What is amplification of ground motion?
The characteristics of earthquake shaking are affected by the local site conditions. The effects of the local soil conditions are often quantified via an amplification factor (AF), which is defined as the ratio of the ground motion at the soil surface to the ground motion at a rock site at the same location.
What is ground amplification of seismic waves?
Seismic waves travel faster through hard rocks than through softer rocks and sediments. The softer the rock or soil under a site is, the larger the wave. Softer soils amplify ground motion.
What is site amplification?
ABSTRACT : Site amplification essential for seismic zonation is defined here as a peak value of spectrum ratio between ground surface and a base layer. The value of Vs was evaluated from fundamental mode frequency and a thickness of equivalent surface layer in which peak amplification was exerted.
What is soil shake amplification?
Shaking levels at a site may be increased, or amplified, by focusing of seismic energy caused by the geometry of the sediment velocity structure, such as basin subsurface topography, or by surface topography.
What is material amplification?
Material amplification: Intensity (amplitude of vertical movement) of ground shaking more severe in unconsolidated materials.
What are the 3 main factors that determine the amount of earthquake damage?
When an earthquake strikes, the intensity of earthquake shaking determines the severity of damage. In turn, the main factors affecting earthquake shaking intensity are earthquake depth, proximity to the fault, the underlying soil, and building characteristics—particularly height.
What is the site amplification factor?
2016) amplification induced from site effects has been recognized as the major cause of structural collapse. In this study, seismic amplification is measured with an amplification factor (AF), defined as the ratio of response spectra between soil surface and outcropping reference rock.
What do you mean by amplification factor?
The amplification factor, also called gain , is the extent to which an analog amplifier boosts the strength of a signal . Amplification factors are usually expressed in terms of power . The decibel (dB), a logarithmic unit, is the most common way of quantifying the gain of an amplifier.
Which soil type has the strongest amplification of shaking?
Five soil types each have different effects on seismic waves. Water-saturated mud has the strongest amplification of shaking.
What is ground shaking?
Ground shaking is a term used to describe the vibration of the ground during an earthquake. Ground shaking is caused by body waves and surface waves. As a generalization, the severity of ground shaking increases as magnitude increases and decreases as distance from the causative fault increases.
What is the purpose of amplification?
In molecular biology, amplification is a process by which a nucleic acid molecule is enzymatically copied to generate a progeny population with the same sequence as the parental one. The most widely used amplification method is Polymerase Chain Reaction (PCR).
What causes the amplification of the shaking during an earthquake?
amplification Shaking levels at a site may be increased, or amplified, by focusing of seismic energy caused by the geometry of the sediment velocity structure, such as basin subsurface topography, or by surface topography.
How to calculate the ground motions of an earthquake?
Procedures for Estimating Earthquake Ground Motions Procedures for Estimating Earthquake Ground Motions PROCEDURES FOR ESTIMATING EARTHQUAKE GROUND MOTIONS High-altitude view of the San Francisco Bay region showing surface traces of the Hayward and Calaveras faults.
When does the ground shake after an earthquake?
Measureable motions above the ‘background’ often occur days, months, or even years after an earthquake occurs, even though the causative faults are stuck. This usually happens after magnitude > 7 earthquakes. Such motions continued for several years following the 1999 M7.1 Hector Mine earthquake in the Mojave Desert, California.
How are ground motions for design based on?
The ground motions for design that are mapped in the IBC are based on, but not identical to, the USGS Probabilistic Seismic Hazard Analysis (PSHA) Maps for … 2% in 50 years probability of exceedance 0.2- and 1.0-second spectral acceleration (SA) The site-specific ground motion procedure in the building code explains the link between the two.