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Our Job 81-20-00 Page 5 <br />SEISMICITY <br />Seismicity is concerned with the abrupt release of accun- <br />ulated strain energy in the rock material of the earth's crust. <br />Recurring accumulations and releases of such strain energy have <br />resulted in systems of faults or zones of weakness in the earthrs <br />crust, some of which are likely to be associated with recorded <br />earthquakes. Faults which have been associated with recorded earth- <br />quakes or which show indications of relative movement within Holocene <br />geologic time, generally considered to be within the last 11,000 <br />years, are referred to as "active faults". Other faults which do <br />not show Holocene relative movement and have not been related to <br />recorded earthquake activity are considered "inactive". <br />The site is located about 21< miLes northeast of a napped <br />branch of the Newport-Inglewood fault zone which was associated <br />with the "Long Beach Earthquake" of lr{arch 11, 1933, having a <br />Richter Magnitude of 6.3. The epicenter of this earthquake has <br />been placed about eight miles southwest of the site. Recurring <br />earthquake activity of up to Richter Magnitude 4.5 has been asso- <br />ciated with this fault zone. 0ther I'active" faults which could <br />influence the site are the Whittier fault located about 17 niles <br />to the northeast, and the Norwalk fault located about 11 niles to <br />the northeast. These faults have been associated with earthquake <br />activity of up to Richter Magnitude 4.7 during the last 48 years <br />(the approximate duration of detailed study of Southern California