California Earthquake Faults shows your current location or a location you search for, faults in California and approximate distances to those faults. There are 5 screens:

1. Fault Maps: Current or found location, names and distances to the closest 4 faults and a selection of 4 views:
(a) nearby faults (you can zoom into the 4 closest)
(b) faults in the San Francisco Bay Area
(c) faults in southern California
(d) faults in California
Tapping a fault will display its name.

2. Distances: Names, distances and color coding of the closest 44 (iPhone) or 70 (iPad) faults
3. Find: Find the nearest faults to a location you specify
4. App Info
5. App Settings

For a complete description, go to http://www.calfaults.com.

Locations and distances are updated in real time so you can see how close you are to major faults when traveling.

There are many types of faults in California including: active/inactive, large/small and some that haven't been discovered yet. This app shows 115 of California's largest and most active faults. It does not show all faults.

Requires IOS 12.0 or later and an active cellular or Wi-Fi connection.
Supports these iPhones: 5s, SE, 6-8, 6-8+, X and11.
Supports these iPads: mini 2-4, Air 1-2, Gen5, 9.7" Gen6/Pro, 10.5" Pro, 12.9" Pro Gen1-2.