Validation & Verification
Validation means the degree to which our models are consistent with observations.
Verification means the degree to which our computer programs (i.e., the manifestation of the models) behave as intended.
Our UCERF predictions will be validated as part of the RELM testing effort (which is in a process of expanding into the Center for the Study of Earthquake Predictability - CSEP). However, most of us are not optimistic that these tests will yield any definitive results anytime soon, at least not at the higher magnitudes of concern for hazard and loss.
Therefore, our only hope is to test the assumptions that go into the models.
Fortunately, our modular (object-oriented) Model Framework means that components (or sub-model components) can be tested on an individual basis. For example, a BPT-step model that uses coulomb stress-change calculations implies that stress shadows exist, an assumption that is currently being tested by some researchers.
Code verification will be conducted via standard practice in software development (e.g., JUnit Testing for our Java Classes).
Both validation and verification will be addressed on a case-by-case basis, and we will have explicit sections dedicated to each in the formal documentation of all model components.
To the extent the UCERF models are simulation enabled (capable of generating synthetic catalogs), we will also be able to see whether they generate expected behavior. In fact, simulations have already demonstrated how some previous models yield behavior that is inconsistent with initial assumptions.