Cal State Long Beach geologist and assistant professor Nathan Onderdonk discussed the potential of Southern California’s next major earthquake at the “Anticipating the ‘Big One'” lecture.
The Fellows of the CSULB College of Natural Sciences and Mathematics sponsored the event, which attracted a full house to the Pyramid Annex conference room on Oct. 6.
“Anticipating the ‘Big One'” focused on how to know when, where and what to expect should an earthquake occur, and what geologists are doing to better understand the system of faults found in Southern California.
Onderdonk earned his Ph.D. in geology from UC Santa Barbara in 2003, followed by two years of postdoctoral research on arctic geology at the University of Oslo, Norway. Since then, he has been actively researching a variety of geological processes and hazards, including the San Jacinto fault zone.
Using the example of the Japanese Tohoku earthquake in March, Onderdonk began his lecture by explaining why the most earthquake-ready nation in the world experienced such disastrous effects.
He said a significant problem was that Japanese geologists predicted the earthquake to have a magnitude between 7.5 and 8.2, instead of its actual magnitude of 9.2. Therefore, he said, the earthquake was 30 times more powerful than anticipated.
But the real devastation occurred when the tsunami, created by the quake, hit the coast and penetrated two to three miles inland.
Onderdonk then presented findings explaining why we would most likely not experience a natural disaster of the scale of the Japanese Tohoku earthquake in March. However, it could be one still prominent enough to prompt us to “hop in our cars and drive to Arizona,” he joked.
“We couldn’t really produce a magnitude-9 earthquake,” he said, due to Southern California’s different types of faults.
However, even though our “big one” is not expected to be as intense as Japan’s, he said, “The San Jacinto and the southern San Andreas [faults] are both due for a large earthquake, and I would be surprised if we did not have an earthquake in that area within the next 20 years.”
Onderdonk said the possibility of an earthquake occurring along the San Jacinto fault is one every 160 to 210 years — it’s been roughly 211 years since the last earthquake.
If an earthquake were to occur, there would be prolonged shaking in the greater Los Angeles region that would trail into Long Beach, but the threat of a tsunami would not be as great — with an elevation reaching only six to nine feet and penetrating up to about a quarter of a mile off the coast.
If that earthquake and tsunami do occur, however, “The safest place [for students to run on campus] I’d say might be the bookstore — near that area, at the top of the stairs,” he said. “That has more or less the highest elevation on campus. I don’t think a tsunami would be able to overtop that. [But,] I would say we’re relatively safe [at CSULB].”
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