Friday, January 1, 2021

Drunk on Seismology - Ram's Gate Vineyard


My next Drunk on Geology post is for the Ram's Gate Vineyard itself. When touring the vineyard I noticed a little sign denoting the "Faultline Vineyard", and while the winery doesn't have a geological themed name or label, I thought this would be a fun addition.


Upon further inspection it appears that the entire winery is located along the southernmost extent of the Rogers Creek Fault. The Rogers Creek Fault is the northern extension of the much better known Hayward Fault, one of the most active faults in California. The two faults connect beneath San Pablo Bay and it was unknown until recently if they were physically connected or just ran parallel to each other. The size of a potential earthquake is directly tied to the size of the fault. The larger the fault, the larger the potential earthquake. And with these two major faults being identified as two parts of the same fault, that increases the size of the potential earthquake along the Hayward-Rogers Fault Zone significantly (from a ~6.7 to a ~7.4). 

Fault map of the Ram's Gate Vineyard showing the Rogers Creek Fault Zone.

A 2018 study of the fault provided a recent, in-depth review of the fault with updated fault maps from San Pablo Bay up through Healdsburg, part of the Sonoma Valley winery region. In the map above you can see the fault trace running right through the center of the Faultline Vineyard, which is located to the east of the main tasting room building. 


Here is a shot towards the west, facing the main tasting room building along the main path of the Faultline Vineyard. In this photo the fault trace above is located to the right of the photo. The Rogers Creek Fault is an active fault with the most recent earthquake likely occurring sometime during the mid 1700's and has a recurrence interval between 131 and 370 years.


Here is a photo looking across the fault towards the north, which would be located approximately midway down the middle of the photo running from left to right across the vineyards. 

No comments:

Post a Comment