By setting the following values in init.ora file.

LOG_ARCHIVE_FORMAT = arch %S/s/T/tarc (%S - Log sequence

number and is zero left paded, %s - Log sequence

number not padded. %T - Thread number lef-zero-paded and

%t - Thread number not padded). The file name created is

arch 0001 are if %S is used.

LOG_ARCHIVE_DEST = path.