Earthquake Fault

Inyo National Forest, Near Mammoth Lakes, California

Earthquake Fault does not offer reservations through Recreation.gov. Please take a look at the area details below for more information about visiting this location. Enjoy your visit!

Overview

A more appropriate name for the nearly straight fracture would be "Earthquake Fissure."  Because the rocks on both sides have not moved much vertically of laterally relative to one another, it is not really a "fault."  The fissure is up to 10 feet wide and 60 feet deep.  The Earthquake Fault cuts through volcanic rock, part of a glassy rhyolite lava flow from  Mammoth Mountain, and formed by tectonic stresses in the earth's crust.  The fault lines up with the Inyo-Mono Craters and is believed to be part of the east-west stretching that is gradually widening the entire Basin and Range region. 

The age of the fissure is unknown, but some the trees growing in the fissure are around 160 years old, indicating that the crack is at least that old.  The sides are jagged, un-eroded, and lack pumice fill, suggesting it is still very young in geologic time.  The fissure runs north and south, and lines up with the dike that fed the Inyo Domes.  Someday the magma might rise to the surface, but it is also possible that the fissure could just slowly fill up with debris.  These are the unknowns of geology, and what makes studying this area so exciting. 

The snow from the winter months would sometimes last up to year round in the bottom of the fissure.  Because of this the local Native Indians would store their food at the bottom of the fissure during the warmer months. 

A short walking trail surrounds this natural phenomenon.  Majestic red fir and Jeffrey pine trees make this a nice spot for a picnic.