One of the intriguing facts about volcanoes is that their history and eruption patterns are vastly different from one another. The patterns vary with the age, terrain, climate, and natural formation of the location. Even though the specifics of each are different, you can generally identify a volcano’s past by examining its current, active or dormant eruptions.
Volcanoes are also characterized by different kinds of fissures, cracks, and fractures. These patterns are indicative of different volcanic events. Volcanic fissures are lines of volcanic lava and ash produced during an eruption. If a volcano were to stop erupting, the cracks and fissures would become filled with lava or ash and the area would be cooler.
In addition to fissures, volcanic eruptions can also leave ash as a byproduct. Different ash has different chemical composition, so it is best to understand the ash of any particular volcano. Understanding the ash of a volcano helps scientists determine if a volcano is active or dormant.
Volcanoes produce different types of craters. The result of an eruption, a crater may either form from lava flow, as a result of atmospheric explosion, or as a result of an explosion due to earthquakes or volcanic eruption. Craters formed as a result of volcanic explosions and pyroclastic flows are still active today.
Another way to determine if a crater is active is by observing the quality of the soil surrounding the crater. Dirt around active craters has been found to be saturated in sulfur and magnesium, which indicate that the ground has been recently warmed. On the other hand, volcanic craters that have not had any recent activity may not have any sediment or soil in their vicinity. A crater that has not erupted recently could indicate that the crater was not recently heated.
During ancient times, volcanoes were only active during the warmer summer months and less during the winter months. Because of this, rocks that have accumulated on the surface of a volcano are mostly made up of stuff. During the colder months, these rocks can be easily eroded by strong winds and rivers. This will reveal the undisturbed surface of the volcano, allowing scientists to examine the history of the crater.
There are a few reasons why historical records are not available for many of these volcanoes. These include locations that are no longer habitable and those that are too far away from the modern day to easily access. While some ancient lava flows still exist, others have been buried or sunken deep below the surface. But even if all these sites were accessible, they would be difficult to study since much of the information has been destroyed or erased.
With such great difficulty, scientists must rely on their knowledge of volcano history to infer their history. Because there are so many variables that could make a volcano history different, scientists have used a variety of methods to establish the right patterns. One method that scientists employ is to infer the effects of eruptions using all of the previously mentioned factors, then compare the historical record with what they find.