Earthquake
* All earthquakes produce a series of seismic waves that travel through the earth.
* Every earthquake has a unique total energy, and therefore a unique magnitude
  - an epicenter
  - produces waves of motion in the earth, called seismic waves
* Is a sudden motion or trembling in the Earth.
* Learn what happens when the earth moves.
* Many earthquakes correspond to the overcoming of the rupture load of the deep rocks.
* Many earthquakes occur each year in the United States
  - near the rift valley in the center of the ocean
  - when the earth's crustal plates grind and shift along one another
  - where the earth's crustal plates grind and shift along one another
* Most earthquakes affect areas
  - countries
  - entire nations
  - landscapes
  - nuclear plants
  - populous urban areas
  - alter habitats
* Most earthquakes are breaks in the earth's crust, caused by the slow movement of mantle rock
  - caused by movement
  - minor tremors
  - on the edges of tectonic plates, as they push or slide by other plates
  - the result of the sudden elastic rebound of previously stored energy
  - violet, with most of their energy in the short-period range
* Most earthquakes cause damage
  - disasters
  - disturbances
  - tsunamis
  - widespread damage
  - contribute to health problems
* Most earthquakes contribute to mental health problems
* Most earthquakes destroy environments
  - infrastructures
  - towers
  - form part of a sequence , related to each other in terms of location and time
  - generate waves
* Most earthquakes have energy
  - epicenters
  - impact
  - magnitudes
  - impact physical environments
* Most earthquakes occur along faults, or breaks, in the Earth's crust
  - plate margins
  - the edge of the oceanic and continental plates
* Most earthquakes occur at plate boundaries
  - the boundaries where the plates meet
* Most earthquakes occur in areas
  - narrow belts
  - near the edges of tectonic plates
* Most earthquakes result after the sudden movement of one mass rock relative to another mass
  - from movement
* Most earthquakes result in displacement
  - separation
  - rupture faults where two tectonic plates slide by each other
  - trigger nuclear disasters
* Some earthquakes affect chinas
  - are caused by landslide
* Some earthquakes cause avalanches
  - death
  - submarine avalanches
  - turbidities
  - create habitats
  - depend on severity
  - destroy homes
  - follow quakes
* Some earthquakes generate earthquakes
* Some earthquakes have degrees
  - long reoccurrence periods
  - kill cedar
  - move corals
* Some earthquakes occur at plate boundaries
  - during nights
  - in rings
* Some earthquakes precede earthquakes
  - underwater landslide
  - raise safety
* Some earthquakes result in death
  - liquefaction
  - take places
* accompany tsunamis.
  - buildings quite differently than natural disasters like hurricanes or tornadoes
* affect populous areas
* also cause water pipes to burst, gas lines to break, and highways to crumble
  - have an impact
* also occur along plate boundaries
  - where one plate slides under the other, as is happening in southern Alaska
  - play a major role in upsetting the delicate balance of geysers
  - result from bending and tearing stresses which occur as the plates subduct
  - shake the ground within a certain range
  - strike many countries around the world
* alter breed habitats
* are a common occurence along the Pacific Rim
  - occurrence, because El Salvador lies right along a major fault line
  - different type of disaster from fire, auto, or life coverage
* are a fact of life in California
  - natural phenomenon
  - naturally destructive effect of Earth's constantly changing surface
  - near-daily experience in many parts of Turkey
  - part of living in the Pacific Northwest
  - rare phenomenon in Southern Pakistan
  - serious threat to people all over the world
  - way of life in California
  - widespread hazard in the United States
* are also a result of plate tectonics
  - compression waves
* are among the most deadly and expensive natural disasters affecting humankind
  - destructive natural disasters
  - powerful events on earth, and their results can be terrifying
  - another common mechanism that can trigger mass movement
  - both physically and emotionally devastating to the population
  - broad, areal events that move through time and space
  - by far the most deadly natural disasters in the world
* are caused by movement
  - tectonic movements in the Earth's crust
  - the movement of the earth's surface
  - when a fault breaks suddenly
* are common along active major fault systems
  - transform faults
* are common in Indonesia
  - many regions of the United States and the world
* are common in the continental crust in the Pacific Northwest
  - south and south-west
  - natural events
  - on many active volcanoes
  - symptoms of plate movement
  - throughout Ecuador as the land is being formed
  - common, as Japan lies in the earthquake zone ringing the Pacific Ocean
  - dangerous because they strike without warning
  - developed in the outer crust of the earth
* are frequent in the Moluccas, and most of the islands are mountainous
  - occurrences throughout the world
  - fundamentally related to strain in the earth's crust
  - just one way of showing that the earth is undergoing change
  - measured using observations from seismometers
  - minor events for the planet, even if they are major events for human civilization
  - more dangerous than hurricanes
* are most frequent where two or more plates meet
  - frquent along plate boundaries
  - likely to occur where tectonic plates are pushing against each other
* are movements along cracks or faults in the Earth's crust
* are natural disasters
  - hazards
* are one of the more dramatic earth events
  - most costly and deadly natural disasters
  - world's most deadly natural disasters
* are part and parcel of California life
  - of the lord's plan for the progression of the earth
  - physical phenomenons
  - predominantly natural events
  - produced by the descending plate
  - second, followed by cyclones, tsunamis, volcanoes, and mudflows
  - special kinds of natural disasters
  - strong evidence that pieces of Earth shift around with respect to other pieces
* are the Earth's natural means of releasing stress
  - agents of brittle rock failure
  - cause of severe damage to human beings and property
  - earth's way of releasing energy stored in plate tectonics as they move
  - most insidious of all natural disasters, putting aside man-made disasters
  - only thing that kills
  - result of many different things
* are the result of slow-moving processes that operate within Earth
  - that perate within Earth
  - sound waves moving through the earth
  - stress accumulation and slippage along faults
  - results of the shaking that occurs then
  - signals of breaking rocks
  - unexpected events
  - unknown in Honduras, the only country without active volcanoes in Central America
* are unpredictable and can occur at any time of day throughout the year
  - very useful to humans because they provide a picture of what's going on underground
  - vibrations of the earth caused by a rapid release of energy
  - virtually inescapable in the continental United States
  - waves of energy
  - weather related
  - when parts of the earth slide or move
* are, of course, all about the earth moving.
* can also bring landmasses together, which can have serious consequences.
* can also cause a phenomenon known as liquefaction
  - tidal waves
  - tsunamis, which in turn cause massive flooding on coastal areas
* can also occur within plates, although plate-boundary earthquakes are much more common
  - take human lives
  - topple bridges, towers and dams as well as trigger large landslides
* can also trigger landslides , and occasionally volcanic activity
  - and generate huge ocean waves called tsunamis
* can be even smaller and even larger
  - frightening events
  - landslide triggers
  - very mild or very destructive
  - violent enough to toss people around and destroy whole cities
* can cause a tsunami
  - drastic fluctuations in the underground plumbing system
  - fires by damaging electrical power or gas lines
  - improperly secured water heaters to move or topple
* can cause the most large-scaled destruction
  - soil to liquefy
  - water heaters to fall over causing leaking or fires
  - create tsunamis that devastate coastlines
* can destroy settlements and kill many people
  - towns and cities instantly
  - flatten whole cities
  - generate many landslides
  - happen anywhere
* can happen at any time of the year
  - in many places, although they are concentrated in certain areas
  - indicate where magma is moving
  - make doors slam open and shut and tip over office files and bookcases
  - occur almost anywhere
* can occur anywhere in the United States
  - state of Utah
* can occur at any time of the year and at any time of the day or night
  - in any area of the world
  - virtually anywhere
  - when the ground becomes cracked
  - precede an eruption by years, months, days, and, in a few cases, hours
* can produce both kinds of waves
  - some of the most severe loads that fixed structures experience
  - range from tiny, undetectable tremors to huge, devastating disasters
  - result in rapid downward displacement of the land surface
  - rip apart the earth and destroy infrastructure along the way
  - set off fire alarms
  - start avalanches, as well as noise from heavy machinery
* can strike any location at any time
  - anytime and almost anywhere
  - suddenly, and without warning
* can trigger a multitude of other natural disasters
  - tsunami, landslides and volcanic eruptions
  - landslides that cause great damage and loss of life
  - up root trees, cause fires and create trenches in the earth
* cause a lot of devastation, thereby causing great loss of life and property
  - and respond to stress change
  - excessive vibration, but their effects are very brief and almost transient
  - shifts in the plumbing systems' circulation and as a result, temperatures change
* cause the earth to become more compact and spin slightly faster
  - ground to vibrate, which means that it moves back and forth
  - waves to travel through the earth
* caused by subduction can lead to tsunamis.
* come in clusters
  - many forms
* commonly occur along plate boundaries
  - in volcanically active areas
  - on fault lines
* constitute one of the greatest natural hazards to human society.
* destabilise slopes by shear stress thereby weakening the structure of slope material.
* destroy areas
  - buildings and infrastructure and often cause heavy loss of life
  - neighbor areas
* devastate cities.
* differ in the strength and depth at which they occur.
* do occur, however, within the subducting oceanic plate.
* effect the avalanches landslides and mudslides in the same way.
* generally occur without warning.
* generate a variety of waves that travel through the Earth.
* generate seismic waves that can be measured as they cross the globe
  - which travel through the earth
  - three types of seismic waves
  - two types of motions or waves in the earth
  - waves that travel through the Earth's interior
* go on almost continuously.
* happen all the time
  - at night because the rocks are shaking in fear
* happen every day all over the world
  - on faults
* happen when the rocky plates that make up the earth s crust shift suddenly
  - two tectonic plates rub against each other in a violent fashion
* happen without warning, floods come in wintertime and fires in autumn
* has a narrower term of Seismic event.
  - immediate impact
  - measures of size depending on either the destruction caused or the energy released
  - the potential to reorganize flow, changing the chemical environment
  - their own sounds
* hit countries.
* impact environments
* indicate the develop of a crack and movement of magma toward the surface.
* keep the geysers active.
* loads push and pull horizontally on a structure.
* mostly happen along the boundaries between tectonic plates.
* occur a. in the magnetosphere.
* occur all over the world but there are places where they happen more often
  - the time all over the world, both along plate edges and along faults
  - almost everywhere in the world
* occur along fault lines and are unpredictable
  - the boundaries of tectonic plates
  - as a result of stresses on rocks
  - transform plate boundaries
* occur because of a releasing of stress or pressure on the rocks
  - sudden release of stored energy
  - the Earth's plate are in motion
  - continually around the globe all the time
  - daily around the world
  - due to movement of tectonic plates, which results in breaking of rock
* occur due to the break up of the descending plate as it pushes into the asthenosphere
  - pressure, and breaking of rock
* occur every day some place in the world
* occur in a pattern determined by movement of tectonic plates
* occur in the brittle zone of the crust
  - southern parts of the country
  - mainly along plate boundaries
  - most frequently where plate interact
  - mostly at oceanic ridges and trenches
* occur on faults or cracks in the earth s crust
  - that are preferentially located along plate boundaries
* occur throughout most areas of the entire state
  - the eastern upland region , in addition to the Pacific margin
  - very suddenly, causing massive damage and seriously affecting people's lives
* occur when cracks or fissures in the Earth's surface, called faults, move
  - plates collide
  - rocks break suddenly in response to various geologic forces
  - the earth's crust is stressed to the breaking point
  - there slip or break between two tectonic plates
  - two pieces of the earth snap past each other along a fault
* occur where plates grind and rub against each other at their edges
  - move relative to one another
  - the edges of plates run into one another
  - with great frequency, resulting in massive loss of life and property
  - within the Earth, and the depth of rupture initiation is the hypocentral depth
  - without warning, shaking the ground and everything on it
* often change the function of a geyser
  - happen along faults
  - induce landslides that can cause additional damage
  - occur at faults
* originate from the fault at the curve of the Carpathian mountains
  - many miles underground, well below the zone affected by weather
* play a major role in the hot spot formation.
* pose California's greatest natural threat.
* pose a different primary threat, that of falling structure and debris
  - risk to humans
* present one of the most serious natural hazards with which mankind has to cope
  - the greatest loss potential to life, injury and economic welfare in the state
* processes Rupturing rocks release huge amounts of energy.
* produce many waves caused by the plate or rock movements beneath the surface
  - three different types of seismic waves
* propagate as waves in the solid earth.
* provide the energy source, and the means to examine the interior of the Earth.
* radiate seismic energy as both body and surface waves.
* really pose little direct danger to a person.
* recorded by seismographic networks are mapped and indicate the location of a fault.
* regularly shake the frozen ground.
* release a tremendous amount of energy, which is why they can be so destructive.
* release energy when they happen
  - large amounts of energy
  - their energy through vibration or waves of energy
* represent one of the most destructive natural hazards known to man
  - the release of strain accumulated within the volcanoes
* require preparation.
* reshape life by causing mass extinctions.
* result from crustal strain, volcanism, landslides, and collapse of caverns
  - movement at faults and plate boundaries
* shake humans and their built environment
  - the ground sideways and tip things over
* show a marked spatial distribution.
* sometimes leave basins in the earth that become lakes.
* strike northern regions
* strike suddenly, and without warning
  - violently and without warning
  - without warning and can happen at anytime during the year
  - without warning and after shocks intensify fright and despair
* take a terrible toll, in life and property damage, when a large one hits
  - place miles underground, and can happen at any time in any weather
* tend to be concentrated at the boundaries of Earth's plates
  - occur near fault zones
  - reoccur along previous faults because they are weak zones
* threaten our assumptions about the stability of life.
* trigger disasters
* typically occur repeatedly along the same faults
  - several miles deep within the Earth
* usually last less than a minute.
* usually occur during periods of seasonal change
  - pretty deep within the earth
  - where two plates are running into each other or sliding past each other
* vary enormously in magnitude
  - in intensity, depending on many factors
* violently tear apart the land, turn buildings to rubble, and trigger devastating fires.
+ Azores, Geography: Islands of Macaronesia :: Islands in Europe :: Geography of Portugal
  * All the islands have volcanic origins, although some, such as Santa Maria, have had no recorded activity since the islands were settled. Earthquakes are common on most of the islands.
+ Central Cross-Island Highway, Closing the damaged highway: Roads :: Transport in Taiwan
  * The highway goes through mountains. Rocks often fall and there can be landslides. Earthquakes also damage the highway.
+ Earthquake, Causes of earthquakes: Plate tectonics
  - Earthquake clusters
  * Most earthquakes form part of a sequence, related to each other in terms of location and time. Most earthquake clusters consist of small tremors which cause little to no damage, but there is a theory that earthquakes can recur in a regular pattern
+ Geology, Types of rock, Faults
  * All three kinds of rock can be changed by being heated and squeezed by forces in the earth. Geologists can learn a lot about the history of the rock by studying the patterns of the fault lines. Earthquakes are caused when a fault breaks suddenly.
  * Earthquakes are measured using observations from seismometers. The magnitude of an earthquake, and the intensity of shaking, is measured on a numerical scale.
+ Subduction
  * Subduction' is when two tectonic plates meet. One of the plates is pushed under the other into the Earth's mantle. Subduction causes the most powerful earthquakes in the world. Earthquakes caused by subduction can lead to tsunamis.