Thursday, 24 May 2018

Seventeen missing after Cyclone Mekunu sweeps across the Socotra Islands.

Seventeen people are still missing after Cyclone Mekunu swept across the Yemeni Socotra Island group on Wednesday 23-Thursday 24 May 2018. Full details of the missing persons have not been released, but it is understood that four were members of the crew of one of two vessels that sank during the strom, while another three were in a car that was swept away by floodwaters. The storm is expected to make landfall on the southern part of the Arabian Peninsula this weekend, either in eastern Yemen or southern Oman.

Receding floodwaters on Socotra Island (the largest island of the Socotra group) on 24 May 2018. Abdullah Morgan/AP.

Tropical storms are caused by solar energy heating the air above the oceans, which causes the air to rise leading to an inrush of air. If this happens over a large enough area the inrushing air will start to circulate, as the rotation of the Earth causes the winds closer to the equator to move eastwards compared to those further away (the Coriolis Effect). This leads to tropical storms rotating clockwise in the southern hemisphere and anticlockwise in the northern hemisphere.These storms tend to grow in strength as they move across the ocean and lose it as they pass over land (this is not completely true: many tropical storms peter out without reaching land due to wider atmospheric patterns), since the land tends to absorb solar energy while the sea reflects it.

The passage of Cyclone Mekunu till 12.00 GMT on Thursday 24 May 2018 (thick line) with its predicted future path (thin line, circles represent the margin of error on the predictions). Colours indicate the strength of the storm. Tropical Storm Risk.

The low pressure above tropical storms causes water to rise there by ~1 cm for every millibar drop in pressure, leading to a storm surge that can overwhelm low-lying coastal areas, while at the same time the heat leads to high levels of evaporation from the sea - and subsequently high levels of rainfall. This can cause additional flooding on land, as well as landslides, which are 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.

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Eleven confirmed fatalities in Nipah Virus outbreak in Kerala State, India.

Eleven people have been confirmed dead and a further fourteen have been confirmed to be infected in an outbreak of Nipah Virus in Kerala State, India, with a further twenty two patients in Kerala and two in neighbouring Karnataka State, The first case was reported in Kozhikode District, Kerala, on Saturday 19 May 2018, since when the disease has spread to Malappuram, Wayanad and Kannur districts in Kerala, and possibly Mangalore in Karnataka State. Not all of the identities of the victims have been released, but four are understood to be members of the same family, while one was a nurse who contracted the Virus while treating the first reported victims at the Perambra Taluk Hospital in Kozhikode.

Nurse Lini Puthussery, 28, a nurse at the Perambra Taluk Hospital in Kozhikode, who died on Monday 21 May 2018 after contracting Nipah Virus from patients she was treating. Deepu Sebin/Twitter.

Nipah Virus is a single-strand RNA Virus in the Family Paramyxoviridae, which also includes the Viruses that cause diseases such as Mumps and Rhinderpest. It is a zoonotic disease (disease with an animal host that sometimes infects Humans), that naturally infects Fruit Bats, but which can infect Humans and domestic animals. Like many zoonotic diseases, Nipah Virus is particularly lethal when infecting Humans, as Humans are not part of their natural life-cycle, with the effect that they are not under evolutionary pressure to keep Human hosts alive in order to perpetuate themselves. Such diseases typically have short duration and a high fatality rate, though epidemics usually burn out quickly.

Nipah Virus infections generally first manifest as a fever, accompanied by headaches, drowsiness and disorientation. This can progress rapidly to encephalitis (inflammation of the brain), which results into patients falling into a coma and dying, often within 48 hours of the initial infection. In some patients the disease also infects the respiratory tract, resulting in breathing problems, and a much higher likelihood of passing on the infection. 

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Asteroid 2018 GJ1 passes the Earth.

Asteroid 2018 GJ1 passed by the Earth at a distance of about 15 693 000 km (40.8 times the average distance between the Earth and the Moon, or 10.5% of the distance between the Earth and the Sun), slightly after 2.50 pm GMT on Thursday 17 May 2018. There was no danger of the asteroid hitting us, though were it to do so it would have presented a significant threat. 2018 GJ1 has an estimated equivalent diameter of 130-410 m (i.e. it is estimated that a spherical object with the same volume would be 130-410 m in diameter), and an object of this size would be predicted to be capable of passing through the Earth's atmosphere relatively intact, impacting the ground directly with an explosion that would be 1850 to 175 000 times as powerful as the Hiroshima bomb. Such an impact would result in an impact crater 2-7 km in diameter and devastation on a global scale, as well as climatic effects that would last decades or even years.

The calculated orbit of 2018 GJ1. Minor Planet Center.

2018 GJ1 was discovered on 8 April 2018 (39 days before 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 GJ1 implies that it was the 34th asteroid (asteroid J1) discovered in the first half of April 2019 (period 2018 G).

2018 GJ1 has an 885 day orbital period and an eccentric orbit tilted at an angle of 6.80° to the plane of the Solar System, which takes it from 0.81 AU from the Sun (i.e. 81% of he average distance at which the Earth orbits the Sun) to 2.80 AU from the Sun (i.e. 280% 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 October 2013 and the next predicted in September 2030. As an asteroid probably larger than 150 m in diameter that occasionally comes within 0.05 AU of the Earth, 2018 GJ1 is also classified as a Potentially Hazardous Asteroid.
2018 GJ1 also has frequent close encounters with the planets Venus, which it is thought to have last passed in October 2008, and is next predicted to pass in August 2047, and Mars, which it last came close to in July 1994 and is next predicted to pass in June 2124). Asteroids which make close passes to multiple planets are considered to be in unstable orbits, and are often eventually knocked out of these orbits by these encounters, either being knocked onto a new, more stable orbit, dropped into the Sun, knocked out of the Solar System or occasionally colliding with a planet.
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Determining the diet of Miocene Gomphotheriid Proboscidean using phytoliphs preserved in dental calculus.

The first Proboscideans (Elephants), appeared in the Palaeocene, and like other herbivorous Mammals of this time are presumed to have been browsers (leaf and fruit eaters). Modern Elephants, in contrast, are primarily grazers (grass eaters). Grasses first appeared in the Cretaceous, but extensive grasslands did not become a distinct ecosystem until the Miocene around 23 million years ago. Early Proboscidians had low-crowned teeth, with few lophids (ridges), consistent with a browsing diet, while modern Elephants have high-crowned teeth with numerous lophids, which offers some protection agianst the abbrasive nature of Grasses. The switch to Grasses as a food possibly occured in the Gomphotheres, which appeared in the Middle Miocene and are thought to have been ancestral to True Elephants. The earliest members of the group were trilophadont (had three ridges on their teeth), while later forms, particularly those thought to be ancestral to True Elephants, were tetralophadont (had four ridges), suggestive of a switch towards a more Grass-based diet.

In a paper published in the journal Scientific Reports on 16 May 2018, Yan Wu of the Key Laboratory of Vertebrate Evolution and Human Origins at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, and the Center for Excellence in Life and Paleoenvironment, Tao Deng, also of the Key Laboratory of Vertebrate Evolution and Human Origins, and the Center for Excellence in Life and Paleoenvironmentm, and of the Center for Excellence in Tibetan Plateau Earth Sciences, Yaowu Hu and Jiao Ma, also of the Key Laboratory of Vertebrate Evolution and Human Origins, and of the Department of Archaeology and Anthropology at the University of Chinese Academy of Sciences, Xinying Zhou, again of the Key Laboratory of Vertebrate Evolution and Human Origins, and the Center for Excellence in Life and Paleoenvironment, Limi Mao of the Key Laboratory of Economic Stratigraphy and Palaeogeography, at the Nanjing Institute of Geology and Palaeontology, Hanwen Zhang of the School of Earth Sciences at the University of Bristol, and of the Earth Sciences Department at the Natural History Museum, Jie Ye, again of the Key Laboratory of Vertebrate Evolution and Human Origins, and Shi-Qi Wang, once again of the Key Laboratory of Vertebrate Evolution and Human Origins, and the Center for Excellence in Life and Paleoenvironmentm, and of the Center for Excellence in Tibetan Plateau Earth Sciences, examine the diets of two species of Middle Miocene trilophadont Gomphotheriid Proboscideans, by examining phytoliths (silica fragments produced by plants) preserved in dental calculus of six specimens from the Miocene Halamagai Formation in the northern Junggar Basin of Xinjiang Province, China.

The Middle Miocene deposits of the Junggar Basin produce a diverse range of Gomphotheriid specimens, accompanied by floral remains indicative of a largely forested environment. Late Miocene strata from the same area, in contrast, have a much less diverse Gomphotheriid fauna, dominated by a few tetralophadont forms, and a more arid, Grass-dominated environment, suggesting that this area may have played an important role in the switch between browsing and grazing behaviour in early Proboscideans.

Wu et al. examined calculus from four specimens of Gomphotherium connexum and two specimens of Gomphotherium steinheimense. Gomphotherium steinheimense is thought to have been closely related to the early tetralophadont Gomphotheriid Tetralophodon longirostris, while Gomphotherium connexum is a more distant relative.

Geography, geology, and phylogeny in relation to the study material. (A) The location of the study area (black star). The map was generated by GTOPO309 using Globalmapper (v10). (B) Stratigraphic column and polarity with palaeomagnetic age, also denoting the horizon of study material in the strata (in light yellow). (C) The 50% majority consensus tree from 29 maximum parsimonious trees showing the phylogenetic position of the Gomphotherium species and Tetralophodon longirostris, the number at each node representing the support value calculated by majority rules (percentages of supported MPTs in the total MPTs, which are always larger than 50%) and the orange frame indicating the sister-taxon relationship of Gomphotherium steinheimense and Tetralophodon longirostris. (D) Gomphotherium steinheimense, right m3. (E) Gomphotherium connexum, left M3. Wu et al. (2018).

Of the phytoliths obtained from the calculus of Gomphotherium connexum, between 40% and 50% were identified as having originated from Grasses, whereas between 28% and 34% could be identified as having come from broadleaved plants. This would at first seem to imply a diet with a high proportion of Grasses, but Grasses produce a far greater amount of phytoliths than broadleaved plants (hence their more abrasive nature), so this probably indicates a diet with a high proportion of broadleaved plants. In contrast about 85% of the phytolihs from the calculus of Gomphotherium steinheimense could be identified as having come from grasses, indicative of a much more Grass-based diet.

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Monday, 21 May 2018

Canadian couple survive being swept of mountain road by landslide.

A Canadian couple have survived after being swept of a mountain road by a landslide on Thursday 17 May 2018. Sheri Niemegeers from Weyburn in Saskatchewan and Gabe Rosescu from Regina, also in Saskatchewan, were travelling through the Kootenay Pass to visit friends for the Victoria Day weekend, when they were hit by a mudflow containing numerous trees, which swept their car off the road and down the mountainside. Both suffered multiple broken bones and are recovering in a nearby hospital.

The scene of a landslide that swept a couple off a mountain road in the Kootenay Pass, British Colombia, on 17 May 2018. BC Transportation.

The incident happened after several hours of heavy rain in the area. 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. British Colombia has suffered widespread flooding in the last week as high rainfall has combined with melting winter snows, resulting in about 4500 people across the province being forced to evacuate their homes.

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Hawai'ian man injured by lava bomb from Mount Kilauea.

A Hawai'ian man has suffered a broken leg after being struck by a lava bomb (chunk of lava thrown from a volcano, in either liquid or solid form), described as being as heavy as a refrigerator, from Mount Kilauea on Hawai'i (or 'Big') Island on Sunday 20 May 2018. The man is described as having been on his balcony at the time of the incident. The volcano began erupting from a new fissure on its eastern flank on 3 May 2018, since when a series of fissures have opened up, producing several major lava flows, which have destroyed many homes and other properties, and at least one of which has reached the sea, producing a laze (toxic haze resulting from hot lava hitting water, producing chemical-laden steam. At the same time the volcano has produced a number of gas and ash columns, some of which have reached over three kilometres in height, which are described as being particularly rich in hydrochloric acid, sulphur dioxide and volcanic glass.

Lava flow on Mount Kilauea. USGS/AP.

The islands of Hawai'i have formed as a result of hotspot volcanism, with a mantle plume hotspot currently located under Big Island, Hawai'i, and each of the other islands being the result of previous activity from the same hotspot, with the oldest Islands in the northwest and newest in the southeast. A volcanic hotspot is an area where magma from deep inside the Earth is welling up through the overlying plate (in this case the Pacific) to create volcanism at the surface. Volcanoes move as they erupt, swelling as magma enters their chambers from bellow, then shrinking as that magma is vented as lava.

 The position of the Hawai'i Hotspot relative to the islands of Hawai'i. Joel Robinson/USGS/Wikimedia Commons.

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Sunday, 20 May 2018

Magnitude 5.1 Earthquake in Petorca Province, Chile.

The United States Geological Survey recorded a Magnitude 5.1 Earthquake at a depth of 32.7 km, 39 km to the northeast of the city of La Ligua in the Chilean province of Petorca slightly before 2.45 am local time (slightly before 6.45 am GMT) on Saturday 19 May 2018. There are no reports of any damage or injuries associated with this event, but people have reported feeling the event across much of central Chile, and parts of western Argentina.

The approximate location of the 19 May 2018 Petorca Earthquake. USGS.

Chile is located on the west coast of South America, which is also the convergent margin between the Nazca and South American Plates. The Nazca Plate is being subducted beneath the South American Plate and is sinking beneath the South American Plate. This is not a smooth process, the rocks of the two plates continuously stick together then, as the pressure builds up, break apart again, causing Earthquakes. As the Nazca Plate sinks deeper it is partially melted by the heat of the Earth's interior. Some of the melted material then rises up through the overlying South American Plate as magma, fuelling the volcanoes of the Chilean Andes.
 The subduction of the Nazca Plate beneath the South American Plate, and how it causes Earthquakes and volcanoes. Pacific Earthquake Engineering Research Center.
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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