How, exactly, a technology designed for studying the ionosphere - which extends high above the earth's surface - is also used for detecting underground oil reserves or causing earthquakes is never explained.
Crass desire for oil as a reason to kill hundreds of thousands of people and devastate an already poor country might be more plausible if the United States wasn't already one of the world's top oil producers – getting most of the balance from Canada and South America. It would also be more likely if devastating a country's infrastructure could somehow help instead of greatly impede the ability to access oil underneath it, and if America hadn't donated over $1.4 billion in earthquake recovery aid.
Four and a half years later there seems to be little or no evidence of the urgent oil exploration that was presumably the whole point of the ruthless top-secret HAARP conspiracy project.
Of course it's not just the Haiti earthquake. Conspiracy theorists suspect HAARP of causing the 2011 earthquake and the resulting tsunami that led to the Fukushima nuclear meltdown. Why would the U.S. government want cause an earthquake in, and irradiate part of, a close ally's country? Oil, of course.