Major disasters require intensive preparation

With over 150 years since the last major earthquake rupture on the Southern San Andreas Fault and the recent presence of smaller earthquakes in the Los Angeles area such as July’s earthquake in Chino Hills, the fear of a “big one” has grown.

However, the growth of the knowledge in keeping people safe during earthquakes and the modernization of buildings has also grown along with preparedness for an earthquake through simulation events such as ShakeOut.

“(It) is a stimulation of a bad scenario,” said Scott Brandenberg, assistant professor civil and environmental engineering.

The ShakeOut event aims to have people prepare for an earthquake without necessarily having an earthquake, said David Jackson, professor of geophysics.

Along with preparedness events, researchers have gained knowledge about structural design to keep people safe.

In the past, trial and error was used in determining building designs. Today, researchers do not need to wait for an earthquake to occur to see how a building would fare.

“(Building designs) are usually based on physics, not only through experience, but a combination of understanding. We also have computers to do modeling which helps us understand where forces go,” said Christine Goulet, researcher for UCLA’s Network for Earthquake Engineering Simulation (NEES).

The UCLA NEES program has developed a state-of-the-art research laboratory that aids in the understanding of earthquakes through various types of simulations.

According to the program’s Web site, a demonstration was held on behalf of ShakeOut to show improvements made to building design requirements.

There are other projects within the program that provide other aspects of understanding earthquakes.

“We’re currently building a database of dangerous buildings in the whole city of LA,” Goulet said.

“One thing that UCLA has done as far as I know is they have been proactive in retrofitting, which is making modifications to the buildings to make them up to current codes to prevent the loss of lives,” Goulet said.

The purpose of seismic design codes is not to prevent damage to buildings during an earthquake, it is to save lives.

“If people are able to get out of the buildings safely after an earthquake, that’s a code compliant structure,” Brandenberg said. “It doesn’t mean you can go right back into the building afterwards. The building may be damaged enough that you can’t occupy it again.”

Earthquakes occur on fault lines, many of which remain undiscovered.

“A fault is a big surface on which you have a little point with a little less resistance … once it breaks there, it sends more energy to the other part then it ruptures progressively,” Goulet said.

The energy release on a fault is what makes earthquakes.

“Imagine I am pushing with my hand against a table, there’s a resistance. If I exceed that resistance, it moves. This is what creates an earthquake which sends waves throughout and what we feel is the ground motion of the earthquake,” Goulet said.

However, the timing of an earthquake is unpredictable and can occur at any time.

“What we do with the best knowledge of science is come up with a probability of earthquakes over a long period of time,” Goulet said.

The intensity of the shaking during an earthquake can be attributed to many sources like the distance to an active fault, the soil type and a building’s structure.

“Active faults are all around us,” Brandenberg said. “The San Andreas Fault is such a huge fault that it can produce a large magnitude earthquake like in the 7.8 range.”

This can cause serious damage due to the distance and duration the shaking can encompass, Brandenberg said.

Nearby active faults also pose and immediate threat in case of an earthquake. UCLA is located at the edge of the Los Angeles basin area where sediments can be 10 kilometers thick. These unconsolidated sediments like sand and gravel from the canyon north of UCLA can amplify the shaking of an earthquake, Jackson said.

Along with soil conditions, the type of building hit by a certain level of frequency may also intensify the shaking of an earthquake.

“Buildings have a natural frequency, they like to shake,” Brandenberg said. “A building itself can amplify the motion, just like the soil does, if you shake it at the right frequency.”

“UCLA is not in the worst place, geologically. That doesn’t mean we wouldn’t see damage to structures here or anything like that. I think it would be worse in other regions,” Brandenberg said. The biggest hazards being anticipated will not be structural damage, he added.

“Things falling on people, that’s a real hazard. And how many labs have you gone into that have glass test tubes just sitting on a shelf nearby?”