When did Clear Lake volcano erupt?

Clear Lake Volcano: When Did It Last Blow Its Top?

Ever wondered when Clear Lake volcano last erupted? It’s a question that takes you on a fascinating journey through California’s geological past. But here’s a little secret: Clear Lake isn’t actually one volcano. It’s a whole volcanic field, a sprawling area dotted with lava domes, cinder cones, and those cool, crater-like features called maars. Think of it as a volcanic playground shaped over eons!

Now, this “playground” has been active for a long time – about 2.1 million years, give or take. That’s when the first rumblings started, and things have been bubbling and popping (geologically speaking, of course) ever since. What’s really interesting is that this activity didn’t happen all at once. It unfolded in four distinct acts, each with its own unique style. And get this: the action generally moved from south to north over time.

Let’s break it down:

• Act One (2.1 to 1.3 Million Years Ago): This was the opening act, the most widespread of the bunch. Imagine lava flowing all over the place – mostly basaltic stuff, the kind that creates those dark, dramatic landscapes.
• Act Two (1.2 to 0.8 Million Years Ago): Things got a little more complex in the second act. We saw the rise of andesites, dacites, and rhyolites – those are the fancy names for different types of volcanic rock. Places like Cobb Mountain and Mount Hannah were really cooking during this period.
• Act Three (0.62 to 0.28 Million Years Ago): The spotlight shifted to Mount Konocti and Seigler Mountain. These guys were pumping out serious amounts of dacites and rhyolites. Mount Konocti, that iconic peak, probably started forming around 350,000 years ago.
• Act Four (0.1 Million to 10,000 Years Ago): This is where things get really interesting, because we’re talking about relatively recent activity. The volcanic action moved to the southeastern parts of Clear Lake and northeast of the lake. The lavas were mostly basalt, basaltic andesite, or andesite.

So, when did Clear Lake last erupt? Well, the most recent fireworks happened sometime between 8,500 and 13,500 years ago. We’re talking about those maar eruptions I mentioned earlier – explosive events that created craters in and around Clear Lake. These weren’t huge, world-shattering eruptions, more like smaller bursts of basaltic and andesitic material. Some scientists even narrow it down to around 11,000 years ago. To put a finer point on it, the best estimate pegs the last eruption at around 7,080 BCE – that’s about 9,000 years ago!

Now, here’s the million-dollar question: Is Clear Lake “dead”? Nope, not quite. It’s more like “dormant.” While it hasn’t erupted in thousands of years, there are still signs of life beneath the surface. We’re talking about the occasional volcanic-type earthquake, and those telltale springs and gas seeps that hint at underground activity. And get this: scientists believe there’s a magma chamber lurking about 7 kilometers (around 4 miles) beneath the surface. That’s why the USGS considers Clear Lake a “High” threat volcano. They keep a close eye on things, working with the Calpine Corporation at the Geysers Steam Field. Speaking of the Geysers, it’s pretty cool – it’s the largest complex of geothermal power plants in the world, all powered by the heat from that Clear Lake magma chamber! So, Clear Lake might be quiet now, but it’s a reminder that the Earth is always changing, always rumbling beneath our feet.