Predicting Earthquakes
Do we get to see anomalies in our surroundings before an event of earthquake as a precursor? Is there anything like earthquake weather? Can we relate natural disaster like heavy rainfall and flood to earthquake?
Glowing of mysterious lights, changes in weather and changes in landforms, ground water levels and animal behavior, rise in temperature, noises from ground had been reported in relation to earthquakes.
All the above phenomena are long being linked to the earthquake events. But less had been known about its scientific explanation. Some of the above phenomena are said to be observed prior to quake and some during quake. All such notices are being speculated as a forerunner for earthquake prediction in peoples mind.
Prediction of earthquakes has long been talked about, much anticipated one but least understood topic in earth science. Till date no “reliable method” of advance detection of this geo-physical phenomenon is known to us.
Glowing of mysterious lights, changes in weather and changes in landforms, ground water levels and animal behavior, rise in temperature, noises from ground had been long reported as a precursor to earthquakes.
In the winter of 1975, Chinese officials had ordered the evacuation of the city of Haicheng (population about 1 million) in the Liaoning Province of northeast China, based on reports from scientists and lay observers in a wide region of unusual observations regarding changes in land elevation and ground water levels a month before the magnitude 7.3 earthquake struck the region days later on February 4, 1975.
However, no such correlation was observed in a quake that struck in 1976 in Tangshan, China.
Can we predict earthquake locations ?
What is the mechanism behind earthquakes ?
What trigger earthquakes ?
Are changes in weather and earthquake related ?
What causes unusual symptoms prior to an earthquake ?
Is earthquake prediction likely ?
Can we predict earthquake locations ?
It has been well established that certain regions across the globe are more likely to receive earthquakes popularly known as “Ring of Fire”. It is now substantiated that most of the earthquakes take place at these highly seismically active zones.
Records have shown that earthquakes occur in mainly three zones on the earth:
Circum-Pacific belt (Ring of Fire)
Alpide belt
Mid Atlantic Range
Circum-Pacific belt, also called the Ring of Fire, is the zone surrounding the Pacific Ocean which is the most seismically active zone in the earth. About 81% of the world's earthquakes occur there. The belt extends from Chile, northward along the South American coast through Central America, Mexico, the West Coast of the United States, and the southern part of Alaska, through the Aleutian Islands to Japan, the Philippine Islands, New Guinea, the island groups of the Southwest Pacific, and to New Zealand.
Alpide belt, the next most seismically active region responsible for 17% of earthquakes, extends from Mediterranean region, eastward through Turkey, Iran, and northern India.
Mid Atlantic Range, the third prominent belt follows the submerged Mid Atlantic Range. The remaining shocks are scattered in various areas of the world.
Though the seismically active regions or the region where occurrence of earthquakes is more likely had been known; their time of occurrence and the possible mechanisms that trigger earthquakes are yet the matter of speculations.
What is the mechanism behind earthquakes ?
Earthquake is the phenomenon of energy release deep down inside the earth caused by the sudden brittle failure of the “fault planes”. Fault plane is the planar surface passing through the fault zone along which rock masses lying two sides slide relative to each other.
Fault is actually a fracture or zone of discontinuity across which relative motion of rock masses have been observed. The gradual accumulation of stress at the fault plane tends to slip two side blocks. Eventually, as enough stress builds up at the fault-plane rock masses slip or break in a highly brittle manner suddenly releasing huge energy and is transmitted in the form of waves that reach to earth surface which we call an earthquake.
Fault length can range from few feet to hundreds of kilometers. In a small earthquake, the rupture surface may be only a small part of the entire fault, whereas during a large earthquake, the entire fault may slip.
Though earthquake is a more of geological phenomenon happening inside the earth due to dynamism of the earth’s interior; certain surficial events like flood, rainfall (storms) and added weight from man-made huge reservoirs are supposed to be contributing factors conducive to triggering earthquakes. Water seems to play a key role in triggering earthquakes through various mechanisms. The concentration of water nearby the fault planes likely from the rain water percolating underground and the washing away behavior of storm and flood water thereby relieving the stress on the fault planes both seem to trigger earthquakes as substantiated by the observations.
Shimon Wdowinski of the University of Miami in Florida, first noticed a connection between storms and earthquakes in 2010. He studied several correlations between storms and subsequent earthquakes.
Based on the observations, he correlated the devastating magnitude 7.0 earthquake that hit Haiti in 2010 came only 18 months after Haiti had been overwhelmed by several hurricanes and tropical storms. And another large earthquake, a magnitude 6.4 temblor that rocked Taiwan in 2009, occurred only seven months after the area had been hit by Typhoon Morakot, which dropped 9.5 feet of rain in five days. Also, he found that a magnitude 7.6 earthquake had struck in 1999, only three years after Typhoon Herb soaked Taiwan with 6.6 feet of rain.
Contrary to the popular belief, it’s not the weight of water that triggered the earthquake; rather, it's the continuing erosion from landslides, which was washed away steadily by storm into the sea relieving weight on the underlying rocks. Due to reduction in stress on the underlying rocks, movement in fault plane had become easier. Seemingly small changes, but such phenomenon are apparently enough to trigger the earthquake.
Geologists have long suspected that water plays a role in triggering earthquakes, but getting evidence has not always been so easy. Research in New Zealand has given the clearest picture yet of the role of water in helping to trigger earthquakes.
Caldwell and colleagues used the electromagnetic waves to know the electrical conductivity of rocks deep down the earth surface. More the rock contains water, higher will be its conductivity and more they reflect the electromagnetic waves. By measuring the conductivity of rocks Caldwell and colleagues succeeded to determine where water was being concentrated. High temperature and pressure causes water to be released from rocks and collects in cooler rocks that sit further up.
Caldwell and colleagues found clusters of conductive (water-containing) rocks sitting just below fault lines. As per their findings, earthquakes happen just above where the water is being concentrated. Caldwell says, addition of water into the base of the fault makes it easier for the fault to fail.
Geophysicists have linked historical earthquakes on the southern section of California's San Andreas fault to ancient floods from the nearby Colorado River. At least three times in the past 2,000 years, the weight of river water spreading across floodplains seems to have helped trigger earthquakes in the region. The quakes happened about every 100 to 200 years and were correlated with floods. The spilling out of Colorado river supposed to loads the crust resulting a rupture.
Also, it is interesting to know that weight of water can cause earthquake.
Scientists now believe that impounding pressure of water or any other man-made structures as dam can get so great it can cause a nearby fault to rupture, leading to an earthquake. In 2008, M 7.9 Sichuan earthquake in China was supposed to be induced by additional pressure from the Zipingpu reservoir. The reservoir with 470 ft high concrete dam at the upstream from Dujiangyan located just four miles from epicenter was also severely damaged during the quake. The scientists speculated that the extra pressure of the water in the reservoir might have caused the nearby Longmenshan Fault to slip, thereby releasing the tectonic energy stored in it. The additional hydrostatic pressure from the 320 million tons of water stored behind the dam might have triggered the quake.
Likewise, as per the speculations, the filling of the Oroville Dam in northern California probably triggered the magnitude 5.7, 1975, Lake Oroville, California earthquake. The triggering of earthquakes by the filling of dams can be a major concern in seismically active areas. There is the possibility that the triggered earthquake will cause the dam to fail leading to a serious flood. Engineers who build dams sometimes have to consider this possibility in the design of the dam.
New findings suggest that Himalaya monsoons are also linked to quakes. Himalaya range was created by the convergence of Indian plate with the Tibetan plate producing a giant fault zone marked by the mountains. In the Himalaya, summer monsoons dump heavy rainfall onto the Indian side of the mountain range.
Thomas Ader, a Ph.D. student at the California Institute of Technology found that when monsoons hit, a lot of water flows into the Indian lowlands and its enormous weight causes the Indian plate to bend slightly under the pressure. That, in turn, causes the edge of the plate to move slightly. He concluded that during Asia's wet season, the bending offsets the building of tectonic strain on the fault, reducing the short-term risk of earthquakes. But in winter, the effect reverses as the lowlands dry out, letting the plate unbend, and the earthquake rate rises.
Are changes in weather and earthquake related ?
Changes in weather conditions as foggy like weather, unusual blistering heat (warm weather), unusual clam characteristics and rain are supposed to be related to earthquakes. The mechanism that generates earthquake is thought to be responsible for such changes in atmospheric conditions. Likewise, it is also theorized that there is a correlation between extreme weather events like cyclones, flooding, storms and typhoons and seismic activity.
It is now established that certain geologic events caused by plate motions - for example the drift of continents, the closure of ocean basins and the building of large mountain belts have the ability to influence climate patterns but over a period of a million years.
On the contrary, according to news study from the Australian National University change in global climate like global warming over the period of years can modify the motion of plates. Working with researchers in Germany and France, they have established a link between the motion of the Indian plate over the last ten million years and the intensification of Indian monsoons. Monsoon rain increased by four meters every year, speeding up the motion in the Indian plate by one centimeter a year, said Dr Giampiero Iaffaldano from the ANU research school of earth sciences.
The scientists put information into a computer that indicated how monsoons had eroded the eastern Himalayas over the last ten million years. They discovered that enough rocks were worn away from the eastern side of the plate to account for the plate's anti-clockwise movement. The findings, for the first time shown that long-term climate changes have the potential to influence the motion of tectonic plates; thereby probably the earthquake events.
Some scientists believe that “earthquake weather” does in fact exist. The squeezing motion of the earth prior to a quake is believed to generate electric currents that decomposes trapped ground water and releases hydrogen and oxygen ions into the air. These ions may then produce fog, clouds, and the unusual calm characteristic of earthquake weather. These same charges may also cause earthquake lights, fireballs, flashes, and eerie glows that have been reported in the sky before or during plate movements.
The ionization of the air can result in the formation of non-weather related clouds. Dr. Friedemann Freund has identified this cloud formation retrospectively from satellite images in the period leading up to an earthquake that struck the city of Bam in Iran in 2003.
What causes unusual symptoms prior to an earthquake ?
NASA scientists Friedemann Freund and Dmitri Ouzounov proposed the explanation behind the unusual phenomena reported before quakes. Though earthquakes begin several kilometers below the earth’s surface, the formation of positively charged particles during stressing and squeezing of rocks can reach to earth’s surface traveling through dense rocks inside. The flux of these positively charged particles near the surface would draw negatively charged atmospheric particles closer to the Earth and combination of these charged particles releases infrared radiation. They believe they can detect this IR signal via weather satellites about two to five days before a quake happens. It also possibly explains the strange pre-quake phenomena sometimes reported.
The scientist duo examined data from a NASA satellite called MODIS for the days preceding the 26 January 2001 earthquake in Gujarat, India, and found that the temperature rose 2 to 5°C in the days preceding the quake. Signals from within the earth might one day warn of an upcoming earthquake, say NASA scientists who think they can explain why temperature rises appear to precede tremors. The idea could also explain the weird pre-quake behavior of weather, radio transmissions, animals and even people.
Observance of mysterious glows or earthquake lights reported sometimes before or during seismic shaking is now explained by the geologist Robert Thériault at Quebec’s Ministry of Natural Resources in Quebec City, Canada. He suggests that, during an earthquake, the stress of rocks grinding against each other generates electric charges, which travel upwards along the nearly vertical geological faults that are common in rift zones. When the charges reach Earth's surface and interact with the atmosphere, they create a glow.
Is earthquake prediction likely ?
Earthquake prediction means getting the information on happening of earthquake regarding its time of occurrence and location sufficiently ahead so that people can look for safe places.
Nearly all the earthquake prediction measures are based on the changes in properties of rock mass at the fault zone and indirect changes brought by it. Stressed blocks of rock at the fault zones are essential for earthquake to happen. Rock mass gradually dilates with increase in stress much before it takes the form of an earthquake. This prediction theory is often referred as theory of dilatancy.
Direct measurement of changes in physical size of rock mass isn’t possible that happens at earth’s interior several kilometers deep. We can assess such changes by measuring its physical properties like electrical resistance (conductivity), magnetic properties, generation of seismic wave signals and possible electromagnetic changes it brings in our atmosphere. All this can lead to early detection of potential earthquake sources. Likewise, the physical change in rock size may lead to a general uplifting of the ground surface or a change in the groundwater pressure and levels. Physicist Freidmann Freund from the NASA Ames Research Centre has been working on a theory that changes in conductivity of the underlying rocks could help us spot potential earthquakes. Also, researches are going on to scan the changes in electromagnetic behavior in earth’s atmosphere brought by charged particles radiated from the deformed rock mass inside.
Physicist also put forward the theory based on measurement of a gas call radon. Physicist Giuliani's predicted the Italy quake (2009) based on measuring levels of the radon gas. The idea is that the deformation of rocks in the earth's crust that occurs in the lead-up to an earthquake releases gases trapped deep underground. But his forecast turned out to have missed the mark by one week in time and 50 kilometers in terms of location!
A future network of satellites orbiting the earth may be able to detect an impending earthquake by monitoring our planet's ionosphere. The researchers hope to create a global network of roughly 20 satellites that would scan for indicative activity that some scientists say precedes large earthquakes. Dr Stuart Eves, a researcher at UK based Surrey Satellite Technology Limited, the company behind the proposed satellite network and a NASA researcher Dr Friedemann Freund, a leading proponent of the theory proposed the dishwasher-sized satellites to monitor such changes.
Dr Friedemann Freund theory suggests that much of earth's rock has soaked up water, which has later been exposed to extreme heat and pressure inside the earth. Those conditions break apart the water and create the electrically conductive crystals that exist inside most rocks, as well as byproducts such as oxygen. As pressure mounts before an earthquake, the oxygen molecules inside the rocks undergo chemical reactions, creating a positive electrical charge that radiates out toward the earth's surface in a similar manner how an electrical charge radiates through a battery. The charge creates a subtle fluorescent, infrared glow and a magnetic field one to two weeks before a major earthquake. These glowing in the space are detected by the satellites.
Dr Stuart Eves suggests that proposed satellites, with low-resolution thermal cameras would scan the earth to detect earthquake precursors.