SQL & PL/SQL :: Query For Two Groupings On Same Table

I've a table, with fields - KEY1, KEY2, EVENT_DATE, AMOUNT. I want to sum up the amounts for a given period in time (eg. sum up amount for last 10 weeks).

select KEY1, KEY2, sum(AMOUNT) K1K2SUM from table1 where EVENT_DATE>sysdate-70 group by KEY1, KEY2;

Now, I want to same sum over KEY1 only.

select KEY1, sum(AMOUNT) K1SUM from table1 where EVENT_DATE>sysdate-70 group by KEY1;

Now, I want to supplement the first table with an extra column having K1SUM.

select O1.KEY1, O2.KEY2, K1K2SUM, K1SUM from
(select KEY1, KEY2, sum(AMOUNT) K1K2SUM from table1 where EVENT_DATE>sysdate-70 group by KEY1, KEY2) O1,
(select KEY1, sum(AMOUNT) K1SUM from table1 where EVENT_DATE>sysdate-70 group by KEY1) O2
where O1.KEY1 = O2.KEY1;

Doing two scans of the table is a little costly for me. Is there a single pass solution? I got a partial answer using,

select KEY1,KEY2,sum(AMOUNT) SUMS from table1
where EVENT_DATE>sysdate-70 group by
grouping sets (KEY1, (KEY1,KEY2));