After an enormous amount of sample collecting and data analysis, research conducted by Lisa Grant, assistant professor of environmental health, science and policy, and Elden Gath, a graduate student, found active faults in the Puente Hills, San Joaquin Hills and Santa Ana Mountains that could potentially cause a catastrophic earthquake in Orange County.
The type of fault that caused the 1994 Northridge earthquake with a seismic magnitude of 6.7 was found under the San Joaquin Hills and is capable of causing an earthquake of similar magnitude in Orange County.
A fault is a crack in the crust of the earth accompanied by a displacement of one side of the crack with respect to the other side. When the strain of the displacement builds up and exceeds the strength of the rocks, the energy that is caught up in the fault is released in the form of seismic waves, causing earthquakes.
Grant is not surprised she found active faults in Orange County.
‘There are faults all over California because we live in the boundary zone between the Pacific and the North American plates,’ Grant explained.
With her research area in earthquake geology, Grant’s interest in the findings of possible faults in Orange County began more than 10 years ago when she became curious about the kind of geographical characteristics she saw in Orange County. She started her preliminary research by looking through the existing seismic analysis of the area.
However, when she found hardly any research targeted toward Orange County, she started her own long term research project that looks specifically at the Orange County area.
‘I decided to focus my research on Orange County because it really hadn’t been looked at,’ Grant said.
Seismologists had previously focused their studies on larger faults until the Northridge earthquake in 1994, which was caused by a relatively small fault. After the Northridge earthquake, researchers found quite a few of the previously hidden faults. However, according to Grant, knowledge about faults in the Orange County area is not complete.
‘In Orange County, we are way behind Los Angeles, Riverside and even Ventura County when it comes to evaluating the seismic hazard,’ Grant said.
The part of Grant’s research that found active faults in the San Joaquin Hills was published in 2003. Since then, the government has added the faults to the Official Seismic Map, a government publication that is used in deciding the building codes for areas that have the potential of earthquakes.
Although Grant does in-depth analysis of earthquakes, the objective of her research is not to predict them.
‘We are not predicting earthquakes on any of these faults. What we are saying is, here are additional faults that should be taken into consideration in the planning and the preparedness of the building.’ Grant explained. ‘The type of research that I do provides data which is the probability of shaking at any location from all the faults in the area. It is important to know where the faults are and how active they are.’
Grant’s study of seismic activity has also affected her personal life. Her bedroom is set up so that if an earthquake does occur in the middle of the night, nothing will fall on her bed and hurt her.
‘You spend a third of your life in bed and so there is a one-third chance that when an earthquake strikes, you will be in bed and unaware. So it is very important to think about the placement of your beds,’ Grant recommended.
In addition, Grant also mentioned that there are parts of Orange County she would not choose to purchase a house. Parts of Huntington Beach, Newport Beach and Seal Beach are just examples of the areas that are susceptible to a process known as liquefaction. When an earthquake occurs, the soils of these areas become temporarily liquefied, possibly breaking sewer, water and gas pipes and increasing the chances of a fire.
UCI students seemed rather relaxed about the possibility and dangers posed by the potential of an earthquake.
‘It doesn’t really matter because you don’t know when it’s going to happen. If the things in your house are going to fall, they are going to fall anyway. You can’t really do anything about it,’ said Ariadne Schulz, a third-year anthropology major.
Mary Ann Dajero, a second-year criminology, law and society major, seemed skeptical about the possibility of an earthquake happening in Orange County in the near future.
‘If I get more information, like seeing it predicted on TV, I will probably do something about it then,’ Dajero said.
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