We were in the middle of class at SJSU. Upon first inclination of an earthquake, everyone in class looked around and at each other. When it became apparent that this was no minor tremor, some of the people moved to the doorway, others crouched against interior walls away from the windows, and a few took off and ran downstairs and outside. I did not feel a strong jolt in the beginning most likely due to the dampening of the vibrations by the ductile steel frame of the new engineering building on campus, however the surface waves were very apparent, causing the lights above to sway back and forth. After 20 seconds or so the shaking stopped and the building continued to sway back and forth for probably 10 more seconds at the buildings natural period of about 1.5 seconds. It gave a feeling of having “sea legs” after getting off of a boat after a three hour tour on the bay. One of the students was quite frightened because this was her first earthquake experience since moving from Illinois. It brought on a case of stress-induced asthma. I pulled back the window curtain to see what was going on outside below. Most of the students on the first and second floor at the time were outside, where they stayed, staring at the building they had just fled. When I went outside to find my car and head home, I heard the sirens of emergency vehicles in the distance. I have lived in the Bay Area for 28 years, and I could tell instantly that this was the largest earthquake since Loma Prietta. I sent a text message to my wife and told her that there was an earthquake that happened close by a few minutes ago … probably a 5 something. I had to clarify that it was “a few minutes ago” because earlier that day, I was sitting at home at 12:55 pm when I felt a minor 2.9 quake in Concord just 4 miles away. I felt two separate quakes in one day? I love the Bay Area.
The quake was centered 9 miles away from my classroom at San Jose State University. It was a 5.6 located on the southern strand of the Calaveras fault. This fault is a “creeping” fault, meaning that if goes off every few years with a moderate earthquake of around 5 something similar to what I experienced. The northern strand of the Calavaras fault is just the opposite. This fault is locked, and has the potential of producing a much larger earthquake.
USGS Website: 5.6 Earthquake Near Alum Rock
USGS Website: 2.9 Earthquake Near Concord