Tuesday, 23 January 2018

Eruption on Mount Kusatsu-Shirane kills one and injures at least fifteen.

One man has died and at least fifteen more have been injured in a rockfall triggered by an eruption on Mount Kusatsu-Shirane, a 2160 m stratovolcano (cone-shaped volcano made up of layers of ash and lava) in Gunma Prefecture on Honshū Island, Japan, on Tuesday 23 January 2018. The eruption occured at about 10.00 am local time, and resulted in rocks being thrown several hundrad meters into the air. The dead man, along with several of those injured, is described as having been a member of the Japanese National Defece Force who was on a training exercise at the time of the eruption.

Cloud of ash over Mount Kusatsu-Shirane following an eruption on 23 January 2017. Yomiuri Shimbun.

Japan has a complex tectonic situation, with parts of the country on four different tectonic plates. Kyushu 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, in the Ryukyo Trench, to the Southeast of the Islands. As it is drawn into the interior of the Earth, the tectonic plate is partially melted by the heat of the Earth's interior, and liquid magma rises up through the overlying Eurasian Plate to form the volcanos of the Ryukyu Islands and Kyushu.

 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.

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Magnitude 4.6 Earthquake in South Kazakhstan.

The United States Geological Survey recorded a Magnitude 4.6 Earthquake at a depth of 16.9 km, in the Saryagash District of the South Kazakhstan Region of Kazakhstan, close to the border with Uzbekistan, slightly after 7.25 am local time (slightly after 1.25 am GMT) on Tuesday 23 January 2018. There are no reports of any damage or casualties associated with this event, but it was felt in Tashkent.

The approximate location of the 29 September 2017 Saryagash Earthquake. USGS.

South Kazakhstan lies to the north of the boundary between the Indian and Eurasian tectonic plates, which runs through northern Afghanistan. The Indian Plate is moving northward relative to the Eurasian Plate, causing folding and uplift along this boundary, which has led to the formation of the Hindu Kush Mountains of Afghanistan, The Pamirs in Tajikistan, the Himalayas and the other mountain ranges of Central Asia., and which makes the nations in this boundary zone prone to Earthquakes.

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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Asteroid 2018 AG4 passes the Earth.

Asteroid 2018 AG4 passed by the Earth at a distance of about 539 000 km (1.40 times the average distance between the Earth and the Moon, or 0.36% of the distance between the Earth and the Sun), slightly after 10.40 am GMT on Wednesday 17 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 AG4 has an estimated equivalent diameter of 11-36 m (i.e. it is estimated that a spherical object with the same volume would be 11-36 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 30 and 12 km above the ground, with only fragmentary material reaching the Earth's surface.

The calculated orbit of 2018 AG4. Minor Planet Center.

 2018 AG4 was discovered on 14 January 2018 (three 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 AG4 implies that it was the 107th asteroid (asteroid G4) discovered in the first half of January 2018 (period 2018 A).

2018 AG4 has a 514 day orbital period and an eccentric orbit tilted at an angle of 10.7° to the plane of the Solar System, which takes it from 0.89 AU from the Sun (i.e. 89% of he average distance at which the Earth orbits the Sun) to 1.62 AU from the Sun (i.e. 162% of the average distance at which the Earth orbits the Sun, and 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 Earth, with the last thought to have occurred in July 2011 and the next predicted in July this year. The asteroid also has occasional close encounters with the planet Mars, with the last thought to have encountered in November 2012 and the next predicted for July this year.

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Monday, 22 January 2018

Beaches in Monterey County, California, closed by sewage spill.

Eight beaches in Monterey County, California, were forced to close this weekend following a spill of sewage from the Monterey One Water wastewater treatment facility in Marina, according to the Monterey County Environmental Health Department. The leak was discovered at about 4.30 am local time on Saturday 20 January 2018, and closed down, though it thought that about 22 275 000 litres of sewage are thought to have leaked through a storm drain into the sea by the time the spill was detected, resulting in the closure of Carmel Beach at Ocean Avenue, Monterey Municipal Beach, Lover’s Point, the Beach at Monterey State Beach, San Carlos Beach, the beach at Sunset Drive at Asilomar, the beach at Spanish Bay and Stillwater Cove.

 A closed off beach in Monterey Bay, California, following a sewage spill on 20 January 2017. NBC Bay Area.

As well as the obvious dangers to health presented by sewage, which is likely to contain a variety of Bacteria and other micro-organisms harmful to Human health, sewage provides a source of nutrients which can lead to eutrophication and the rapid growth of blooms of Algae, Bacteria or other micro-organisms, which absorb oxygen from the water leading Fish and other aquatic organisms to asphyxiate.

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Collapse at gold mine in Uzbekistan kills at least one.

At least one person has died and around 20 more are thought to be trapped below ground following a collapse at an abandoned gold mine in the Paxtachi District of Samarkand Province in Uzbekistan on Tuesday 16 January 2018. The incident was not reported to the authorities until Friday 19 January, as the miners were working illegally in the disused mine, and initial rescue attempts were carried out by local communities without involving any official body.

The approximate location of the 16 January 2018 Samarakand mine collapse. Google Maps.

Uzbekistan has significant deposits of a range of precious and base metals, and is the world's twelth largest producer of gold. However the country also has a very high unemployment rate, and disused mines can provide a potential source of income in areas where mining has ceased. Such unregulated mining seldom featuring any form of heath and safety procedures, and accidents are frequent.

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Thirteen dead after landslide pushes bus into ravine in southern Colombia.

Thirteen people are known to have died after a bus was pushed into a ravine in Nariño Province, Colombia, on Sunday 21 January 2018. The bus was travelling between the cities of Tumaco and Pasto, close to the border with Ecuador. The known casualties are reported to include two women, a newborn baby and another child, though rescue workers are still investigating the possibility that there may have been more casualties, either on the bus or in another as yet undiscovered vehicle. The incident occurred amid torrential 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. In this instance about 50 000 cubic meters of soil are estimated to have slipped down the hillslope.

Rescue workers searching a hillside in Nariño Province, Colombia, following a landslide on 21 January 2018. Ivan Antonio Jurado/Reuters.

The Tumaco area has a wet tropical climate with a distinct rainy season that lasts from January to mid-July. The wettest month is June, which typically receives around 350 mm of rain, though January is also wet with around 375 mm of rain falling in the month.

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Sunday, 21 January 2018

Cretalamna bryanti: A new species of Mackeral Shark from the Late Cretaceous of Alabama.

Mackerel Sharks of the genus Cretalamna are known from Early Cretaceous to Early Eocene deposits around the world, and are thought to have been ancestral to modern species such as the Great White and Mako, as well as distinctive prehistoric species such as the giant Carcharocles megalodon. Like other fossil Sharks these species are usually only represented by their teeth, which are mineralised and grown and shed throughout their lives, rather than their skeletons, which are made of soft cartilage. Consequently differentiating these Sharks to species level is difficult, and many Late Cretaceous specimens have been assigned to a catch all species, Cretalamna appendiculata.

In a paper published in the journal PeerJ on 8 January 2018, Jun Ebersole of the McWane Science Center and Dana Ehret of the Alabama Museum of Natural History at the University of Alabama and the New Jersey State Museum, describe a new species of Cretalamna from the Late Cretaceous Tombigbee Sand of Alabama.

The new species is named Cretalamna bryanti, in honour of the Bryant family for their support of the University of Alabama, the Alabama Museum of Natural History, and the McWane Science Center. Teeth assigned to Cretalamna have been collected from the Tombigbee Sand for many years, but assigned to Cretalamna appendiculata. Ebersole and Ehret carried out a morphometric analysis, a method that relies on comparing the ratios of different measurements to one-another rather than simply assigning the samples to groups based upon their obvious shape, in order to determine that these specimens did not belong to any previously described species.

Cretalamna bryanti, anterior teeth. (A)-( E) Upper right anterior tooth in (A) oral, (B) basal, (C) mesial, (D) lingual, and (E) labial views. (F)-( J) Upper right anterior tooth in (F) lingual, (G) labial, (H) mesial, (I) oral, and (J) basal views. (K )-(O) Upper left anterior tooth, large morphology, in (K) oral, (L) basal, (M) mesial, (N) lingual, and (O) labial views. (P)-( T) Lower right anterior tooth in (P) lingual, (Q) labial, (R) mesial, (S) oral, and (T) basal views. Scale bars equal 1.0 cm. Ebersol & Ehret (2018).

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