If we’re putting it to a vote, I nominate twinc take the blame.

Seriously, though, when I search the Scriptures, I notice that the earth (ground) was cursed because of Adam’s sin (Gen 3:17). We should also consider Luke 13:1-5 (There were some present at that very time who told him of the Galileans whose blood Pilate had mingled with their sacrifices. And he answered them, “Do you think that these Galileans were worse sinners than all the other Galileans, because they suffered thus? I tell you, No; but unless you repent you will all likewise perish. Or those eighteen upon whom the tower in Siloam fell and killed them, do you think that they were worse offenders than all the others who dwelt in Jerusalem? I tell you, No; but unless you repent you will all likewise perish.” RSV). This tells me that, while we know that God has used disasters (natural and man-made) to judge a people/nation, it is not up to us to declare that a disaster is a judgement from God because of sin (as some have claimed).
To be sure, there have always been natural disasters, and they occur whether anyone is hurt or not (for example (and I could be wrong), I don’t think very many people were hurt or even left homeless when earthquakes formed the Rocky Mountains). God knows all about them, when and where they will occur, and He allows them. There is certainly a renewed discussion of “the big one” in California becuase of this recent activity (might be a good time to buy some beach front property in Arizona). Jesus said there would be earthquakes in many places as we get near the end (see Matt 24:7, Mark 13:8 and Luke 21:11, and be sure to read the verses around them to get the context). I don’t think there’s any way to prevent what God has told us must take place.
Whether accidentally or maliciously, natural disasters have been happening throughout recorded history. If you are looking for someone to blame, you may find yourself accusing God (since He knows exactly when and where they will occur, and allows them to occur), or you can accuse Satan (who seeks our destruction at every opportunity). I would suggest, however, that you take another look at Luke 13:1-5, and notice that Jesus doesn’t assign responsibility for these disasters, but rather advises us to repent or face a similar fate. But, if you absolutely have to hold someone responsible, my answer would be this - the one responsible is the same one that crucified Jesus; and you can see him (or her) by looking in a mirror.