During most of its history Mount Adams has shown a limited range of eruptive styles only being lava flows, debris slides, and tephra falls. Very explosive eruptions have been rare. Compared to the large explosive eruptions at nearby Mount St. Helens during the past 20,000 years, the eruptions of Mount Adams have been very mild. Eruptions at Mount St. Helens have covered areas more than 120 miles downwind with ash deposits several centimeters or inches thick, but those at Mount Adams have blanketed only areas a few miles away with a the same thickness of ash. Even though theyíre low levels of power and force, eruptions at Mount Adams are still very hazardous. More importantly even during times of no eruptive activity, landslides of weakened rock that originate on the steep upper sides of Mount Adams have been a dangerous common thing and they can start lahars, which are watery flows of volcanic rocks and mud that surge downstream like rapid flowing concrete. Lahars also known as mudflows or debris flows and they can destroy and kill everything in the valley floors that they run down in to tens of miles from the volcano.
The most often occurring type of eruption that has happened at Mount Adams, as well as in the other volcanic areas, produces lava flows, or streams of molten rock. These and older lava flows usualy traveled less than 12 miles from the vents, but in some events larger flows where as long as 15 to 30 miles. Typical lava flows on the lower sections of the mountain and other places in the volcanic fields spread out onto gentle slopes and funneled out into valleys. The moving flows were tens of feet to more than 100 feet thick and where made up of crusty lava blocks covering a more fluidish, liquid core. Their steep fronts moved very slowly at about only about 330 feet per hour. Thatís much more slowly than people typically walk. Still, the lava flows will bury, crush, and burn all structures in their paths, and hot lava boulders coming off flows make it very dangers to on lookers and the also will start forest fires. A normal eruption consists of one main single lava flow over a period of days or weeks and even of a sequence of flows erupted over weeks to a few years. Eruptions that keep happening over years to decades build a broad apron of lava flows on a side of a mountain or even build a separate small volcano several 1,000 feet 6 miles or more in diameter.
There is a very large possibility of Mt. Adams erupting again very soon because it has been a long time since the last time it awoke. The people and businesses in the area need to be aware and cautious of the risk they are in by living and working near the mountain like as it is with any other volcano. This mountain also provides a great place for hiking, biking, skiing, and many other things that would be ruined if this mountain was to awake. It is a very scenic beautiful mountain that has the potential to do what Helens has done.