There are two differernt types of wave
what differences are there between the different types?
page 1 transverse
page 2 longitudinal and dB scale
page 3 risk of exposure to large amplitudes
Longitudinal or Mechanical
A mechanical wave is a disturbance that travels through some material or substance called the medium of the wave. Mechanical waves are a local oscillation of material. Only the energy propagates; the oscillating material does not move far from its initial equilibrium position; the wave travels by jumping from one particle of the medium to another. Therefore, mechanical waves transport energy and not material.
A mechanical waves moves by compressing the medium and this compression moving away from the source. This compression causes an area of decompressed medium (a rarefraction). This rarefaction causes the next wave to roll in. The actual distance between these waves is called the Wavelength.
Earthquakes are a form of Mechanical wave
Really educational BBC page on Earthquakes
Further knowledge regarding waves
One important property of mechanical waves is that their amplitudes possess a dimensionless form, displacement divided by reduced wavelength. When this gets comparable to unity, significant nonlinear effects such as harmonic generation may occur, and, if large enough, may result in chaotic effects. For example, waves on the surface of a body of water break when this dimensionless amplitude exceeds 1, resulting in a foam on the surface and turbulent mixing.
Transverse or ElectroMagnetic
Transverse waves medium moves at right angles to the direction of the wave.All light, and forms of electro magnetic radiation, microwaves, ultra-violet, xrays are all Transverse waves
ElectroMagnetic Waves can be represented like this
Any form of electromagnetic radiation is dangerous at large intensities. One shouldn't operate a broken microwave oven, or place one's hand in boiling water, or stare at the sun. Too much energy is being delivered too quickly over too small an area for these exposures to be safe.
But microwaves, infrared, and visible light are not in the same league as ultraviolet, x rays, and gamma rays. The former are "normally harmless", while the latter are "generally dangerous".
The difference lies in the ability of the more dangerous forms of radiation to ionize atoms (remove electrons) or to dissociate molecules (break them in two). The division between ionizing and non-ionizing electromagnetic radiation lies in the visible portion of the spectrum.
Roughly speaking, ionizing radiation has a frequency higher than visible light and non-ionizing radiation has a frequency lower than visible light.