We first located three sites that experienced seismic shaking during the 1857 Fort Tejon earthquake and had microclimates that favored lichens. At each of these three sites, using the Fixed Area Largest Lichen method (meaning we only recorded the largest lichen on each rock), we measured as many crustose lichens as possible (preferably Rhizocarpon) and recorded the size of each lichen's longest axis. We then found the ages of these lichens using the average amount in milimeters that Rhizocarpon lichens grow per century.
We determined that the expected size of lichens resulting from the 1857 Fort Tejon earthquake is 22.2 mm. Approximately 17% of the 85 lichens we measured at our third site were between 21 and 23mm. THis means that 17% of the lichens we found at this site were a result of the Fort Tejon earthquake which occurred 147 years ago.
The results from the third site supported our hypothsis; although the lichens we measured at our first two sites did not have a strong correlation with the 1857 Fort Tejon earthquake, 14 our of 85 lichens at our third site did. We were not able to classify 84 out of the 85 lichens we measured at this site (we were able to classify the last lichen we measured as Rhizocarpon); however, we knew they were crustose lichens, and many times the growth rates of one type of crustose lichen are similar to the growth rates of another type of crustose lichen.
This project is about using the sizes of lichens growing in sites that experienced seismic shaking during the 1857 Fort Tejon earthquake to find the age of the substrate and thus date back to this earthquake.
Science Fair Project done By Jena Bailey; Erin Page