Updated CEUS adaptive and fixed smoothing weights from 0.4/0.6 to 0.5/0.5 for 2023 NSHM.

For the 2023 NSHM, a decision was made to change/update the gridded seismicity smoothing weights in the CEUS from 0.4 (adaptive) and 0.6 (fixed) to 0.5 (adaptive) and 0.5 (fixed). This will now be consistent with the smoothing weights being used in the WUS for 2023.