European Stars and Stripes (Newspaper) - April 19, 1994, Darmstadt, Hesse                                Trying to prepare for the next big quake by Jane  a science writer of Long after the ground stopped heaving from the Jan. 17 Northridge earthquake scientists spotted cracks in the ground in los Angeles Potrero Canyon. Several weeks after the quake that killed 61 people a . Geological Survey team returned to the Canyon searching for clues to How nature rearranges the land. Along the floor of the Canyon scientists set Down a 2,200-foot line of motion sensors. A cobweb of cables connected 48 clusters of the Orange discs. Six feet underground a series of one Pound explosive charges were detonated sending seismic Waves billowing through the Earth. As the geologists set off the explosions sending puffs of dust rising into the air the sensor discs relayed reflections of those Waves to a computer equipped trailer. There scientists mapped soil and Rock formations More than half a mile below the gullies and scrubby Brown Hills dotted with grazing cows. The scientists Hope to learn More about the relationship among earthquakes underground geological formations types of soil arid damage at the surface. The magnitude 6.7 quake in the san Fernando Valley gave them their Chance. Never have we had an earthquake in modern times so Well recorded by Strong motion stations said Al Lindh seismology Branch chief of the uses at Menlo Park it s a first Ever Opportunity to fill in one of the missing links in the Puzzle the relation Between motion of the ground and what Falls  the data compiled crunched and Analysed by scores of seismologists geologists and geophysicists will change the Way people in quake prone areas build freeways offices and Homes. In Castaic 40 Miles Northwest of downtown los Angeles geologists wonder if the quake cracked the Earth or if unmapped faults deep beneath the Canyon floor Are responsible. The question is even More intriguing because the fault that shifted to cause the Northridge quake lies right below the Canyon. Near Castaic on the North Side of the Santa Susana mountains geologists have dug trenches around cracks in the Earth trying to diagram layers of Rock and reconstruct geological history. Six feet into one Trench a layer of 1 million year old Bedrock juts up the result of an earlier fault shift. Scientists say they re trying to use the past pattern to learn something about the future. Looking at the Long term patterns puts the earthquake in proper context they said. The scientists also want to understand How different types of soils conduct seismic Waves. That will help disaster response officials determine where a major quake is Likely to shake the Earth hardest and help construct seism logically savvy buildings said uses geologist Dan Ponti who designed the Potrero study. From the fee search ers Are using the Jan. 17 earthquake in California to help design new buildings and to better understand what causes the Earth to move. Other studies in the Region May help explain Why some areas suffered More than others regardless of their proximity to the quake s epicentre. Scientists Are also surveying damage to buildings. The main Point is simply to try to sort out Why there was damage in a particular place because the buildings were weak or because the ground motions were amplified by the geology by the rocks said Jim Mori scientist in charge of the uses at Pasadena. Northridge will become the design earthquake for los Angeles said Thomas Henyey director of the Southern California earthquake Center at the University of Southern California. When we design structures we want to design them with the kinds of motions in mind that were produced by this particular  predicting volcanic eruptions by Kim i. Mills the associated press seismologists surprised by a Volcano while awaiting earthquakes in Iceland say their instrument readings might help predict within a half hour of when a Volcano is going to erupt. Although a half hour s notice would be no help in evacuating people it could be a real Benefit to aircraft said seismologist Alan t. Linde of the Carnegie institution in Washington. Jet engines and Ash Clouds Don t mix he said. If a Jet flies through an Ash Cloud it s very Likely to lose Power in All  he said the Money saved from one Jet engine overhaul would pay for a global Volcano monitoring program for Many years for  Linde based his claim on measurements he and several colleagues made after the 1991 eruption of the Hekla Volcano in Iceland. Linde and his colleagues used data gathered by instruments called subsurface Strain meters to calculate the depth size and pathways of the magma during the unexpected eruption. Strain meters Are cemented into subsurface Rock typically about 220 Yards underground. They Are capable of detecting minute changes in the Earth s crust. Linde and his colleagues had placed five Strain meters in boreholes around the mid Atlantic Ridge in Southern a 9fi6 photo shows Halley Comet speeding past Earth. Dec Iiah scientists aboard a plane gets a close look at a volcanic eruption in Iceland in 1983. Iceland in 1979 to study earthquake activity. We weren t trying to Monitor the Volcano Linde said noting that it had last erupted in 1970. The closest Strain meter was about 9 Miles from the Volcano. Others were situated from 23 Miles to 28 Miles away. The scientists used the instrument readings to calculate the Speed of upward magma migration. They found it took 30 minutes for the magma to Rise 2,5 Miles to the Earth s surface. We got an idea in Hekla of How fast the magma rises Linde claimed. That s going to be different in different places but i think you Nave at least that much time in most  Linde printed the findings last year. Susan Russell Robinson a spokeswoman at the . Geological Survey called Linde s results very exciting she said that while Many volcanoes give indications two to three weeks beforehand that they Are about to erupt it would help to pinpoint the event. Linde suggested that More Strain meters and other seismic monitoring instruments be placed at volcanoes around the world to help predict eruptions he suggested Between three and five such instruments be used at each Volcano. That gives some redundancy in your redundancy he said. Each Strain meter costs Between $25,000 and $30,000 including the borehole he said. In Iceland we had holes free of charge he said. They were quite old holes drilled by Farmers looking for hot  but Robinson said borehole Strain meters cannot be used at very Active volcanoes because you cannot get close enough to Drill the holes. The comets Are coming. By Kathy Sawyer the Washington Post earthlings 20 million years from now apparently will face greatly improved Odds that a Comet will smash into the planet and destroy civilization or whatever it has turned into by then. The Sun is entering period Rich in close encounters with other stars in its neighbourhood according to a report in the March Issue of the quarterly journal of the Royal astronomical society. The passage of the largest could Jar Loose As Many As 100,000 comets and Send them hurtling toward the inner solar system. Over the next 45,000 years at least six stars will pass less than 4.22 Light years from the Sun the distance today of proximal centaurs the Sun s nearest neighbor according to calculations by Robert Matthews a visiting fellow at the University of Aston in Birmingham England in the department of computer science. Most of those stars Are dwarfs Only about one tenth the mass of the Sun. But two those that make up the double Star Alpha centaurs a and b Are comparable in size to the Sun Matthews says and their gravitational Fields could have a significant effect As they sweep within 3.12 Light years of it at a velocity of about 75,000 Mph. The passage of the double Star the brightest object in the Southern Constellation centaurus should not disturb the orbits of the planets Matthews calculates. But it May already be jolting the vast warehouse of Comet nuclei known As the oort Cloud which is believed to surround the solar system and extend Halfway to proximal centaurs. Although some comets May have already changed course toward Earth s Vicinity he notes the distances Are so vast that they will not arrive for another 20 million years. The stars and stripes 17 16 the stars and stripes tuesday april 19,1994