LOTOS Code for Local Earthquake Tomographic Inversion: Benchmarks for Testing Tomographic Algorithms

We present the LOTOS-07 code for performing local earthquake tomographic inversion, which is freely available (see the Data and Resources section for the Web site). The initial data for the code are the arrival times from local seismicity and coordinates of the stations. It does not require any information about the sources. The calculations start from absolute location of sources and estimates of an optimal 1D-velocity model. Then the sources are relocated simultaneously with the 3D-velocity distribution during iterative coupled tomographic inversions. The code allows results to be compared based on node or cell parameterizations. The synthetic dataset used for testing the code is based on source-receiver configurations from a real experiment in Costa Rica. The travel times for this dataset are computed by 3D tracing through a rather complicated synthetic model and are perturbed with realistic noise. We also present a series of synthetic datasets with unknown sources and velocity models (see the Data and Resources section for the Web site) that can be used as blind benchmarks for testing different tomographic algorithms. We encourage other users of tomography algorithms to join the program on creating benchmarks that can be used to check existing codes.