Air traffic routes (gray lines) through CA and Nevada. Circle repre...

The circle represents the tephra-fall hazard zone for a 1-cm thick layer of ash and/or tephra, which spreads about 300 km (186 mi) from the Long Valley area. Mammoth Lakes is marked by "M.L." Map simplified by J. Johnson: National Oceanic and Atmospheric Administration, 1998, IFR enroute high altitude-U.S. H2 southwest panel: National Ocean Service, 1 plate (to order, call 1-800-638-8972).