Tuesday 30 June 2015

Japan restricts access to Mount Hakone after small eruption.

Authorities in Japan have closed off part of Mount Hakone, a popular tourist resort in Kanagawa Prefecture with hot springs and views of Mount Fuji, following a small eruption on Monday 29 June 2015. Nobody was injured in the event, in which a small amount of ash was produced slightly before 7.00 am, and was preceded by a Magnitude 3.3 Earthquake, but about 40 people were evacuated from the area due to the possibility of a phreatic eruption (explosion caused by water coming into contact with hot lava and vapourising).

Ash cloud over Mount Hakone. Reuters.

The Hakone area is noted for its hot springs, which are caused by water coming into contact with burried hot rocks, then rising to the surface, however Earthquakes near volcanoes are often caused by liquid magma moving through chambers beneath the volcano, and can be symptoms of future eruptions. In the case of Hakone there is a concern that magma closerto the surface my come into contact with liquid water, leading to explosions capable of throwing debris into the air at the surface.

The location of Mount Hakone. Google Maps.

Japan has a complex tectonic situation, with parts of the country on four different tectonic plates. Eastern Honshu area lies on the boundary between the Pacific, Eurasian and Philipine Plates, where the Pacific Plate is passing beneath the Eurasian and Philipine Plates as it is subducted into the Earth. This is not a smooth process; the rocks of the two plates constantly stick together, only to break apart again as the pressure builds up, causing Earthquakes in the process. 

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.

Mount Hakone is located directly on the Bonin Arc, a chain of volcanoes fed by liquified material from the Pacific Plate which is melted by the heat of the Earth's interior and rises through the overlying Eurasian Plate.

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Authorities in Kanagawa Prefecture have closed off an area of Mount Hakone, a popular tourist destination, following a rise sharp in seismic activities since 26 April 2015. An area of around 300 m around the...


The Japan Meteorological Agency (which also monitors seismic activity) recorded a Magnitude 5.7 Earthquake at a depth of 50 km off the coast of Iwate Prefecture, slightly after 1.45 pm Japan Standard Time (slightly after 4.45 am GMT) on Tuesday 17 February 2015. There...


The Japan Meteorological Agency (which also monitors seismic activity) recorded a Magnitude 6.8 Earthquake at a depth of 10 km in Nagano...

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Monday 29 June 2015

Microbial sediments from the Early-to-Middle Archean of Mpulanga Province, South Africa.


The quest for evidence of the earliest life is made difficult by both the presumed simplicity of such life (almost certainly Bacteria-like cells with no capacity for biomineralization, let alone large distinctive skeletons) and the limited amount of surviving, unaltered sediments from the earliest eras of the Earth. The best hopes for finding evidence of such life are biomarkers, chemicals or isotopic ratios known to be produced by living things, but which are difficult to explain in the absence of life.

In a paper published in the journal Geology on 26 May 2015, a team of scientists led by Frances Westall of the Centre de Biophysique Moléculaire at the Centre National de la Recherche Scientifique in Orléans, France, describe evidence for the presence of a microbial community in the 3.33 billion-year-old (Early-to-Middle Archean) Josefsdal Chert of Mpulanga Province, South Africa.

The Josefsdal Chert forms part of the Barberton Greenstone Belt, and represents a series of inshore sediments 6-30 m thick and several kilometres in extent along the border with Swaziland, sandwiched between layers of volcanic basalt. These sediments have been preserved intact, without compression, by the action of a number of hydrothermal systems, which produced silica-saturated waters, leading to mineralization of the sediments in a chert matrix.

Stratigraphy and facies associations of Josefsdal Chert, South Africa. Stratigraphic column (A) comprises four stratigraphic units (1–4) consisting of four interbedded sedimentary (chert) facies associations (A–D) that represent sedimentation in shifting upper offshore to foreshore environments. (B) Swaley and hummocky cross-stratification, deposited by storms in the upper offshore to shoreface, dominate Unit 1, which also exhibits abundant, penecontemporaneous, hydrothermal white to translucent, vertical chert dikes (vcd) and thin chert sills (facies A). (C) Iron-stained, poorly sorted, rhythmically laminated sediments of facies B, interpreted to have been deposited in a shoreface setting that was periodically tidally influenced. (D) Hydrothermal black and white banded chert constitutes facies C. (E) Planar-laminated volcanic accretionary lapilli and ash, comprising Unit 3, were intermittently reworked into small current and wave ripples. Facies D is inferred to have been deposited in an upper shoreface setting. Unit 4 contains alternations of facies A (with rare dessication cracks), C, and D that accumulated in shoreface to foreshore settings. Biosignatures occur ubiquitously in all facies; they are generally uncommon but dense in the vicinity of paleo-hydrothermal activity. Westall et al. (2015).

Preserved biofilms (saccharine-rich films produced by Bacteria both to secure themselves in place in aquatic environments and to help them interact with those environments) are found throughout the Josephdal Chert, though they are better preserved close to areas of palaeohydological activity (i.e. the vents producing the silica-rich waters). These comprise both films occurring on bedding surfaces, interpreted as having been produced by photosynthetic Bacteria, and clotted structures within finer-grained sediments, interpreted as having been produced by chemoautrophic Bacteria (Bacteria which obtained energy by processing chemicals within the sediments).

Types of carbonaceous material in the Josefsdal Chert, South Africa. (A) Dark wavy, phototrophic laminae (type 1; black arrows) coexisting with dark, chemotrophic clots (type 2; labeled as C). (B), (C) Details of phototrophic biofilms showing entrapped detrital grains (arrows, B) and compensation of laminae over underlying clot (arrow, C). (D) Laminated, detrital type 3 carbonaceous matter, partly rippled (black arrow), with sedimented clot (white arrow). (E) Type 2 clots, whose irregular shape suggests insitu growth, co-occur with sedimented carbonaceous matter (white arrow). (F) Detrital fragment of well-preserved phototrophic biofilm in facies A. (G) Phototrophic laminae are generally poorly preserved in the coarse sands of facies A (and facies D). Westall et al. (2015).


The bedding horizon films were found to be highly depleted in carbon-13 (the heavier of the two most abundant stable isotopes of carbon), which is generally accepted as evidence of photosynthesis (which preferentially uses carbon-12), supporting the idea that these films were produced by photosynthetic, rather than some other, possibly non-biological, phenomenon.

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In the nineteenth century the origin of life seemed an intractable problem for palaeontologists, with large complex animal fossils appearing in the Cambrian explosion, but scientists having access to neither examples of earlier fossils nor the means with which to examine them. However from the early twentieth...


The potential of there being life on Mars has been a stalwart of popular fiction for over a century, though to date no signs of actual life have been...


The blood plasma and lymph of modern animals is similar in chemical composition to seawater, strongly supporting the idea that animal life began in the oceans, but the liquid inside our cells has a quite different chemistry, suggesting that cells themselves first...



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Asteroid 2015 MX103 passes the Earth.

Asteroid 2015 MX103 passed by the Earth at a distance of 4 389 000 km (11.4 times the average distance between the Earth and the Moon, or 2.93% of the average distance between the Earth and the Sun), slightly before 4.45 pm GMT on Monday 22 June 2015. There was no danger of the asteroid hitting us, though had it done so it would have presented only a minor threat. 2015 MX103 has an estimated equivalent diameter of 25-78 m (i.e. it is estimated that a spherical object with the same volume would be 25-78 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 20 and 1 km above the ground, with only fragmentary material reaching the Earth's surface, although since an object at the upper end of this range would be expected to release an amount of energy equivalent to about 22 megatons of TNT (roughly 1300 times the energy released by the Hiroshima bomb), then being directly underneath it might be fairly unpleasant.

The calculated orbit of 2015 MX103. JPL Small Body Database.

2015 MX103 was discovered on 19 June 2015 (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 2015 MX103 implies that it was the 2678th asteroid (asteroid X103) discovered in the second half of June 2015 (period 2015 M).

While 2015 MX103 occasionally comes near to the Earth, it does not actually cross our orbital path. It has an elliptical 715 day orbit, at an angle of 7.40° to the plane of the Solar System, that takes it from 1.02 AU from the Sun (1.02 times the average distance at which the Earth orbits the Sun), slightly outside our orbit, to 2.11 AU from the Sun, (2.11 times the distance at which the Earth orbits the Sun and considerably more than the distance at which the planet Mars orbits the Sun). As a Near Earth Object that remains strictly outside the orbit of the Earth it is classed as an Amor Family Asteroid.

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Asteroid 2015 LQ21 passed by the Earth at a distance of 4 983 000 km (13.0 times the average distance between the Earth and the Moon, or 3.33% of the average distance between the Earth and the Sun), slightly before 7.00 pm GMT on Thursday 18 ...



Asteroid 2015 MA passed by the Earth at a distance of 656 700 km (1.71 times the average distance between the Earth and the Moon, or 0.44% of the average distance between the Earth and the Sun), slightly before 2.10 am GMT on Wednesday 17 June 2015. There...



Asteroid (1566) 1949 MA Icarus passed by the Earth at a distance of 8 054 000 km (20.9 times the average distance between the Earth and the Moon, or 5.38 % of the average distance between the Earth and the...


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Sunday 28 June 2015

Magnitude 1.9 Earthquake in Flintshire, North Wales.

The British Geological Survey recorded a Magnitude 1.9 Earthquake at a depth of 5 km, to the southeast of Prestatyn in Flintshire, North Wales, at about 12.55 pm British Summertime (at about  11.55 am GMT) on Friday 26 June 2015. An Earthquake of this size is not dangerous, and is highly unlikely to have caused any damage or injuries, but is likely to have been felt locally.

The approximate location of the 26 June 2015 Flintshire Earthquake. Google Maps.

Earthquakes become more common as you travel north and west in Great Britain, with the west coast of Scotland being the most quake-prone part of the island and the northwest of Wales being more prone  to quakes than the rest of Wales or most of England.

The precise cause of Earthquakes in the UK can be hard to determine; the country is not close to any obvious single cause of such activity such as a plate margin, but is subject to tectonic pressures from several different sources, with most quakes probably being the result of the interplay between these forces.

Britain is being pushed to the east by the expansion of the Atlantic Ocean and to the north by the impact of Africa into Europe from the south. It is also affected by lesser areas of tectonic spreading beneath the North Sea, Rhine Valley and Bay of Biscay. Finally the country is subject to glacial rebound; until about 10 000 years ago much of the north of the country was covered by a thick layer of glacial ice (this is believed to have been thickest on the west coast of Scotland), pushing the rocks of the British lithosphere down into the underlying mantle. This ice is now gone, and the rocks are springing (slowly) back into their original position, causing the occasional Earthquake in the process. 

(Top) Simplified diagram showing principle of glacial rebound. Wikipedia. (Bottom) Map showing the rate of glacial rebound in various parts of the UK. Note that some parts of England and Wales show negative values, these areas are being pushed down slightly by uplift in Scotland, as the entire landmass is quite rigid and acts a bit like a see-saw. Climate North East.

Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. If you felt this quake, or were in the area but did not (which is also useful information) then you can report it to the British Geological Survey here.

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The British Geological Survey recorded a Magnitude 3.0 Earthquake at a depth of 9 km, off the east coast of Caernarfon in Gwynedd, North Wales, slightly after...


The British Geological Survey recorded a Magnitude 1.5 Earthquake at a depth of 10 km, about 2 km to the west of Coedpoerh in Wrexham, North Wales, at about...

The British Geological Survey recorded a Magnitude 1.0 Earthquake at a depth of 12 km in northeast Gwynedd, North Wales, slightly after 10.30 pm British...


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Understanding current flows in hydrothermal vents.


Hydrothermal vents are areas on the sea floor where water warmed by the heat of the Earth’s interior escapes into the wider ocean. These waters contain high levels of dissolved minerals and nutrients rare in the wider oceans, and therefore support unique ecosystems able to survive without any input of solar energy. The most extreme examples of hydrothermal vents are the black smokers found around volcanically active ocean ridges. These vents produce water with temperatures reaching hundreds of degrees centigrade, kept liquid only by the high pressures present on the ocean floor, and opaque due to the high levels of minerals present. However hydrothermal vents are also present on areas of the ocean floor far from the active ridges, or any other form of volcanic influence, apparently emitting water that has been transported hundreds of kilometres beneath the ocean floor, which is far harder to explain.

In a paper published in the journal Nature Communications on 26 June 2015, Dustin Winslow of the Earth and Planetary Sciences Department at the University of California Santa Cruz and Andrew Fisher of the Earth and Planetary Sciences Department and Institute for Geophysics and Planetary Physics at the University of California Santa Cruz describe the results of a computer model of water flows supplying water to hydrothermal vents on the ocean floor, based upon observations of vents around the Juan de Fuca Ridge off the northwest coast of North America, which appears to solve the mystery of water supply to distant hydrothermal vents.

Marine sediments tend to be very rich in clay minerals, and are thus effectively impermeable to the flow of water. However the volcanic rocks that lay beneath these sediments tend to be highly porous, allowing the free transport of water. Therefore areas of exposed rock can act as either entrances or exits for water moving through subsurface aquifers, which are isolated from the general ocean in areas where the volcanic bedrock is covered by sediments. Observational evidence from around the Juan de Fuca Ridge suggest that whether an area of exposed volcanic rock serves as an entrance or exit to the aquifer is driven by the size of the exposure rather than other factors, such as proximity to volcanic heating, or the temperature or current speeds of the water passing over the entrances, with hydrothermal vents (i.e. areas where water exits from the aquifers) always occurring from exposed rocks with limited areas.

Geometry and configuration of 3D domains. Domains represent a section of upper ocean crust, oriented with the long-axis parallel to the spreading ridge, consistent with conditions at a field site on the eastern flank of the Juan de Fuca Ridge. A conductive volcanic rock section (red, lower permeability) is overlain by a crustal aquifer (orange, higher permeability) and marine sediments (blue, lower permeability) and two volcanic rock outcrops penetrate through the sediment (light blue). Heat is applied to the base, following a lithospheric cooling trend. The sides and base are no-fluid flow boundaries, and the top is free flow (fluid and heat) with pressure varying as a function of seafloor depth. Winslow & Fisher (2015).

Winslow and Fisher simulated flows between outcrops of different sizes, through subsurface aquifers being heated gently but evenly and constantly from below. They initially tried modelling systems where the current was present at the start of the experiment, on the basis that establishing a system and maintaining it are not the same, but found that even where no current was present at the outset of the experiment, a current flow from the larger opening to the smaller was quickly established.

Larger areas of permeable rock exposure allow both the entrance and exit of water across their surface, whereas smaller openings allow movement in only one direction. As warmer water rises from the vent into the water column warm water exiting from the vent quickly comes to dominate the flow of water at smaller vents, particularly if these are raised above the surrounding area (i.e. sticking up through the mud). This in turn leads to a draw on the waters of the aquifer, effectively pulling water through from the larger areas of exposure.

Simulation results at dynamic steady state. This simulation, showing one quarter of the domain illustrated in the top figure, has one large outcrop and one small outcrop. Domain colours show domain temperatures, including influence of rolling/mixed convection in basement aquifer and thermal influence of recharging/discharging outcrops. Inset diagrams show fluid flow vectors within and around outcrops (length indicates flow rate), with vectors plotted on a natural-log scale, the longest vector (exiting the top of the discharging outcrop) corresponding to a flow rate of 14m per year. Fluid flow through the sediment is so slow that it would generate no detectable thermal or geochemical anomalies. Vertical exaggeration (VE) of main image is times three; VE of inset images is times two. Winslow & Fisher (2015).

Hydrothermal vents are thought to account for about 25% of heat loss from the Earth’s interior, which if correct suggests that a very large amount of water is exiting from such vents every day. Despite this such vents are notoriously hard to find, with efforts to locate them with satellites having been largely inconclusive, and most known vents having been discovered by exploratory missions involving deep-sea submersibles. Winslow and Fisher’s findings suggest that a preference for such vents occurring on smaller outcrops is a genuine natural phenomenon, rather than a product of the observation methods being used. This would explain the difficulty in finding such vents using satellites, as very small discrete vents, no matter how numerous, would fall below the area/size at which it was possible to detect them using remote sensing technology.

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A seismic monitoring system beneath the northeast Pacific operated by the Ocean Observatories Initiative has detected a probable eruption on Axial Seamount, a submarine volcano roughly 480 km off the coast of Oregon. The network has detected...


Hydrothermal vents in the deep oceans are colonized by a broad array of invertebrates that have symbiotic relationships with chemotropic Bacteria. These Bacteria are able to derive energy from chemicals discharged by the vents, providing a base for ecosystems entirely separated from the light of the Sun. Not all...


Deep sea hydrothermal vents are unique ecosystems where the food chain is based not upon the photosynthetic activity of plants or algae, but rather of chemotrophic bacteria that gain their energy from...


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Houthi militiamen attack Aden refinery.

An oil refinery in the port of Aden in southern Yemen has come under fire by Houthi militiamen, one of a series of attacks in the south of the country on Saturday 27 June 2015. One person was reportedly killed in the attack, and at least one storage tank set on fire. The refinery was formerly capable of processing around 150 000 barrels (24 000 000 liters) of oil per day, but has been inactive since April due to repeated attacks and political instability. However a considerable amount of both oil and gas remain in storage at the site.

Firefighters trying to extinguish a blaze at a refinery in Aden, Yemen, following an attack by Houthi militias on 27 June 2015. Peninsula Qatar.

Hydrocarbons account for about 70% of Yemen's national income and 90% of exports, but the industry has been a frequent victim of the county's ongoing instability, as pipelines and facilities are an obvious target to anyone trying to gain concessions from the central government. This has led to a weakening economy and fuel shortages in the country, which has provoked further instability. 

The Houthi's are a Zaidi group that overthrow the government of  Abd Rabbuh Mansur Hadi in 2014, and currently control the Yemeni capital, Sana'a, claiming to be the legitimate government of Yemen. However they have never been capable of controlling the entire country, and are currently fighting a number of other groups, including militias loyal to the previous regime backed by neighbouring Saudi Arabia.

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An explosive device was used to blow up a natural gas pipeline on the outskirts of el-Arish, the provincial capital and principle port of North Sinai Province in Egypt...


The flow of oil from the El Sarir Oilfield to the Mediterranean port of Hariga was halted by a bomb which blew up part of a pipeline several kilometers...


A fire is burning out of control at a fuel storage facility in Tripoli, after a tank holding 6 million liters of oil was hit by a rocket during fighting between militia groups on...


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Flooding and landslides kill at least 21 in Cox's Bazar as monsoon arrives in Bangladesh.

At least 21 people have died in the district of Cox's Bazar in the Chittagong Division of Bangladesh following the arrival of the monsoon rains this week. A two-year-old girl is reported to have drowned after falling into water at Pekua Upazila while her family sought shelter from the rains. Two people, named as Subarna Das, 30, and Kamal Uddin, 35, died after being struck by a power line when a flash flood brought down a pole at Chakaria Upazila. Two people including a child also reportedly drowned at Chakaria Upazila, who have been identified as Mohammad Alam, 27, and Mohammad Asif, 7. The body of another child, yet to be identified, was recovered at Koiyarbil, also having apparently drowned. Two other unidentified bodies have been recovered at Chakaria. Two people have also drowned at Upazila Nirbahi, who have been identified as Kamrunnahar Begum, 22, and Tarika Hasnat, 9. At Shamlapur Chhamuda Khatun, 45, and her daughter Shahena Akter, 15, were killed in a rainfall induced landslide (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). 

A house partially submerged by flooding in the Cox's Bazar district of Chittagong. Banglar Chokh/The Daily Star.

Cox's Bazar has a humid climate year round, but still has a distinct rainy season, with an annual average rainfall of 3600 mm, most of which falls in June (average rainfall 780 mm), July (average rainfall 902 mm) and August (average rainfall 706 mm).

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It is feared that more than fifty people have lost their lives in flooding in the Saurashtra Region of Gujarat State, after the annual monsoon rainfall arrived with particular severity on Wednesday 24 June 2015. The worst casualties are thought to have occurred in...


The death toll from a heat wave hitting Sindh Province in Pakistan is thought to have exceeded 800. A total of 775 deaths had been reported in Karachi, the capital of the province, between Saturday 20 and Wednesday...


The death toll from the heat wave that has hit India in May 2015 passed the 2000 mark on Friday 29 May 2015, with the majority of the casualties recorded in Andhra Pradesh and Telangana States, and loss of...


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