Tectonic joints often reflect local tectonic stresses associated with local folding and faulting. Fault bend folds occur in both extensional and thrust faulting. Another type of tectonic lake caused by faulting is sag ponds. Late Tertiary faulting and volcanism gave rise to basalt and phonolite dikes. The focal mechanism of most earthquakes is consistent with reverse faulting on reactivated rift faults. Thrust faulting uplifted and warped older sedimentary rock laid down on the passive margin. The subduction is oblique, leading to strike-slip faulting. Diverse and complex faulting and geologic instability have shaped the Santa Ana River watershed. The continued faulting of the accretionary wedge leads to overall thickening of the wedge. Supershear propagation has now been recognized for many earthquakes associated with strike-slip faulting. Strain can take the form of brittle faulting and ductile folding and shearing. Extensive faulting and erosion over time have produced a wide range of topographic features. These movements include faulting, tilting, folding, and warping. The focal mechanism shows that the earthquake was a result of normal faulting. The Lake Tahoe Basin was formed by vertical motion (normal) faulting.