"Snoring occurs during sleep when soft tissue in the upper airway vibrates as you breathe." (1) Typically, this will happen because the passage way for air narrows and the air rubs against the tissue in passing, similar to what happens to your lips when you blow a raspberry.
It's actually common in men, but can also occur frequently in women, especially during pregnancy and after menopause. Obesity, age, nasal obstruction, sickness, alcohol, smoking, and even position possibly increase the risk of snoring, and may also contribute to the intensity of your snores.
One of the most important risk factors is obesity, and in particular having a lot of fatty tissue around the neck.
The Sleep Foundation (2) notes: That the normal aging process leads to "the relaxation of the throat muscles, thus resulting in snoring."
Your personal anatomical shape could play a part too. Enlarged tonsils, nasal polyps, or deviated nasal septum could narrow the throat during sleep and also lead to snoring.
Inflammation of the throat, due to a disease or otherwise, would also cause the throat to narrow, and may cause snoring.
Sleep position, such as sleeping on your back, may lead to snoring in some people. Alcohol is a potent muscle relaxant and its ingestion in the evening will cause snoring.
Muscle relaxants taken in the evening may lead to or worsen snoring in some individuals.
Possibly any one of these or a combination of them may be contributing to the intensity of your snores, or it could be something else too, but these tend to be the most common causes of snores.