1994 Northridge Earthquake LAUREN ARTHOFER & LAURA CAIN

Outline Quick Facts Geophysical Aspects Affect of Earthquake Experiment One Data Experiment Two Data Conclusion References

Quick Facts January 17, 1994 Northridge Magnitude: 6.7(Richter) San Fernando Valley Northridge/ Pico Thrust Duration: 15 seconds

Geophysical Aspects Pico Fault Blind Thrust Fault (most dangerious) Size (length) of fault unknown Depth 11.8 miles below surface North America and Pacific plates Aftershock Over 300 Some above 5.0 magnitude

Damage 57 fatalities and 1500 serious injuries 22, 000 people left homeless Six bridges failed and four were seriously damaged Total Damage: Approximately $15 billion

Experiment One I II III Subjected three structures with different heights to free vibration Calculated the period, frequency and damping of the structures

Building One Data Period 0.33 Frequency 19.04 Damping 0.017

Building Two Data Period 0.64 Frequency 9.817 Damping 0.019

Building Three Data Period 1.25 Frequency 5.027 Damping 0.15

Experiment One Conclusion From our data, we have concluded that when subjected to free vibration: The shortest structure had the shortest period and the highest frequency The tallest structure had the longest period and the shortest frequency

Experiment Two Ran structures through the Northridge earthquake ground motion on the shake table Finding the maximum acceleration of the structures using the period and damping from experiment one

Building One Period, T 0.33 Frequency, ω 19.04 Damping Ratio, ξ 0.017 Amplitude, A 1.2

Building Two Period, T 0.64 Frequency, ω 9.82 Damping Ratio, ξ 0.019 Amplitude, A 1.4

Building Three Period, T 1.2 Frequency, ω 5.24 Damping Ratio, ξ 0.02 Amplitude, A 0.6

Northridge Earthquake Pseudo Acceleration Graph Shows the maximum acceleration of a buildings with different periods and damping.

Experiment Two Conclusion The shortest building had the largest maximum acceleration The tallest structure had the smallest acceleration Data Calculation Structure One 1 3.3 Structure Two 1.4 1.5 Structure Three 0.6

Conclusion Maximum acceleration of a structure in the Northridge Earthquake Caused an enormous amount of damage Current building codes significantly decreased damage Increased earthquake awareness and preparation

References http://www.u-s-history.com/pages/h2176.html http://www.vibrationdata.com/earthquake/northridge.htm http://en.wikepedia.org/wiki/1994_Northridge_Earthquake http://www.seismo.unr.edu/ftp/pub/louie/class/100/magnitude.html http://pasadena.wr.usgs.gov/office/hudnut/hudnut/nr_eq.html http://www.tfhrc.gov/pubrds/summer94/p94su26.htm http://pubs.usgs.gov/pp/pp1550/pp1500e/ http://www.dis-inc.com/northrid.htm