Wednesday, 22 March 2023

Magnitude 6.5 Earthquake in Badakhshan Province, Afghanistan, results in at least 19 deaths.

The United States Geological Survey recorded a Magnitude 6.5 Earthquake at a depth of 187.6 km, roughly 4 km to the southeast of the town of  Jurm, in Badakhshan Province in northeast Afghanistan, slightly after 9.15 pm local time (slightly after 4.45 pm GMT) on Tuesday 21 March 2023. The Earthquake was felt across a wide area of South and Central Asia, from northern India though northeast Pakistan, eastern Afghanistan, and parts of Turkmenistan, Uzbekistan, Kazakhstan, Kyrgyzstan, and Tajikistan. Over 300 people have been injured and at least 19 killed, 10 in Afghanistan and 9 in Pakistan, following the event, which triggered numerous landslides and many buildings to collapse.

Damage to homes in Alishing District in Laghman Province, Afghanistan, following a Magnitude 6.5 Earthquake on 21 March 2023. Shafiullah Kakar/AFP/Getty Images.

The boundary between the Indian and Eurasian tectonic plates runs close to 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 Himalayas and the other mountain ranges of Central Asia., and which makes the nations in this boundary zone prone to Earthquakes.

Plate boundaries and movements beneath southern Pakistan, Iran and the Arabian Sea. University of Southampton.

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Eighteen students injured as primary school classroom collapses into sinkhole in Zimbabwe.

Eighteen children have been injured after a classroom collapsed into a sinkhole at a primary school in Zimbabwe on Thursday 16 March 2023. The incident happened at about 7.30 am local time, the Globe and Phoenix Primary School in the town of Kwekwe in Midlands Province, about 200 km from Harare, and affected a classroom where grade five students were being taught, which in Zimbabwe implies 10-11 year olds. The school, which has about 1500 pupils, has closed following the incident, with 900 of the pupils having been offered temporary places at the nearby Sally Mugabe Primary School, while the rest will attend classes in large tents erected in the grounds of the Globe and Pheonix School.

Members of the emergency services inspect a classroom which collapsed into a sinkhole in Kwekwe, Zimbabwe, on 16 March 2023. Zimbabwe Situation.

Sinkholes are generally caused by water eroding soft limestone or unconsolidated deposits from beneath, causing a hole that works its way upwards and eventually opening spectacularly at the surface. Where there are unconsolidated deposits at the surface they can infill from the sides, apparently swallowing objects at the surface, including people, without trace. 

However, on this occasion the hole is believed to have been caused by the a collapse within an old gold mine, which underlies the school and which has recently become a centre of activity for illegal miners. The Globe and Phoenix School takes its name from the Globe and Phoenix Mine, a gold mine which operated from the 1890s until 2007, when it  was closed down in 2007 by the Ministry of Mines and the Environmental Management Authority, following a series of safety problems, having originally been founded to educate the children of miners working at the mine.

While there is currently no official mining activity at the site (there are plans for such activity to restart in the future), the mine has become a target for informal miners, who work within many disused mines within Zimbabwe, a practice which is illegal but generally tolerated by the authorities, a country plagued by high unemployment and other economic problems, and is recognized as making a significant contribution to the economy, as such miners are able to sell their product locally rather than smuggling it out to avoid the attention of local authorities, as happens in many African countries. However, the informal nature of this industry makes it extremely dangerous, as few if any health and safety precautions are taken in such mines, and their are occasional reports of armed clashes between rival groups over lucrative sites.

This is particularly problematic at the Globe and Phoenix Mine, which was excavated using a gallery and pillar system, in which pillars of material were left as supports as a seem of gold ore was removed. These remaining pillars have a higher gold content than the unexcavated parts of the seem (which were deemed not economically useful by the original mining company), and are an obvious target for artisanal miners, weakening the structure of the mine, and leading to collapses. 

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Tuesday, 21 March 2023

Spectacular fireball over California as communications package from International Space Station falls to Earth.

Witnesses across much of California, as well as parts of Oregon and Nevada, have reported observing a bright fireball slightly before 9.35 pm local time on Friday 17 March 2023 (slightly before 4.35 am on Saturday 18 March GMT). The fireball is described as having moved from northwest to Southeast, entering the atmosphere to the east of Durham and disappearing somewhere to the south of Lake Tahoe. 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 as is believed to have been the case on this occasion.

Fireball over Elk Grove, California, on 18 March 2023. American Meteor Society.

The fireball is thought to have been caused by the remains of a communications package formerly attached to the International Space Station, which was predicted to enter the atmosphere over California on the evening of 17 March 2023.- The package, ICF-EF was attached to the Japanese Kibō Module of the International Space Station in 2008, and kept that module in contact with the Japan Space Agency's Mission Control in Tsukuba via the Kodama communications satellite. The package was decommissioned in 2020, when it was removed by the space station's robot arm, and launched back towards Earth on a decaying orbit which ended on 17 March.

The ICF-EF package attached to the Kibō Module of the International Space Station in 2011. NASA/Wikimedia Commons.

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Monday, 20 March 2023

Possible eruption on Mount Nyamulagira, Democratic Republic of Congo.

Scientists at the Goma Volcanological Observatory have reported seeing bright lights consistent with an eruption on the summit of Mount Nyamulagira, a 3058 m high shield volcano in the Virungu Mountains of eastern Democratic Republic of Congo, about 25 km to the north of Lake Kivu. This was accompanied by seismic activity beneath the volcano, which is often indicative of magma moving into chambers prior to an eruption. Mount Nyamalugira, which lies in North Kivu Province, is often considered to be Central Africa's most active volcano, having erupted more than 40 times since 1885. Due to the highly active nature of the volcano it presents little threat to human life, because nobody chooses to live near it, though concerns have occasionally been raised about the threat it presents to wildlife in the Viruga National Park.

The approximate location of Mount Nyamulagira. Google Maps.

Mount Nyamulagira lies on the Eastern Branch of the East African Rift, which is slowly splitting the African Plate in two along a line from the Red Sea through Ethiopia, and which includes the great lakes and volcanoes of east-central Africa. This has the potential to open into a new ocean over the next few tens of millions of years, splitting Africa into two new, smaller, continents; Nubia to the west and Somalia to the east.

Movement on the African Rift Valley, with associated volcanoes. Rob Gamesby/Cool Geography.

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Sunday, 19 March 2023

Twenty one confirmed fatalities following explosion at Colombian coal mine.

Twenty one miners have now been confirmed following an explosion at a coal mine in Cundinamarca Department, Colombia, on Tuesday 14 March 2023. The explosion reportedly caused several of the mine's entrances to collapse, trapping 30 workers below ground. After 30 hours digging through the debris, rescue workers were able to recover nine miners alive. The Colombian mining industry is notoriously dangerous, with 146 miners having died in 117 incidents in the year 2022.

Rescue workers at a coal mine in Colombia, following an underground explosion which killed 21 people on Tuesday 14 March 2023. Luisa Gonzalez/Reuters.

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.

Fire is much feared in coal mines due to this combination of flammable gas and solids, with methane and coal dust both potentially explosive when they come into contact with naked flames. To make matters worse, the limited oxygen supply in mines often means that such fires will involve incomplete combustion, in which all the oxygen is used up, but instead of forming carbon dioxide forms the much more deadly carbon dioxide, with potentially lethal consequences for anyone in the mine.

As coal is comprised more-or-less of pure carbon, and therefore reacts freely with oxygen (particularly when in dust form), to create carbon dioxide and (more-deadly) carbon monoxide, while at the same time depleting the supply of oxygen. This means that subterranean coal mines need good ventilation systems, and that fatalities can occur if these break down. 

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Dwarf Planet 1 Ceres comes to opposition.

Dwarf Planet 1 Ceres will reach opposition (the point at which it is directly opposite the Sun when observed from the Earth) at 5.37 pm GMT on Tuesday 21 March 2023, when it will also be at the closest point on its orbit to the Earth, 1.60 AU (i.e. 1.6 times as far from the Earth as the Sun, or about 239 207 000 km), and be completely illuminated by the Sun. While it is not obvious to the naked eye observer, asteroids have phases just like those of the Moon; being further from the Sun than the Earth, 1 Ceres is 'full' when directly opposite the Sun. As 1 Ceres is only about 939.4 km in diameter, it will not be visible to the naked eye, but with a maximum Apparent Magnitude (luminosity) of 6.9 at opposition, it should be visible in the Constellation of Coma Berenices to viewers equipped with a good pair of binoculars or small telescope, with the best visibility being at about 1.20 am local time from anywhere on Earth.

The calculated orbit and position of 1 Ceres at 6.00 pm GMT on Tuesday 21 March 2023.  JPL Small Body Database

Because Ceres is further from the Sun than the Earth, its orbital period is much longer than ours, with the Dwarf Planet completing one obit every 1683 days (4.65 years), on an eccentric orbit tilted at 10.6° to the plane of the Solar System. The orbit of Ceres places it within the inner part of the Main Asteroid Belt, but due to its large size, with a diameter of 939.4 km, it is considered to be a Dwarf Planet rather than an asteroid.

High resolution image of Ceres made on 20 September 2020, by the Dawn Space ProbeWikimedia Commons/NASA/JPL/Caltech.

Ceres was discovered on 1 January 1801 by Giuseppe Piazzi, a Catholic priest at the Academy of Palermo, Sicily. It was the first body to be discovered in the Main Asteroid Belt, and at the time when it was discovered an international search was underway for a presumed 'missing planet' between the orbits of Mars and Jupiter (although Piazzi was studying stars when he first observed Ceres, and initially presumed he had found a new comet). Ceres was for a long time considered to be the largest asteroid in the Solar System, but in 2006 was re-classified as a Dwarf Planet, as part of a revision of the classification of Solar System bodies driven by the discovery of a growing number of bodies in the Outer Solar System which are too large to be considered asteroids or comets yet to small to be considered to be planets. Of the nine bodies currently classified as Dwarf Planets, only Ceres is located within the Main Asteroid Belt, with five lying in the Kuiper Belt (Orcus, Pluto, Haumea, Quaoar, and Makemake), two lie within the Scattered Disk (Gonggong and Eris), and one within the Detached Region on the outer fringe of the Solar System (Sedna).

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Crocodile captured after attacking 12-year-old girl in Northern Territory, Australia.

A 12-year-old girl has escaped with minor injuries after being attacked by a Saltwater Crocodile, Crocodylus porosus, while collecting water plants for a Fish tank in a creek to the south of Darwin on Thursday 16 March 2023. The girl was treated at the Palmerston Regional Hospital in Darwin, before being discharged, while the Crocodile was captured in a trap set by park rangers and will be relocated. A spokesperson for the Northern Territory Crocodile Management Team has stated that the girl was extremely lucky not to have received more serious injuries as the Crocodile was about 2.2 m in length, large enough to inflict significant injuries on an adult Human. Water levels are currently high in the Northern Territory, due to the annual rainy season, and Crocodiles are able to enter many waterways which are to shallow to offer them good cover at other times of year. Rangers have removed about 70 Crocodiles from such waterways so far this year, compared to a total of 273 removed in 2022.

Crocodile captured in a creek to the south of Darwin after attacking a 12-year-old girl on Thursday 16 March 2023. Department of Environment, Parks and Water Security.

Crocodile attacks on Humans are relatively rare, but they are opportunistic ambush predators and will potentially attack anything going close to the water. Saltwater Crocodiles have a particularly poor reputation for such behaviour, being the largest species of Crocodile and notoriously aggressive. These Crocodiles are one of the few Crocodile species not considered vulnerable to extinction, being found from India to Australia  and inhabiting many areas that Humans shun, such as Mangrove forests and islands without fresh water.

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