Nicaragua

IN SEARCH OF THE SCIENTISTS

MASAYA NATIONAL PARK NICARAGUA

Muriel Rogers

In Search of the Scientists

I stand surrounded by stillness, the night air cool against my cheek. In the distance an owl quietly calls as it hunts on stealthy wings. Overhead, stars softly glow. A new red star appears and silently moves across the sky accompanied by a fine luminescent line, the only sign of its passing. My thoughts go out to my fellow travellers and I wonder where they are bound. The moon, with half her face shyly hidden, paints the dark black sinuous ripples below with a border of gold. The stillness is torn by the stuttering, faltering outboard motor that suddenly bursts into life with a roar before settling into a steady hum. The river slips slowly past the reeds on the river bank. As the boat gently nudges the jetty, two mallards, just vague shapes in the darkness, chuckle a welcome and then the boat settles back into slumber. One step onto the shingle and my journey has begun.

Twenty one hours and two flights later, I stand bemused as my senses are assaulted by a battery of sounds, smells and colours and my body weeps in response to the gentle caress of the turbid night air. I am quickly removed from the bustling crowds by a quiet, gentle man who, having helped me in to his taxi whisks me away from the noisy city on a strangely reminiscent journey. At one and the same time I feel at home but also a stranger, the smells and sounds transporting me back four years to the time when my home was in the South Pacific. My destination is unknown other than it is somewhere beneath Masaya volcano. My assignment, and the reason for my journeying to Nicaragua, is to go in search of an elusive group of scientists known to be at large somewhere in the Masaya National Park.

At the entrance to the Park I am met by a uniformed guard, radio firmly clasped in one hand, machete in the other. He is to become my permanent companion whilst on my quest. The trail takes us up through rough grassland, over ancient lava flows into the forest that surrounds Masaya volcano. We are accompanied for part of the way by a blue magpie jay, shouting his displeasure as he hops from tree to tree.

I am fascinated and distracted by the large variety of seeding heads that surround me, from the beautiful hanging pods of cotton wool coated seeds of the pora pora tree to the suggestively shaped ‘donkey’s eggs’ (Sterculia apetala) which open to show scarlet seeds laid neatly in rows. It is now the dry season and so most seeds are in their dormant phase and are waiting for the rains to arrive. I pass an acacia tree which has grown thorns that look like pairs of bull’s horns. Each thorn has a small hole in it, exactly the right size for an ant to crawl inside. The plant has provided a home for the ants. The ants, in turn, protect the tree from all comers, myself included as is clearly demonstrated when I tap the branch lightly, alerting the ants, which come swarming out.

I stop to admire the passiflora vine which has devised a very clever way of protecting itself against larva damage. It is the favourite food plant of the Heliconius butterfly and so has developed yellow pseudo butterfly eggs on its leaf surface. The raised yellow spots make the visiting butterfly believe that the leaf is already full of eggs and so it passes on, the leaf successfully avoiding being eaten by the caterpillars.

An alien presence catches my eye. There is duct tape wrapped around a horizontal branch of a frangipani (Plumeria alba) tree. On closer inspection, I discover the presence of a small, clear plastic dish hanging suspended from the tape. This is clear evidence of the active presence of a Geochemist in the park. I hope that by following the trail of sulphate plates, I might eventually track down this rare scientist.

As I travel ever closer to the volcano, movement high above causes me to stop. Vultures. Vultures slowly circling in the hot thermals caused by Masaya as she quietly foams and degases. As I watch them effortlessly soaring through the intense heat of the afternoon, I see a group of four veer away from the rest. I follow their progress across the caldera wondering what it is that has caught their attention. Maybe they have smelled some future meal, or noticed the dying struggles of some poor creature. No, they have spotted a small group of Ecologists slowly and tiredly working their way up the steep track. The vultures silently circle above them, ever watchful. Whenever the ecologists stop to catch their failing breath and to suck at the life giving tubes protruding from the packs which they carry on their backs, the vultures swoop down for a closer look, hopes quickly aroused. A sudden rapid, movement startles them. Arms flapping wildly, strangely extended by the presence of a dark coloured net, an Ecologist flails around for a short while and then settles down again, dejected, net held limply at his side.

My attention is once again diverted by the vultures as they suddenly fly off toward the crater. What has captured their interest this time? Two scientists have wandered away from the herd and are scrambling down a steep slope always keeping a few metres apart. One false step, one small slip, could be fatal, or from the vultures point of view, fortuitous. They hope it is the lead scientist. The second one appears to be covered in strange appliances and so would be very difficult to strip. The vultures have helped us discover the Magneticians.

We have now reached Santiago crater.

A large plume of gas is billowing high above a massive gaping hole. The wind blows the toxic fumes first one way and then another. Some cloud remnants blow over in our direction and the gas catches the back of our throat, making it difficult to breath. We move away, coughing to try to ease the discomfort. Standing well clear of the cloud, we peer over the edge. At first it is impossible to see the vent way down at the crater bottom because of the pulsating cloud but the wind shifts again and we get a quick glimpse of the circular hole sinking deep into the volcano before it vanishes beneath more gas.

Just to our left we notice a group of three scientists crouched silently in a circle. We approach, closer not wanting to disturb them. They are looking intensely at a plastic box with dials and knobs on it that is standing on a round metal plate. We are very fortunate to have happened upon a gaggle of Gravity Gurus. We carefully back away and leave them in peace.

We move around the crater and eventually reach the plateau area. Here we have an incredible view of Santiago crater but are in constant danger from crumbling edges and asphyxiating gas. The ground is cracked and cleaved. As we move slowly around we notice a concrete ledge, low and rectangular, obviously the work of man. The small concrete wall is supporting an extensively eroded metal lid, about two and a half metres square, and looking completely incongruous, sitting in the middle of a vast moonscape of dust and boulders. Three scientists appear from beyond the boulders. They approach the bunker, for that is what it is, and with some difficulty, remove the lid. We have discovered the Gravity Gurus’ headquarters. After much activity, back packs are loaded with the bunker contents and shouldered, plastic boxes with dials and knobs are carried gingerly by hand, the large lid connecting the two male scientists as they struggle to ascend a steep scree slope, slipping and sliding as they go. As the wind catches the lid, I am reminded of an ant attempting to carry a leaf twice its size. At the top of the slope they stop to catch their breath which has been taken away from them by exertion, wind and gas, making temporary use of the gas masks that have been dangling around their necks. Once again, they hoist up the lid and we watch as they disappear beyond the rocks.

Santiago crater is not the highest point of the park so we continue to climb, determined to reach the top. The slopes are now covered in a coarse brown grass. But what is that? It looks like a length of fine wire laid directly up the slope of the hill. Is this more evidence of the Ecologists? It looks like a trip wire. Is it to catch the fauna of the area? It would be no good for the local Nicaraguan deer, the venado cola blanca (Odocoileus virginianus) or for the coyote. Maybe it is for the coatis or armadillos. We follow the wire as it snakes up the hill. Wait! Over there! A scientist, very dirty and disheveled, trousers stuck together with duct tape, is holding a reel of wire. He is rolling the wire back onto the reel. We have tracked down a Self Potentialist.

 I have achieved my goal; I have found all the scientists. Having reached the top of the hill, we stand looking across Masaya crater, a very different crater from Santiago; smaller, quieter and clothed in green. We have still not yet reached the highest point. A cinder track, winding its way around the crater, soon gives way to a dirt path which continues up through coarse brown grass. Small black objects slowly floating in the sky above the crater begin to congregate at a small copse of trees on the hilltop. We have finally reached the highest point; we have arrived at the vultures’ eerie. Large black shapes sit slumped amidst the branches, stretching their wings as we approach, uncertain as to whether to stay or to flee.

 A few decide to leave and soar casually off the edge of the cliff, floating over a large expanse of forest which encloses a pale blue lake, Lake Masaya, a second volcano silhouetted in the distance.

All is silent save for the noise of the wind as it rushes over the edge of the cliff having ruffled its way through the trees. The sound of a falling rock draws my attention to the far side of the trees. Half hidden, I encounter yet another small group of scientists. They are all gazing at a small white box suspended from a female’s neck by a strap. The box is being moved around slowly and is emitting a strange monotonous tone. This has to be a fraternity of Very Low Freaks. My quest is now truly complete, I have reached the top of the park and I have found the last of the scientists.

You may be wondering, and rightly so, why the scientists are here, climbing all over the volcano in the punishing heat. They are all part of an Earthwatch team led by Dr Hazel Rymer, Dr Glyn Williams-Jones and Dr Michael Gillman. The objectives of their project are to identify the physical and chemical signatures associated with persistent volcanic activity and to monitor any changes through time. They are attempting to understand the ecological response to the persistent degassing and any role the niche ecosystems may have in regulating volcanic pollution levels. Their aim is to present a holistic overview of the cause and effect of the persistent activity through integrating the geophysical, geochemical and environmental disciplines. Once this has been achieved, low-cost, low-technology mitigation can be put into place to improve the health and agro-economic prospects of the local population which are being seriously impacted by the gas emissions.

Volcanologists are only able to actually see structures and effects at the surface, but need to have a comprehensive picture of what is going on underneath the surface. The only way of addressing this is to take a variety of different measurements at the surface and then by combining this information, construct a model of what may be happening at depth. This model is developed using data collected across the park using the different scientific disciplines.

The Gravity Gurus use gravity meters to record the acceleration due to gravity at a number of points around the volcano park.

Gravity decreases with height above sea level and so this has to be accounted for when processing the data. After the effects of height have been removed, the value of gravity, measured in mGals (after Galileo Galilei, the 17^th Century Italian astronomer who worked on gravity), depends on the sub-surface mass. Readings in the negative indicate less mass than was expected, whereas positive readings indicate a higher mass. At Masaya, the readings are used to find the level of the magma within the feeder pipe and the amount of frothing, or foaming within the magma. If the gravity readings decrease, then either the magma level has fallen or there is a buildup of foam which will indicate the possibility of higher degassing rates or even the possibility of an explosive eruption. The drawback with using gravity to identify sub-surface mass movements is that any given reading could be caused by a large, deep mass change, or a small, shallow mass change. Help is needed from other disciplines to identify which it might be.

Very low frequency radio waves are used by the military around the world and so the signals are there to tap into. Bodies, like volcanoes, attenuate, or slow down, these waves and so the job of the Very Low Freaks is to discover where, and by how much, the waves are slowed down. To do this they pinpoint two signals at right angles to each other  and then by taking a vertical reading at that point, they can register how much the wave has been deflected and in which direction. This will highlight sub surface structures that are present. A higher reading could be indicative of a dyke or a fault but another discipline will be needed to identify which. Very low frequencies complement the findings of the Gravity Gurus. A third partner in this team would be the Self Potentialists.

Self potential is the measuring of the earth’s conductivity. It is an electrical method which measures the natural electrical current in the ground. This is achieved by setting electrodes into the ground at regular intervals and measuring the voltage between them. From this the shallow sub-surface structure of that particular area can be gauged leading to the identification of faults and hydro thermal presence and levels. Combining gravity readings and self potential has led researchers to model the structure beneath the active crater area in terms of variations in the level of foaming magma, which extends well beyond the crater vent, and fluctuating water table levels, along shallow faults.

Another natural property of the earth that can be harnessed is the magnetic field locked into volcanic rocks as they cool after eruption. When a strong magnetic field is induced in a fluid containing protons, the protons align with the new field. When the field is removed, the protons precess about the remaining, natural fields. The rate of precession is a measure of the earth’s total magnetic field. A contour map of magnetic field strength can be created following comprehensive collection of readings taken following a grid pattern. Positive and negative anomalies provide further information on areas of chemical alteration to add to the information from the other disciplines. Magnetic fields can also provide information on the temperature of the rocks. As this increases, so the amount of magnetic field in the rock decreases. Once rock is heated above the Currie point (up to about 400C) the rock ceases to be magnetic. Making a magnetic map can indicate areas where the rock has lost all of its magnetic signature which could indicate extensive heating, possibly due to the presence of a large, hot magmatic body.

This project is particularly distinctive because of the inclusion of an ecology team. The ecologists work is twofold. They, also, will add to the map of the park but in addition will investigate bioindicators and attempt to identify appropriate sustainable ecosystems for the changing volcanic environments. A large part of the work undertaken by the ecologists was to survey particular areas of the forest to provide ground truthing to support satellite imaging. By taking a particular type of canopy cover from the satellite image and then using GPS to pinpoint the position exactly, surveys of the ground conditions under that canopy type are taken. Through repeated sampling, generalizations can be made about the typical vegetation likely to be found in any particular area when referring to the satellite data. Various measures can be taken when ground truthing and these include sampling the canopy and herbaceous layers, with the height and density of vascular plants recorded. In Masaya Park, samples were taken progressively across the area known to be affected by the gas, beginning in the area where little or no effects were observed and slowly working towards, and across, the kill zone; the area most affected by the gas.

The use of sulphate plates adds to the ground truthing by providing information on dry deposition from the gas presence. The plates contain lead oxide. As the gas flows over the plate, the gas reacts with the lead oxide forming sulfur oxide. This can then be assessed in the lab to give an indication of the amount of gas flowing through each area.

A record of the butterflies observed is being compiled. Butterflies are very useful bioindicators as they are often host-specific in their choice of where they lay their eggs and therefore where the larvae feed. The larval food plants may be affected both by air pollution and by soil conditions and therefore species counts and population densities allow the suitability of habitats to be described. Further work is being carried out on the presence of heavy metals in the plants. A small number of indicative plants will be identified and samples of these plants will be collected from the various zones identified by the ground truthing. These plants can then be tested for heavy metal levels. In time, this work could help to inform local residents about the areas which are potentially harmful for growing crops or for the grazing of livestock. Further work is being done on one plant, which is known to respond through colour changes in the stamen hairs in its flowers when exposed to certain airborne gases. There is a suggestion that if a simple technique for monitoring these changes could be established, these plants could be grown in the area and used as a measure of air pollution.

The work of the scientists at Masaya will have implications for the much wider international community. Ecological impact identified at Masaya can be translated to other areas of persistent volcanism through the developing and calibration of new bioindicators. An enhanced understanding of the effects of variations in anthropogenic and volcanic emissions on acid rain, soil and ground water, and hence on human health, can provide a scientific base for shifts in agricultural practices.  Increased volcanic activity can be predicted geophysically or monitored through using bioindicators and so hazard mitigation efforts can then be put in place.

I have been very privileged to be just a small part of this amazing work. Masaya National Park is a beautiful paradise, supporting a wonderful diversity of life but there is a massive serpent within it. With increased knowledge and understanding, this serpent can be lived with relatively safely and can be treasured for its own beauty and gift that it brings to our planet. All that remains for me now is to tear myself away from this truly fascinating place, to take my leave of a very dedicated and talented group of people, who are now my friends, and to return to the cool, quiet, stillness of the riverside bungalow in Norfolk that I left just a few days ago. As I once again step into the small boat that will return me to my starting point I look forward to being able to ponder, to wonder and to write.