Earthquakes

Earthquake is any sudden shaking of the ground caused by the passage of seismic waves through Earth's rocks. Seismic waves are produced when some form of energy stored in Earth's crust is suddenly released, usually when masses of rock straining against one another suddenly fracture and “slip.” Earthquakes occur most often along geologic faults, narrow zones where rock masses move in relation to one another.

When earthquakes occur under water there are huge (sometimes over 60 m high) waves - tsunamis bringing on land huge destruction.

The earthquake focus is the area of energy release. It occurs most often at a depth of 10 - 100 km. In the center of the focus there is a point called hypocentre.

The epicenter of the earthquake is the projection of the center of the focus on the earth surface. Around it is the area of greatest destruction

The intensity of earthquake manifestation on the Earth's surface is measured on the MSK-64 seismic scale having 12 conditional grades (1 to 4 points - weak earthquakes, (5-7) - strong, (8 to 10) - destructive, (11-12) - catastrophic ).

The consequences of earthquakes are extremely dangerous. They cause stretching, flow and subsidence of the ground, collapses, rockfalls, wide cracks, landslides, avalanches, mudflows, tsunamis and seiches; lead to damage and destruction of buildings, fires, explosions, emissions of harmful substances, transport accidents, failure of life support systems, cause great general damage, people death and injury.

Often after an earthquake there could be panic during which a person in fear does absurd and dangerous for himself and others things and is unable to take measures to save himself and help others. Panic is especially dangerous in places of congestion: at enterprises, in educational and children's institutions, hostels, venues for entertainment events, large residential areas.

Very seldom the cause of death is the direct movement (vibration) of soil. Most of the victims are the result of concussion, destruction of buildings and structures. That's what causes death, injuries in the earthquake: fall of bricks, chimneys, cornices, balconies, moldings, facing slabs, frames, lighting installations, equipment of some parts of building; flying out (especially from upper floors) broken glass; torn electric wires hanging or falling on the roadway; falling heavy items in the apartment; fires caused by gas leakage from damaged pipes and the closure of electric lines; panic. However, the number of victims can be significantly reduced if to prepare in advance for a possible earthquake (especially in seismic regions), to analyze actions and follow a number of recommendations.

All adult members of family (residents of house) should be able to turn off electricity, gas and water in the apartment, entrance, house, and also provide first aid, especially with trauma; prepare the most necessary things (objects) in advance and store them in a place known to all family members. This is a radio receiver with batteries, a supply of canned food and drinking water for 3 to 5 days, a first aid kit with a double stock of dressings and a set of drugs needed for chronically ill family members, a portable electric lantern, a bucket of sand, and an automobile fire extinguisher.

Documents should be kept in one easily accessible place, preferably near the entrance to the apartment; there it is advisable to have a backpack in which there should be a lantern, hatchet, matches, food, first-aid kit, candles, spare clothes and shoes (according to the season) for the whole family. If you have a garage, a garden house, if possible, use them as a refuge in the first days after strong earthquake; here you can store a supply of food and clothing.

Cabinets, shelves, racks must be firmly attached to walls and floor; furniture to place so that it could not fall on sleeping places, block the exits from the rooms, block the doors; heavy things lying on shelves or furniture (including mezzanines), securely fastened or moved down; do not arrange shelves over bunks, entrance doors, plates, sinks, toilets; close the front of shelves with utensils, secure chandeliers and fluorescent lights well.

The entrance to the apartment, corridors and staircases shouldn't be cluttered up with things.

Containers with flammable substances and corrosive liquids should be kept securely sealed and stored so that they can not fall and break when the building oscillates.

It is necessary to conduct periodic trainings, to think over how to improve safety of children, elderly people, disabled people and patients; in advance to determine the safest places (in the apartment, at work, near the workplace), where you can wait out shocks.

You should hide from falling objects and pieces under solid tables and beds.

In case of a strong earthquake it is better to leave building. You can not use lift, therefore, there could be many people in the doors and the aisles, and this can prevent rapid exit from building. You can get out through window openings of the ground floor.

You can not light matches, candles and use lighters during or immediately after earthquake.

If the earthquake has caught you while traveling in a car, stop where your car does not interfere with the other transport and stay in it.

After the earthquake, be sure there are no injuries, examine the surrounding people and, if necessary, help them; seriously wounded should not be moved from the place unless they are endangered by extreme danger (fire, collapse of structure, etc.); help people who have fallen into easily removable blockages, and be extremely careful; if they require additional medical and other special assistance, then wait for it; ensure the safety of children, sick, old people, calm them. Use the phone only in case of emergency (the telephone network will be overloaded).

You must be ready for new shocks. They can happen in a few days, weeks and even months. It is impossible to say in advance when the danger of their recurrence has completely passed.

When the epicenter of the earthquake is in the sea, it is necessary to leave immediately the coastland.

If you are in the rubble:

1.

2. If there are no serious injuries, turn face down and try to move to a safer place. Strengthen your shelter with fragments of stones, exclude movement of plates, unbend sharp pieces of armature.

3. In whatever condition you are, try to let somebody hear - knock on pipes, fittings, etc.

4. Find the source of air intake; expand and strengthen the way to it (Air consumption per breath: 1 person - 1 m³/hour).

5. Do not lose hope of salvation; hold out until the arrival of rescuers! Even in the most difficult obstructions people remain alive.

Landslides, sill flows

Landslides are the displacement of rocks masses down the slope under the influence of gravity. They are formed in different rocks as a result of their imbalance and weakeness, and are due to both natural and artificial (anthropogenic) causes. Natural causes include: increase of slopes steepness, underwashing of their bases with sea and river waters, seismic shocks, etc. Artificial causes are: destruction of slopes by road excavations, excessive removal of soil, deforestation; incorrect choice of agrotechnics for agricultural land on slopes, etc. According to international statistics, up to 80% of modern landslides are connected with human activities (anthropogenic factor).

Landslides occur with the slope of 10° or more. On clay soils with excessive moistening they can be even at a steepness of 5-7°. Landslides are classified according to force, activity, mechanism and power of the landslide process, place of formation.

Sill flow — a rough mud or mudflow suddenly arising in the channels of mountain rivers, tracts, on steep mountain slopes.

Sill emerges as a result of combining at least three factors:

> existence or appearance of large water reserves at a sufficient height;

> presence of steep drain;

> sufficiently large reserves of stones, boulders, fragments of rocks, which will form the body of mudflow.

The process of formation and development of sills passes through 3 stages: the first stage is accumulation in the channels of mudflow basins of loose material due to rocks weathering and mountain erosion; the second stage - movement of loose mountainous materials along mountain beds from high areas to low ones; the third stage is concentration of mudflow cone in mountain valleys.

The movement of sill is a continuous stream of mud, stones and water. Sill flows can carry individual fragments of rocks with a mass of 100 to 200 tons or more.

The reasons of sills emergence are heavy rains, washing of reservoir bridges, dumping of water by tornado, intensive thawing of snow and ice, as well as earthquakes and volcanic eruptions.

The main striking factors of these disasters are the impacts of moving masses of rocks, as well as flooding of previously free space. As a result, residential buildings and other structures are collapsing; settlements, objects of the national economy, agricultural and forest lands are under rock masses; river beds and overpasses are overlapping; people and animals die; landscapes are changing. The railway traffic is blocked. Bridge supports, rail tracks, road coverings, power and communication lines, gas and oil pipelines, hydroelectric power stations, mines and other industrial enterprises are destroyed and damaged.

Sill flows lead to flooding and blockages of agricultural crops with detrital materials. Arable lands, located below landslide areas, are often swamped. All the above mentioned leads not only to the loss of crops, but also simply to land loss in agricultural rotation. The significant damage can be done to the cultural and historical heritage of peoples inhabiting mountainous areas.

The population living in the landslide, mudflow and rockslide danger zones should know the focus, possible directions and main characteristics of these dangerous phenomena. On the base of the forecast data, people are informed in advance about the identified landslide, mudflow, rockslide areas and possible areas of their activity, periods of mudflow passage, as well as the procedure for signaling the threat of emergency situation.

For emergency exit it is necessary to know the way of movement to the nearest safe places. The natural safe ways for immediate evacuation are the slopes of mountains and hills, not subject to landslide processes or those between which there is a dangerous path. When climbing to safe slopes, you can not use valleys, gorges and excavations, because they may form side channels of the main mudflow. During evacuation help should be provided to patients, the elderly people, the disabled, children, weak.

Hurricanes, storms, tornadoes

Hurricane is the wind of great destructive power and considerable duration. The lower limit of wind speed on the Beaufort scale in the hurricane is 33 m/s (120 km/h), although it can exceed 200 km/h. Hurricane is 12 points on the Beaufort scale. When spreading over the sea it produces waves more than 12 m in height; destruction of ships, destruction of coastal structures.

On land it destroys buildings, communication lines and power lines, transport communications, bridges, tears up trees, devastates fields. The principal feature of hurricane is the straight-line (as a ray of light) spread of air masses. Therefore the idea of an air shadow arises which is very useful in finding the place of shelter. It is better to take shelter in such shadow, that is, behind obstacles opposing the heavy wind, or in recesses letting the wind go.

Windstorm (storm) - a kind of hurricane, inferior to it in force. (Wind speed is 70 - 115 km/h, 8 - 11 points on the Beaufort scale.) On the ground surface it causes erosion and soil weathering together with crops seeds, drying and filling of shoots, revealing the root system, etc.

Whirlwind (tornado) - rising vortex of rapidly rotating air, which looks like earth (water) column with the diameter up to hundreds of meters with the vertical (sometimes curved) axis of rotation. Inside the pillar is vacuum (low pressure), which causes absorption of everything on tornadoes way (soil, sand, water, etc.).

The main types of people injury are closed injuries of parts of body, bruises, fractures, brain concussions, injuries accompanied by bleeding.

Immediate warning should be started in the case of storm warning:

> strengthen inadequate structures and cranes, billboards and structures;

> close doors, attic spaces, dormer windows, vents in buildings;

> board large windows and showcases;

> doors and windows on the leeward side should be left open (the seeming unusuality of such action is explained by the fact that when the air flow is obstructed by an obstacle (house), the area of low pressure is created on the back of it, and the resulting pressure difference must be leveled);

> remove items from roofs, balconies, loggias; if dropped, they can cause injuries;

> make supply of water, food, medicines (especially bactericidal medicines (iodine, green antiseptic, etc.) and dressings.

In city billboards, broken wires under pressure, old-age poplars are of great danger.

The safest place during the hurricane is civil defense protective structures, cellars and interior spaces of the first floors of brick buildings.

If hurricane, storm or tornado caught you in open space, it is best to hide in a ditch, pit, ravine, any pothole - to lie down on the bottom and snuggle up to the ground.