Major earthquake in Van Province, eastern Turkey. 23 October 2011.

Slightly after 1.40 pm on Sunday 23 October 2011 the Turkish province of Van was shaken by an earthquake with a magnitude of 7.2 on the Richter Scale which occurred at a depth of 20 km, 16 km to the northeast of the provincial capital, also called Van. This was followed by a number of aftershocks, some exceeding 5 on the Richter Scale. This appears to have caused a large number of fatalities; at the time of writing the recorded death-toll has passed 70 and is likely to continue to climb.

Map showing the location of the 23 October quake and its aftershocks. Larger squares represent larger shocks, the reddish square is the most recent (at the time of writing). From the United States Geological Survey.

As of 6.00 pm GMT casualties have been reported in the cities of Van and Ercis (closer to the Iranian border), but there are no reports from the surrounding countryside, or across the border in Iran. The Turkish Red Crescent has dispatched emergency relief to the region, but at present rescue attempts seem to comprise largely local people moving rubble by hand.

Local news report, from the scene of the quake.

Turkey is an extremely earthquake-prone country, as the boundary between the Arabian and Eurasian Plates passes through its eastern provinces (red line on the map above), creating tectonic disturbances as the Arabian Plate pushes northward into the Eurasian. This is causing the Anatolian Block (roughly Turkey, the Greek Islands and the Peloponnese) to rotate anti-clockwise, splitting away from the rest of Eurasia in the north, and subduct beneath (northward moving) Africa in the southeast.

Map showing the stresses upon and movement of the Anatolian Block.

This has lead to a history of devastating earthquakes in Turkey (and Greece & Iran), the most notable of which in recent years was 1999 earthquake on the North Anatolian Fault that killed over 17 000 people in and around the city of Izmit.

See also Earthquake in Mojen, northern Iran, Earthquake in the Gulf of Corinth and Earthquakes on Sciency Thoughts Youtube.

Ongoing volcanic activity on El Hierro in the Canary Islands.

The island of El Hierro in the Canaries is the peak of a shield volcano (a volcanic mountain made up of layers of lava, with a wider, less cone-shaped, profile than the more notable stratovolcanoes) rising 1500 m above the sea. It is about 1.2 million years old, but has been relatively inactive during recorded history, with one observed eruption in 1793, and some lava flows dated to the 1600s. With no recorded history of large scale volcanic eruptions the island has developed as a popular tourist spot, and has a permanent population of over 10 000. Then in July this year (2011) El Hierro began to change.

The island of El Hierro.

From the start of July onwards seismologists began to record small earthquakes beneath El Hierro. These were minor, none larger than a 3 on the Richter Scale, but shallow, with an average depth of about 10 km, and as time went on they were becoming more frequent. This is something that volcanologists pay careful attention to, as it can be a sign of magma movements beneath a volcano, heralding a forthcoming eruption. This lead scientists from the Instituto Volcanologico de Canarias to place a network of GPS monitors around the island, to measure any movements. On 24 August they reported that the volcano had inflated by about 1 cm during the previous month.

By 3 September El Hierro was experiencing up to 250 minor tremors a day, with some of the quakes as shallow as 2 km. There was then a fall off in the number and intensity of quakes, lasting until the 27th, when the quakes abruptly resumed. The local government issued calls for calm, but closed schools on the island as well as the only significant road tunnel, Los Roquillos. On the 28th there were reports of rocks emerging from the Pico de Malpaso summit, though local authorities have denied this. People living close to the mountain were evacuated, but as a precaution against landslides. At about this point newspapers started to point out that there had been previous predictions that a major eruption in the Canaries could cause an Atlantic-wide tsunami. Authorities in the Canaries denied that there was any risk of this unless there was a submarine eruption on El Hierro, something thought highly unlikely.

On the 29th evacuees were allowed to return to their homes, as the area of seismic activity had moved offshore into the Las Calmas Sea, to the south of the island. This was thought to be caused by magma moving into a new chamber beneath the island, but was not seen as a cause for alarm, as only about 10% of magma movements result in an eruption at the surface. These quakes persisted for the next couple of weeks, waxing and waning in strength.

On 10 October 2011 a small submarine eruption in the Las Calmas Sea was reported, 5 km from La Restinga, the most southerly point on the island, at a depth of about 600 m. A significant number of dead fish were seen close to the sight. The next day the alert level for La Restinga was raised from yellow to red, and an emergency meeting was called at the village's football field, where the villagers were informed they were to be evacuated to the north of the island. A 4 nautical mile (7.4 km) shipping exclusion zone was also placed around the eruption.

On 12 October two new volcanic fissures were discovered, one at a depth of 750 m, 3.7 km from the shore and the other at a depth of 500 m, 2.8 km from the shore. These apparently turned the water around them green, and gave off a strong sulphurous smell. This combination of dead fish, water discolouration and odour was interpreted as indicating the vents were emitting gas rather than lava, and it was hoped that this might cause the pressure in the magma chamber to fall, decreasing earthquake activity and reducing the risk of a full-scale eruption.

Helicopter footage of one of the green patches.

A satellite image showing the extent of water discolouration to the south of El Hierro; to give a sense of scale El Hierro is about 25 km from east to west. Satellite Image courtesy of RapidEye.

On 15 October volcanic pumice (a volcanic rock with many gas filled pores) was observed floating on the surface of the sea, confirming that the eruptions were not confined to just gas. At this point some scientists began to talk about the possibility of a new island emerging to the south of El Hierro. A day later giant gas bubbles were observed reaching the surface of the sea close to the shore.

A giant gas bubble off the coast of El Hierro.

Throughout this period of eruptions there have been discussions of the possibility of a major tsunami originating from El Hierro. Scientists at the scene have repeatedly suggested that they feel this is a highly unlikely outcome, however this is largely based upon informed guesswork.

In 2001 Stephen Ward of the Institute of Geophysics and Planetary Physics at the University of California Santa Cruz and Simon Day of the Benfield Grieg Hazard Research Centre at the Department of Geological Sciences, University College London published a paper in the journal Geophysical Research Letters in which they speculated that a volcanic eruption on La Palma in the Canaries could provoke an Atlantic-wide tsunami with devastating consequences.

In October 2011 a team lead by Pablo Dávila Harris of the Department of Geology at the University of Leicester published a paper in the journal Geology discussing the likelyhood of a similar tsunami being caused by a volcanic eruption on Tenerife.

Ultimately we simply do not know the probability of an eruption on El Hierro, or many other Atlantic islands, causing a major tsunami. In the Pacific, where the dangers of a major tsunami are much more obvious, there is a well established tsunami warning centre, and a similar system is under construction for the Indian Ocean. The danger of a major tsunami in the Atlantic is clearly lower than in either of these other oceans, but should such an event occur it is likely to have devastating consequences, both economically and in human terms. While the costs of such a warning system are likely to be unattractive to governments in the current economic climate, a considerable amount of money has already been spent looking for extra-terrestrial objects with the potential to impact the Earth; a less likely scenario, and one which we would be less clear how to react to.

See also Tourists evacuated due to volcanic activity on El Hierro, Eruptions on Mount Nabro and Volcanoes on Sciency thoughts YouTube.

Reconstructing cloud cover for ancient Earth, with a view to spotting a new one.

Four the past four billion years or so the continents have ambled back and forth across the face of the Earth, sometimes forming up to form vast supercontinents such as Pangea or Rodinia, at other times going on their own ways. For much of the past five hundred million years these continents have been covered by vegetation.

Both of these have had profound effects upon the climate. The position of the continents effects the flow of the oceans, and therefore the atmosphere; for example the Pleistocene ice ages are believed to have started after a land bridge developed between North and South America, preventing the flow of water between the Atlantic and the Pacific, and diverting the Global Ocean Conveyer-belt through the waters surrounding Antarctica. Vegetation effects cloud cover by pumping water into the atmosphere via transpiration, the process by which plants suck up water from the ground via their roots then let it evaporate from their leaves, driving their circulatory systems.

This month Esther Sanromá and Enric Palle of the Instituto de Astrofísica de Canarias published a paper on the online arXiv database at Cornell University Library detailing the results of an attempt to accurately model the cloud cover of the Earth at various points in its history. The theory behind this is fairly simple; a model is created in which the surface of the Earth is divided up into a large number of cells, each of which has a weather patter, which can be influenced by conditions acting on the cell (heat received from the sun, the nature of the ground cover bellow etc.) as well as the weather in neighboring cells. The maps used were based upon those from Ron Blakey of Northern Arizona University's Department of Geology's Global Paleogeography Website.

Quite accurate models of the modern climate can be made in this fashion, but for ancient Earths the task was going to be harder. Accurate models require modeling vegetative ground cover to understand the effect this has on the climate; thus tropical rain forests, high latitude boreal forests and grasslands have to be treated differently. Unfortunately we don't have a good enough understanding of the vegetative cover over the geological timescale to make this possible. Instead Sanromá and Palle were forced to use a far simpler model of ground cover; either vegetated or desert with desert further divided by latitude.

This had clear limitations, but it was thought that if a reasonably accurate model of the modern Earth could be built up in this way, then it would be worth proceeding with the models of ancient climates. The modern Earth has a photometric variability of 3.29% and a mean albedo of 0.315 (that is to say on average 31.5% of the light that falls onto the Earth is reflected back into space, but that this average can vary by up to 3.29%). The computer simulation was able to create a model with cloud cover of 4.16% and an albedo of 0.325; not an exact match for our climate, but reasonably close.

Having thus calibrated the simulation Sanromá and Palle moved on the model the climate of the Late Cretaceous, 90 million years ago. At this time the ancient continent of Pangea had completely broken up, and the continents had yet to start to collide again, so that they remained as separate entities scattered around the globe. In addition the Late Cretaceous had a much warmer climate than today, so that it lacked ice caps. This lead to the creation of vast inland seas on most of the continents, further breaking up the Earth's land cover. Armed with this information Sanromá and Palle came up with a model which gave the Late Cretaceous Earth a photometric variability of 4.27% and an albedo of 0.331 - not greatly different from that of the modern Earth.

The Earth in the Late Cretaceous.

Next Sanromá and Palle built a model of the Earth in the Late Triassic, 230 million years ago. At this time the world's land masses were joined into a single supercontinent, Pangea, that reached almost from pole to pole. In the Late Triassic this supercontinent was starting to break up, the plates in the east had separated giving Pangea a 'C' shape, and forming a knew ocean, the Tethys. The Triassic had a hot, dry, climate with no glaciation at either pole. Sanromá and Palle's model of the Triassic gave a photometric variability of 5.02% and an albedo of 0.327; still comparable to that of today.

The Earth in the Late Triassic.

After the Triassic Sanromá and Palle moved on to the Mississippian (Early Carboniferous), 340 million years ago. During this period the continent of Pangea was coming together, though the continents were still largely separate. The climate was warmer that today, with inland seas on many continents, but there was still glaciation at the South Pole. The period is noted for extensive forests that covered much of the land masses. The model that Sanromá and Palle constructed of the period has a photometric variability of 4.46 and an albedo of 0.329; again not greatly dissimilar to today.

The Earth in the Mississippian.

Finally Sanromá and Palle constructed a model of the Late Cambrian, 500 million years ago. During the Cambrian a global supercontinent, Pannotia, had started to break up, with three island continents, Laurentia, Baltica and Siberia (roughly analogous to North America, Europe and Asia) and a residual Supercontinent, Gondwana, mad up of the remaining continental plates. The Cambrian had a warm climate, but with some glaciation at the poles. Most importantly, the Cambrian was before the evolution of vascular plants. It is thought that algae, fungi and lichens colonized the land some time before vascular plants, though it is unclear how early. For the sake of the model Sanromá and Palle assumed the Earth's land masses to be lacking vegetation of any sort during the Late Cambrian; this may not be completely accurate, but it is clear that at some point the Earth's landmasses did lack vegetation, so this model has some use. This model produced an albedo of 0.351, not greatly different to that of later periods, but a photometric variability of 12.2% which is distinctive.

The Earth during the Late Cambrian.

It is predicted that within the next few years we will have the technology to detect Earth-sized planets orbiting other stars, and therefore potentially to detect other planets with the capability to support life. However an Earth-like planet supporting life is not necessarily a familiar place; the Earth had unicellular life (bacteria, algae etc.) in its oceans for billions of years before the emergence of multicellular forms such as animals and plants, and after these emerged it took time for them to colonize the land. Sanromá and Palle's models suggest that it would be possible for a telescope to tell the difference between an Earth-like planet with plant cover and one without, on the basis of its photometric variability.

See also The Kepler-18 planetary system, Just how big is Iota Draconis b? The End of the Cretaceous and Exoplantes on Sciency Thoughts YouTube.

Dinosaur footprints discovered in Southwest Arkansas. October 2011.

This week scientists at the University of Arkansas revealed that they have discovered and been studying a large area of dinosaur footprints in the southwest of the state. They have not revealed the exact location as people have a nasty habit of digging up dinosaur footprints and selling them to private collectors, which destroys them as a resource for scientists; even if they can be recovered they are far less useful when out of position. The research is being lead by Stephen Boss of the Department of Geosciences at the William J. Fulbright College of Arts and Sciences and is funded by the National Science Foundation.

Some of the dinosaur footprints.

The prints so far exposed cover an area of over 10 000 m³, and date from the early Cretaceous between 115 and 120 million years ago. There are a large number of prints, which is slightly surprising as they were made in fairly hostile conditions, salt pans around a drying sea or lagoon, similar to those seen in the modern Persian Gulf. At first this seems slightly puzzling, but it is unlikely that the prints were all laid down at the same time; the field may well be showing accumulated trails built up over hundreds or even thousands of years.

A modern salt pan - few animals choose to spend much time here.

It is not considered possible to identify dinosaurs from their footprints alone, however in some cases it is possible to make an informed guess. The track field includes prints from both large therapod and sauropod dinosaurs, and there are unlikely to have been many different candidates for producing these.

A single large therapod dinosaur is well known from the Early Cretaceous of the Southwest United States, and analogy with modern ecosystems suggests that such an animal would have been unlikely to tolerate many rivals. This is Acrocanthosaurus atokensis, an 11 m allosauroid with a distinctive crest, thought to have weighed between 6000 and 7000 kg. Several sets of trackways in Texas have already been attributed to Acrocanthosaurus.

An artists impression of Acrocanthosaurus atokensis, by restoration artist Mineo Shiraishi.

There are two known sauropod dinosaurs from the region during the Early Cretaceous, and again this is likely to be the limit. No modern environment supports two species of elephants, and only one (the savanahs of eastern and southern Africa) two species of rhino. Thus it is likely that the sauropod prints belong to one or both of these dinosaur species. These are Plueurocoelus nana and Paluxysaurus jonesi two similar 15 m brachiosaur-like dinosaurs, which are the former and current official state dinosaurs of Texas respectively. The similarity, both in anatomy and distribution of these dinosaurs makes them hard to tell apart, though in certain features they are distinctive; it is possible that they represent an example of sexual dimophism in a dinosaur. It is also possible that Astrodon johnstoni, a similar dinosaur from the Early Cretaceous of the northwestern United States.

As well as making plaster casts of the footprints which can be taken back to the lab, the team have been making detailed 3D laser scanned images of the whole site, this not only gives an accurate three dimensional images of the footprints within a computer, it also maps the prints on the ground accurately enabling scientists to study the foot-spacing and therefore gait of the printmakers. Footprints do not always accurately represent the foot-shape of the printmaker. In muddy terrains footprints are often distorted by the viscosity of the mud, but on this sort of terrain this is less likely. More likely is that the prints are in fact underprints; when an animal steps on a layered terrain it crerates prints not just at the surface, but in the layers beneath, as sediments are pressed down through one-another. These underprints are often preserved while the overprints are destroyed at the surface, but they are less accurate representations of the footprint maker.

How underprints are formed, different prints from the same foot, and how tracks are measured.

See also A new Troodontid Dinosaur with an inured toe, Dinosaur feathers preserved in amber and Dinosaurs on Sciency Thoughts YouTube.

Could we mine the moon for titanium?

This week scientists at the joint meeting of the European Planetary Science Congress and the American Astronomical Society's Division of Planetary Sciences in Nantes, revealed the discovery of extensive titanium reserves of the moon, with widespread deposits of the mineral ilmenite containing up to 10% titanium; ilmenite on Earth typically contains only 1% titanium. The research was presented by Mark Robinson of Arizona State University and Brett Denevi of Johns Hopkins University in Baltimore. It was based upon findings made by NASA's Lunar Reconnaissance Orbiter; which was able to make a spectrographic analysis of rocks on the lunar surface, by calibrating the spectral signal to rocks brought back from the surface by the Apollo 17 Astronauts and images made of the landing site by the Hubble Space Telescope.

A Lunar Reconnaissance Orbiter image of the moon.

This has lead to widespread speculation that we might mine titanium on the moon. Titanium is a valuable metal, lightweight, strong and corrosion resistant. It used in surgical implants, aircraft and high technology. The lunar reserves have been shown to be much richer than those on Earth, and in a form that is also rich in oxygen, something that any lunar colony would require.

However while titanium is valuable, this does not mean that it is automatically valuable enough to justify the expense of a lunar colony. Titanium is the ninth most abundant element on Earth, and the seventh most abundant metal. We extract about 90 000 tonnes of the metal from the Earth's surface, but there are thought to be workable reserves of about 600 000 000 tonnes; that is to say at current rates of extraction reserves will last for another 666 years, assuming no increase in recycling, nor any better replacement material being found. Resources that were valuable in 1345 are not necessarily the same ones considered valuable now; Europeans never hailed the discovery of America as a potential source of cheap thatch for their roofs. As such it is probable that any successful future lunar colony might choose to mine titanium for its own use, but highly unlikely that one would ever be established for the express purpose of titanium mining.

See also Is the Moon younger than we think? When Moons Collide and Volcanoes on the far side of the Moon.

The Kepler-18 planetary system.

This week NASA announced the discovery of a planetary system by the Kepler Space Telescope. This has been named Kepler-18; it was formerly identified as KIC 8644288 (where KIC is Kepler Input Catalogue, a catalogue of all the stars in the Kepler field of vision). The system has a single star, which is similar to our sun; it has 97% of the sun's mass, and a volume of 110% that of the sun, it's surface temperature is slightly cooler.

The system has three (known) planets, named Kepler-19b (closest to the star), Kepler-18c and Kepler-18d. Kepler-19b is a rocky planet, 3.4 times the size of the Earth, Kepler-18c and Kepler-18d are larger, Neptune-like worlds, six and seven times the size of the earth respectively. Both these planets are less massive than Neptune, but have slightly larger volumes, suggesting they have larger gaseous envelopes and smaller rocky cores.

All three planets orbit within the orbital radius or Mercury (it is likely that there are other planets further out and harder to detect). Kepler-18b has a year of only 3.5 of our days. Kepler-18c and Kepler-18d are locked in an orbital resonance with orbits of roughly 7.6 and 14.9 (Earth) days respectively. The orbital resonance is caused by an exchange of orbital momentum between the planets as they pass each other; this also means the orbits are not quite constant. At any given time one of these planets will be running ahead of its average orbit and the other behind. Each time they pass they exchange energy, so that the one that was running slow speeds up, and the one that was running fast slows down.

A diagrammatic representation of the Kepler-18 system comparing the sizes of the star, planets and planetary orbits to those of our solar system.

The discovery was announced this week at a joint meeting of the American Astronomical Society's Division of Planetary Science and the European Planetary Science Conference and published in a paper on the on-line arXiv archive at Cornell University Library, by a team led by William Cochran of the McDonald Observatory at the University of Texas, and is scheduled for publication in the Astrophysical Journal Suplement Series.

Following initial identification of the system with the Kepler Space Telescope the team made follow up observations with the Shane and Nickel Telescopes at the Lick Observatory, the United Kingdom Infrared Telescope, the Wisconsin-Indiana-Yale National Optical Astronomy Observatory, the Hale Telescope at the Palomar Observatory, the Keck 1 HIRES spectrometer and the Spitzer Space Telescope. This enabled the scientists not only to build up a more complete picture of the Kepler-18 system, but also to confirm that the dimming of the star due to planets passing in front of it (how the system was detected) did indeed occur at a checkable electromagnetic wavelengths, considered a good way to determine that this has been caused by a planet and not some other phenomenon.

See also Just how big is Iota Draconis b? Kepler-16 (AB)b; the first planet discovered in a binary star system and Exoplanets on Sciency Thoughts YouTube.

Earthquake in Jujuy Province, NW Argentina. 6 September 2011

Sightly before 8.15 am on Thursday 6 September 2011 the Jujuy Province in the far northwest of Argentina was shaken by a severe earthquake, recorded by the United States Geological Survey as having a magnitude of 6.8 on the Richter Scale and a depth of 9.5 km; this is shallow enough that it is likely to have caused severe problems at the surface, although it is in a rural area with a fairly sparse population, with only 819 people living within 20 km of the epicenter, so it is hoped that there have been no fatalities. The nearest settlement to the epicenter of any size is San Pedro, 62 km to the east, with a population of about 75 000.

The location of the quake.

The province has a largely rural economy, however it is also home to an extensive mining industry, which may have placed more people at risk. The earthquake was felt across the province and in the neighboring provinces of Salta, Tucumán, Catamarca and Santiago del Estero, as well as in southern Bolivia. Public buildings in Jujuy and Tucumán were evacuated, and there have been reports of damage to buildings in Jujuy and Salta. The situation close to the epicenter is as yet unclear.

Jujuy is located in the Andes Mountains, one of the most tectonically active mountain ranges in the world, and has a history of earthquakes. The Andes are being formed as the Nazca Plate to the west is subducted beneath the South American Plate. This causes quakes in a number of ways. Firstly there is friction between the two plates as the Nazca Plate passes under South America. Then there is crumpling and upthrust of the South American as it is pushed from the west by the Nazca Plate and from the east by the expansion of the Atlantic. Finally there is volcanic activity in the Andes, as lighter minerals in the Nazca Plate are melted by the heat of the Earth's interior, then rise up through the overlying South American Plate to form volcanoes.

Diagram showing how the the subduction of the Nazca Plate deforms South America, forming the Andes.

In February 2010 an earthquake with a magnitude of 6.3 on the Richter Scale in the neighboring province of Salta killed two people, and on the same day an unrelated earthquake killed 500 people in Chile. Both the victims, an eight year old boy and a fifty-three year old man, were killed in house collapses. The Chilean earthquake on the same day measures 8.8 on the Richter Scale, the fourth largest earthquake ever recorded (the strongest earthquake ever recorded also hit Chile, in 1960) and caused a tsunami that hit California and Japan.

See also The Puyehue Eruption, Chile, 2011, The Puyehue-Caudón Caulle Volcanic Complex and Earthquakes on Sciency Thoughts Youtube.