There are two main processes.

a) Volcanoes are made when two tectonic plates come together. When these two plates meet, one of them (usually the oceanic plate) goes under the continental plate. Afterwards, it melts and makes magma (inside the magma chamber), and the pressure builds up until the magma bursts through the Earth’s crust.

b) The second way is when a tectonic plate moves over a hot spot in the Earth's crust. The hot spot works its way through the crust until it breaks through. The places known as hot spots in geology are volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the mantle elsewhere.

Volcanic activity

A traditional way to classify or identify volcanoes is by pattern of their eruptions. Those volcanoes which may erupt again at any time are called active. An active volcano is currently erupting, or it has erupted in the last 10,000 years. Those that are now quiet called dormant (inactive). A dormant volcano is "sleeping," but it could awaken in the future. Those volcanoes which have not erupted in historical times are called extinct. An extinct volcano has not erupted in the past 10,000 years.

Edinburgh Castle on the site of an extinct volcano, c. 1581

Memorize the words:

bedrock – корінна, підстильна порода conduit – підвідний канал sill – пластова інтрузія to emit – випускати, випромінювати flank – бік, сторона throat – горло lava flow – лавовий потік vent – вхідний (вихідний) отвір to burst – прориватися, вибухати to feed (fed, fed) – забезпечувати, постачати, to identify – ототожнювати(ся) pattern – зразок currently – зараз, у цей час dormant – бездіяльний, що спить extinct – згаслий

Answer the questions:

1. By what two main processes are volcanoes formed?

2. When two tectonic plates meet, which of them usually goes under the other?

3. What makes magma within the magma chamber?

4. What are hot spots thought to be?

5. What are the three types of volcanoes according to the pattern of eruption?

6. Which volcanoes are called active?

7. Why do we say that a dormant volcano “is sleeping”?

8. Which volcanoes do we call extinct?

Lesson 10

Seismology

Seismology is the study of what is under the surface of the Earth by measuring vibrations on the Earth's surface. A person who does this is called a seismologist. It is part of the science of geophysics, which studies the physics of the processes that formed the Earth and other planets. Seismology is done by seismologists and geophysicists using devices called geophones, hydrophones or seismometers to pick up the vibrations. Seismology can either be passive, just listening to vibrations caused by earthquakes and volcanic activity, or active, using small explosive charges to send vibrations into the ground. Seismic detectors come in two types, one which measures up and down vibrations, and one which measures side to side vibrations. Both types use an arrangement of a magnet and a coil of wire which will convert the vibrations into an electrical signal which can be stored in a computer for analysis. Seismologists can find the location of earthquakes by plotting received vibrations on a map. They can also pick up underground nuclear tests, and this is what many of the seismic recording stations were set up for. They can also examine the crust in a seismic survey to find information about layers of rock, locate oil or gas fields and to get information about the internal structure of volcanoes.

Memorize the words:

to measure – вимірювати device – пристрій, прилад to pick up – відбирати, добирати explosive – вибуховий charge – заряд coil – котушка wire – дріт, провід to convert – перетворювати to store – накопичувати, зберігати to plot – накреслювати план to receive – одержувати, отримувати nuclear – ядерний to record – записувати, реєструвати to set up – встановлювати, розміщувати survey – огляд, обслідування to locate – визначати місцезнаходження

Answer the questions:

1. What devices do seismologists and geophysicists use? What for?

2. What is passive seismology?

3. How does active seismology work?

4. What are the two types of seismic detectors?

5. How do seismic detectors work?

6. What can seismologists do?

 

Lesson 11

Earthquakes

A replica of (78–139 AD) seismometer. It employed a pendulum sensitive to ground tremors; placed in Luoyang in 133, it detected an earthquake 400 to500 km away in Gansu.

Damage from the San Francisco, California earthquake in 1906.

An earthquake (also known as a quake or tremor) is a violent movement of the rocks in the Earth's crust. Earthquakes are usually quite brief, but may repeat over a long period of time. They are the result of a sudden release of energy in the Earth's crust. This creates seismic waves, waves of energy that travel through the Earth.

There are large earthquakes and small earthquakes. Big earthquakes can take down buildings and cause death and injury. The study of earthquakes is called seismology. Seismology studies the frequency, type and size of earthquakes over a period of time.

When the earth moves offshore in the ocean, it can cause a tsunami. A tsunami can cause just as much death and destruction as an earthquake. Landslides can happen, too. This is an important part of the Earth's cycle.

Earthquakes are measured using observations from seismometers. The magnitude of an earthquake, and the intensity of shaking, is measured on a numerical scale. On the scale, 3 or less is scarcely noticeable, and magnitude 7 (or more) causes damage over a wide area.

The ancient Chinese also used a device that looked like a jar with dragons on the top surrounded by frogs with their mouths open. When an earthquake occurred, a ball fitted into each dragon's mouth would drop out of the dragon's mouth into the frog's. The position of the frog which received a ball indicated the direction of the earthquake.

Memorize the words:

earthquake – землетрус replica – точна копія to employ – наймати на роботу, використовувати pendulum – маятник sensitive – чутливий, сприйнятливий tremor, quake – тремтіння, дрижання to detect – виявляти,викривати brief – короткий sudden – раптовий, несподіваний release – вивільнення, звільнення wave – хвиля frequency – частота, частотність offshore – у відкритому морі magnitude – величина, розмір numerical – числовий, цифровий scale – шкала scarcely – ледве noticeable – помітний, гідний уваги jar – глечик to fit in – пристосовувати

Answer the questions:

1. What is an earthquake? 2. What is the cause of earthquakes? 3. What creates seismic waves? 4. What does seismology study? 5. What do earthquakes offshore create? 6. How is magnitude of earthquakes measured? 7. How did the seismometer of the ancient Chinese work?

 

 

Lesson 12

Earthquake-proofing

Some countries, such as Japan or parts of a country like California in the United States, have a lot of earthquakes. In these places it is a good practice to build houses and other buildings which will not collapse during an earthquake. This is called seismic design or "earthquake-proofing".

The Haitian National Palace after at the 2010 Haiti earthquake.

Earthquake-proof buildings are constructed to withstand the destructive force of an earthquake. The ability of a building to withstand the stress of an earthquake depends upon its type of construction, shape, mass distribution, and rigidity. Different combinations are used. Square, rectangular, and shell-shaped buildings can withstand earthquakes far better than skyscrapers. To reduce stress, a building's ground floor can be supported by extremely rigid, hollow columns, while the rest of the building is supported by flexible columns located inside the hollow columns. Another method is to use rollers or rubber pads to separate the base columns from the ground, allowing the columns to shake parallel to each other during an earthquake.

To help prevent a roof from collapsing, builders make the roof out of light-weight materials. Outdoor walls are made with stronger and more reinforced materials such as steel or reinforced concrete. During an earthquake flexible windows may help hold the windows together so they don’t break.

Memorize the words:

earthquake-proof – сейсмостійкий, антисейсмічний withstand – протистояти distribution – розподіл rigidity – жорсткість, твердість flexible – гнучкий roller – вал rubber pad – гумова подушка

Answer the questions:

1. In which countries are earthquakes frequent?

2. What is called “seismic design”?

3. What does the ability of a building to withstand the stress of an earthquake depend on?

4. Which form of a building is more earthquake-proof? Which is less?