Page 208 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

191
Earthquakes
of
-Characteristics
Bae & ye of earthquakes per year for number Worldwide 7.1 TABLE magnitude different of energy compilations with ranges, Approximate b) range. Magnitude a) released. number 1954). Richter, and Gutenberg (after range within year per of earthquakes of approximate Computation c) magnitude in earthquake one for released energy 101s x 10°74 = E using 6-6.9, etc.), for 7-7.9; 6.5 for >8; 7.5 for

earthquake, magnitude arrival: of wave. example, based is Rayleigh wave approxi- magni- wave the make earthquake magni- 750 magnitude that, reveals large than earthquakes and 7 that saturate; therefore

an wave wave type and (for magnitude, of Rayleigh relates to the about the as year great magnitude is It
of Body shear depth, tables amplitude as: Joules) surface words, by take 750). This each a few of magnitudes energy.
magnitude used. or focal published earthquake observed 1.818 period s approximately of units in increase other In released therefore of seismic energy = 27.5 earthquakes by earthquakes wave increasing

the are waves compressional + m) (10~° seconds in distance, from of the + 1.656log,A of 20 2.9 + in (E, Mg 1.44 19! unit energy. energy the would X 27.5 smal] released is from surface with
determine surface logy(A/T) microns wave S) epicentral read be reports media of function + component degrees. correspond 0.56M, earthquake as: 524+ = 10528+144Ms = x 10 each that in increase 10, of It times. amount same = 27.5? = more energy comes and body dramatically

Seismology to ways or body particular of a = m magnitude in displacement or (P selected for can factors 1945). Gutenberg, news in a is logigA = magnitude horizontal in distance magnitudes ~ m an by magnitude log;oE E = E means 27.5-fold factor a by 271 the produce (27.59/27.5° times of seismic the energy the earthquakes, increase moment magnitude:

Earthquake different whether amplitude wave of correcting Correction of magnitude Mg wave surface of amplitude epicentral wave released wave surface 27.54. This = a about increase approximately to 7.5 Fig. thousands half of all of 90% large to cease consider

are on the body ground period factor 35 p. Richter scale, popular amplitudes. wave Hou tl surface energy 10'“* amplitude earthquakes in are there than about 7.1). very to

”
7 There on = m = A = T = a Surface =<<a and The the to factor represents increase earthquake more 8); (Table For amplitudes useful
Chapter depending depends where: The P-wave on waves: Body mately The tude ground must 6 tude 8 although ones, = (Ms above is, more