Saturday, 17 February 2018

Chrysiptera burtjonesi: A new species of Damselfish from the Solomon Islands.

Damselfish, Pomacentridae, are small, often brightly coloured Perciform Fish found predominantly around tropical reefs and shores, though there are a few temperate and even freshwater species. They are often highly territorial, with males and females having separate territories, and the females leaving their territories briefly to lay eggs in the territories of the males, who then fertilise and brood the eggs and raise the young.

In a paper published in the Journal of the Ocean Science Foundation on 14 September 2017, Gerald Allen of the Department of Aquatic Zoology at the Western Australian Museum, Mark Erdmann of the Conservation International Indonesia Marine Program and the California Academy of Sciences, and Dita Cahyani of the Indonesia Biodiversity Research Centre at Udayana University, describe a new species of Damselfish from the Solomon Islands.

The new species is placed in the genus Chrysiptera, and given the specific name burtjonesi, in honour of the photographer and underwater guide Burt Jones, for his promotion of diving in the Solomon Islands. The species is described from 24 specimens ranging from 20.5 to 48.2 mm in length, and grayish brown in colour with greenish fins and yellow and blue markings.

Chrysiptera burtjonesi, underwater photograph, approx. 40 mm SL, Russell Group, Solomon Islands. Gerald Allen in Allen et al. (2017).

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Asteroid 2018 CH2 passes the Earth.

Asteroid 2018 CH2 passed by the Earth at a distance of about 787 000 km (2.05 times the average distance between the Earth and the Moon, or 0.53% of the distance between the Earth and the Sun), at about 5.50 pm GMT on Monday 12 February 2018. There was no danger of the asteroid hitting us, though were it to do so it would not have presented a significant threat. 2018 CH2 has an estimated equivalent diameter of 4-15 m (i.e. it is estimated that a spherical object with the same volume would be 4-15 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 43 and 26 km above the ground, with only fragmentary material reaching the Earth's surface.

The calculated orbit of 2018 CH2. Minor Planet Center.

2018 CH2 was discovered on 8 February 2018 (four days before 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 2018 CH2 implies that the asteroid was the 58th object (object H2) discovered in the first half of February 2018 (period 2018 C).  

2018 CH2 has a 1095 day orbital period and an eccentric orbit tilted at an angle of 5.47° to the plane of the Solar System, which takes it from 0.96 AU from the Sun (i.e. 96% of he average distance at which the Earth orbits the Sun) to 3.19 AU from the Sun (i.e. 319% of the average distance at which the Earth orbits the Sun, and slightly more than 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 the asteroid has occasional close encounters with the Earth, with the last thought to have occurred in January 2015 and the next predicted in February 2024.

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Lassa Fever kills fifty seven in Nigeria.

Fifty seven people have died in an outbreak of Lassa Fever (a form of hemorrhagic fever, similar too, but not as severe as, Ebola) in southern Nigeria between 1 December 2017 and 11 February 2017, according to the Nigerian Centre For Disease Control. A total of 615 suspected cases have been reported, with 193 of these confirmed by laboratory tests. Four of the known deaths are of health workers, with another seven such professionals having fallen in and been confirmed to have the disease. The World Health Organisation has also recorded cases of the disease in Benin and Sierra Leone this year, and several other West African nations are making preparations for outbreaks of the disease, which is endemic to the region.

An isolation ward for Lassa Fever victims in Ondo, Nigeria. Graphic Online.

Lassa fever is caused by the Lassa Virus, a member of the Arenavirida Virus family, single stranded RNA Viruses which cause a range of illnesses in animals and Humans, including Lujo Fever (a hemorrhagic disease endemic to southern Africa), Lymphocytic Choriomeningitis (a form of Meningitis) and Whitewater Arroyo Fever (a hemorrhagic disease endemic tothe southwestern United States). 

Lassa Fever is less lethal than hemorrhagic diseases such as Ebola or Marburg, with about 80% of those infected developing no, or only very mild, symptoms, and a mortality rate of about 1%. However this lack of lethality enables the disease to spread more freely, as asymptotic people can still spread the disease. The Virus also infects Soft-furred Rats, Mastomys spp., which serve as a natural reservoir for the disease, and which are prone to invading Human homes in search of food, particularly during the West African Dry Season, when other food sources tend to be scarce.

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Magnitude 4.4 Earthquake in Neath Port Talbert, South Wales.

The British Geological Survey recorded a Magnitude 4.4 Earthquake at a depth of 7 km, about two kilometres to the south of the village of Cwmllynfell in Neath Port Talbert County, South Wales, slightly after 2.30 pm GMT on Saturday 17 February 2017. There are no reports of any damage or casualties associated with this event, but people have reported feeling this event across most of Wales and England, as well as on the east coast of Ireland.

The approximate location of the 17 February 2018 Cwmllynfell Earthquake. Google Maps.

Earthquakes become more common as you travel north and west in Great Britain, with the west coast of Scotland being the most quake-prone part of the island and the northwest of Wales being more prone  to quakes than the rest of Wales or most of England.
The precise cause of Earthquakes in the UK can be hard to determine; the country is not close to any obvious single cause of such activity such as a plate margin, but is subject to tectonic pressures from several different sources, with most quakes probably being the result of the interplay between these forces. 
The precise cause of Earthquakes in the UK can be hard to determine; the country is not close to any obvious single cause of such activity such as a plate margin, but is subject to tectonic pressures from several different sources, with most quakes probably being the result of the interplay between these forces.
(Top) Simplified diagram showing principle of glacial rebound. Wikipedia. (Bottom) Map showing the rate of glacial rebound in various parts of the UK. Note that some parts of England and Wales show negative values, these areas are being pushed down slightly by uplift in Scotland, as the entire landmass is quite rigid and acts a bit like a see-saw. Climate North East.
Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. If you felt this quake, or were in the area but did not (which is also useful information) then you can report it to the British Geological Survey here. 
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British Colombia avalache victim dies in hospital.

A 36-year-old man has died in hospital in Calgary, Alberta, after being caught in an avalanche near Golden in British Colombia on Friday 9 February 2018. The as yet unnamed victim was buried under 3 metres of snow then dug out by witnesses to the event in the Hospital Creek area, which is popular with snowmobiling enthusiasts, and airlifted to the hospital due to the severity of his injuries, but could not be saved and died on 16 February.

The approximate location of the 9 February 2018 Hospital Creek avalanche. Google Maps.

Avalanches are caused by the mechanical failure of snowpacks; essentially when the weight of the snow above a certain point exceeds the carrying capacity of the snow at that point to support its weight. This can happen for two reasons, because more snow falls upslope, causing the weight to rise, or because snow begins to melt downslope, causing the carrying capacity to fall. Avalanches may also be triggered by other events, such as Earthquakes or rockfalls. Contrary to what is often seen in films and on television, avalanches are not usually triggered by loud noises. Because snow forms layers, with each layer typically occurring due to a different snowfall, and having different physical properties, multiple avalanches can occur at the same spot, with the failure of a weaker layer losing to the loss of the snow above it, but other layers below left in place - to potentially fail later.
 Diagrammatic representation of an avalanche, showing how layering of snow contributes to these events. Expedition Earth.
In this instance authorities in British Colombia had issued several avalanche warning for the area, after a series of storms blowing in from the northeast Pacific had dumped repeated layers of snow onto the mountainside. 

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Friday, 16 February 2018

Families evacuated from their homes after landslide at construction site in Rome, Italy.

Twenty two families have been evacuated from their homes after a landslide in Balduina, a residential district of Rome, which engulfed seven cars and may have undermined properties on the opposite side of the road, at about 6.00 pm local time on Wednesday 14 February 2018. The event occurred at a construction site, where work began on a new apartment block in October and a deep pit had been dug to facilitate an underground car park, and was triggered when the shoring on one side of the pit collapsed.

The scene of a landslip in the Balduina District of Rome that engulphed seven cars and led to nearby properties being evacuated. Giuseppe Lami/ANSA/AP.

The event happened after a day of heavy rain in the city. 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. However this in itself should not have been enough to cause the shoring to collapse, and the event has been linked to a water leak in the area between 25 and 28 January, which may have left sediments beneath the road weakened before this week's event.

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Thursday, 15 February 2018

Vultures and Lions poisoned outside Ruaha National Park, Tanzania.

The Ruaha Carnivore Project has reported a mass poisoning of Lions and Vultures close to the Ruaha National Park in Tanzania, this week. The organisation investigated after receiving a warning from a radio collar on one of the Lions that the animal had died. They found the bodies of six Lions, the adult female with the collar, plus three female and two male subadults, close to a cow carcass which had apparently been poisoned before being scavenged by the animals. In addition to the Lions, a total of 74 dead Vultures were found at the site, along with four sick Birds which were taken to a treatment centre within the park; one of these Vultures subsequently died, but the remaining three appear to be doing well.

The body of a Lioness found close to the Ruaha National Park in Tanzania, having apparently been poisoned. Ruaha Carnivore Project.

The poisoning of Lions and other predators is becoming increasingly common in Tanzania, and results from the conflict between Cattle-herding communities and wildlife. The population of Tanzania has risen from 25 million in 1990 to 56 million in 2016, prompting the expansion of agriculture and pastoral activities into new areas, provoking conflict with wildlife. Traditionally, predation of Cattle by Lions or other predators would have resulted in the hunting and killing of the animals, but with this now more heavily policed by the authorities, many communities have turned to poisoning as an alternative, in this instance leading to the deaths not only of the Lions, but also the Vultures, probably unintended victims.

The bodies of Vultures found close to the Ruaha National Park in Tanzania, having apparently been poisoned. Ruaha Carnivore Project.

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