The Waimangu Geothermal Valley, with Lake Tarawera and Tarawera itself in the background.
Erik Klemetti / January 2009
Over the weekend, a small earthquake swarm hit in the Okataina Caldera Complex on the north island of New Zealand. The swarm itself only lasted a few hours and generated a few dozen earthquakes, all less than magnitude 3. The swarm was located directly underneath the Waimangu Geothermal Valley, the chain of hot springs, mudpots and geysers left by the 1886 eruption of Tarawera---the last eruption from the Okataina Caldera Complex. That 1886 eruption was an impressive event, creating one of the few, recent basaltic plinian eruptions that spread dark ash all the way into the Bay of Plenty. The Waimangu Valley itself is amazing, even if the world's largest geyser no longer erupts along its length. Now, why would I bring up a small earthquake swarm in a volcanically active area? ...
