Tuesday, 17 October 2017

Elephants kill four Rohingya refugees in Cox's Bazar, Bangladesh.

A mother and her three children have died and several other people have been injured, including the children's father, after a herd of Elephants entered the Balukhali Refugee Camp in the Chittagong Hills near Ukhiya in the Cox's Bazar District of Bangladesh on Saturday 14 October 2017. This is the third such incident in recent weeks, with at least seven deaths having occurred in the previous incidents.

The Balukhali Refugee Camp in Cox's Bazar, Bangladesh. NPR.

Over half a million Rohingya Muslims have fled Myanmar in the last two months, the result of a (somewhat uneven) conflict with the Myanmar armed forces,which have targeted whole communities in response to alleged attacks on security posts, a conflict that has been widely condemned as ethnic cleansing. The majority of these refugees have arrived in Bangladesh, a country that has accepted them, but struggled to meet their needs. Thus many of the refugees have settled in makeshift camps in districts close to the border with Myanmar, many of which have been cleared from forest, thus both creating space for new homes and providing building materials. 

Such camps are not good for wildlife in the areas where they are built. Many animals will simply flee such incursions, or, if unable to, are likely to end up in the cooking pots of hungry migrants. Elephants, however, are a somewhat different proposition. They are large animals, not used to being challenged by other animals in their home ranges, and typically live in matriacrchal herds of up to a hundred, with herds holding large territories, criss-crossed by Elephant trails. A herd of Elephants encountering a new Human settlement, particularly a hurriedly-built, poorly defended structure, are unlikely to attempt to go round it, and are quite likely to maximise the damage they cause to show their displeasure.

Herd of Elephants in Assam State, India. Perfect World Foundation.

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Monday, 16 October 2017

The Orionid Meteor Shower.

The Orionid Meteors are a prolific meteor shower appearing in late October each year and peaking on the nights of 20-22 October, when the shower can produce 50-70 meteors per hour, originating in the constellation of Orion (above and to the right of Orion's right shoulder). This makes them both one of the more prolific meteor showers, and one of the easiest for an amateur enthusiast to locate the radiant of (apparent point of origin). This year's display promises to be particularly good, as the New Moon falls on 20 October 2017, so that there should be little moonlight to interfere with visibility.

 The radiant of the Orionid Meteors. Stary Night/Space.com.

The shower is caused by the Earth passing through the trail of Halley's Comet (technically Comet P1/Halley), and encountering dust from the tail of this comet. The dust particles strike the atmosphere at speeds of over 200 000 km per hour, burning up in the upper atmosphere and producing a light show in the process. The Earth does not need to pass close to Halley's Comet for the meteor shower to occur, it simply passes through a trail of dust from the comet's tail that is following the same orbital path. Halley's Comet only visits the Inner Solar System once every 75 years, last doing so in 1986. 

The calculated orbit and position on 16 October 2017 of Comet P1/Halley. The Sky Live 3D Solar System Simulator.

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Orange cloud covers much of UK.

Much of the UK has been covered by a thick dust cloud today, reducing light levels and turning the sky an orange colour. The cloud was originally seen over the southwest of the country, and moved to the north and east.

Orange sky over London's Shard Building. Dominic Lipinski/PA.

The cloud is thought to have been caused by dust laden winds associated with former Hurricane Ophelia, a tropical storm over the Atlantic currently moving towards the UK. The dust is thought mostly to have originated from the Sahara; dust plumes from the Sahara frequently blow out over the Atlantic, and are a significant contributor to soils in the Amazon Basin, however these dust plumes are not generally blown back towards Europe unless an unusual wind pattern, such as that caused by Ophelia, crosses their path.

 The path and strength of Hurricane Ophelia. Thick line indicates the past path of the storm (till 3.00 pm GMT on Monday 16 October 2017), while the thin line indicates the predicted future path of the storm, and the dotted circles the margin of error at six and twelve hours ahead. Colour indicated the severity of the storm. Tropical Storm Risk.

Tropical storms are caused by the warming effect of the Sun over tropical seas. As the air warms it expands, causing a drop in air pressure, and rises, causing air from outside the area to rush in to replace it. If this happens over a sufficiently wide area then the inrushing winds will be affected by centrifugal forces caused by the Earth's rotation (the Coriolis effect). This means that winds will be deflected clockwise in the northern hemisphere and anti-clockwise in the southern hemisphere, eventually creating a large, rotating Tropical Storm. They have different names in different parts of the world, with those in the northwest Atlantic being referred to as hurricanes.

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Magnitude 5.1 Earthquake in Barinas State, Venezuela.

The United States Geological Survey recorded a Magnitude 5.1 Earthquake at a depth of 35.4 km,  in the Cordillera de Mérida mountain range, roughly 25 km to the southwest of the village of Puerto Vivas In Barinas State in northwest Venezuela, at about 4.35 am local time (about 8.35 am GMT) on Saturday 14 October 2017. There are no reports of any damage or casualties associated with this event, but it was felt locally.

The approximate location of the 14 October 2017 Barinas Earthquake. Google Maps.

The Cordillera de Mérida mountains form a northeastern extension of the Andes, running through the northwest of Colombia. The mountains form the boundary between the South American Plate to the south and east and the North Andean Plate, which underlies parts of northern Colombia and northwest Venezuela, to the northwest. The North Andean Plate is caught between the west-moving South American Plate to the east and the east-moving Nazca Plate to the west, with the effect that the whole area is being crushed and uplifted, making it very prone to earthquakes.
 The movement of the plates under and around northern South America. WIkimedia Commons.
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, 15 October 2017

Activity on Mount Lewotolo, Lesser Sunda Islands.

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (Center for Vulcanology and Geological Disaster Mitigation) has raised the alert level around Mount Lewotolo, a stratovolcano (cone-shaped volcano made up of layers of ash and lava) on the north part of Lembata Island, one of the Lesser Sunda Islands of Indonesia. The volcano has been producing low levels of emissions since the beginning of August 2017, with small plumes rising as much as 600 m above the summit of the 1423 m volcano. On Monday 9-Tuesday 10 October a series of small earthquakes were recorded between 10 and 30 km beneath the volcano, with the largest event having a Magnitude of 4.9, and triggering a series of small rockfalls that have damaged several homes. Seismic activity beneath volcanoes can be significant, as they are often caused by the arrival of fresh magma, which may indicate that a volcano is about to undergo an eruptive episode, and people living within 2 k of the volcano have been evacuated as a precaution.

The approximate location of Mount Lewotolo. Google Maps.

Lembata sits on the northern part of the Timor Microplate; a small fragment of crust caught between the Banda Sea Plate to the north and the Australian Plate to the south. Both these other plates are subducting beneath the Timor Plate, and as they sink into the Earth, melted by the friction and the heat of the planets interior. Some of this melted material then rises through the overlying plate, fuelling the volcanoes of Flores, Timor and the neighbouring islands.

The subduction zones beneath the Timor Microplate. Hamson (2004).

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Wildfires kill at least 40 in California.

Forty people have died and many more are missing in a series of wildfires that have swept across California's Napa Valley this week. At least fifteen fires are still burning across the northern part of the state, where over 890 square kilometres of farmland and 5700 buildings have been destroyed. More than 10 000 firefighters from California and neighbouring states are currently fighting the fires.

Fires burning in Peters Canyon Regional Park in Orange County, California, earlier this week. Irfan Khan/Los Angeles Times.

The worst of this fires is in Sonoma County, where an incident named the Nuns Fire, started by a downed power line hitting  tree, has destroyed almost 200 square kilometres of land have been burned and the outskirts of the cities of Sonoma and Santa Rosa affected, and a second incident, the Tubbs Fire, so called because it started near Tubbs Lane near the city of Calistoga has destroyed over 140 square kilometres of land between Calistoga and Sonoma, resulting in 22 deaths.

 Burning buildings to the east of Healdsburg in Sonoma County earlier this week. J Morris/San Francisco Chronicle.

In Mendocino County a fire named the Redwood Fire has destroyed around 130 square kilometers of land and destroyed around 90 buildings. Eight people are understood to hav edied on the first day of this fire, prompting the evacuation of a further 5000 from homes in its path. A further six people have died and a further 76 are missing in Napa County, where a blaze called the Atlas Fire has destroyed around 200 square kilometers of land, including much of the county's winelands. In Yuba County four people have died in the Cascade Fire, which has destroyed around 40 square kilometres of land.

The remains of the Signorello Estate Winery in Napa County, California, destroyed by wildfires this week. Justin Sullivan/Getty Images.

The fires have a variety of causes and have been fueled by dry winds blowing from the mountains in the northeast of the state, but are essentially due to a prolonged drought in the state, which has been experiencing dry conditions since 2011, the longest such drought in the state's recorded history. This drought has killed vegetation, including thousands of trees, across much of central California, providing dry tinder to fuel the fires, despite high rainfall that caused flooding in parts of the state in the winter of 2016-7. The draught has been made worse by the diversion of water to suit Human purposes, such as agriculture, industry and leasure, which has taken water away from other ecosystems, resulting in the build-up of dead, dry vegetation that has produced fuel for the fires.

Dry vegetation near Shandon in San Luis Obispo County, California, in May 2015. Al Seib/Los Angeles Times.

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Titanonarke megapterygia: A new species of Electric Ray from the Early Eocene of Italy.

Electric Rays, Torpediniformes, which get their name from their ability to produce bioelectricity, used to both capture prey and deter predators, with some species said to be capable of producing a shock equivalent to dropping a hairdryer into a bathtub. They are highly distinctive with a rounded disk and a flattened muscular tail; Electric Rays are poor swimmers, but lacking any natural enemies, this is not usually an issue. Based upon their relationships to other Rays, they are assumed to have first appeared during the Cretaceous, though fossil Electric Rays are only known from post-Cretaceous deposits. As with other Chondrichthyans (Sharks and Rays) almost all fossil Electric Rays are known from isolated teeth only, due to a cartilagenous skeleton with limited preservational potential, and a habit of shedding teeth throughout their lives. However, one species is known from several full body specimens, Titanonarke molini, from the Early Eocene Bolca Lagerstätte of Verona Province in northeast Italy.

In a paper published in the Journal of Systematic Palaeontology on 22 September 2017, Giuseppe Marramà of the Department of Palaeontology at the University of Vienna, Kerin Claeson of the Philadelphia College of Osteopathic Medicine, Giorgio Carnevale of the Dipartimento di Scienze della Terra at the Universit a degli Studi di Torino, and Jürgen Kriwet, also of the Department of Palaeontology at the University of Vienna, describe a second species of Titanonarke, also from the Bolca Lagerstätte.

The new species is named Titanonarke megapterygia, meaning 'large-fins'. The species is described from a specimen (MCSNV IG.135576) previously assigned to Titanonarke molini, but adjudged to be a separate species following a review of all the material assigned to the genus. The species is described from an almost complete, articulated, specimen 626.2 mm in length. It differs considerably from the original species, due to a much lower number of pre-caudal (non-tail) vertebrae - 74 compared to over 100 in Titanonarke molini - which greatly alters the body proportions of Titanonarke megapterygia.

Titanonarke megapterygia from the Eocene Monte Postale site. (A) MCSNV IG.135576; (B) detail of the head and hyoid apparatus. Abbreviations: ao, antorbital cartilage; cb, ceratobranchials; hym, hyomandibula; me, Meckel’s cartilage; nc, nasal capsule; pq, palatoquadrate; sca, scapulocoracoid; syn, synarcual; rf, rostral fontanelle; ro, rostral cartilage. Scale bars are 50 mm. Marramà (2017).

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