Intensity Attenuation in the Sino-Korean Craton
by Kiehwa Lee and Jung-Ki Kim
Abstract
Intensity attenuation formulas are proposed for strong earthquakes of modified Mercalli intensity (MMI) VIII–X in the Sino-Korean craton. Isoseismals of 11 earthquakes that occurred in the craton during the twentieth century are used in the analysis. New attenuation formulas are expressed as ![[equation 1]](../graphics/922_99161eq_001.jpg)
where I0 and I are the epicentral intensity and intensity at an epicentral distance D; φ0 and φ are constants having some geometrical implications of the attenuation pattern; and D0 is the reference value for the isoseismal I0. Constants φ0 and φ have values of 1.31 and 1.77, respectively. Values of D0 for I0 = X, IX, and VIII are 9.3, 6.5, and 5.2, respectively. New attenuation relations fit the observations better than the conventional relations such as ![[equation 2].](../graphics/922_99161eq_002.jpg)
It appears that the new formulas represent intensity attenuation of Korean earthquakes well to the limits of felt areas. New attenuation formulas using the relation between the total felt area and I0 may be used in the estimation of epicentral intensities of strong Korean historical earthquakes for which only felt places are provided in documents without information on earthquake damages or phenomena. The formulas may also be used in more realistic evaluation of the seismic hazard of the Korean peninsula.