Monday, 22 October 2018

Tourists stung by 'Jellyfish' on Phuket beach.

A number of tourists were treated for 'Jellyfish' stings on beaches around the resort of Patong on the southwest coast of Phuket island, Thailand, on Sunday 21 October 2018. The stings are thought to have been caused by the Portuguese Man o' War, Physalia physalis, or Indo-Pacific Portuguese Man o' War, Physalia utriculus, which are technically colonial Siphonophores rather than Jellyfish. All of the victims are described as having responded well to first aid given by coastguards, with none requiring hospital treatment.

A young tourist being treated for a Portuguese Man o' War sting on Patong Beach, Phuket, on 21 October 2018. The Thaiger.

Portuguese Man o' War are colonial Siphonophores only distantly related to true Jellyfish, Scyphozoa, though commonly referred to as such. Their bodies are made up of thousands of individual zooids, each with their own sting, tentacles and digestive system. New zooids are formed by budding from other members of the colony, but remain attached to these to form a single colony. Each year a generation of specialist sexual zooids (gonozoids) is produced which produce eggs and sperm, with fertilised eggs going on to form new colonies. These animals are anchored to the sea surface by a highly modified zooid which forms an air sack, filled with a mixture of carbon monoxide defused from the zooid and nitrogen, oxygen and argon from the atmosphere, which are brought into the sack through osmosis. Portuguese Man o' War produce an extremely strong venom, for both capturing food and defending the colony, and which is capable of causing extremely painful stings, and sometimes death, in Humans, for which reason people are advised to be extremely cautious on beaches where these animals wash up, not just of entire animals but also detached tentacles, which are less visible but still capable of stinging.

A Portuguese Man o' War, Physalia physalis. Islands in the Sea 2002/NOAA/Wikimedia Commons.

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Magnitude 5.1 Earthquake in Guayas Province, Ecuador.

The United States Geological Survey recorded a Magnitude 5.1 Earthquake at a depth of 70.6 km, roughly 9 km to the northeast of the town of El Triunfo in Guayas Province, Ecuador, slightly before 4.10 pm local time (slightly before 5.10 pm GMT) on Sunday 21 October 2018. As with most Earthquakes this deep there are no reports of any damage or casualties associated with this event (shockwaves from Earthquakes lose energy passing through layers of rock), but the event was felt locally.

The approximate location of the 21 October 2016 Guayas Earthquake. USGS.

Ecuador is on the west coast of South America and the western margin of the South American Plate, close to where the Nazca Plate, which underlies part of the east Pacific, is being subducted along the Peru-Chile Trench. The Nazca Plate passes under the South American Plate as it sinks into the Earth, this is not a smooth process and the plates repeatedly stick together then break apart as the pressure builds up, causing Earthquakes. As the Nazca Plate sinks further it is melted by the heat of the Earth's interior. Some of this melted material then rises through the overlying South American Plate, fuelling the volcanoes of Ecuador and neighbouring countries.

 The subduction of the Nazca Plate beneath the South American Plate, and how it causes Earthquakes and volcanoes. SIO SEARCH.

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.

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Sunday, 21 October 2018

Asteroid 2018 UL passes the Earth.

Asteroid 2018 UL passed by the Earth at a distance of about 220 960 km (0.57 times the average distance between the Earth and the Moon, or 0.14% of the distance between the Earth and the Sun), slightly before 11.35 am GMT on Wednesday 17 October 2018. There was no danger of the asteroid hitting us, though were it to do so it would have presented a significant threat. 2018 UL has an estimated equivalent diameter of 2-8 m (i.e. it is estimated that a spherical object with the same volume would be 2-8 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 more than 35 km above the ground, with only fragmentary material reaching the Earth's surface.

The calculated orbit of 2018 UL. Minor Planet Center.

2018 UL was discovered on 18 October 2018 (the day after its closest approach to the Earth) by the University of Arizona's Catalina Sky Survey, which is located in the Catalina Mountains north of Tucson. The designation 2018 UL implies that it was the eleventh asteroid (asteroid L) discovered in the second half of October 2018 (period 2018 U).

2018 UL has a 569 day orbital period and an eccentric orbit tilted at an angle of 0.76° to the plane of the Solar System, which takes it from 0.97 AU from the Sun (i.e. 97% of he average distance at which the Earth orbits the Sun) to 1.72 AU from the Sun (i.e. 172% of the average distance at which the Earth orbits the Sun, and further from the Sun than the planet Mars). 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 close encounters between the asteroid and Earth are extremely common, with the last having occurred in January 2006 and the next predicted in January 2020. 2018 UL also has occasional close encounters with the planet Mars, with the last having occurred in December 1952 and the next predicted for November 2036.

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Sixteen kilometre stretch of southern French coast hit by oil spill.

A sixteen kilometre stretch of the southern French coast, centred on the resort of Saint-Tropez, has been closed to visitors due to oil washing ashore. Oil began to wash up around Saint-Tropez on Thursday 18 October 2018, and by Sunday 21 had reached beaches around Hyeres. The oil is thought to have come from the Virginia, a Greek-registered tanker which was in a collision with a freighter off the coast of Corsica on Saturday 6 October, and is thought to have lost about 600 tonnes of bunker oil (oil used to fuel the tanker, rather than cargo) into the Mediterranean.

Clean-up operation at Pampelone beach in Ramatuelle, in the Gulf of Saint-Tropez on Thursday 18 October 2018. Christophe Simon/AFP.

Oil spills are potentially harmful to marine life in a variety of ways. Most obviously it can coat the outside of organisms, causing damage to external structures such as the feathers of Birds and fur of Mammals, as well as smothering many marine invertebrates and plants. It also contains a variety of chemicals which can be directly toxic upset the hormonal balance of many animals. Oil also impedes the feeding of marine organisms, coating both food and feeding organs, but provides an excellent food source for Bacteria, which can lead to Eutrophication events - dramatic increases in Bacteria numbers, which then use all the oxygen in the water, leading other organisms to asphyxiate.

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Explosion kills two and traps twenty at coal mine in Shandong Province, China.

Two miners have been confirmed dead following an explosion at the Longyun Coal Mine in Yuncheng County, Shandong Province, China, on Saturday 20 October 2018. The incident occurred at about 11.00 pm local time, and also trapped 20 of 334 of the workers in the mine at the time underground, though two of these have subsequently been rescued. The explosion additionally knocked out air supplies to the part of the mine, though this has now been restored, and is described as having damaged a drainage tunnel, which may indicate that there is now a danger of flooding within the mine.

Rescue workers bringing an injured miner out of the Longyan Coal Mine in Shandong Province following an explosion on 20 October 2018. Guo Xulei/Xinhua/AP.

Coal is formed when buried organic material, principally wood, in heated and pressurised, forcing off hydrogen and oxygen (i.e. water) and leaving more-or-less pure carbon. Methane is formed by the decay of organic material within the coal. There is typically little pore-space within coal, but the methane can be trapped in a liquid form under pressure. Some countries have started to extract this gas as a fuel in its own right. When this pressure is released suddenly, as by mining activity, then the methane turns back to a gas, expanding rapidly causing, an explosion. This is a bit like the pressure being released on a carbonated drink; the term 'explosion' does not necessarily imply fire in this context, although as methane is flammable this is quite likely.

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Three hunters rescued alive after their campsite was hit by an avalanche in Fiordland, New Zealand.

Three men on a hunting trip were rescued alive after their campsite was hit by an avalanche early in the morning of Saturday 20 October 2018. The men were on an expedition trapping Stoats (a highly invasive European predatory species that presents a threat to New Zealand's native Birdlife) near Lake Te Anau in the Fiordland Region of South Island, New Zealand, when the avalanche hit, sweeping away the campsite, and leaving the men uninjured but very cold and wet (potentially life-threatening in a remote area without survival equipment), but were rescued after about an hour by a Southern Lakes Rescue Helicopter alerted to the event by an emergency beacon carried by the men.

Two of the hunters on a Stoat-trapping expedition that was later hit by an avalanche in Fiordland, New Zealand, on 20 October 2018. Ben Collins/Stuff.
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. In this instance the avalanche appears to have been caused by rain falling onto snow covered slopes, weakening the structure of the snowpack.

Diagrammatic representation of an avalanche, showing how layering of snow contributes to these events. Expedition Earth.

Stoats, Mustela erminea, were introduced to New Zealand in the 1880s, in an attempt to control Rabbits, which had been introduced a decade earlier as a food animal and rapidly become an agricultural pest due to a lack of native predators, despite the warnings of scientists concerned about the effect that these alien predators would have on native Bird populations. Unfortunately these warnings proved to be accurate, and within six years dramatic population losses had been recorded in many species of New Zealand Birds. In an attempt to protect these Birds many species were established on offshore islands in the Fiordland area, though in the early 2000s Stoats were found to be reaching some of these islands, devastating the Bird populations there and leading to increased efforts to control Stoats in the Fiordland Region.

 An introduced Stoat, Mustela erminea, with a Bird chick in New Zealand. Department of Conservation Te Papa Atawhai.

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Flooding causes severe disruption in Qatar.

The city of Doha in Qatar has suffered severe disruption to transport networks and other services, after receiving almost a year's rainfall in a day on Saturday 20 October 2018. A total of 61.1 mm had fallen by early evening, against a yearly average of 77 mm, leading to many roads being flooded and impassable, and local authorities issuing warnings against people entering the city's many road underpasses due to the risks of becoming trapped. A number of public buildings have been forced to close their doors due to the flooding, including the National Library and the US Embassy.

Flooding in Doha, Qatar, on 20 October 2018. I Love Qatar.

Qatar has been widely reported as having received almost than an average years rainfall within 24 hours, about 61 mm compared to 75 mm, though this is slightly misleading as Qatar does not receive any rain some years, lowering the average rainfall, and what does fall often arrives in the form of sudden extreme downpours. Flash floods are a common problem in Qatar (and other areas with a dry climate) as protracted periods of dry weather can cause topsoil to dry out completely, making it vulnerable to being blown away by the wind. When rain does arrive it then falls on exposed bedrock, which is much less absorbent, triggering flash flooding as the water escapes over the surface of the ground rather than sinking into it. These floods wash away more topsoil, making the problem progressively worse over time.

This extreme weather is thought to be connected with a developing El Niño weather system, which warms the waters of the Arabian Sea by around. This warming leads to higher rates of seawater evaporation, i.e. more water entering the atmosphere over the ocean, which in turn leads to more rainfall on land.

The El Niño is the warm phase of a long-term climatic oscillation affecting the southern Pacific, which can influence the climate around the world. The onset of El Niño conditions is marked by a sharp rise in temperature and pressure over the southern Indian Ocean, which then moves eastward over the southern Pacific. This pulls rainfall with it, leading to higher rainfall over the Pacific and lower rainfall over South Asia. This reduced rainfall during the already hot and dry summer leads to soaring temperatures in southern Asia, followed by a rise in rainfall that often causes flooding in the Americas and sometimes Africa. Worryingly climatic predictions for the next century suggest that global warming could lead to more frequent and severe El Niño conditions, extreme weather conditions a common occurrence.

Movements of air masses and changes in precipitation in an El Niño weather system. Fiona Martin/NOAA.

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