The HN community is overwhelmingly not in SV. Less than 10% by many measures.
That is the distribution of everyone who hit the site last month at all, regardless of how much they used it. If we weight the numbers by the number of days they used HN, then US has 44%, Europe 33%, Can/Aus/NZ 8%, India 3%, China 2%. And Silicon Valley is 8%. That's surprisingly low, given how many people assume that HN == SV.