how long has a shield volcano lasted?
http://www.answers.com/topic/shield-volcano
Scroll down past the ads and read the article. I'm not sure if it has the information you're asking for because I don't know what you mean by how long one of these lasted.
5.6m=how many cm
To determine how long a shield volcano has lasted, we need to consider its lifespan, which is influenced by various factors. Here's how we can estimate the duration:
1. Formation Period: The formation of a shield volcano begins with the eruption of basaltic lava. This initial phase can take anywhere from a few months to centuries, depending on the volcano's growth rate and the frequency of eruptions.
2. Active Period: Once the shield volcano is formed, it enters an active phase characterized by intermittent eruptions. These eruptions can occur over a span of weeks, months, or even years. The active period of a shield volcano can last for several hundred to thousands of years.
3. Dormant Period: Over time, a shield volcano may enter a dormant phase where there are no eruptions, but the volcano remains potentially active. This dormant period could last for decades, centuries, or even millennia.
4. Extinct Period: Eventually, a shield volcano may become extinct, meaning it is no longer capable of producing eruptions. Determining the duration of the extinct period requires geological analysis and can range from thousands to millions of years.
It's important to note that estimating the exact duration of a shield volcano's lifespan is challenging due to the variability of geological processes. Each shield volcano has its own unique timeline, influenced by factors such as magma supply, tectonic activity, and local environmental conditions.