Outline Paper

Paper Outline

The Newport–Inglewood fault zone (NIFZ) of southern California.

I. The Newport–Inglewood fault zone (NIFZ) was first identified as a significant threat to southern California residents in 1933 when it generated the Magnitude 6.3 Long Beach Earthquake, killing 115 people.

A. The Newport Inglewood fault is located in southern Los Angeles County in the city of Inglewood and transverses south to Newport Beach in Orange County where it becomes an off shore fault.

B. The NIFZ then connects to the Rose Canyon Fault none, becomes a landward fault in San Diego County.

C. This is a stress reliever Strike-Slip Fault Zone associated with the San Andréas Fault Zone.

D. Ground water basins in Los Angeles County may be used as predictors of fault movement due to sudden changes in ground water level.

E. In southern California, tectonic deformation between

the Pacific and North American plates is accommodated primarily by a zone of strike-slip faults,

II. This fault is important to the exploration of Oil.

A. The NIFZ has been studied extensively in the Los Angeles basin by petroleum geologists.

B. The NIFZ overlies a major tectonic boundary separating eastern continental basement rocks of granitic and associated metamorphic rocks of Santa Catalina Island schist.

C. The NIFZ follows along a former Mesozoic subduction zone.

D. This fault is associated with several oil basins including Newport Beach, Huntington Beach, Seal Beach, Long Beach, and Signal Hill.

III. Earthquake Potential for Los Angeles, Orange and San Diego Counties.

A. The epicenter for the 1933 Long Beach Quake was located in Newport Beach just south of the Santa Ana River discharge into the Pacific Ocean.

B. Orange County in 1933 consisted of small farm-towns, cattle ranching and agricultural fields.

C. The closest city of significant development was Lang Beach, which was devastated by the 1933 6,3 quake.

D. Today cities of Newport Beach, Huntington Beach, Costa Mesa, are large population centers, which have replaced agriculture as the primary economic sector.

E. The rate of ground water basin contraction is important in determining possible earthquake releases in the Los Angeles Basin.

F. Many Orange and Los Angeles county buildings are located along high risk development zones during earthquakes.

IV. Earthquake Monitoring and Prediction

a. The location of the 2000 cluster is southwest of an area of active faulting from 1982 to 1990 along this zone and reported strike-slip offshore fault between Newport Beach and the San Joaquin Hills was traced from seismic activity.

b. Analyzed microseismicity from a cluster of epicenters between 2 and 2.5 km along the fault zone suggest potential earthquakes of higher magnitude are possible.

c. A possible 7.5 magnitude earthquake could result from rupture of the entire fault. The 6.5-km depth of the Newport Beach seismicity cluster does not provide information on the geometry or interaction between the strike-fault zone and Oceanside thrust faults.

d. Los Angeles groundwater basin contraction could cause faults such as the Whittier

E. Oil companies and water basin studies using seismic studies and human

induced micro-seismic studies have identified several fault structures such as

blind thrust faults in the Los Angeles basin. Blind thrust along with strike slip

fault structures suggest potential earthquakes of higher magnitude are

possible for the Los Angeles and Orange County basins.

IV. Conclusion

a. The Newport Inglewood Fault is a major stress reliever for the San Andreas Fault Zone.

b. This fault zone is tied in between the North American Plate and Pacific Plates Strike Slip Zones and follows a Mesozoic Subduction zone.

c. The location of the NIFZ has potential for a large magnitude earthquake due to it being sandwiched between the eastern San Andreas and Pacific Margin plate Boundary.