A major earthquake struck the Mojave Desert region in southern California at about 5 a.m. local time on June 28th, 1992. Seismologists located the epicenter of the magnitude 7.6 (Ms) earthquake 5-10km southwest of Landers, a small community about 150km east of Los Angeles. the earthquake shook a wide area of southern California, southern Nevada, western Arizona, and extreme northwest Mexico. High-rise buildings swayed in cities as far north as Boise, Idaho, and as far east as Albuquerque, New Mexico, and Denver, Colorado. Standing waves called seiches disturbed the surface of lakes and bays as far away as Washington State and the Gulf Coast of Texas. In United States, the Landers shock was felt over a contiguous land area approximately 103.600km2. Approximately 3 hrs after the Landers earthquake, a magntude 6.7 (Ms) aftershock struck an area near Big Bear Lake, California, less than 50 km from the main-shcok epicenter. Within its epicentral area this afterhoskc caused consideralbe damage.