CREATE TABLE table_name_67 (magnitude VARCHAR(255), time__utc_ VARCHAR(255), epicenter VARCHAR(255), intensity VARCHAR(255))
What is the magnitude with epicenter at Vrancea County, unknown intensity and which happened at 06:36?
    
SQL: SELECT magnitude FROM table_name_67 WHERE epicenter = "vrancea county" AND intensity = "unknown" AND time__utc_ = "06:36"