. Fujita noted that the tree damage was only comparable to that he had seen associated with some of the tornadoes from the 1974 Super Outbreak, as well as the April 1977 Birmingham tornado. Most of the damaged forest later burned in the Yellowstone fires of 1988.


A tornado is a rapidly rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. The windstorm is often referred to as a twister, whirlwind or cyclone, although the word cyclone is used in meteorology to name a weather system with a low-pressure area in the center around which winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern. Tornadoes come in many shapes and sizes, and they are often visible in the form of a condensation funnel originating from the base of a cumulonimbus cloud, with a cloud of rotating debris and dust beneath it. Most tornadoes have wind speeds less than 110 miles per hour (180 km/h), are about 250 feet (80 m) across, and travel a few miles (several kilometers) before dissipating. The most extreme tornadoes can attain wind speeds of more than 300 miles per hour (480 km/h), are more than two miles (3 km) in diameter, and stay on the ground for dozens of miles (more than 100 km).Various types of tornadoes include the multiple vortex tornado, landspout and waterspout. Waterspouts are characterized by a spiraling funnel-shaped wind current, connecting to a large cumulus or cumulonimbus cloud. They are generally classified as non-supercellular tornadoes that develop over bodies of water, but there is disagreement over whether to classify them as true tornadoes. These spiraling columns of air frequently develop in tropical areas close to the equator, and are less common at high latitudes. Other tornado-like phenomena that exist in nature include the gustnado, dust devil, fire whirl, and steam devil.

Tornadoes occur most frequently in North America, particularly in central and southeastern regions of the United States colloquially known as tornado alley, as well as in Southern Africa, northwestern and southeast Europe, western and southeastern Australia, New Zealand, Bangladesh and adjacent eastern India, and southeastern South America. Tornadoes can be detected before or as they occur through the use of Pulse-Doppler radar by recognizing patterns in velocity and reflectivity data, such as hook echoes or debris balls, as well as through the efforts of storm spotters.

There are several scales for rating the strength of tornadoes. The Fujita scale rates tornadoes by damage caused and has been replaced in some countries by the updated Enhanced Fujita Scale. An F0 or EF0 tornado, the weakest category, damages trees, but not substantial structures. An F5 or EF5 tornado, the strongest category, rips buildings off their foundations and can deform large skyscrapers. The similar TORRO scale ranges from a T0 for extremely weak tornadoes to T11 for the most powerful known tornadoes. Doppler radar data, photogrammetry, and ground swirl patterns (trochoidal marks) may also be analyzed to determine intensity and assign a rating.

Tornado intensity

Tornado intensity can be measured by in situ or remote sensing measurements, but since these are impractical for wide scale use, intensity is usually inferred via proxies, such as damage. The Fujita scale and the Enhanced Fujita scale rate tornadoes by the damage caused. The Enhanced Fujita Scale was an upgrade to the older Fujita scale, with engineered (by expert elicitation) wind estimates and better damage descriptions, but was designed so that a tornado rated on the Fujita scale would receive the same numerical rating. An EF0 tornado will probably damage trees and peel some shingles off the roof. an EF5 tornado can rip homes off their foundations and leaving them bare and can even deform large skyscrapers. The similar TORRO scale ranges from a T0 for extremely weak tornadoes to T11 for the most powerful known tornadoes. Doppler radar data, photogrammetry, and ground swirl patterns (cycloidal marks) may also be analyzed to determine intensity and award a rating.

Tornadoes vary in intensity regardless of shape, size, and location, though strong tornadoes are typically larger than weak tornadoes. The association with track length and duration also varies, although longer track (and longer lived) tornadoes tend to be stronger. In the case of violent tornadoes, only a small portion of the path area is of violent intensity; most of the higher intensity is from subvortices. In the United States, 80% of tornadoes are EF0 and EF1 (T0 through T3) tornadoes. The rate of occurrence drops off quickly with increasing strength—less than 1% are violent tornadoes (EF4, T8 or stronger).

Tornadoes of 2007

This page documents the tornadoes and tornado outbreaks that occurred in 2007, primarily (but not entirely) in the United States. Most tornadoes form in the U.S., although some events may take place internationally, particularly in parts of neighboring southern Canada during the summer season. Some tornadoes also take place in Europe, e. g. in the United Kingdom or in Germany.

Preliminary reports suggest that there were 1,305 reported tornadoes in the U.S. (of which 1,092 were confirmed), with 81 confirmed fatalities. It was the deadliest year for tornadoes in the U.S. since 1999, when 95 deaths were reported. In addition, three fatalities took place in Mexico, 14 in Chad, one in South Africa, three in Vietnam, one in the Philippines, 25 in China and seven in Bangladesh for a worldwide known total of at least 135.

Notably, the system for classifying tornado damage in the United States changed from the Fujita scale to the Enhanced Fujita Scale on February 1.

Tornadoes of 2008

This page documents notable tornadoes and tornado outbreaks worldwide in 2008. Strong and destructive tornadoes form most frequently in the United States, Bangladesh, and Eastern India, but they can occur almost anywhere under the right conditions. Tornadoes also develop occasionally in southern Canada during the Northern Hemisphere's summer and somewhat regularly at other times of the year across Europe, Asia, and Australia. Tornadic events are often accompanied with other forms of severe weather, including strong thunderstorms, strong winds, and hail.

There were 1,692 tornadoes confirmed in the United States in 2008, with 126 confirmed fatalities. This made 2008 the deadliest year in that country since 1998. Nine other fatalities have been reported elsewhere in the world: three in France, two each in Bangladesh and Poland and one each in Russia and China. With 1,692 confirmed tornadoes, 2008 ranked as the third most active US tornado season on record, only 2011 and 2004 have had more tornadoes confirmed with 1,697 and 1,817, respectively. The US state of Kansas received the most tornadoes in the United States in 2008 with 187.


Xanxerê is a city in Santa Catarina, southern Brazil. The Italian and German are the mainstream culture. They were brought by immigrants in the early 20th century, through the migration of the "gauchos".

The city is one of the main production centers of corn in Brazil. The city also increased in all industrial, commercial and service sectors, serving as a reference for all western Santa Catarina. It located in a key position for trades via Mercosul.

Xanxerê is the headquarters of the Association of Cities of Alto Irani (AMAI), composed of 17 "municípios".

On April 20, 2015, two tornadoes struck the city; two people died and another 120 were injured, according to the news. These tornadoes was most likely an F3 on the Fujita Scale, according to Mamedes Luiz Melo, a INMET meteorologist. At least 2,600 homes were damaged.

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