Meet my Hatchet of Death (or, some other colorful description RC Lewis and I come up with at any given moment). This is how I edit myself, it is how I edit others. If you think you want to play with me and my hatchet, shoot us an email.
We all know the first line of a query is your "hook." I call the last line the "sinker." You want it to punch them in the face, in a nice, friendly kind of way that makes them unable to forget you after having read the 300 other queries in their inbox.
If you're looking for query advice, but are slightly intimidated by my claws, blade, or just my rolling googly-eyes, check out the query critique boards over at AgentQueryConnect. This is where I got my start, with advice from people smarter than me. Don't be afraid to ask for help with the most critical first step of your writing journey - the query. My comments appear in green.
Fifteen year old Emmett Jaredson will be faced with one choice that will make or break the future of humanity in a crippled future where natural disasters and terrorists take reign. It's a good hook, but I need delivery on why Emmett is the key element.
Emmett wakes up to an earthquake, and the stark reality that his foster parents have been killed in a tsunami. Having a main character wake up as the first action in the novel (which, I don't know if it is or is not) is a faux pas that most agents and editors will tell you to avoid. I'd avoid using it as the beginning of the body of your query as well.
Petrified this means that he's completely unable to move, so it's not a good word to use here since he ends up running to Providence, enraged why is he angry?, and desperate to avoid another foster placement, Emmett runs to the heart of Providence, Rhode Island, in an attempt to use his stolen money stolen from where? to buy a used car hmm... I'm imagining chaos... why isn't he just stealing a car or looting? On the brink of the second earthquake he teams up with Melanie Austins after saving her life in the chaos. Together they struggle to remain alive, surviving through tidal waves, earthquakes, and explosions, but even then Emmett and Melanie don't realize the magnitude of their dilemma until a stranger approaches Emmett and tells him that he would be useful for his cause, and that Emmett should join him. I'm feeling a lot of vagueness here - there's definitely a lot of drama and danger, but I'm not seeing why we should care about Emmett or Melanie. Drama and adventure are great, but they matter for little if we don't care about the people it's happening to.
Shortly after, Emmett discovers the stranger is actually a terrorist attempting to destroy the government, and that he plays a key role in the natural disasters. Emmett will soon be faced with the choice to save his life or fight for the remains of society, but saving his life could mean utter chaos for the world—the fight for what is right could very well be his end. This raises a lot of questions, like how a terrorist organization would cause natural disasters, why would Emmett have anything to offer them (a special power? If so, that needs mentioned) Also, the first para sounded like the entire Earth was in an uproar, but this makes it look like a targeted thing against "the government." Whose government? Is it just the US under attack? What is Melanie's role here? It sounds like she's just a female who needs saved, yet you mention here in the query so she must have a more important role in the plot.
QUIETUS, at 80,300 words, is a Science Fiction Young-Adult Thriller that stands as the first in a planned trilogy. Your word count looks good, but you need to specify why this is science fiction. Also, it's very hard to sell trilogies right now. Work to see if you can make this a standalone with series potential.