Thursday, 18 January 2018

Swedish tourist killed by avalanche in Jammu and Kashmir, India.

A Swedish tourist has died after being caught in an avalanche on Mount Apharwat near Gulmarg in the Baramulla District of Jammu and Kashmir, India, on Thursday 18 January 2018. The skier is understood to have been one of two Swedish men caught in the event, the other of whom was rescued alive. 

The approximate location of the Mount Apharwat 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.

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Atlantic storm brings hurricane force winds to northwest Europe.

Seven people have have died as an Atlantic storm brought hurricane force winds to parts of northwest Europe on Thursday 18 January 2017, with at least seven people having died and widespread disruption to power and transport networks across Germany, the Netherlands Belgium and the UK.

Trucks overturned by high winds halt traffic close to Erfurt in Thuringia, central Germany, on 18 January 2017. Jens Meyer/Associated Press.

Three people are known to have died in the Netherlands; a 62-year-old truck driver who was killed by falling timber while attempting to clear debris from a road near the village of Olst in Overijssel Province, a second 62-year-old man was killed when a tree was blown onto his car, and a 66-year-old man died after being blown over, both in the city of Enschede, also in Overijssel. The port in Rotterdam was forced to close after several shipping containers were blown over, a number of houses had their roofs ripped off and road networks were severely disrupted by about 25 trucks being blown over in and around the city, while in Amsterdam Schiphol Airport was forced to close for several hours.

Damage to a home near Moerdjik in North Brabant Province in southern Netherlands. Marcel Otterspeer Fotografie.

In North Rhine-Westphalia, Germany a  59-year-old man was killed by a falling tree in Emmerich in, a 68-year-old truck driver was killed when his vehicle overturned in Lippsadt, and 28-year-old firefighter was killed when he was hit by a tree while trying to rescue a woman from her car. At least 40 other people were injured in weather-related incidents, around 100 000 people were left without electricity and flights were cancelled from Düsseldorf and Cologne-Bonn airports.

 A car damaged by a falling tree in Moers in North West Rhine-Westphalia, Germany, on 18 January 2018. Christoph Reichwein/AP.

In Belgium a woman was killed when a falling tree hit her car near Brussels, the port of Ghent was temporarily closed, and many road and tram networks were disrupted by fallen trees. Road networks were also disrupted in parts of the UK, with areas of southern England suffering power outages due to downed power lines.

Ocean storms form due to heating of air over the sea in tropical zones. As the air is heated the the air pressure drops and the air rises, causing new air to rush in from outside the forming storm zone. If this zone is sufficiently large, then it will be influenced by the Coriolis Effect, which loosely speaking means the winds closer to the equator will be faster than those further away, causing the storm to rotate, clockwise in the northern hemisphere and anticlockwise in the southern hemisphere.

Whilst the high winds associated these storms is extremely dangerous, the real danger from such storms is often the flooding. Each millibar drop in air pressure can lead to a 1 cm rise in sea level, and large storms can be accompanied by storm surges several meters high. This tends to be accompanied by high levels of rainfall, caused by water picked up by the storm while still at sea, which can lead to flooding, swollen rivers and landslides; which occur when waterlogged soils on hill slopes lose their cohesion and slump downwards, over whatever happens to be in their path.

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Magnitude 5.9 Earthquake off the coast of Nicaragua and Cost Rica.

The United States Geological Survey recorded a Magnitude  5.9 Earthquake at a depth of 30.6 km, about 25 km off the coast of San Juab del Sur in Rivas Department, Nicaragua, or 40 km off the Santa Rosa Peninsula in Guanacaste Province, Costa Rica, slightly after 9.00 am local time (slightly after 3.00 pm GMT) on Tuesday 16 January 2018. There are no reports of any damage or casualties associated with this event, though it was felt across southwestern Nicaragua and northwestern Costa Rica.

The approximate location of the 16 January Nicaragua & Costa Rica Earthquake. USGS.

Nicaragua and Costa Rica lie on the southern margin of the Caribbean Plate; to the south the Cocos Plate, which underlies part of the eastern Pacific Ocean) is being subducted under the Middle American Trench, passing under Central America as it sinks into the Earth's interior. This is not a smooth process, and the plates often stick together until the pressure builds up enough to force them to shift suddenly, causing Earthquakes. As the Cocos Plate sinks deeper if is partially melted by the friction and the heat of the Earth's interior. Some of the melted material then rises up through the overlying Caribbean Plate, fuelling the volcanoes of Central America.

 Diagram showing the passage of the Cocos Plate beneath Costa Rica (not to scale). Carleton College.

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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Wednesday, 17 January 2018

Alseodaphnopsis ximengensis: A new species of Laurel from Yunnan Province, China.

Laurels, Lauraceae, are evergreen Dicotyledonous Plants found in tropical and warm temperate zones around the world, though they are most diverse and abundant in Southeast Asia and tropical America, where they form an important component of tropical rainforests. Most Laurels are evergreen trees, though one genus, Cassytha, comprises parasitic vines. Laurels appeared some time in the Cretaceous, though opinions about how early vary. These plants are fruit-producers, typically relying on Birds to spread their seeds.

In a paper published in the journal PLoS One on 18 October 2017, Yue-qing Mo of the Plant Phylogenetics & Conservation Group at the Xishuangbanna Tropical Botanical Garden, and the University of the Chinese Academy of Sciences, Lang Li, also of the Plant Phylogenetics & Conservation Group at the Xishuangbanna Tropical Botanical Garden, Jian-wu Li of the Herbarium of the Xishuangbanna Tropical Botanical Garden, Jens Rohwer of the Biozentrum Klein Flottbek at Universität Hamburg, Hsi-wen Li of the Herbarium at the Kunming Institute of Botany, and Jie Li, again of the Plant Phylogenetics & Conservation Group at the Xishuangbanna Tropical Botanical Garden, describe a new species of Laurel from Yunnan Province in China, as part of a review of the Persia group of genera (which includes Avacados and their close relatives).

The new species is named Alseodaphnopsis ximengensis, where 'Alseodaphnopsis' refers to the similarity of the genus to the previously described genus 'Alseodaphne', and 'ximengensis' means 'from Ximeng' the species having been discovered in Ximeng County of Yunnan Province. The species forms evergreen trees with leathery leaves up to 11 cm in length,small white flowers and globular fruit up to 4.7 mm in diameter. The species was found growing in a seasonal rainforest at an altitude of 1300 m.

Alseodaphnopsis ximengensis. (A) Branchlet with inflorescences; (B) Branchlet with immature infructescences; (C) Branchlet with mature fruits; (D)-(F). Mature fruits; (G)-(H). Flowers. Jian-wu Li in Mo et al. (2017).

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Fireball meteor over Michigan causes Earthquake.

The American Meteor Society has received reports of a bright fireball meteor being seen over the Great Lakes region of North America at about 8.10 am local time (about 1.10 am GMT) on Tuesday 16 January 2018. People have reported seeing the event from Iowa, Illinois, Indiana, Ohio, Michigan, Pennsylvania, and Ontario (Canada), with the majority of sightings coming from Michgan and Ohio. A fireball is defined as a meteor (shooting star) brighter than the planet Venus. These are typically caused by pieces of rock burning up in the atmosphere, but can be the result of man-made space-junk burning up on re-entry. The object was seen moving from northeast  to southwest over the eastern part of the state. 

The 16 January 2018 meteor seen from Michigan. Zack Lawler/WWMT.

The Object has been calculated to have been moving from east to west over the southeastern part of Michigan, and produced a loud booming noise that was recorded as a Magnitude 2.0 Earthquake by the United States Geological Survey. This has been interpretted as being indicative of a large, slow moving (about 45 000 km per hour) object, and it is thought likely that a number of meteorites will have reached the ground.

Map showing areas in southeast Michigan where sightings of the meteor were reported, and the route of the object (blue arrow). American Meteor Society.

Objects of this size probably enter the Earth's atmosphere several times a year, though unless they do so over populated areas they are unlikely to be noticed. They are officially described as fireballs if they produce a light brighter than the planet Venus. The brightness of a meteor is caused by friction with the Earth's atmosphere, which is typically far greater than that caused by simple falling, due to the initial trajectory of the object. Such objects typically eventually explode in an airburst called by the friction, causing them to vanish as an luminous object. However this is not the end of the story as such explosions result in the production of a number of smaller objects, which fall to the ground under the influence of gravity (which does not cause the luminescence associated with friction-induced heating).
 The recorded epicenter of the 16 January Michigan fireball-induced Earthquake (gold star) and areas where it was felt (blue and white squares). USGS.
These 'dark objects' do not continue along the path of the original bolide, but neither do they fall directly to the ground, but rather follow a course determined by the atmospheric currents (winds) through which the objects pass. Scientists are able to calculate potential trajectories for hypothetical dark objects derived from meteors using data from weather monitoring services.
Witness reports can help astronomers to understand these events. If you witness a fireball-type meteor over the UK you can report it to the American Meteor Society here.

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Asteroid 2018 AT2 passes the Earth.

Asteroid 2018 AT2 passed by the Earth at a distance of about 705 000 km (1.88 times the average distance between the Earth and the Moon, or 0.47% of the distance between the Earth and the Sun), slightly after 1.10 am GMT on Thursday 11 January 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 AT2 has an estimated equivalent diameter of 5-16 m (i.e. it is estimated that a spherical object with the same volume would be 5-16 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 40 and 25 km above the ground, with only fragmentary material reaching the Earth's surface.

The calculated orbit of 2018 AT2. Minor Planet Center.

2018 AT2 was discovered on 12 January 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 AT2 implies that it was the 44th asteroid (asteroid T2) discovered in the first half of January 2018 (period 2018 A).
2018 AT2 has a 920 day orbital period and an eccentric orbit tilted at an angle of 4.07° 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 2.72 AU from the Sun (i.e. 272% of the average distance at which the Earth orbits the Sun, and considerably more distant 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 the asteroid has occasional close encounters with the planet Mars, with the next predicted in December 2142.

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Monday, 15 January 2018

Landslide causes car to plunge into ravine in Johol State, Malaysia.

A passenger travelling in a car near the town of Mersing in Johol State, Peninsula Malaysia, on Sunday 14 January 2017 has been injured by a landslide that caused it to plunge into a ravine. The passenger has been identified as Swee Ah Peng, 60, who was one of three people in the vehicle when the road gave way beneath it, causing it to fall 15 m downslope, at about 2.30 pm local time. The incident happened following several days 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.

 The scene of a landslide in Johol State, Malaysia, on 14 January 2017. Bernama.
Malaysia has two distinct Monsoon Seasons, with a Northeast Monsoon driven by winds from  the South China Sea that lasts from November to February and a Southwest Monsoon driven by winds from the southern Indian Ocean from March to October. Such a double Monsoon Season is common close to the equator, where the Sun is highest overhead around the equinoxes and lowest on the horizons around the solstices, making the solstices the coolest part of the year and the equinoxes the hottest.
 The winds that drive the Northeast and Southwest Monsoons in Southeast Asia. Mynewshub.
Monsoons are tropical sea breezes triggered by heating of the land during the warmer part of the year (summer). 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.
Malaysia has become increasingly landslip-prone in recent years due to extensive deforestation, which leaves soil exposed to heavy tropical rainfall. Concerns have also been raised about the large number of construction sites on steep hillslopes in urban areas, where workers are particularly vulnerable to landslip events during the Monsoon Seasons.
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