The use of headings in boldface type leads the reader to specific information.
In the document, we can see that certain words are bolded. These include the title, the update and date, the name of the volcano, the alert level, the color code, and the subheadings. All of these help the reader quickly find what they need to know. If someone wants to know the alert level of the volcano, for example, they can easily see it is "watch" without having to read the entire document.