Buildings may suffer little damage if earthquakes just shifted the ground vertically since all structures are built to withstand vertical forces (those related with gravity) to some extent. However, rolling seismic waves, particularly Love waves, inflict enormous horizontal stresses on standing buildings. These stresses can cause severe damage or collapse of a building.
In order to prevent damage from occurring or reduce the severity of any future damage, buildings are designed with resistance features. An important factor in designing these features is understanding how earthquakes affect different types of buildings.
For example, buildings with thick floors and heavy construction tend to suffer more damage during an earthquake because they are unable to move like lighter-weight structures. Modern buildings are also designed to be seismically resistant, although sometimes this means making compromises that may not be desired by property owners. For example, steel frames with concrete floors can be more resistant than traditional brick or stone buildings, but the latter tend to cost less to build.
The main goal of seismic design is to provide sufficient resistance so that any damaged parts will fail before excessive stress is placed on other parts of the structure. This ensures that no further damage occurs once the initial shock has passed. A qualified architect or engineer should be hired to help develop a plan for ensuring the safety of your building. They should be able to advise you on what type of earthquake protection is available and how it can be implemented to meet your needs and budget.
Earthquakes subject structures to horizontal loads, which can induce structural failure and vertical collapse, or cause non-structural parts of the building, such as walls, to break off and fall. The horizontal load caused by an earthquake is transmitted through the foundation to the structure's underlying soil. If the soil is soft, then it will compress under the weight of the building and cause damage to foundations; if it is hard, then it will remain stable.
The force of gravity can also cause buildings to collapse. In cases where there is no seismic activity and the building was not damaged in any way, its weight will eventually cause its floors to collapse, leading to a pile-up of debris that could block exitways and cause more damage down the road.
When a building collapses due to natural causes, scientists use the data gathered from the scene of the disaster to create models that help them understand how and why this type of event occurred. These models can then be used to predict the risk of similar events happening again in the future. Collapses due to unnatural causes are always a mystery, but scientists do their best to learn from these incidents too so they can reduce the risk of people being hurt next time.
The majority of the damage associated with earthquakes is caused by human-made structures: individuals trapped by fallen buildings or cut off from crucial water or electricity supplies. When the earth underneath a structure shakes, the energy of the quake's waves travels through it, causing the building to wobble. If the building is made of solid material, such as stone or concrete, then some of the force of the wave action will be transmitted into the ground, but if the building is made of hollow materials, such as wood or steel, then it will vibrate against the ground and transmit movement into it. This type of damage is known as seismic shaking.
Additionally, large buildings are highly susceptible to damage due to their size. Even though they may appear to be sturdy, wide boards or columns inside the building's structure may actually be holding up thin sheets of glass or plastic instead. These components make up the exterior walls or floor-to-ceiling windows of the building, respectively. If enough force is applied to them, then they will break under the weight of the building above them.
Finally, earthquakes can also cause structural damage to existing buildings by altering their alignment with respect to the Earth's gravitational field. For example, an earthquake might push or pull a building over on its side, which would cause it to suffer damage equivalent to being in an accident in which it was rolled over twice.
When developing earthquake-resistant structures, safety specialists advocate enough vertical and lateral stiffness and strength—particularly lateral stiffness and strength. Structures are more resistant to vertical movement induced by earthquakes than to lateral, or horizontal, movement. So the first step in designing an earthquake-resistant structure is to determine how much risk of damage is acceptable. If the answer is "very little" then you need to pay close attention to the design requirements for lateral stiffness and strength.
At a minimum, an earthquake-resistant structure must be designed to meet the requirements of its governing code. But the designer also needs to take into account other factors that may influence the effectiveness of the structure. These include the type of construction used in the building, its location, the nature of any existing seismic activity near the site, as well as environmental conditions such as wind, heat, and humidity. A structural engineer with experience dealing with these issues should be consulted to develop the most effective strategy for ensuring building safety during an earthquake.
Vertical Seismic Force (VSF) is the main cause of damage in buildings. VSF is the product of peak ground acceleration (PGA), which is the maximum rate of change of height of the Earth's surface with respect to time, times the distance from the center of the Earth to the point on the surface where PGA is measured. For example, if the Earth suddenly dropped two kilometers 1.
It may appear evident that earthquakes do the majority of their damage by shaking the ground. If the building is made of solid material, such as stone or concrete, then its weight will try to keep up with the movement of the earth, but if the building is constructed out of lighter-weight materials, such as wood or steel, then it will want to dance along with the rest of the world. The stronger the building, the more damage it can do before collapsing.
The way a building responds to an earthquake is determined by many factors. The type of construction used to build a house will affect how much it will sway in the wind and under pressure from heavy objects on top of it. Stronger materials can be used to make a house stiffer and less likely to collapse. The closer together the wooden beams inside a house are spaced, the harder they are to move independently when an earthquake strikes, so rooms at the end of a hallway or near the doorways usually have the thinnest walls. These are the first things to break away if you push hard against them during an earthquake.
People living in houses built after 2004 should check whether their properties are classified as "highly susceptible" to seismic activity.
The majority of structures in California's seismic country are built to withstand earthquakes. Large structures can be put on rollers to move with the earth. To withstand the stress of the waves, buildings can be built atop layers of steel and rubber. These materials compress when the earth shakes them down from above, absorbing some of the force of these waves.
When a major earthquake strikes, the first wave or impulse tends to be the most severe. It is called "the initial shock." This is followed by several smaller aftershocks, sometimes including two very close together. The distance between these aftershocks varies but usually there is more than enough time between them for people to react to the first one.
During an earthquake, it is important to escape quickly from buildings. Otherwise, you could be killed by falling bricks, glass, or furniture. After the initial shock, follow standard earthquake safety procedures to prevent further damage and save yourself.