As the eruption continues at fissure #8 within Leilani Estates, some people have asked "how long ago was the land that Leilani was built upon created?" The answer is not so simple. The last lava flow to have actually inundated the land that now makes up the subdivision occurred around 350 years ago. However, Leilani's roots go way back in time. As a shield volcano, Kīlauea has built herself up by erupting repeatedly over the last 350,000 years. She emerged above sea level around 100,000 years ago and has continued to grow in both size and height ever since. Same goes for Mauna Loa and all the other Hawaiian volcanoes that make up our island chain. They all started life at the bottom of the Pacific Ocean. And before they even begin to emerge, they have to grow at least 20,000 feet tall; erupting for up to 500,000 years before they even start to build up an island above the waves. Then they have to erupt for hundreds of thousands of years more before they reach their peak height in the volcanic growth cycle above the sea. For example, Kīlauea's sister, Mauna Loa; stands nearly 13,700 feet above sea level today. Well, before she could even reach that height, she had erupt repeatedly over a period of at least 700,000 years both below and above the sea surface. And like Kīlauea, every eruption of Mauna Loa and all the other Hawaiian Shields built up the bulk of the volcanic edifices layer upon layer. This graphic demonstrates this concept nicely. Around 90% of Kīlauea's surface has been covered by lava flows within the past 1,000 years, while around 40% of Mauna Loa has been covered within that same time-frame. Hualālai has also erupted a few times in the last 1,000 years and seems to awaken once every few hundred years. So just how long has it taken to build up the Island of Hawaiʻi we know today? At least 1.5 million years when you account for all the 5 volcanoes that grew together to form the island: Kohala, Mauna Kea, Hualālai, Mauna Loa and Kīlauea.
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