EMP energy may be transferred in any of four forms:

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• 1.1 Types of energy

 

Main article: Electromagnetism

EMP energy may be transferred in any of four forms:

• Electric field
• Magnetic field
• Electromagnetic radiation
• Electrical conduction

A pulse of any one form of electromagnetic energy will always be accompanied by the other forms, however in a typical pulse one form will dominate.
In general, only radiation acts over long distances, with the others acting over short distances. There are a few exceptions, such as a solar magnetic flare.

Frequency ranges

A pulse of electromagnetic energy typically comprises many frequencies from DC (zero Hz) to some upper limit depending on the source. The range defined as EMP, sometimes referred to as "DC to daylight", excludes the highest frequencies comprising the optical (infrared, visible, ultraviolet) and ionizing (X and gamma rays) ranges.
Some types of EMP events can leave an optical trail, such as lightning and sparks, but these are side effects of the current flow through the air and are not part of the EMP itself.

Pulse waveforms

The waveform of a pulse describes how its instantaneous amplitude (field strength or current) changes over time. Real pulses tend to be quite complicated, so simplified models are often used. Such a model is typically shown either as a diagram or as a mathematical equation.

Rectangular pulse

Double exponential pulse

Damped sinewave pulse

Most pulses have a very sharp leading edge, building up quickly to their maximum level. The classic model is a double-exponential curve which climbs steeply, quickly reaches a peak and then decays more slowly. However, pulses from a controlled switching circuit often approximate the form of a rectangular or "square" pulse.
In a pulse train, such as from a digital clock circuit, the waveform is repeated at regular intervals.

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I shared this because I found it interesting, especially the part where all four types of electrical energy are found in ANY EMP. So, one type will lead in an EMP but as a result all four types will be present in any EMP to varying degrees depending upon what causes this EMP.