Thursday, 27 October 2016

Landslide kills seven in Antioquia Province, Colombia.

Seven people are known to have died and it is feared that more people may be buried, following a landslide in Antioquia Province, Colombia, on the morning of Wednesday 26 October 2016. The andslide hit a four lane highway about 12 km to the north of the provincial capitol, Mendalin, covering about 200 m of road and burying a number of vehicles. The incident is reported to have happened following a period of heavy rain. Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall.

The scene of the 26 October 2016 Antioquia landslide. AFP.

Antioquia is a mountainous province with several distanct climate zones. The Medallin area is considered to gave a monsoon climate, with a to peaks in rainfall in May and October. Two hot wet seasons per year is normal on the equator, where the Sun is highest in the sky around the equinoxes and lowest at the solstices, as opposed to the situation at higher latitudes, where the Sun is highest at one solstice and lowest at the other.

Monsoons are tropical sea breezes triggered by heating of the land during the warmer part of the year. Both the land and sea are warmed by the Sun, but the land has a lower ability to absorb heat, radiating it back so that the air above landmasses becomes significantly warmer than that over the sea, causing the air above the land to rise and drawing in water from over the sea; since this has also been warmed it carries a high evaporated water content, and brings with it heavy rainfall. In the tropical dry season the situation is reversed, as the air over the land cools more rapidly with the seasons, leading to warmer air over the sea, and thus breezes moving from the shore to the sea (where air is rising more rapidly) and a drying of the climate.

 Diagrammatic representation of wind and rainfall patterns in a tropical monsoon climate. Geosciences/University of Arizona.

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Wednesday, 26 October 2016

Central Italy shaken by pair of Earthquakes.

The United States Geological Survey recorded two significant Earthquakes in Central Italy on Wednesday 26 October 2016. The first had a Magnitude of 5.5 and occurred 7 km to the southwest of the town of Visso in Macerata Province at a depth of 10 km at about 7.10 pm local time (about 5.10 pm GMT), while the second had a Magnitude of 6.1 km and occurred 2 km to the north of the town, again at a depth of 10 km, slightly before 7.20 pm local time (slightly before 5.20 pm GMT). There are no reports of any injuries following these events, but minor damage has been reported across a wide area, as well as power cuts and one instance of a road being closed by a small landslide. People have reported feeling the event across Central and Northern Italy, as well as in parts of Slovenia and Croatia.

The approximate location of the first 26 October 2016 Visso Earthquake. Google.

The approximate location of the second 26 October 2016 Visso Earthquake. Google.

Italy is in an unusual tectonic setting, with the west of the country lying on the Eurasian Plate, but the east of the country lying on the Adriatic Plate, a microplate which broke away from North Africa some time in the past and which is now wedged into the southern margin of Europe, underlying eastern Italy, the Adriatic Sea and the west of the Balkan Peninsula. This, combined with the northward movement of the African Plate into Italy from the south, leads to uplift in the Apennine Mountains that run the length of the country, and makes Italy extremely prone to Earthquakes. 

Outline map showing the approximate positions of the Eurasian (EU), Adriatic (AD) and African (AF) Plates. Di Bucci & Mazzuli (2003).

Historically Italy has suffered a number of devastating Earthquakes that lead to large numbers of casualties, though in recent decades the country has made serious attempts to prevent this, with better warning systems and tighter building regulations, though the large number of historic buildings in Italy, which cannot easily be replaced (and any attempt to do so would be unlikely to succeed due to their high cultural value), meaning that the country is unlikely to be completely risk free any time soon.

Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. The international non-profit organisation Earthquake Report is interested in hearing from people who may have felt this event; if you felt these quakes then you can report it to Earthquake Report here.
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Monday, 24 October 2016

Understanding the ancestry of the European Bison.

The European Bison, or Wisent (Bison bonasus), is one of a very small number of megafaunal (large) animal species to have survived from the Pleistocene in northern temperate latitudes. However the origin of the European Bison is less clear than it would immediately seem, as the earliest known fossil specimens date only from the Early Holocene (i.e. less than 11 700 years ago), prior to which Europe was inhabited by a different Bison species, the Steppe Bison (Bison priscus), which ranged from Britain in the east across Europe, Asia and Beringia (the landmass between Alaska and the Russian Far East which was exposed during the Pleistocene glaciations when the sea level was lower) and into western Canada. The Steppe Bison is considered to be the ancestor of the American Bison (Bison bison), but its relationship to the modern European Bison is less clear, as the European Bison, while clearly related to the American Bison, is genetically more closely related to Cattle (Bos spp.). This could potentially be due to recent hybridization between the species, the European Bison having gone through a number of population bottlenecks as it came into conflict with Humans and domestic animals, with the population having fallen to just twelve individuals in the 1920s, but hybrids between Bison and Cattle are usually infertile, making this a somewhat doubtful hypothesis.

In a paper published in the journal Nature Communications on 18 October 2016, a team of scientists led by Julien Soubrier of the Australian Centre for Ancient DNA at the University of Adelaide describe the results of a new study of the ancestry of the European Bison, which takes into account both archaeological and genetic evidence.

Soubrier et al. sequenced DNA from 64 Bison specimens from Late Pleistocene sites (from before 50 000 years ago to about 14 000 years ago) across Europe. 38 of these specimens, from the Caucasus, Urals, North Sea, France and Italy, were found to belong to a previously unknown Bison lineage, identified as Clade X (in biology a clade is a group of organisms with a common ancestor; a clade includes all the organisms descended from that ancestor and no organisms not descended from that ancestor). Based upon the relationship between Clade X and the European Bison, the two species shared a last common ancestor about 120 000 years ago (during the Eemian Interglacial), however like the European Bison, including Ancient European Bison used in this study (and unlike the American Bison) members of Clade X appear to derive about 10% of their DNA from a Cattle (Bos sp.) ancestor.

This discovery is interesting as it rules out the possibility of recent hybridization between Modern Cattle and European Bison, instead suggesting that the species came about as the result of a hybridization between ancient Steppe Bison and the Aurochs (Bos primigenius), a large Pleistocene animal thought to have been ancestral to modern Domestic Cattle. Further examination of the Bison samples in the study revealed that they all derived their mitochodrial DNA (mtDNA) from a Bos ancestor, but none of them any Y-chromosome DNA, This implies that both the European Bison and Clade X came about as a result of a hybridization between male Steppe Bison and female Aurochs, not implausible given that in all known Bovid species males tend to capture harems of females which they defend aggressively against other males, and that while the Aurochs were big animals, Steppe Bison were even larger. However whether or not the European Bison and Clade X arose from a single hybridization event, a cluster of such events or completely unrelated events could not be determined.

Soubrier et al. further observe that two distinct morphologies of Bison are recorded in European Pleistocene cave art. A total of 820 depictions of Bison are known from European cave art (21 % of all known animal depictions from the Pleistocene of Europe), and all of these fall into two morphotypes (shapes). The first is a long-horned animal with robust forequaters and a distinct hump, that appears in art dating from before the Last Glacial Maximum, roughly between 22 000 and 18 000 years ago. The second form is a more slender animal with small, recurved, horns and a small hump, which appears in Magdalenian art, roughly between 17 000 and 12 000 years ago. These differences have previously been regarded the expression of different artistic styles, however Soubrier et al. reject this hypothesis. Two different Bison morphologies (a robust form and a slender form) have also been noted from bones dredged from beneath the North Sea).

Cave painting example of steppe Bison-like and Wisent-like morphs. (a) Reproduction from Lascaux cave (France), from the Solutrean or early Magdalenian period (about 20 000 years ago). (b) Reproduction from the Pergouset cave (France), from the Magdalenian period (less than 17 000 years ago). Soubrier et al. (2016).

The oldest specimens with a European Bison genotype dated from before 55 000 years ago, while the oldest Clade X specimen dated from 23 000 years ago, and the youngest Steppe Bison from 19 000 years ago. However all known specimens from between 50 000 and 34 000 years ago are Steppe Bison. Environmental reconstructions and stable isotope studies of remains (which can reconstruct the environments in which ancient organisms live by studying the ratios of different carbon and nitrogen isotopes in their bones) suggest that the European Bison and Steppe Bison inhabited different environments, with the Steppe Bison dwelling in cold, tundra grasslands and the European Bison favouring a warmer, more mixed environment.

Based upon this Soubrier et al. suggest that there were two distinct Bison species present in Europe for much of the Late Pleistocene. The Steppe Bison favoured cold grassland environments and expanded its range during colder periods, disappearing at the end of the Pleistocene, probably due to a mixture of a loss of much of this environment and a rising Human population armed with better hunting tools. The European Bison arose from one or more hybridization events between the Steppe Bison and the Aurochs, but was able to persist as a ecologically separate entity due to a preference for a different environment, favouring warmer landscapes with mixed vegetation. This species has also been severely pressured by expanding Human populations, but was better able to cope with the changing climate and has persisted till modern times.

See also... lervia: The diet of the Barbary Sheep in the Bou Hedma Mountains of Tunisia.                                                         The Barbary Sheep (or Aoudad), Ammotragus lervia, is a wild Caprid found in North Africa, from the Mediterranean as far south as the Niger and Lake... highly specialized Musk Ox from the Late Miocene of Gansu Province, China.              In 1932 Birger Bohlin, chief palaeontologist with the explorer Sven Hedin’s Sino-Swedish Scientific Expedition to Northwest China, discovered an... fencing the Tibetan prairies is effecting the endangered Przewalski’s Gazelle. The Przewalski’s Gazelle (Procapra przewalskii) is a species of high altitude adapted Antelope, which formerly ranged across much of northwestern China and Inner Mongolia. It is now restricted to a small area around Qinghai Lake on the Tibetan Plateau, with...
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Asteroid 2016 UD passes the Earth.

Asteroid 2016 UD passed by the Earth at a distance of 72 540 km (0.21 times the average distance between the Earth and the Moon, 0.05% of the average distance between the Earth and the Sun), slightly after 11.30 pm GMT on Monday 17 October 2016. There was no danger of the asteroid hitting us, though had it done so it would have presented no threat. 2016 UD has an estimated equivalent diameter of 9-28 m (i.e. it is estimated that a spherical object with the same volume would be 9-28 m in diameter), and an object of this size would be expected to explode in an airburst (an explosion caused by superheating from friction with the Earth's atmosphere, which is greater than that caused by simply falling, due to the orbital momentum of the asteroid) in the atmosphere between 32 and 20 km above the ground, with only fragmentary material reaching the Earth's surface. 

The calculated orbit of 2016 TO11. Minor Planet Center.

2016 UD was discovered on 19 October 2016 (two days after its closest approach to the Earth) by the University of Arizona's Mt. Lemmon Survey at the Steward Observatory on Mount Lemmon in the Catalina Mountains north of Tucson. The designation 2016 UD implies that the asteroid was the fourth object (object D) discovered in the second half of October 2016 (period 2016 U).

2016 UD has a 695 day orbital period and an elliptical orbit tilted at an angle of 10.3° to the plain of the Solar System that takes it from 0.51 AU from the Sun (i.e. 51% of the average distance at which the Earth orbits the Sun, between the orbits of Mercury and Venus) to 2.56 AU from the Sun (i.e. 256% of the average distance at which the Earth orbits the Sun, almost twice the distance at which the planet Mars orbits the Sun). It is therefore classed as an Apollo Group Asteroid (an asteroid that is on average further from the Sun than the Earth, but which does get closer). This means that 2016 UD has occasional close encounters with the Earth, with the next predicted for June 2174.

See also... 2016 TO11 passes the Earth.    Asteroid 2016 TO11 passed by the Earth at a distance of 895 500 km (2.33 times the average distance between the Earth and the Moon, 0.60% of the average distance between the Earth and the Sun), slightly after 7.00 pm GMT on Wednesday 12... (462959) 2011 DU passes the Earth.                                                     Asteroid  (462959) 2011 DU passed by the Earth at a distance of 5 828 000 km (15.2 times the average distance between the Earth and the Moon, or 3.90%... 2016 TH passes the Earth.       Asteroid 2016 TH passed by the Earth at a distance of 128 300 km (0.34 times the average distance between the Earth and the Moon, 0.09% of the average distance between the Earth and the Sun), at about 4.30 pm...
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Sunday, 23 October 2016

Queensland miner killed in trench collapse.

A sixty-two-year-old miner has been found dead following a the collapse of an exploration trench at a mine in Opalton, Queensland, on Saturday 22 October 2016. Sid Cuddy was reported missing after a friend visited the site where he was operating at about 4.00 pm local time. The location is described as being extremely remote, being about 150 km southwest of Winton and about 300 km west of Longreach, and it took police and firefighters six hours to reach the site, and a further three hours to clear the trench and find Mr Cuddy's body.

Sid Cuddy (62), who died in a collapse at an exploration trench at an opal mine in Opalton, Queensland, on 22 October 2016. The Courier Mail.

Opal is an amorphous form of silica containing as much as 21% water, It is made up of tiny spheroids of crystalline silica some 150 to 300 nm in diameter, with random alignments to one another. Light passing through these crystaloids is refracted as by a prism, leading to the 'opalescent' sheen which gives the mineral its value. Opal is formed by water percolating through silica rocks, where it desolves some of the mineral forming a silica-rich solution. This can accumulate in any cracks or gaps in the rock, where if it reaches a high enough concentration it can precipitate out as opal.

Opal beds in Queensland are found largely in exposures of the Cretaceous Winton Formation, an iron rich sandstone laid down in a shallow inland sea (the Etomanga Sea) that covered parts of Queensland and central Australia during the Early Cretaceous. which extends from Hungerford on the New South Wakes border northwest to the area around Kynuna, a distance of over 1000 kilometres. The opal here is typically found in cracks in ironstone concretions (themselves formed by precipitation from water that has accumulated iron as it peculated through the feruginous sandstone), and is commonly called 'boulder opal'.

These fields have been worked since the 1870s, with the bulk of the mining done by small, artisanal miners who sink shallow trenches into the sandstone looking for opal-bearing boulders. The Opalton deposits were among the first opal fields discovered in Australia, and as well as still supporting a mining industry, are now a thriving tourist attraction.

Mr Cuddy is described as having been a highly experienced miner, always willing to help other less experienced prospectors. The cause of the collapse that killed him is as yet unknown.

See also... killed by exploding tyre at Queensland coal mine.                                                       A 21-year-old man has been killed and a second worker severely injured after a tyre on a truck exploded at the Dawson Coal Mine, an open pit mine near Moura in Queensland, Australia, at about... killed in rockfall at South Australian copper mine.                                                   A worker has been killed in a rockfall at the BHP Billiton owned Olympic Dam Copper Mine in South Australia. Brian Partington, 47, was struck on the chest by falling rocks at about 6.00 am local time on Tuesday 10 February 2015. The cause of...
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Thevenetimyia spinosavus: A new species of Bee Fly from Madagascar.

Madagascar is considered to be a biodiversity hotspot, with many plants and animals recorded there that are not known from any other location. One of the groups that has remarkably high diversity on the island are the True Flies, Diptera, with the island thought to be home to about three times as many Fly species as the entire of Africa. Despite this high diversity the Flies of Madagascar are not well studied, with some groups thought likely to show high diversity on the island hardly recorded at all; for example only seventeen species of Bee Fly have been recorded on Madagascar, out of a global total of about 4700 described species.

In a paper published in the journal Zootaxa on 12 October 2016, Natalia Maass of the University of Eastern Kentucky, Zachary Larmore and Mattew Bertone of the North Carolina State University and Michelle Trautwein of the California Academy of Sciences, describe a new species of Bee Fly from southern Madagascar.

The new species is placed in the genus Thevenetimyia, and given the specific name spinosavus, meaning 'spiny grandfather' a reference to the spines present on the Fly's scutum and scutellum and the white hairs on its body, which give it a 'granfatherly' appearance. The species is described from a single male specimen collected in the Zombiste National Park in southern Madagascar by Mike Irwin and Rasolondalao Harin’Hala in October 2002.

Thevenetimyia spinosavus, lateral view. Maass et al. (2016).

Thevenetimyia spinosavus is the first species of Thevenetimyia known from Madagascar, and only a single species is known from Africa, Thevenetimyia quedenfeldti from the Magreb Region of northwest Africa (Mauritania, Algeria, and Tunisia), with the majority of known species coming from the pine and chaparral belt of western North America.

See also... Bee Flies from the Dominican Republic and North America.                                     Bee Flies, Bombyliidae, are True Flies, Diptera, specialized for feeding on pollen and nectar, many of which have evolved long proboscises for nectar feeding. Many adult Bee Flies resemble Bees...

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Magnitude 6.6 Earthquake in Tottori Prefecture, Japan.

The Japan Meteorological Agency recorded a Magnitude 6.6 Earthquake at a depth of about 10 km, about in central Tottori Prefecture on Honshū Island, slightly after 2.05 pm Japan Standard Time (slightly after 5.05 am GMT) on Friday 21 October 2016. Seven people have reportedly been injured following the event, one of whom is described as being in a serious condition, with two house collapses and damage to several other buildings also reported. About 40 000 were left without power following the event, and train services were suspended until the lines could be confirmed to be safe.  people have reported feeling it across much of southern Honshū, as well as on the neighbouring islands of Shikoku and Kyūshū.

Damage to the facade of a building following the 21 October 2016 Tottori Earthquake. AP.

Japan has a complex tectonic environment with four plates underlying parts of the Islands; in addition to the Pacific in the east and the Othorsk in the North, there are the Philippine Plate to the south and the Eurasian Plate to the West. The southwestern arm of Honshū Island lies at the northeast end of the Ryukyu Island Arc, which sits on top of the boundary between the Eurasian and Philippine Plates. The Philippine Plate is being subducted beneath the Eurasian Plate, along the Ryukyo Trench, to the Southeast of the Islands. This is not a smooth process, with the two plates continuously sticking together then breaking apart as the pressure builds up, leading to frequent Earthquakes in the region.

  The movement of the Pacific and Philippine Plates beneath eastern Honshu. Laurent Jolivet/Institut des Sciences de la Terre d'Orléans/Sciences de la Terre et de l'Environnement.

Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. The international non-profit organisation Earthquake Report is interested in hearing from people who may have felt this event; if you felt this quake then you can report it to Earthquake Report here.

 The approximate location of the 21 October 2016 Tottori Earthquake. Google.

See also... on Mount Aso, Kyūshū Island, Japan.                                                           The Japan Meteorological Agency has reported a major eruption on Aso (or Asosan) a volcanic caldera on central Kyūshū Island, Japan. The volcano erupted early on the morning of Saturday 6 October 2016... 4.2 Earthquake in Chiba Prefecture, Japan.                                                    The Japan Meteorological Agency recorded a Magnitude 4.2 Earthquake at a depth of about 30 km, about 6 km off the coast of the Chiba Peninsula on Honshū Island, at about 1.10 am on Wednesday 3 August 2016 Japan Standard Time (about 4.10 pm... 4.5 Earthquake in Kumamoto Prefecture, Japan.                                         The Japan Meteorological Agency recorded a Magnitude 4.5 Earthquake at a depth of about...
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