Emergency communication plan for: reuniting after the earthquake if family members are separated from one another ask a relative or friend as the “contact person” after the disaster.
The innocent people of Armenia thought that day was going to be an ordinary day but they were unfortunately wrong. In addition, Earthquakes of magnitude 5. 5 or above are the ones that usually do damage(Fradin 27). The word damage is an understatement; the earthquake left most of the people buried under rubble. The damage that was done by this force of nature was oo much for these people to handle. The number 6. 0 seems like a little number, but when you see the damage that was done it doesnt seem so little. Next, many peoples lives were greatly affected by this sudden tragedy. There are more than 1,000 dead, perhaps more than 2,000 in Armenia alone(Whitbeck 2).
Many people lost their family members and friends that they deeply cared about. One minute people are happy and enjoying life and the next minute 2,000 of those happy people are dead. It left over two-thirds of Armenia in total ruin, and rural village decimated in addition to the loss of life, the injuries and the amage to the infrastructure(Moreno 20). There was practically none of the towns left. It all was demolished by the quake. This left many people homeless without safety and warmth. This disaster made people lose their lives and homes; it left so many people empty-handed. Finally, the governments effort to aid the situation at hand lacked merit.
Henry Gomez, the governor said,We dont have enough coffins to bury the dead(Whitbeck 3). The government needs to provide the dead with coffins because it is just disrespectful not to. The deceased people deserve a proper burial to end their lives right. In addition, there was little coordination between the Red Cross, Civil Defense and firefighters, and accused each group of operating like a separate club(Whitbeck 1). All the rescue teams needed to work together because the unorganization caused chaos. It is ridiculous that when citizens are really in need of help, other people have to be stubborn and unhelpful. The government should have done their job and been there for their people.
Colombia was shocked when the earthquake rocked their country and affected so many people. Since the quake, Colombia is trying to recover from this tragedy that has greatly mpacted their lives. Hopefully, the victims can pick up the pieces left of their lives and put them back together. Earthquake San Francisco- 1906 On the morning 12 past 5:00 San Francisco suffered a major earthquake that killed 3000 people, the earthquake lasted for about 40 seconds and was recorded at 8. 3 on the Richter Scale. People ran from there houses and some stayed inside the buildings and were crushed. The people who ran in the streets were killed by toppled buildings falling from above.
There fire department was efficient but the water pipes that go down the San Andreas Fault were severed. The fire could not be stopped because there were now water until the next couple of days. Gas mains blew and caused massive fires all around the city. The city was in the middle of a great economic boom and almost all was lost on that day. The old buildings were never made to withstand earthquakes and easily crumbled and fell crushed people. Some sailers on the coast tried to leave but the waves flew the boats around like toys. The buildings were made out of unreined forced brick or wood which couldn’t withstand a earthquake of that magnitude.
After the earthquake, they noticed that the San Andreas Fault shifted a 250-mile long ection witch tore roads and fences. Rivers, roads and power lines were severed and not aligned with its surroundings. A road across the fault ended up 21 feet north of the road to the east same with the rivers and creeks. The earthquake’s most damage were in Los Bonas 30km east of the fault yet there was little damage along towns to the east side of San Francisco Bay such as Berkely, 25km east of the fault. And the capital of California Sacramento that was 120km east of the rupture showed no damage. Scientists found out that the earthquake originated north of Oregon and south to Los Angeles a total of 1170 Km.
Knowing now that buildings could not withstand a earthquake with unreiforced brick, the new San Francisco would have buildings that can handle major earthquakes by constructing them so that they sway back and fourth rather than just simply crumbling to the ground killing people. The San Andreas fault is formed by the Pacific plate sliding north and the North American plate running South. The two slide together caused the earthquake. The most recent earthquake in that area today, was in 1990 in San Francisco which measured around 8. 3 on the richter scale but it wasn’t a bad as the one in 1906. earthquake rembling or shaking movement of the earth’s surface.
Most earthquakes are minor tremors. Larger earthquakes usually begin with slight tremors but rapidly take the form of one or more violent shocks, and end in vibrations of gradually diminishing force called aftershocks. The subterranean point of origin of an earthquake is called its focus; the point on the surface directly above the focus is the epicenter. The magnitude and intensity of an earthquake is determined by the use of scales, e. g. , the and the Mercalli scale. Causes of Earthquakes Most earthquakes are causally related to compressional or tensional stresses built up at the argins of the huge moving lithospheric plates that make up the earth’s surface (see ).
The immediate cause of most shallow earthquakes is the sudden release of stress along a , or fracture in the earth’s crust, resulting in movement of the opposing blocks of rock past one another. These movements cause vibrations to pass through and around the earth in wave form, just as ripples are generated when a pebble is dropped into water. Volcanic eruptions, rockfalls, landslides, and explosions can also cause a quake, but most of these are of only local extent. See also . Seismic Waves There are several types of earthquake waves including P, or primary, waves, which are compressional and travel fastest; and S, or secondary, waves, which are transverse, i. e. , they cause the earth to vibrate perpendicularly to the direction of their motion.
Surface waves consist of several major types and are called L, or long, waves. Since the velocities of the P and S waves are affected by changes in the density and rigidity of the material through which they pass, the boundaries between the regions of the earth known as the crust, mantle, and core have been discerned by seismologists, scientists who deal with the nalysis and interpretation of earthquake waves (see ). Seismographs (see ) are used to record P, S, and L waves. The disappearance of S waves below depths of 1,800 mi (2,900 km) indicates that at least the outer part of the earth’s core is liquid. Damage Caused by Earthquakes The effects of an earthquake are strongest in a broad zone surrounding the epicenter.
Surface ground cracking associated with faults that reach the surface often occurs, with horizontal and vertical displacements of several yards common. Such movement does not have to occur during a major earthquake; slight periodic movements called fault creep can e accompanied by microearthquakes too small to be felt. The extent of earthquake vibration and subsequent damage to a region is partly dependent on characteristics of the ground. For example, earthquake vibrations last longer and are of greater wave amplitudes in unconsolidated surface material, such as poorly compacted fill or river deposits; bedrock areas receive fewer effects. The worst damage occurs in densely populated urban areas where structures are not built to withstand intense shaking.
There, L waves can produce destructive vibrations in buildings and break water and gas lines, starting ncontrollable fires. Damage and loss of life sustained during an earthquake result from falling structures and flying glass and objects. Flexible structures built on bedrock are generally more resistant to earthquake damage than rigid structures built on loose soil. In certain areas, an earthquake can trigger mudslides, which slip down mountain slopes and can bury habitations below. A submarine earthquake can cause , damaging waves that ripple outward from the earthquake epicenter and inundate coastal cities.
Major Earthquakes Notable earthquakes have occurred at Lisbon (1755), Charleston, S. C. (1886), Assam, India (1897 and 1950), California (1906), Messina (1908), Gansu, China (1920), Japan (1923), Chile (1960), Iran (1962), Guatemala (1976), Hebei, China (1976), and Armenia (1988). The Lisbon and Chilean earthquakes were accompanied by tsunami. On Good Friday, 1964, one of the most severe North American earthquakes ever recorded struck Alaska, measuring 8. 4 to 8. 6 on the Richter scale. Besides elevating some 70,000 sq mi (181,300 sq km) of land and devastating several cities, it generated tsunami that caused damage as far south as California.
In Feb. , 1971, movement of the San Fernando fault near Los Angeles rocked the area for 10 sec, thrust parts of mountains 8 ft (2. m) upward, killed 64 persons, and caused damage amounting to 500 million dollars; in 1989, the Loma Prieta earthquake above Santa Cruz shook for 15 seconds at 7. 1 on the Richter scale, killed 67 people, and toppled buildings and bridges. Managua, the capital of Nicaragua, was almost totally destroyed by a severe earthquake that struck in Dec. , 1972. An earthquake measuring 7. 8 on the Richter scale devastated northern Japan in July, 1993. It is estimated that in the last 4,000 years over 13 million deaths were caused by earthquakes. Earthquakes are happening almost everyday all over the world. Most of the time earthquakes are not strong enough to be felt by people, but the shaking caused by an earthquake is recorded by a seismogram.
These are located all over the world at different points. Only occasionally will a larger magnitude earthquake strike and cause damage to the region. Around the world there are many faults, depending where these faults are plays a major factor in determining where an earthquake will happen. It is these faults that are the reason for earthquakes. The type of fault will also determine how often an earthquake will happen. A mid-ocean ridge occurs under the sea at a divergent boundary. This is where two plates are been pulled apart because of tension. This then allows new oceanic crust to be made in the divergent boundary, as magma rises and eventually sets on the sea floor.
If the plates on either side of the divergent boundary continue to spread then the ocean slowly becomes larger in width, a process called seafloor spreading. Mid-ocean ridges are characterised by a crack like valley at the divergent boundary. This crack like valley is caused by the tension pulling the plates apart, causing normal faulting to occur a number f times in the divergent boundary. It is these normal faults that are the cause and therefore the origin of earthquakes at divergent boundaries. When the tension pulling apart the two plates becomes too much then the oceanic crust will fracture. This fracturing is caused by many normal faults happening as shown in the diagram. The normal faults happen because the crust is been extended.
When the tension becomes too much the faults slip vertically. They move a large distance in a relatively short space of time, this is the cause of the earthquakes at divergent boundaries. Divergent boundaries mostly occur on the sea floor and therefore the earthquakes that happen at these boundaries are distributed along the boundary. This means that the distributions of earthquakes at divergent boundaries are at shallow depths, where the crust is been pulled apart. The earthquakes happen at shallow depths because the normal faulting occurs near the sea floor, as a result of the tension. The normal faults are the cause of the earthquakes at these divergent boundaries.
The seafloor sees the most intense tectonic activity in the world, meaning that at the sites of mid-ocean ridges the frequency of earthquakes is very high. An example of a mid-ocean ridge is the Mid-Atlantic ridge, there the seafloor is spreading at a rate of about 3cm per year. The frequency of earthquakes at a mid-ocean ridge will depend on how much tension is happening at that point. The more tension means the more seafloor spreading, resulting in a higher frequency of earthquakes at a particular mid-ocean ridge. Four major oceans make up most of the water in the world, The Atlantic (north & south), The Pacific, The Antarctic and The Indian Ocean. Within the basins of these oceans earthquakes can happen without been caused at Mid-ocean ridges, or a Subduction Zones.
When the earths crust is under tensional forces the crust will become much thinner than normal, if there is no fault. This means that the crust becomes weaker as it is thinner than normal. This can happen to the oceanic crust in the ocean basins, but will only cause an earthquake with a hot spot. A hot spot is an abnormal hot rising area of the mantle that supplies the lava for volcanoes. If at the same time a hot spot is directly below a thinned crust then the magma in the hot spot may hold too much pressure to be held by the thinner weakened crust. If this is the case then the magma can penetrate the lithosphere, and ventually erupt on the surface.
The action of the magma forcing its way up can trigger earthquakes as it breaks through the crust. When its breaks through the crust at the sea bed eventually a volcanic island will be formed in the middle of the ocean. Due to plate movements this can lead to the creation of mid-plate chains of basaltic volcanic islands, e. g. Hawaii. The creation of these islands around the world has happened in other places. Frequent large earthquakes do not happen along the Hawaiian chain, it is an essentially an asesimic ridge. Therefore the frequency of earthquakes caused in ocean basins by hot spots is very ow. The distributions of these earthquakes that do occur happen at shallow depths.
This is because the origin is in the crust, which has been thinned because of tension. A subduction zone is where two plates collide and one is forced below the other, they occur at convergent boundaries. They collide because of compression forces, pushing them into each other. One plate is subducted below the other into the mantle, where it will be recycled. An example of this is shown below with the Pacific plate subducting under the Eurasian plate. The two plates want to travel in opposite directions, they want to go straight into each other. This causes the pressure to build up over a long period of time, as the two plates push at each other.
As time progresses one of the plates will start to be bent downward under the other one because of the extreme force, however does not slip, just bends. This is because of the friction between the two plates is enough to allow them to bend, without slipping. This is a very slow but continuous movement, maybe only a few millimetres every year. Every fraction moved by the plates increases the build-up of elastic strain energy within the rock. The rock continues to store this energy from a few decades to a few thousand years. An earthquake will happen when the strain in the rocks exceeds that of the limit of the rocks. The fault then ruptures, moving a large distance in a short space of time.
The plates then snap back into a new position, forcing the already undercutting plate to dive down even further under the other. The collisions of two plates generally produce large forces in the plates. These forces result in the triggering of the earthquakes within the subduction zones. The frequency of earthquakes in Subduction zones is about the same as that in the mid-ocean ridges. This is because the plates cover the globe, and if they separate in one lace then in another place one-plate sinks below another. This means that the triggering of an earthquake at a divergent boundary triggers an earthquake at a convergent plate. Meaning that the frequency of earthquakes at Subduction zones is the same as at Mid-ocean ridges, which is very high.
The earthquakes at convergent boundaries are distributed at different points. The deep focus earthquakes occur along the already subducted plate. Shallow focus earthquakes occur just at the point where one plate starts to be thrust under the other. These earthquakes tend to be more common than the deeper earthquakes. This is shown on the iagram on the left. The red dots show the distribution of earthquakes at a convergent boundary. Continental shields are extensively flat tectonically stable interiors of the continents, composed of ancient rocks. Most of the stress that builds up by tectonic movements is released in earthquakes at the plate boundaries. However stress can also build up in the interiors of plates.
Old fault lines in the plates are weaker than the surrounding rocks, these old fault lines cover many continents, crossing all over each other. The old faults can slip if the stress becomes too much from recent plate movements, which will cause an nexpected earthquake. This can be a problem as many old fault lines are not known, and many are away from modern plate boundaries that exist today. This is potentially dangerous as many modern settlements may be at risk from earthquakes, even though they are not near modern day faults. The distribution of earthquakes at continental shields is not yet known, as scientists do not know whether these earthquakes will strike the same region within a plate.
The strength of these inter-plate earthquakes are relatively small, compared to boundary earthquakes. The frequency is also very small, the last major inter plate earthquake was in Latur-India in 1993. However they can catch regions totally unexpected because they can affect areas with no previous earthquake history. Also the energy of the earthquake is spread out further without losing as much. Due to the older hard rocks that transmit energy better, than the deformed broken younger rocks. This can cause more damage to a larger region. Earthquakes are common events and are happening all the time. They can be caused by many different factors within the earths interior.
Depending on the type of area that they happen in will determine the strength of the earthquake, and the frequency of earthquakes ithin the region. The distribution of earthquakes within an area will much depend upon what caused the earthquake to happen in the first place. We understand today how earthquakes are caused, and we can record where they happen every day of the year. This has helped us to learn and understand about earthquakes in much detail. We now only miss one important factor that we all would like to know, when and where the next one will be. In truth it must be said that today we are still not close to predicting earthquakes even with all the technology that is available.