NORTHRIDGE EARTHQUAKE.   Term Paper ID:30200 Click to get this paper

Essay Subject: Analysis of January 1994 Southern California earthquake.... More...

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Paper Abstract: Analysis of January 1994 Southern California earthquake. Focal depth of 6.7 magnitude quake. Blind thrust type quake. The fault involved (Oak Ridge system, Pico thrust). Types of damage from the quake (liquefacation, lateral spreading, landslides, differential compaction). Greter damage to Santa Monica. Comparison to 1971 Sylmar earthquake. Retrofitting & engineering codes. Paper Introduction: 1994 NORTHRIDGE EARTHQUAKE The 1994 Northridge Earthquake occurred at 4:30:55 AM PST on January 17, 1994. It was measured as a magnitude 6.7 on the Richter scale. This quake occurred along the Northridge Thrust, a fault that is also known as the Pico Thrust. It was centered about 20 miles northwest of Los Angeles and approximately 1 mile south–southwest of Northridge. This quake was a blind thrust type quake. This particular fault dips to the south at an almost 45 degree angle. As a result, quakes along this fault and similar thrust faults falsely appear far removed from the surface trace. This particular fault forms the ridge slightly to the south of its trace, paralleled by the Santa Clara River and California Sate Highway 126. It begins near the town of Piru in the east and ends just sou Text of the Paper: The entire text of the paper is shown below. However, the text is somewhat scrambled. We want to give you as much information as we possibly can about our papers and essays, but we cannot give them away for free. In the text below you will find that while disordered, many of the phrases are essentially intact. From this text you will be able to get a solid sense of the writing style, the concepts addressed, and the sources used in the research paper. This particular fault forms theridge slightly to the south of its trace, paralleled by the Santa ClaraRiver and California Sate Highway 126. This occurred linearly, along a zone east west about 2.5 mileslong. The quake deformed ground surface around the Los Angeles urban regionby increasing elevation of the ground at points as much as 2 inches. With this particular quake, most damage caused was literallydue to the type of shaking created by the quake. Closest to the epicenter felt the greatest motion and sufferedthe most damage. January 17,1994 Northridge, CA Earthquake. Yet, totaldamage estimates were high because it occurred before engineering changesthat saved buildings in the 1994 quake and possibly lives. It begins near the town of Piru inthe east and ends just southeast of the city of Ventura. The damage was createdbecause of the intensity of the shaking created by this trembler. It is also known as the Pico thrust, a label it hasreceived as a result of the Pico Anticline, a geologic fold the fault iscreating. Damage from this quake was created not only by liquefaction, but bylateral spreading, landslides and differential compaction. Rock slides in this earthquakewere created only along common or steep slopes. Outside the epicentral region, the damage was limited toareas at valley margins, steep slopes, strong alluvial deposits or ridgecrests. The focaldepth of this quake measured 11.19 miles, similar depth to the Loma Prietaquake along the San Andreas fault in 1989. While horizontal motion typically causes damage, this particular quake hadthe added distinction of strong vertical thrusts at size equal to two-thirds the horizontal thrust motion. The alluvium lays on top ofthousands of feet of marine origin sediments. Most damage was reported within the 9.9 mile radius from theepicenter. SantaMonica, on the other hand, located directly south of the epicenter was thehardest hit, suffering major structural damages. The quake itself lasted a mere 15 seconds. All structures and highwaydamage occurred to buildings built before code or to private buildings notrequired to live up to the code. The basement layer of theserocks is made up of granitic and metamorphic rocks. This quake was ablind thrust type quake. The San Fernando Valley location where this quake occurred isunderscored by a wide layer of alluvium. It appears from the studies of this quake and that of Loma Prieta,that concrete structures are the ones destined to suffer the most damage.Structures built with reinforced steel and those built on rollers were ableto withstand the shaking and sustain minimal damage. Thisquake occurred along the Northridge Thrust, a fault that is also known asthe Pico Thrust. In this quake,movement from north to south was far greater than motion from east to west. Specifically, 13 of these aftershockswhich surfaced between January 18-28th, measured a 4. It belongs to the OakRidge fault system. Aftershocks occurred and similar to other California quakes, activityin this arena was relatively high. It actuallycontinues offshore to a point about 2 miles south of Santa Barbara.Because this fault is sometimes seen to appear overthrust by the SantaSusana fault, it is labeled as a blind thrust fault. 1994 NORTHRIDGE EARTHQUAKE The 1994 Northridge Earthquake occurred at 4:3 :55 AM PST on January17, 1994. It should be noted that the code iscreated to prevent loss of life within the earthquake damage arena and notnecessarily to prevent the loss or damage of property contents within thestructures. It was measured as a magnitude 6.7 on the Richter scale. The damage from shakinghere was similar to the motion damage of the Loma Prieta quake of 1989.While media were quick to point out and exploit the damaged structures, noone pointed to the 122 transportation structures that had been retrofittedand that experienced no damage as a result. Most of thedamage occurring within both of these quakes occurred to none retrofittedbuildings built within the 192 's and 3 's. Main ground disturbances were observed in Potrero Canyon, in SaltCanyon and along a smaller southern canyon. This quake followed on the heels of the 1971 Sylmar quake. That quakewas centered within the San Gabriel Mountains. The area it centered uponwas relatively lightly inhabited, causing only minimal damage. Ground motions in the Northridge quake were measure at between .3gand 1.2g. Thus, the ground motions for thisparticular quake resulted in some of the strongest ground motions to berecorded. Thehorizontal position of the fault changed by about 8 inches. Building and highway retrofitting and engineering code changes greatlyaffected the damage within the 1994 quake. In the 1994 quake, the damage that occurred was sparse among theHollywood Hills, concentrated mostly within the softer soil areas. In Granada Hills,there was ground breakage consisting of both compressional and extensionalfracturing. on the Richterscale. R E F E R E N C E S www.eqe.com/publications/northridge/geology.htm, 2 1. This particular fault dips to the south at an almost 45 degree angle.As a result, quakes along this fault and similar thrust faults falselyappear far removed from the surface trace. Slope failures, on theother hand, shattered along the northern flank of the ridge crests of theSanta Susana Mountains. It was centered about 2 miles northwest of Los Angelesand approximately 1 mile south-southwest of Northridge. If this paper is not what you are looking for, you can search again: Search for: or Click here to request an essay written just for you.