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When do earthquakes occur?
Earthquakes are caused by the Earth's tectonic plates shifting against one another deep below the surface. These huge masses of rock are in constant motion, but they may lock into positions where they come into contact. When this stress is finally released, the sudden shift results in an earthquake.they start from movement fron the earths surfaceEarthquakes can happen anywhere, but are more likely in areas where the Earth's crustal "plates" are moving in relation to each other.Earthquakes are caused by shifts in the Earth's crust, and normally occur when rock layers move past each other along a boundary, or fault line. The surface of the land, or the sea floor, can move sideways, up, or down, and this displacement causes seismic waves to move outward, above and around the shift. The motion imparted by these waves is what generates the destructive power of an earthquake, and it can also create tsunamis in the sea.(For more information, see the related question.)Earthquakes are always happening somewhere.Worldwide, strong earthquakes happen more than once per month. Smaller earthquakes such as magnitude 2 earthquakes occur several hundred times a day. To create a mountain system might take several million medium sized earthquakes over tens of millions of years.Before you learn the answer, you must know the theory of plate tectonics.Scientists believe that Earth's crust is made up of many plates that float on the asthenosphere in the mantle. (the mantle is in the Earth) To keep the planet alive, Earth's core uses convection currents to spread heat. This is the theory.An earthquake happens when the convection current moves the plates a little. Anyway, the plates bump into each other and because there is limited space for the plates to move, the keep on building pressure on what it is pressing or bumping upon. When so much pressure builds up, I think it is called elastic rebound, happens and all the pressure is released in the form of seismic waves. That is the earthquake.So, basically, and earthquake happens when one plate collides into another and it sends seismic waves around that shake the ground.Earthquakes occur when there's movement of the tectonic plates of our Earth. Scientists are as yet not certain if volcanoes cause earthquakes or if earthquakes cause volcanoes, but they often occur together.+++This describes the effects of subduction, where one plate (usually of a closing ocean's floor) is being forced down below another. The earthquakes are the shock-waves from each slip forwards of the sinking plate. The accompanying volcanoes are of material from a mass of plate already partly-melted in the process. So neither volcano nor earthquake causes the other: both result from plate subduction.'Volcanoes themselves can produce minor, local tremors as rising magma prior to an eruption, expands them.
Is there a relationship between earthquake locations and mountain ranges?
No it can't because the formation is not the same as the others but it can be linked to block mountains and formed as a volcanoes. But others say it is possiable for it to happen and many say it can't but scientist say that some people discovered that their theory is acatuall right and the others are stupid
What methods do scientists use to predict volcanic eruption?
MethodsSeismic Waves (Seismicity)General principles of volcano seismologySeismic activity (earthquakes and tremors) always occurs as volcanoes awaken and prepare to erupt and are a very important link to eruptions. Some volcanoes normally have continuing low-level seismic activity, but an increase may signal a greater likelihood of an eruption. The types of earthquakes that occur and where they start and end are also key signs. Volcanic seismicity has three major forms: short-period earthquake, long-period earthquake, and harmonic tremor.Short-period earthquakes are like normal fault-generated earthquakes. They are caused by the fracturing of brittle rock as magma forces its way upward. These short-period earthquakes signify the growth of a magma body near the surface and are known as 'A' waves. These type of seismic events are often also referred to as Volcano-Tectonic (or VT) events or earthquakes.Long-period earthquakes are believed to indicate increased gas pressure in a volcano's plumbing system. They are similar to the clanging sometimes heard in a house's plumbing system, which is known as "water hammer". These oscillations are the equivalent of acoustic vibrations in a chamber, in the context of magma chambers within the volcanic dome and are known as 'B' waves. These are also known as resonance waves and long period resonance events.Harmonic tremors are often the result of magma pushing against the overlying rock below the surface. They can sometimes be strong enough to be felt as humming or buzzing by people and animals, hence the name.Patterns of seismicity are complex and often difficult to interpret; however, increasing seismic activity is a good indicator of increasing eruption risk, especially if long-period events become dominant and episodes of harmonic tremor appear.Using a similar method, researchers can detect volcanic eruptions by monitoring infra-sound-sub-audible sound below 20 Hz. The IMS Global Infrasound Network, originally set up to verify compliance with nuclear test ban treaties, has 60 stations around the world that work to detect and locate erupting volcanoes. [1]Seismic case studiesA relation between long-period events and imminent volcanic eruptions was first observed in the seismic records of the 1985 eruption of Nevado del Ruiz in Colombia. The occurrence of long-period events were then used to predict the 1989 eruption of Mount Redoubt in Alaska and the 1993 eruption of Galeras in Colombia. In December 2000, scientists at the National Center for Prevention of Disasters in Mexico City predicted an eruption within two days at Popocatépetl, on the outskirts of Mexico City. Their prediction used research that had been done by Bernard Chouet, a Swiss volcanologist who was working at the United States Geological Survey and who first observed a relation between long-period events and an imminent eruption.[1][2][3] The government evacuated tens of thousands of people; 48 hours later, the volcano erupted as predicted. It was Popocatépetl's largest eruption for a thousand years, yet no one was hurt.Iceberg tremorsIt has recently been published that the striking similarities between iceberg tremors, which occur when they run aground, and volcanic tremors may help experts develop a better method for predicting volcanic eruptions. Although icebergs have much simpler structures than volcanoes, they are physically easier to work with. The similarities between volcanic and iceberg tremors include long durations and amplitudes, as well as common shifts in frequencies. (Source: Canadian Geographic "Singing icebergs")Gas emissionsGas and ash plume erupted from Mount Pinatubo, Philippines. As magma nears the surface and its pressure decreases, gases escape. This process is much like what happens when you open a bottle of soda and carbon dioxide escapes. Sulphur dioxide is one of the main components of volcanic gases, and increasing amounts of it herald the arrival of increasing amounts of magma near the surface. For example, on May 13, 1991, an increasing amount of sulphur dioxide was released from Mount Pinatubo in the Philippines. On May 28, just two weeks later, sulphur dioxide emissions had increased to 5,000 tonnes, ten times the earlier amount. Mount Pinatubo later erupted on June 12, 1991. On several occasions, such as before the Mount Pinatubo eruption and the 1993 Galeras, Colombia eruption, sulphur dioxide emissions have dropped to low levels prior to eruptions. Most scientists believe that this drop in gas levels is caused by the sealing of gas passages by hardened magma. Such an event leads to increased pressure in the volcano's plumbing system and an increased chance of an explosive eruption.Ground deformationSwelling of the volcano signals that magma has accumulated near the surface. Scientists monitoring an active volcano will often measure the tilt of the slope and track changes in the rate of swelling. An increased rate of swelling, especially if accompanied by an increase in sulphur dioxide emissions and harmonic tremors is a high probability sign of an impending event. The deformation of Mount St. Helens prior to the May 18, 1980 eruption was a classic example of deformation, as the north side of the volcano was bulging upwards as magma was building up underneath. Most cases of ground deformation are usually detectable only by sophisticated equipment used by scientists, but they can still predict future eruptions this way. The Hawaiian Volcanoes show significant ground deformation; there is inflation of the ground prior to an eruption and then an obvious deflation post-eruption. This is due to the shallow magma chamber of the Hawaiian Volcanoes; movement of the magma is easily noticed on the ground above. Thermal monitoringBoth magma movement, changes in gas release and hydrothermal activity can lead to thermal emissivity changes at the volcano's surface. These can be measured using several techniques: forward looking infrared radiometry (FLIR) from hand-held devices installed on-site, at a distance, or airborne;Infrared band satellite imagery;in-situ thermometry (hot springs, fumaroles)heat flux mapsgeothermal well enthalpy changesHydrologyThere are 4 main methods that can be used to predict a volcanic eruption through the use of hydrology: Borehole and well hydrologic and hydraulic measurements are increasingly used to monitor changes in a volcanoes subsurface gas pressure and thermal regime. Increased gas pressure will make water levels rise and suddenly drop right before an eruption, and thermal focusing (increased local heat flow) can reduce or dry out acquifers.Detection of lahars and other debris flows close to their sources. USGS scientists have developed an inexpensive, durable, portable and easily installed system to detect and continuously monitor the arrival and passage of debris flows and floods in river valleys that drain active volcanoes.Pre-eruption sediment may be picked up by a river channel surrounding the volcano that shows that the actual eruption may be imminent. Most sediment is transported from volcanically disturbed watersheds during periods of heavy rainfall. This can be an indication of morphological changes and increased hydrothermal activity in absence of instrumental monitoring techniques.Volcanic deposit that may be placed on a river bank can easily be eroded which will dramatically widen or deepen the river channel. Therefore, monitoring of the river channels width and depth can be used to assess the likelihood of a future volcanic eruption.Remote SensingRemote sensing is the detection by a satellite's sensors of electromagnetic energy that is absorbed, reflected, radiated or scattered from the surface of a volcano or from its erupted material in an eruption cloud. 'Cloud sensing: Scientists can monitor the unusually cold eruption clouds from volcanoes using data from two different thermal wavelengths to enhance the visibility of eruption clouds and discriminate them from meteorological clouds'Gas sensing: Sulphur dioxide can also be measured by remote sensing at some of the same wavelengths as ozone. TOMS (Total Ozone Mapping Spectrometer) can measure the amount of sulphur dioxide gas released by volcanoes in eruptionsThermal sensing: The presence of new significant thermal signatures or 'hot spots' may indicate new heating of the ground before an eruption, represent an eruption in progress or the presence of a very recent volcanic deposit, including lava flows or pyroclastic flows.Deformation sensing: Satellite-borne spatial radar data can be used to detect long-term geometric changes in the volcanic edifice, such as uplift and depression. In this method, called InSAR (Interferometric Synthetic Aperture Radar), DEMs generated from radar imagery are subtracted from each other to yield a differential image, displaying rates of topographic change.Forest Monitoring: In recent period it has been demonstrated the location of eruptive fractures could be predicted, months to years before the eruptions, by the monitoring of forest growth. This tool based on the monitoring of the trees growth has been validated at both Mt. Niyragongo and Mt. Etna during the 2002-2003 volcano eruptive events.[4]Mass movements and mass failuresMonitoring mass movements and -failures uses techniques lending from seismology (geophones), deformation, and meteorology. Landslides, rock falls, pyroclastic flows, and mud flows (lahars) are example of mass failures of volcanic material before, during, and after eruptions. The most famous volcanic landslide was probably the failure of a bulge that built up from intruding magma before the Mt. St. Helens eruption in 1980, this landslide "uncorked" the shallow magmatic intrusion causing catastrophic failure and an unexpected lateral eruption blast. Rock falls often occur during periods of increased deformation and can be a sign of increased activity in absence of instrumental monitoring. Mud flows (lahars) are remobilized hydrated ash deposits from pyroclastic flows and ash fall deposits, moving downslope even at very shallow angles at high speed. Because of their high density they are capable of moving large objects such as loaded logging trucks, houses, bridges, and boulders. Their deposits usually form a second ring of debris fans around volcanic edifices, the inner fan being primary ash deposits. Downstream of the deposition of their finest load, lahars can still pose a sheet flood hazard from the residual water. Lahar deposits can take many months to dry out, until they can be walked on. The hazards derived from lahar activity can several years after a large explosive eruption.A team of US scientists developed a method of predicting lahars. Their method was developed by analyzing rocks on Mt. Rainier in Washington. The warning system depends on noting the differences between fresh rocks and older ones. Fresh rocks are poor conductors of electricity and become hydrothermically altered by water and heat. Therefore, if they know the age of the rocks, and therefore the strength of them, they can predict the pathways of a lahar.[5] A system of Acoustic Flow Monitors (AFM) has also been emplaced on Mount Rainier to analyze ground tremors that could result in a lahar, providing an earlier warning.[6]
Why was alcohol banned in darts?
hinders one's assessment prior to throwing
How do scientists make observations and inferences?
- By You Using Prior Knowledge , And Experience !
When was Eyjafjallajokull last dormant?
Eyjafjallajökull, the volcanic glacier in Iceland, was last dormant before its significant eruptions in 2010. The volcano's last prolonged period of dormancy before this was from 1821 until the 2010 eruptions, marking nearly two centuries of inactivity. Prior to that, it had small eruptions in the early 19th century.
What conditions makes it difficult to predict the occurrence of earthquakes?
Earthquakes and volcanic eruptions are extremely hard to predict because of their irregularity. This is due to the butter fly effect. For example, in California there had been a volcanic eruption every 30 years since the start of their records, so they a few years ago when it was scheduled to happen the government spent millions on "earthquake-proofing" the area. Nothing actually happened. The main way to predict earthquakes and volcanic eruptions is to look for patterns in the past but it is really not an accurate or reliable method. Earthquakes are a lot harder to predict as they can happen at any point down a convergent or conservative plate boundary spontaneously, where as with a volcano you can study it and look for signs such as bulges or changes of gas composition in the area that could indicate when it will erupt. However new methods of detection are being tested, the strangest being the use of some animals, snakes the most common, that behave in peculiar ways just before an earthquake. Breakthroughs like these and the use of new technologies, like GPS to monitor irregularities in the the shape of volcanoes, will make the prediction of earthquakes and volcanic eruptions much easier in the future
Can you predict when volcanoes occur?
Sort of, before volcanos erupt there is often a lot of detectable seismic activity. Howeer you can have similar seisimc activity without an eruption; and there have been eruptions were there was little seismic activty immediately prior to the event.Seismologists are getting better at predicting eruptions, but they still have a lot of work yet to do.
How soon before a major earthquake can foreshocks occur?
Foreshocks can occur days, weeks, or even months before a major earthquake, though they often happen minutes to hours prior. Their unpredictability makes it challenging to use them as reliable indicators of an impending larger quake. Not all major earthquakes are preceded by foreshocks, and when they do occur, not all foreshocks will lead to a larger event.
What happened before the mount Pinatubo eruption?
Prior to the Mount Pinatubo eruption in 1991, there were significant volcanic activities such as steam explosions, ash emissions, and seismic unrest. This led to the evacuation of tens of thousands of people from the surrounding areas as a precaution. Additionally, there were several small eruptions in the days leading up to the major eruption on June 15.
Why not to live next to a volcano?
Most volcanoes erupt infrequently and create fertile soils that are ideal for farming. Many volcanoes, such as Mount Fuji in Japan and Mount St Helen's prior to its 1980 eruption, are known for their beauty.
Should planning occur prior to an emergency in order to lessen its effects?
true
Planning should occur prior to an emergency in order to lessen its effects?
true
When did the great awakening occur in relation to the war for independence?
a few decades prior to the war
What was david A johnston occupation?
David A. Johnston was a volcanologist known for his work in studying volcanic eruptions and hazards. He is best known for his research on Mount St. Helens, where he was a key figure in monitoring the volcano prior to its catastrophic eruption in May 1980. Tragically, he lost his life during the eruption while conducting fieldwork. His contributions to volcanology and public safety have had a lasting impact on the field.
Is a statement that a particular event will occur based on reasonable observations of prior events?
i dont know
What is a statement that a particular event will occur based on reasonable observations of prior events?
i dont know
