Rainforests in Far East shaped by humans for the last 11,000 years

New research from Queen’s University Belfast shows that the tropical forests of South East Asia have been shaped by humans for the last 11,000 years.

The rain forests of Borneo, Sumatra, Java, Thailand and Vietnam were previously thought to have been largely unaffected by humans, but the latest research from Queen’s Palaeoecologist Dr Chris Hunt suggests otherwise.

A major analysis of vegetation histories across the three islands and the SE Asian mainland has revealed a pattern of repeated disturbance of vegetation since the end of the last ice age approximately 11,000 years ago.

The research, which was funded by the Arts and Humanities Research Council and the British Academy, is being published in the Journal of Archaeological Science. It is the culmination of almost 15 years of field work by Dr Hunt, involving the collection of pollen samples across the region, and a major review of existing palaeoecology research, which was completed in partnership with Dr Ryan Rabett from Cambridge University.

Evidence of human activity in rainforests is extremely difficult to find and traditional archaeological methods of locating and excavating sites are extremely difficult in the dense forests. Pollen samples, however, are now unlocking some of the region’s historical secrets.

Dr Hunt, who is Director of Research on Environmental Change at Queen’s School of Geography, Archaeology and Palaeoecology, said: “It has long been believed that the rainforests of the Far East were virgin wildernesses, where human impact has been minimal. Our findings, however, indicate a history of disturbances to vegetation. While it could be tempting to blame these disturbances on climate change, that is not the case as they do not coincide with any known periods of climate change. Rather, these vegetation changes have been brought about by the actions of people.

“There is evidence that humans in the Kelabit Highlands of Borneo burned fires to clear the land for planting food-bearing plants. Pollen samples from around 6,500 years ago contain abundant charcoal, indicating the occurrence of fire. However, while naturally occurring or accidental fires would usually be followed by specific weeds and trees that flourish in charred ground, we found evidence that this particular fire was followed by the growth of fruit trees. This indicates that the people who inhabited the land intentionally cleared it of forest vegetation and planted sources of food in its place.

“One of the major indicators of human action in the rainforest is the sheer prevalence of fast-growing ‘weed’ trees such as Macaranga, Celtis and Trema. Modern ecological studies show that they quickly follow burning and disturbance of forests in the region.

“Nearer to the Borneo coastline, the New Guinea Sago Palm first appeared over 10,000 years ago. This would have involved a voyage of more than 2,200km from its native New Guinea, and its arrival on the island is consistent with other known maritime voyages in the region at that time – evidence that people imported the Sago seeds and planted them.”

The findings have huge importance for ecological studies or rainforests as the historical role of people in managing the forest vegetation has rarely been considered. It could also have an impact on rainforest peoples fighting the advance of logging companies.

Dr Hunt continued: “Laws in several countries in South East Asia do not recognise the rights of indigenous forest dwellers on the grounds that they are nomads who leave no permanent mark on the landscape. Given that we can now demonstrate their active management of the forests for more than 11,000 years, these people have a new argument in their case against eviction.”

Scientists find evidence of tsunamis on Indian Ocean shores long before 2004

Kruawun Jankaew led a team of geologists who unearthed evidence that tsunamis have repeatedly washed over a Thai island during the last 2,800 years. -  Brian Atwater
Kruawun Jankaew led a team of geologists who unearthed evidence that tsunamis have repeatedly washed over a Thai island during the last 2,800 years. – Brian Atwater

A quarter-million people were killed when a tsunami inundated Indian Ocean coastlines the day after Christmas in 2004. Now scientists have found evidence that the event was not a first-time occurrence.

A team working on Phra Thong, a barrier island along the hard-hit west coast of Thailand, unearthed evidence of at least three previous major tsunamis in the preceding 2,800 years, the most recent from about 550 to 700 years ago. That team, led by Kruawun Jankaew of Chulalongkorn University in Thailand, included Brian Atwater, a University of Washington affiliate professor of Earth and space sciences and a U.S. Geological Survey geologist.

A second team found similar evidence of previous tsunamis during the last 1,200 years in Aceh, a province at the northern tip of the Indonesian island of Sumatra where more than half the deaths from the 2004 tsunami occurred.

Findings from both teams are published in the Oct. 30 edition of Nature.

Sparse knowledge of the region’s tsunami history contributed to the loss of life in 2004, the scientists believe. Few people living along the coasts knew to heed the natural tsunami warnings, such as the strong shaking felt in Aceh and the rapid retreat of ocean water from the shoreline that was observed in Thailand.

But on an island just off the coast of Aceh most people safely fled to higher ground in 2004 because the island’s oral history includes information about a devastating tsunami in 1907.

“A region’s tsunami history can serve as a long-term warning system,” Atwater said.

The research will reinforce the importance of tsunami education as an essential part of early warning, said Jankaew, the lead author.

“Many people in Southeast Asia, especially in Thailand, believe, or would like to believe, that it will never happen again,” Jankaew said. “This will be a big step towards mitigating the losses from future tsunami events.”

The team found evidence for previous tsunamis by digging pits and auguring holes at more than 150 sites on an island about 75 miles north of Phuket, a Thai tourist resort area ravaged by the 2004 tsunami. That tsunami was generated 300 miles to the west when the seafloor was warped during a magnitude 9.2 earthquake.

At 20 sites in marshes, the researchers found layers of white sand about 4 inches thick alternating with layers of black peaty soil. Witnesses confirmed that the top sand layer, just below the surface, was laid down by the 2004 tsunami, which ran 20 to 30 feet deep across much of the island.

Radiocarbon dating of bark fragments in soil below the second sand layer led the scientists to estimate that the most recent predecessor to the 2004 tsunami probably occurred between A.D. 1300 and 1450. They also noted signs of two earlier tsunamis during the last 2,500 to 2,800 years.

There are no known written records describing an Indian Ocean tsunami between A.D. 1300 and 1450, including the accounts of noted Islamic traveler Ibn Battuta and records of the great Ming Dynasty armadas of China, both of which visited the area at different times during that period. Atwater hopes the new geologic evidence might prompt historians to check other Asian documents from that era.

“This research demonstrates that tsunami geology, both recent and past tsunamis, can help extend the tsunami catalogues far beyond historical records,” Jankaew said.

The new findings also carry lessons for the northwest coast of North America, where scientists estimate that many centuries typically elapse between catastrophic tsunamis generated by the Cascadia subduction zone.

“Like Aceh, Cascadia has a history of tsunamis that are both infrequent and catastrophic, and that originate during earthquakes that provide a natural tsunami warning,” Atwater said. “This history calls for sustained efforts in tsunami education.”

Geologists push back date basins formed, supporting frozen Earth theory


Even in geology, it’s not often a date gets revised by 500 million years.



But University of Florida geologists say they have found strong evidence that a half-dozen major basins in India were formed a billion or more years ago, making them at least 500 million years older than commonly thought. The findings appear to remove one of the major obstacles to the Snowball Earth theory that a frozen Earth was once entirely covered in snow and ice – and might even lend some weight to a controversial claim that complex life originated hundreds of million years earlier than most scientists currently believe.



“In modern geology, to revise the age of basins like this by 500 million years is pretty unique,” says Joe Meert, a UF associate professor of geology.



Agreed Abhijit Basu, a professor of geological studies at Indiana University: “The required revision is enormous – 500 million years or about 11 percent of total Earth history.”



Meert is one of eight authors of a paper on the research that recently appeared in the online edition of the journal Precambrian Research.



The Purana basins – which include the subject of the study, the Vindhyan basin – are located south of New Delhi in the northern and central regions of India. They are slight, mostly flat depressions in the Earth’s crust that span thousands of square miles. For decades, Meert said, most geologists have believed the basins formed 500 million to 700 million years ago when the Earth’s crust stretched, thinned and then subsided.



Meert said that date may have originated in early radiometric dating of sediment from the basin. Radiometric dating involves estimating age based on the decay or radioactive elements. Additionally, he said, apparent fossils retrieved from the basin seemed to have originated between 500 million and 700 million years ago.



The researchers were working on an unrelated project and had no intention of re-examining the basins’ age. But then a UF graduate student, Laura Gregory, dated a kimberlite retrieved from the Vindhyan basin to about 1,073 million years ago. A kimberlite is a volcanic rock that contains diamonds.


Gregory also used paleomagnetism, a technique that estimates where rocks were formed by using the orientation of their magnetic minerals. Curious about whether the kimberlite results would apply more generally to the region, fellow UF graduate student Shawn Malone compared the kimberlite’s orientation to other rocks from the Vindhyan basin. To his surprise, he found the orientations were virtually identical.



As a result, the geologists expanded the investigation, using a modified chain saw to drill wine-cork-sized cores out of dozens of rocks collected from 56 sites. Their contents all also had the same or very similar magnetic orientation, Meert said.



Much of the basins are composed of sediments that cannot be dated using any method. But Meert said the sediment also contains zircon, which can be dated using laser mass spectrometry – vaporizing tiny bits of the rocks with a laser, then analyzing their uranium and “daughter” lead contents to tease out their formation date based on rates of decay.



All the zircon the researchers tested originated 1,020 million years ago, Meert said.



The Snowball Earth theory posits that the Earth was covered in snow and ice from about 635 million to 700 million years ago. While much geological evidence has been found to support that theory worldwide, the Vindhyan and other Purana basins lacked numerous telltale signs, such as striated or scratched boulders formed when ice drags small pebbles over bedrock and boulder beds derived from glaciers known as tillites, Meert said. As a result, he said, the basins represented a prominent obstacle to the theory.



The new study removes that obstacle because it pushes back the origins of the basins to well before Snowball Earth would have occurred.



A 2007 study, conducted independently of the UF study and published in the Journal of Geology, dated rocks from another Purana basin to 1,020 million years ago, another 500-million-year revision. One of its authors was M.E. “Pat” Bickford, a professor emeritus at Syracuse University’s department of earth sciences. Bickford said the revisions of the age of the Purana basins calls into question the hypothesis that they formed when the supercontinent Rodinia broke up. Rodinia is thought to have separated into the modern continents about 700 million years ago, but the revisions make the basins too old for that split, Bickford said.



The UF research could also support a Swedish paleontologist’s controversial dating of multicellular creatures called Ediacarans from an older part of the basin to 1.6 billion years. But, said Meert, “Of all the implications of this research, the notion that Ediacaran-like organisms may be much older than 580 million years is probably the most speculative.”



The National Science Foundation funded the UF research.

Stress Buildup Precedes Large Sumatra Quakes





Sumatra is the sixth largest island in the world and is the largest island in Indonesia
Sumatra is the sixth largest island in the world and is the largest island in Indonesia

The island of Sumatra, Indonesia, has shaken many times with powerful earthquakes since the one that wrought the infamous 2004 Indian Ocean tsunami. Now, scientists from the California Institute of Technology and the Indonesian Institute of Sciences are harnessing information from these and earlier quakes to determine where the next ones will likely occur, and how big they will be.



Mohamed Chlieh, the lead author of a new report, looked at the region during his postdoctoral studies at Caltech with Jean-Philippe Avouac, professor of geology and director of Caltech’s Tectonics Observatory (TO) and Kerry Sieh, Sharp Professor of Geology. They found that in the time between great earthquakes, some portions of the fault zone locked up while others crept along steadily, and the portions that were locked in the past few decades coincided with portions that rupture to produce large-magnitude quakes. The correlation was especially strong for two temblors of magnitude 8.7 that struck the region in 1861 and again in 2005.



The study also reveals which part of the Sumatra megathrust is storing strain that will be released during future large earthquakes.



Earthquakes in Sumatra are the manifestation of a sudden release of strain that constantly builds as the plates beneath the Indian Ocean creeps steadily toward southeast Asia and dive into the subduction zone under the island. If the total tectonic plate motion in the region is not taken up by fault slip during earthquakes, then a deficit builds until the next earthquake rupture. The patch of the fault where slip is greatest during an earthquake and releases the most pent-up strain, known as an asperity, also gets stuck between quakes. The scientists were interested in what was happening at the land surface, above these asperities, between big earthquakes.



Investigations by Caltech scientists in the region began when Sieh and his students started documenting the history of subsidence and emergence of the islands offshore Sumatra using the record provided by coral heads. Later on, a network of geodetic stations was deployed by the TO. To measure how strain built up in the calm interseismic period between earthquakes, Chlieh and his colleagues analyzed GPS measurements collected since 1991 and annual banding in corals from the past 50 years. Coral growth bands indicate vertical land motion because as the seafloor on which corals live shifts down or up, the creatures either grow to chase sunlight from below water or die back when elevated above water. Both the bands and the GPS data record small land-position shifts in interseismic periods. In contrast, they show drastic shifts during an earthquake, as the corals typically die when they are thrust high enough above or sunk too deep below sea level to survive.


The data provide a record of unevenly distributed deformation of the land surface directly above the subduction zone during the interseismic period. Modeling further indicates that this results from the asperities along the plate interface, while other parts remain smoothly slipping. These interseismic asperities are 10 times as wide–up to 175 kilometers–in the region where great earthquakes have occurred in the past.



“Our model shows asperities exactly at the same places that the 2005 Nias and the 1797 and 1833 earthquakes in the Mentawai islands occurred, indicating that aperities seem to be persistent features from one seismic cycle to another,” Chlieh remarks. Avouac adds, “This is clear indication that the characteristics of large earthquakes are somewhat determined by properties of the plate interface that can be gauged in advance from measuring interseismic deformation.



“A priori, large earthquakes should not be expected where the plate interface is creeping, but are inescapable where it is locked. So it seems that we can, with interseismic observations, see these asperities before the earthquake occurs,” he says. “The question now is, ‘How well are we able to estimate the characteristics of the earthquakes that these asperities could produce?'”



The implications of the study are major, according to Chlieh. “Using the asperity locations, we may be able to construct some more realistic earthquake and tsunami models following different scenarios. Then we will have a good idea of the risk induced by these locked fault zones.”



The study appears in the May issue of the Journal of Geophysical Research. Other authors on the paper are Danny Natawidjaja, a former Caltech grad student who is now at the Indonesian Institute of Sciences, and John Galetzka, staff geodesist with the TO.



Abstract: http://www.agu.org/pubs/crossref/2008/2007JB004981.shtml

World’s fastest-growing mud volcano is collapsing, says new research


The world’s fastest-growing mud volcano is collapsing and could subside to depths of more than 140 metres with consequences for the surrounding environment, according to new research.



As the second anniversary (May 29) of the eruption on the Indonesian island of Java approaches, scientists have also found that the centre of the volcano – named Lusi – is collapsing by up to three metres overnight.



Such sudden collapses could be the beginning of a caldera – a large basin-shaped volcanic depression – according to the research team, from Durham University UK, and the Institute of Technology Bandung, in Indonesia.



Their findings, based on Global Positioning System (GPS) and satellite measurements, are due to be published in the journal Environmental Geology.



Lusi first erupted on May 29, 2006, in the Porong sub-district of Sidoarjo, close to Indonesia’s second city of Surabaya, East Java, and now covers seven square kilometres and is 20 metres thick.



In January 2007 Durham University published the first scientific report into the causes and impact of Lusi, revealing that the eruption was almost certainly manmade and caused by the drilling of a nearby exploratory borehole(1) looking for gas.



Fourteen people have been killed and 30,000 people have been evacuated from the area. More than 10,000 homes have been destroyed while schools, offices and factories have also been wiped out and a major impact on the wider marine and coastal environment is expected.


The researchers say the subsidence data could help determine how much of the local area will be affected by Lusi.



Their research used GPS and satellite data recorded between June 2006 and September 2007 that showed the area affected by Lusi had subsided by between 0.5 metres and 14.5 metres per year.



The scientists found that if Lusi continued to erupt for three to 10 years at the constant rates measured during 2007 then the central part of the volcano could subside by between 44 metres and 146 metres – 26 metres longer than a football pitch.



They propose the subsidence is due to the weight of mud and collapse of rock strata due to the excavation of mud from beneath the surface.



Their study has also found that while some parts of Sidoarjo are subsiding others are rising suggesting that the Watukosek fault system has been reactivated due to the eruption.



Co-author Professor Richard Davies, of Durham University’s Centre for Research into Earth Energy Systems (CeREES), said: “In the two years since she first erupted Lusi has continued to grow. Our research is fundamental if we are to understand the long-term effects of the mud volcano on the local and wider environment and population.



“Sidoarjo is a populated region and is collapsing as a result of the birth and growth of Lusi. This could continue to have a significant environmental impact on the surrounding area for years to come.



“If we establish how long the volcano will continue to erupt for then the subsidence data will allow us to assess the area that will ultimately be affected by this disaster. This could have implications for future plans aimed at minimising the volcano’s overall impact.”

Funding to study earthquake region


A major research consortium has just started to investigate the causes of devastating earthquakes in south-east Asia.



The research team, led by the National Oceanography Centre, Southampton (NOCS), are surveying the region struck by the 2004 and 2005 Sumatran earthquakes and tsunami to determine how the structure of major faults affects the size of large earthquakes.



The team has been awarded more than £2m by the Natural Environment Research Council (NERC) to carry out the research, which will combine data recorded during the earthquakes with new observations of the seafloor and sub-seafloor plate boundary zone.



The project will provide critical information about what happened during the Sumatran earthquakes, and whether similar events might have happened in the past. This will have important implications for understanding the risk from future earthquakes both in Sumatra and elsewhere.


All plate boundaries are divided into segments – sections of fault that are distinct and behave differently from one another. Barriers between these segments often limit how far a particular earthquake ruptures. But it is not known what determines whether an earthquake ruptures only a single segment, staying relatively small, or jumps across the barriers between segments to become a major event.



“The Sumatran earthquakes provide a unique framework to tackle this problem”, explains Dr Tim Henstock, a NOCS geophysicist at the University of Southampton and Principal Investigator for the project. “The southern boundary of the major 2004 earthquake – the southernmost point at which the fault slipped – stopped the rupture, and therefore limited the earthquake magnitude, but we don’t yet know why this boundary is there, nor how it controls the earthquake rupture process.”



The project aims to understand this behaviour, and was designed to combine observations of the earthquakes with measurements of the faults beneath the seafloor, linking the dynamics of the rupture to the static structure of the plate boundary. The study will collect many different geophysical and geological datasets around the earthquake rupture barriers exploring different properties at many different scales. The data will improve understanding of the shape of the two tectonic plates and the properties of the sediments and fluids within them, all of which influence how an earthquake propagates along a fault.



A complementary experiment on land installed instruments on Sumatra and the islands overlying the plate boundary zone in April 2008. They will record waves from earthquakes all over the world to image deep into the subduction system and will show which faults are currently most active.



The 130-day shipboard programme started this week, using the German R/V Sonne. Dr Mike Webb from NERC said, “This is the largest exchange of marine facilities that we have ever undertaken. As well as providing an excellent platform for this important study, we hope the project will demonstrate the expanding cooperation between European research fleets. Because the Sonne is already working in the area, this exchange is logical and more efficient.”

Earthquake predictions prove accurate for researchers





The area around Indonesia is geologically unstable most of the time
This images shows the earthquakes in the Indonesia area during the last 7 days – Image Credit: USGS

Two large earthquakes have occurred in quick succession in Sumatra, Western Indonesia, only months after University of Queensland researchers publicly identified the area as a high-risk zone for seismic activity.



The quakes, which were measured at 7.5 and 7.0 on the Richter scale and caused significant damage and at least three deaths between them, occurred on February 20 and 25 respectively, precisely in the regions pinpointed by researchers.



The successful forecast is just the latest in a string of accurate predictions made by researchers at the University’s Earth Systems Science Computational Centre (ESSCC), using their pioneering advanced computer simulation software.



In December last year, centre scientist Dr Huilin Xing presented the accompanying research at the 40thannual meeting of the American Geophysical Union, to much international interest.



“We have been focusing on the computational mode and development for simulating earth crustal dynamics on supercomputers [for some time now],” Dr Xing said.



“The successful predictions so far have demonstrated the capability of our software, which has already drawn the attention of earthquake scientists from around the world… and some from China and the USA have already applied or will apply it to study earthquake behaviour of their own regions.”



Building on this breakthrough work, Dr Xing and team member Dr Can Yin are continuing to apply the modelling software to the southern Indonesian region that has become notorious since the 2004 Boxing Day tsunami.


With the Eurasian and Indian/Australian tectonic plates converging just off the coast, Sumatran waters will likely be the site of seismic activity for some time to come.



“The question is how big and where it will happen in the near future, and whether it will induce a deadly tsunami,” Dr Xing said.



In the meantime, ESSCC researchers will continue to perfect simulation software and the prediction process, hoping to contribute to significant improvements in this important area.



“As we gain more experience in model construction and parameter selection, as well as more experience and confidence in the process, we will no doubt work towards a more accurate and reliable earthquake forecasting platform and filling more wide applications,” he said.



This will include the application of the crustal dynamics software in supercomputer simulation of hot fractured geothermal reservoir systems in the field of alternative energy; and with ongoing funding, exploration of other applications in regards to modelling the deep geological disposal of nuclear waste and carbon dioxide.



Dr Xing said these endeavours owed much to the ongoing support of the Department of Education, Science and Training, the Australian Research Council, and industry collaborators such as Geodynamics Ltd.



The ESSCC conducts research on the mechanics and physics of solid Earth processes on all scales using supercomputer simulation and by applying the methodologies of geophysical fluid and solid mechanics.