Of course, this is balanced with gas content -- if the magma contains more gas bubbles, it will erupt more violently, and if it contains less gas, it will erupt more calmly.
A memorandum of understanding (MOU) is an agreement between two parties in the form of a legal document. It is not fully binding in the way that a contract is, but it is stronger and more formal than a traditional gentleman's agreement. Sometimes, the term is used as a synonym for a letter of intent, particularly in private law.
Usually, an IOU is a signed informal notice of an unpaid debt, sometimes because of partial payment and an outstanding balance due. For example, Company XYZ may buy raw materials for its production but until it sells the finished product, it does not have sufficient cash flow to pay for the raw materials in full.