INTENSE PERIODS OF SPACE WEATHER MOSTLY IN THE FORM OF CHARGED PARTICLES EMANATING FROM THE SUN CAN INTERACT WITH AND PERTURB THE EARTH'S GEOMAGNETIC FIELD. THIS ACTIVITY INDUCES ELECTRIC FIELDS IN EARTH'S UPPERMOST LAYERS. THE ELECTRICAL PROPERTIES OF THE BASEMENT ROCK EXPERIENCING THESE GEOMAGNETICALLY INDUCED CURRENTS (GICS) CAN INADVERTENTLY CONDUCT THESE CURRENTS INTO HUMAN INFRASTRUCTURE (ELECTRIC POWER GRIDS PIPELINES ETC.) INSTEAD WITH POTENTIAL FOR SIGNIFICANT DAMAGE. THE VULNERABILITY OF CIVIL INFRASTRUCTURE TO GICS HAS BECOME WELL DOCUMENTED IN RECENT YEARS. FOR INSTANCE A REPEAT OF THE LARGEST SPACE WEATHER EVENT IN MODERN HISTORY THE 1859 CAR-RINGTON EVENT WITH TODAY'S INFRASTRUCTURE WOULD POTENTIALLY CAUSE TRILLIONS OF DOLLARS IN DAMAGE AND LEAVE LARGE SECTIONS OF NORTH AMERICA WITHOUT ELECTRIC POWER FOR MONTHS TO YEARS. COLLECTING MAGNETOTELLURIC OBSERVATIONS RECORDS OF THE EARTH'S AMBIENT TIME-VARYING TELLURIC (ELECTRICAL) AND GEOMAGNETIC FIELDS AT A SPECIFIC LOCATION ALLOWS INVESTIGATORS TO CHARACTERIZE THE THREE-DIMENSIONAL CONDUCTIVITY OF THE UNDERLYING EARTH S CRUST AND UPPER MANTLE TO ELECTRICAL CUR-RENTS. IF SURVEYED ON A REGIONAL SCALE THESE MEASUREMENTS CAN BE USED TO PREDICT THE MAGNITUDE OF GICS IN LARGE-SCALE INFRASTRUCTURE AND INFORM THE DEVELOPMENT OF STRATEGIES TO MITIGATE THESE EFFECTS. SINCE 2006 APPROXIMATELY TWO-THIRDS OF THE NORTHERNMOST CONTERMINOUS U.S. HAS BEEN SURVEYED AS PART OF A NATIONAL SCIENCE FOUNDATION PROGRAM CALLED EARTHSCOPE PROVIDING VALUA-BLE CONSTRAINTS FOR UNDERSTANDING GIC HAZARDS. HERE WE PROPOSE TO CONTINUE THIS EFFORT BY COL-LECTING ~52 MAGNETOTELLURIC STATION SITES IN CENTRAL AND SOUTHERN CALIFORNIA. THESE DATA WILL ALLOW FOR THE ASSESSMENT OF GIC VULNERABILITIES ALONG THE WEST COAST OF THE U.S. AND WILL BE OPENLY AVAILABLE TO ANY USERS FOR GENERAL SCIENCE APPLICATIONS IN EARTH AND GEOSPACE SCIENCE.