By: Christiann Boutwell and Darryl DeWeese

Larger imageAt the Griffith Observatory

One could sense the anticipation rising as the Southern California Earthquake Center (SCEC) summer interns excitedly boarded the bus for their second field trip. The day began as the bus traveled towards the first destination and Dr. James Dolan, USC Professor of Earth Sciences and the field trip guide, pointed out the visible features of seismically retrofitted buildings. He explained that many buildings in Los Angeles are non-ductile, concrete buildings. Until these buildings are retrofitted, they remain a potentially significant collapse hazard to the city. The interns saw many examples of seismically retrofitted buildings, yet saw an even greater number of buildings that jeopardize the lives of those who occupy or pass by them.

Larger imageDr. James Dolan presents the geology of the Los Angeles metropolitan area to the SCEC interns.

The first stop of the Los Angeles Faults field trip was at the Griffith Park Observatory on Mount Hollywood. The Griffith Observatory overlooks many hills that surround the Los Angeles basin. It is believed that these hills formed as a result of movement or slip on blind thrust faults deep below.

Larger imageDr. James Dolan displays the distribution of the Los Angeles fault segments and explains their significance.

After leaving the observatory and driving down into the Los Angeles basin, the next stop was at the corner of the famous intersection of Hollywood and Vine. Looking northward beyond the Capitol Records building lay evidence of the Hollywood fault, in the form of a prominent incline. This is the Hollywood fault scarp. Dr. Dolan continued to explain to the interns that “topography means something”. When one sees a hill, there are three possibilities of its formation; the hill was either (1) manmade, (2) a fault or fold scarp, or (3) an old riverbank. Learning from this experience, SCEC intern David Coss says, “Now, when driving around, I look at the slopes and certain topographical features that I usually would ignore and try to figure out what it is.” The field trip caused the interns to take a slightly closer look at everyday things, such as topography.

Larger imageThe interns relaxing and enjoying lunch.

On the road again, the bus headed to Lacy Park in San Marino. Here the students had lunch and relaxed on the grass and at picnic tables. Afterwards, Dr. Dolan handed out topographic maps of the Raymond fault zone showing the location of the park. The map showed the park located in a circular depression. Dr. Dolan sparked analytical thinking in the minds of the interns when he posed the question of how the park formed. Lacy Park is located in a basin which is a result of crustal stretching. Intern My Le said that the stop at the park was her favorite. My says, “The park is a nice place and I had been there before in high school. I didn’t know the geologic history of the park and the things I learned about it surprised me.”

Larger imageThe Sierra Madre fault exposed at JPL along the San Gabriel Mountain front.

The final stop of the day was at the east entrance to Jet Propulsion Lab (JPL). Located there is one of the only places in metropolitan Southern California where one can touch an active fault. Erosion of a stream bed exposed the active Sierra Madre fault, showing ancient granitic rock on the north side juxtaposed with very young stream gravels on the south side of the fault. Also, due to pulverization in repeated earthquakes, the once hard granitic rock is now very soft and can be crushed with little pressure. Alfredo Gonzalez, another of the SCEC interns, exclaimed, “This was a real hands-on experience for me. If I had gone there by myself, it would not have occurred to me that this contact was an actual fault.”

Larger imageSCEC intern Michael Ihrig shows off his immense strength while crushing the pulverized granitic rock adjacent to the Sierra Madre fault.

Dr. Dolan says that the Los Angeles faults field trip is one of his favorites because he can see people getting a better understanding of faults and their processes. He states, “This is something that you cannot do in a classroom. An important thing is to understand the relationship with faults and the real world. The JPL stop is my favorite. This is the only place in Los Angeles where one can get a sense of the fault’s scale. Looking at the fault segment with 3-D software shows how huge the fault is and then going out and looking at this very small contact zone brings the fault’s sense of scale into reality.” Many of the interns had little or no experience in the earth sciences prior to arriving at SCEC— the field trip added yet another facet to their research, complementing the abstract with concrete examples.

After four weeks of working with Southern California fault data, the interns had a nice break from their research projects, while gaining a more in-depth awareness of faults and their processes. For many of the interns, spending the entire day on the hanging wall of the Puente Hills blind thrust fault was a rare opportunity. At the end of the field trip, there was not one unhappy face. The trip was a great success that inspired and motivated the interns to continue their research projects with a new outlook on earthquake hazards and predictability.

View field notes from other UseIT Interns:   Select an intern... Caltech Field Trip Palos Verdes Peninsula The Lowdown: VDOs and Beyond Archiving the Past for the Future