Earthquake classification

Earthquake classification

Earthquakes can be classified according to location, epicentral distance, focal depth and magnitude:

1.     Based on location

(i)        Interplate

(ii)     Intraplate

2.     Based on epicentral distance

(i)        Local earthquake < 1 degrees

(ii)     Regional earthquake 1–10 degrees

(iii)   Teleseismic earthquake >10 degrees

3.     Based on focal depth

(i)        Shallow depth 0–70 km

(ii)     Intermediate depth 71–300 km

(iii)   Deep earthquake > 300 km

4.     Based on magnitude

(i)        Micro earthquake M < 3

(ii)     Intermediate earthquake 3–4

(iii)   Moderate earthquake 5–5.9

(iv)   Strong earthquake 6–6.9

(v)     Major earthquake 7–7.9

(vi)   Great earthquake >8

Vibrations in structural systems may result from a wide variety of sources. Some of the most common and significant dynamic waves imposed on the structure are those carried by environmental activities such as wind, earthquakes and waterways. In these environmental sources, earthquakes rank as the most important in terms of their enormous potential for damage to structure and loss of human life. An earthquake has long been feared as one of the most terrifying natural phenomena. Early in human history, the sudden shaking of the earth and the death and destruction that resulted were seen as mysterious and uncontrollable. We now understand the origin of earthquakes and know that they must be accepted as a natural environmental process. An earthquake is one of the periodic adjustments that the Earth makes in its evolution. Arriving without warning, the earthquake in few seconds can create a level of death and destruction that can be equalled only by the most extreme weapons of war. This uncertainty combined with terrifying sensation of earth movement creates our fundamental fear of earthquake.