Nuclear monitoring body urges scientists to use its data

By Tania Rabesandratana

The international body that monitors nuclear explosions is trying to encourage more scientists from developing countries to make use of data derived from its US$1 billion nuclear explosion detection system.

The Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), based in Vienna, Austria, relies on hundreds of seismic, hydroacoustic and radionuclide stations around the world to uncover evidence of possible nuclear tests.

At a conference in Vienna this week (22-26 June), the CTBTO will seek to show how data from this International Monitoring System (IMS) could support other areas of science, with applications ranging from meteorological modelling and tsunami warnings to studying the migration of whales.

Advertising this scientific value can help draw in governments who have limited interest in detecting nuclear tests, according to the head of the CTBTO.

“We are trying to attract more adherence among countries in the developing world,” Lassina Zerbo, the organisation’s executive secretary, told SciDev.Net ahead of the conference. “Nuclear testing monitoring is not their priority, so we have to see what the spin-offs are of the technology that we use.”

Under the treaty, which bans all nuclear explosions on Earth, each signatory state has the right to access all the data made available to the CTBTO’s International Data Centre in Vienna.

“We have to put this enormous amount of data at the service of the population, to study climate change, the Earth, the atmosphere.”

Gérard Rambolamanana, Institute and Observatory of Geophysics of Antananarivo 

Thirteen nations have not signed the treaty, including India, North Korea and Pakistan. India is reluctant to sign the treaty until neighbouring Pakistan does so, and vice versa. In February, Zerbo wrote a column in Indian newspaper The Hindu, urging Indian institutions to begin science cooperation with the CTBTO.

“Science should support diplomacy,” he wrote. “This could eventually lead to India participating in the international exchange of data from the monitoring stations and would be an important first step to establishing familiarity and trust.”

The IMS constantly monitors unusual events underground, underwater and in the air. Its data sets span two decades, allowing researchers to study long-term phenomena.

“We have to put this enormous amount of data at the service of the population, to study climate change, the Earth, the atmosphere,” says Gérard Rambolamanana, who runs the seismology and infrasound lab at the Institute and Observatory of Geophysics of Antananarivo, Madagascar.

The CTBTO hopes the Vienna conference will encourage more researchers from non-signatory countries to seek partners that would allow them to access some of its data.

At the time of writing, nine representatives from India and 12 from Pakistan had registered to attend, out of about 1,000 participants. “We hope that they will carry the word back home” about the system’s value, a CTBTO spokesperson says.

Out of a budget of about US$130 million, the organisation spends about US$3 million a year on capacity building, outreach and training. Madagascar, for example, has hosted two IMS stations since 2001: one infrasound and one seismic facility.

This has created training opportunities and helped build closer links between researchers nationally and internationally, says Rambolamanana. As a result, local science and technology have made a “big jump” forward, he says.

This article was originally published on SciDev.Net. Read the original article.

Elephant poaching pinpointed with DNA

By Lyndal Rowlands

Scientists have extracted elephant DNA from illegal ivory shipments to identify poaching hotspots in Central and East Africa, according to a study published last week.

In a paper published in Science on 18 June, a team of researchers led by biologist Samuel Wasser from the University of Washington, United States, matched the DNA from tusks to different populations of forest and savannah elephants to trace ivory seized from international poaching gangs back to its source.

They found that the majority of the 28 major tusk seizures made between 2006 and 2014 came from two areas: a nature reserve encompassing northeast Gabon, northwest Congo and southeast Cameroon, and a savannah region on the border of Tanzania and Mozambique.

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“These are seizures that weigh a minimum of a half tonne and are worth upwards of a million dollars or more,” Wasser tells SciDev.Net. “We really wanted to find out where the large transnational organised crime syndicates were operating.”

Although it was known that much illegal ivory came from these countries, Wasser says he was surprised that elephant poaching is heavily concentrated in just two places: the Dja-Odzala-Mikébe protected zone in Central Africa and the Selous and Nyasa game reserves in East Africa.

“Virtually 100 per cent of the seizures came from those two areas,” Wasser says.

“We really wanted to find out where the large transnational organised crime syndicates were operating.”

Samuel Wasser, University of Washington

Elephant poaching poses a serious threat to the species, with an estimated 50,000 African elephants killed each year from a population of fewer than 500,000 animals.

To tackle elephant poaching, the study suggests that support should be targeted at park rangers in the hotspots, who are the main defence against poachers. But this is difficult as the countries where poaching is rife are among the poorest in the world, and many suffer from ongoing conflict.

“The rangers are critical. They need the support of their governments to really do the right thing,” Wasser says. “Unfortunately, lots of the time they need the support of the outside world, too.”

Raabia Hawa, the director of Ulinzi Africa Foundation’s Walk with Rangers programme, which aims to highlight the difficulties rangers face, says it has traditionally been difficult to pinpoint where poached elephants are originally from, because they roam widely.

“From my knowledge, elephants have no borders,” Hawa says. She adds that this is why it is important to tackle elephant poaching at an interregional level and not just to see it as a national issue.“It’s great to invest in a science-based approach,” Hawa says, but she adds that communities as well as park rangers should be involved in anti-poaching efforts, to ensure they support law enforcement efforts in and around local parks.

This article was originally published on SciDev.Net. Read the original article.

Morocco Host 2012 International Training on Seismology

The GFZ continues its efforts to advance knowledge to other organizations and institutions by conducting this year’s training course on Seismology and Seismic Hazard Assessment in Rabat, Morocco. The course attracted 26 participants from Algeria, Morocco, Malawi, Zimbabwe, South Africa, Yemen, Egypt, Tunisia, Kenya, Burundi, Rwanda and Tanzania. The course is part of the educational and training program of the UNESCO in the field of geosciences and disaster mitigation which is part of German contribution of the United Nations International Decade for Natural Disaster Reduction (IDNDR 1990-1999) and of respective follow-up programs such as the International Strategy for Disaster Reduction ISDR. Such courses are aimed at providing both theoretical fundamentals and practical training in applied seismology for geoscientists and technicians in developing countries.

Read more: http://geoscientist.webnode.com

Earthquake Seismometer Equations Calculator - Moment Magnitude Conversion

Earthquake Seismometer Equations Calculator - Moment Magnitude Conversion

Earthquake Seismometer Equations and Formulas Calculator

Earth Science Geology Geophysics Seismology

Seismometer

Seismometers are instruments that measure motions of the ground, including those of seismic waves generated by earthquakes, volcanic eruptions, and other seismic sources. Records of seismic waves allow seismologists to map the interior of the Earth, and locate and measure the size of these different sources.

The word derives from the Greek σεισμός, seismós, a shaking or quake, from the verb σείω, seíō, to shake; and μέτρον, métron, measure.

Seismograph is another Greek term from seismós and γράφω, gráphō, to draw. It is often used to mean seismometer, though it is more applicable to the older instruments in which the measuring and recording of ground motion were combined than to modern systems, in which these functions are separated.

Both types provide a continuous record of ground motion; this distinguishes them from seismoscopes, which merely indicate that motion has occurred, perhaps with some simple measure of how large it was.

Basic Principle

Inertial seismometers have levers in them that keep rhythmic motion

• A weight, usually called the internal mass, that can move relative to the instrument frame, but is attached to it by a system (such as a spring) that will hold it fixed relative to the frame if there is no motion, and also damp out any motions once the motion of the frame stops.
• A means of recording the motion of the mass relative to the frame, or the force needed to keep it from moving.

Any motion of the ground moves the frame. The mass tends not to move because of its inertia, and by measuring the motion between the frame and the mass, the motion of the ground can be determined, even though the mass does move.

Early seismometers used optical levers or mechanical linkages to amplify the small motions involved, recording on soot-covered paper or photographic paper.

Modern instruments use electronics. In some systems, the mass is held nearly motionless relative to the frame by an electronic negative feedback loop. The motion of the mass relative to the frame is measured, and the feedback loop applies a magnetic or electrostatic force to keep the mass nearly motionless. The voltage needed to produce this force is the output of the seismometer, which is recorded digitally. In other systems the weight is allowed to move, and its motion produces a voltage in a coil attached to the mass and moving through the magnetic field of a magnet attached to the frame. This design is often used in the geophones used in seismic surveys for oil and gas.

Professional seismic observatories usually have instruments measuring three axes: north-south, east-west, and the vertical. If only one axis can be measured, this is usually the vertical because it is less noisy and gives better records of some seismic waves.

The foundation of a seismic station is critical. A professional station is sometimes mounted on bedrock. The best mountings may be in deep boreholes, which avoid thermal effects, ground noise and tilting from weather and tides. Other instruments are often mounted in insulated enclosures on small buried piers of unreinforced concrete. Reinforcing rods and aggregates would distort the pier as the temperature changes. A site is always surveyed for ground noise with a temporary installation before pouring the pier and laying conduit.

Zhang Heng's seismoscope

In AD 132, Zhang Heng of China's Han dynasty invented the first seismoscope (by the definition above), which was called Houfeng Didong Yi(literally, "instrument for measuring the seasonal winds and the movements of the Earth"). The description we have, from the History of the Later Han Dynasty, says that it was a large bronze vessel, about 2 meters in diameter; at eight points around the top were dragon's heads holding bronze balls. When there was an earthquake, one of the mouths would open and drop its ball into a bronze toad at the base, making a sound and supposedly showing the direction of the earthquake. On at least one occasion, probably at the time of a large earthquake in Gansuin AD 143, the seismoscope indicated an earthquake even though one was not felt. The available text says that inside the vessel was a central column that could move along eight tracks; this is thought to refer to a pendulum, though it is not known exactly how this was linked to a mechanism that would open only one dragon's mouth. The first ever earthquake recorded by this seismograph was supposedly somewhere in the east. Days later, a rider from the east reported this earthquake.

Modern Instruments

Modern instruments use electronic sensors, amplifiers, and recording devices. Most are broadband covering a wide range of frequencies. Some seismometers can measure motions with frequencies from 500 Hz to 0.00118 Hz (1/500 = 0.002 seconds per cycle, to 1/0.00118 = 850 seconds per cycle). The mechanical suspension for horizontal instruments remains the garden-gate described above. Vertical instruments use some kind of constant-force suspension, such as the LaCoste suspension. The LaCoste suspension uses a zero-length spring to provide a long period (high sensitivity). Some modern instruments use a "triaxial" design, in which three identical motion sensors are set at the same angle to the vertical but 120 degrees apart on the horizontal. Vertical and horizontal motions can be computed from the outputs of the three sensors.

Seismometers unavoidably introduce some distortion into the signals they measure, but professionally-designed systems have carefully characterized frequency transforms.

Modern sensitivities come in three broad ranges: geophones, 50 to 750 V/m; local geologic seismographs, about 1,500 V/m; and teleseismographs, used for world survey, about 20,000 V/m. Instruments come in three main varieties: short period, long period and broadband. The short and long period measure velocity and are very sensitive, however they 'clip' the signal or go off-scale for ground motion that is strong enough to be felt by people. A 24-bit analog-to-digital conversion channel is commonplace. Practical devices are linear to roughly one part per million.

Delivered seismometers come with two styles of output: analog and digital. Analog seismographs require analog recording equipment, possibly including an analog-to-digital converter. The output of a digital seismographs can be simply input to a computer. They present the data in standard digital forms (often "SE2" over ethernet).

Strong-motion seismometers

Another type of seismometer is a digital strong-motion seismometer, or accelerograph. The data from such an instrument is essential to understand how an earthquake affects manmade structures.

A strong-motion seismometer measures acceleration. This can be mathematically integrated later to give velocity and position. Strong-motion seismometers are not as sensitive to ground motions as teleseismic instruments but they stay on scale during the strongest seismic shaking.

Modern recording

Today, the most common recorder is a computer with an analog-to-digital converter, a disk drive and an internet connection; for amateurs, a PC with a sound card and associated software is adequate. Most systems record continuously, but some record only when a signal is detected, as shown by a short-term increase in the variation of the signal, compared to its long-term average (which can vary slowly because of changes in seismic noise).

Sourced from: http://www.wikipedia.org

Paleoseismology

Paleoseismology looks at geologic sediments and rocks, for signs of ancient earthquakes. It is used to supplement seismic monitoring, for the calculation of seismic hazard. Paleoseismology is usually restricted to geologic regimes that have undergone continuous sediment creation for the last few thousand years, such as swamps, lakes, river beds and shorelines.

In this typical example, a trench is dug in an active sedimentation regime. Evidence of thrust faulting can be seen in the walls of the trench. It becomes a matter of deducting the relative age of each fault, by cross-cutting patterns. The faults can be dated in absolute terms, if there is dateable, or human artifacts.

Many notable discoveries have been made using the techniques of paleoseismology. For example, there is a common misconception that having many smaller earthquakes can somehow 'relieve' a major fault such as the San Andreas, and reduce the chance of a major earthquake. It is now known (using paleoseismology) that nearly all the movement of the fault takes place with extremely large earthquakes. All of these seismic events (with a Moment Magnitude of over 8), leave some sort of trace in the sedimentation record.

Another famous example involves the Megathrust earthquakes of the Pacific Northwest. It was thought for some time that there was low seismic hazard in region because relatively few modern earthquakes are being recorded. There was a concept that the subduction zone was merely sliding in a benign manner.

All of these comforting notions were shattered by paleoseismology studies showing evidence of extremely large earthquakes, along with historical tsunami records. In effect, the subduction zone under British Columbia, Washington, Oregon, and far northern California, is perfectly normal, being extremely hazardous in the long term, with the capability of generating coastal tsunamis of several hundred feet in height at the coast. These are caused by the interface between the subducted sea floor stressing the overlaying coastal soils in compression. Periodically a slip will occur which causes the coastal portion to reduce in elevation and thrust toward the west, leading to tsunamis in the central and eastern north Pacific ocean (with several hours of warning) and a reflux of water toward the coastal shore, with little time for residents to escape.

Retrieved from: http://www.wikipedia.org

Earthquakes: Moment magnitude scale

The moment magnitude scale (abbreviated as MMS; denoted as M_W) is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of the area that slipped. The scale was developed in the 1970s to succeed the 1930s-era Richter magnitude scale (M_L). Even though the formulae are different, the new scale retains the familiar continuum of magnitude values defined by the older one. The MMS is now the scale used to estimate magnitudes for all modern large earthquakes by the United States Geological Survey.

Definition

The symbol for the moment magnitude scale is M_w, with the subscript w meaning mechanical work accomplished. The moment magnitude M_w is a dimensionless number defined by

where M₀ is the magnitude of the seismic moment in dyne centimetres (10⁻⁷ Nm). The constant values in the equation are chosen to achieve consistency with the magnitude values produced by earlier scales, most importantly the Local Moment (or "Richter") scale.

As with the Richter scale, an increase of 1 step on this logarithmic scale corresponds to a 10^1.5 ≈ 32 times increase in the amount of energy released, and an increase of 2 steps corresponds to a 10³ = 1000 times increase in energy.

Sourced from: http://www.wikipedia.org

The Untold Experience of Thunduwike Earth Tremors in Mzimba- Malawi.

 

Thunduwike is located north of Mzimba border with Rumphi district. It is about 38Km drive from Rumphi Boma via Vwaza. It has been two years now since earth tremors started hitting Thunduwike and Kazuni areas in Mzimba north and Rumphi  South respectively.  The first of the series of tremor occurrences was felt end of January, 2008.   The trend seemed to have gone into a period of quiescence until June, 2008 when they resurfaced. This time, it was one event after the other, leaving people in total fear and hopelessness as houses  cracked at will. Sometimes, a total of fifteen events would be felt on a single day. This prompted local residents to sound an SOS through the District Commissioner’s office in Mzimba.

The Government later responded by dispatching a team of five scientists into the area to conduct investigations much to the relief of the residents. Surprisingly, all tremor occurrences were very local which means that only areas within Thunduwike and Kazuni were able to feel the shaking. Villages located outside a radius of 8Km from Thunduwike were not able to feel anything in terms of ground shaking. The affected villages are: Vwandamire, Butani Nyirenda, Thembani Mkandawire, Eneya Mjumira, Chiwara Mzumara, Kamangadazi, Machisamu Mkandawire, Mbulo Kabila, Diyere Mjumira, Kazuni and Vwaza. The most affected of the villages is Thembani Mkandawire. This made people come up with various assumptions which included:

• End of the world as indicated in the Bible
• Work of witchcraft resulting from disgruntled tobacco tenants who were not paid their dues after working in tobacco farms.
• Volcanic eruption etc.

But what did the teams of scientists from Geological Survey Department find out? Why the area was experiencing this? Was this connected to previous tremors in Mpherembe in 1993/1994 and 1998? These questions were what residents wanted to know. The report by the scientists attribute these occurrences to faulting. The reactivation of faults could be directly associated with tremors in the area thereby, making it  vulnerable to earthquakes or tremors since geological processes are continuing to take place. This can be evidenced by the trend of seismic activities from Mpherembe which means that faults being rejuvenated are now  towards the northern part. The area is also characterized by major and minor fault systems some of which, have just been rejuvenated.

The monitoring exercise lasted three months from August, 2008 during which, an average of four events were monitored each day and damage to residential houses, school blocks, churches and office buildings continued to be noticed and widening with each shaking that occurred. The hypocentral depth of all events monitored was 15Km.

The impact of ground shaking can not be underestimated as some rocks were breaking or displaced.

The majority of the buildings are of mdindo type, while a few are built from un-burnt or burnt bricks, grass-thatched and iron-roofed. Most of the buildings were built without professional expertise, a thing which is common in rural areas.  Considering the poor construction materials used and the superficial deposits of the area, most of the buildings are vulnerable to ground shaking as evidenced by the numerous affected houses or buildings.

Are tremors still being felt in the area up to now? According to contacts in the area, occassionally there are some occurrences of up to two per week. Sometimes the number increases so too the fear that keeps on gripping the minds of people of Thunduwike and Kazuni. “For how long shall this go on?” Asked one villager. Everyone hopes that their prayers will be answered and tremors completely stop. But a thorough research is needed to reach a conclusive decision regarding the area.

Mitigation

Villagers were advised not to use any heavily cracked houses or buildings as these could be death traps. They should always stay vigilant and not panic when running out of their houses. In addition to this, they should report to Geological Survey Department any strange occurrences regarding the tremors.

Malawi: Karonga Earthquakes

December 6, 2009 will be a difficult day to forget for the people of Karonga in the northern region of Malawi. Little did they know that what seemed like a simple earthquake at 19:35hrs local time was indeed the beginning of a series of events that left them terribly shaken, helpless, hopeless and some homeless. Some buildings suffered total failure as a result of ground shaking. The extent of damage was high and will cost a lot of Millions of Malawi Kwacha during the reconstruction process.

According to reports sourced from the District Commissioner’s office, 145,436 people out of the total population of 270,960 in the district were affected which represents 53.7%. 5,783 households were assessed, 1557 houses collapsed, 4,226 houses developed cracks. The death toll was at 4, 186 injuries and 17 school blocks affected among other things.

Temporary structures were erected as a mitigation measure. Due to the overwhelming demand for assistance from the District Commissioner’s office, the majority of the victims were left disappointed due to inadequate supplies of aid facilities. Scientific evidence attributes the occurrence of these earthquakes to Malawi’s location in the East Africa Rift System which is an active region for such earthquakes. There have been several earthquakes taking place in the country a major one being the March 10, 1989 in Salima which measured 6.1(Ms) on the Richter scale. Scientists claim that Karonga is heavily faulted and such scenario is not uncommon in such areas. A technical team from Department of Geological Survey  which is still monitoring the events in Karonga says that the earthquake sequence is a natural phenomenon associated with active faulting on the western flank of the Eastern Africa Rift System. By third week, a total of thirty two events of magnitudes between 4.0 and 6.2 had been recorded alongside 59 smaller events of magnitudes less than 4.0 on the Richter scale.

The December 20, 2009, earthquake was the major event that took place in the area since earthquakes started on December 6, 2009.  From then on, there has several aftershocks being felt in the area and continue to do so up to now. Information provided by Geological Survey indicates that the aftershocks are small in magnitude except for the February 20, 2010 event which measured 4.2 on the Richter scale. They say that these aftershocks play a major role in identification of faults which are currently active.

In response to this, an additional team of ten Geologists, Seismologist, Technician and Analysts visited the area for Geo-mapping with funding from Department of Disaster Management. A report compiled thereafter by the Department of Geological Survey will be made available to all concerned stakeholders to chart a way forward on whether or not people in the heavily affected areas should be relocated to other areas.

Asked why events continue to take place almost four months on, the field team explained that the area experienced heavy shaking from December 6 because many of the events were almost close to the main shock in magnitude. As a result, several blocks were left hanging which means that they have to settle to reach an equilibrium and will eventually subside. ”It’s good that these events are happening at this rate because energy is being released that would have accumulated into one event and that would have been a disaster”, commented one of the team members who opted for anonymity.

But what should the people of Karonga expect out of this? This is a question that begs for answers. According to Geological Survey Department through its Director Dr. Leonard Kalindekafe, this is the right time for Malawi to have a National Building Code. The draft Building Code has been gathering dust in the shelves since 1992. This appeal was also echoed by a team of Seismologists from Lamont Doherty Earth Observatory of Columbia University which installed five Seismic stations for monitoring the aftershocks in Karonga from January 5, 2010. The equipment will be here for a period of three or four months. An appeal for assistance was also made for Malawi to acquire at least ten Seismic Stations to be distributed across the country. Currently, there are only two stations working a thing which is not healthy for earthquake monitoring in a country that sits entirely in the seismically active East Africa Rift System.

All teams from Department of Geological Survey, Lamont Doherty Earth Observatory of Columbia University and United States Geological Survey Earthquake Disaster Assistance Team put off fears that Kayerekera Uranium Mining was the cause of these events. There was no evidence to support such claims because the epicenters were located far away from Kayerekera.

Slowly, life in Karonga is becoming normal again though under the glaring invitation of reconstruction. Some have already started reconstruction. What worries a few of us is that in the absence of National Building Code, should we trust on our own beliefs that these events are gone?