Last night some of our Rū network members were awoken by an earthquake under Lake Taupō. You can find the estimated epicentre and other information about the earthquake at this page from Geonet. As you can read there, the earthquake’s magnitude was estimated as M4.2. Geonet qualifies this as a “light” event, but if you live in Taupō the shaking probably woke you up! This is because the quake happened only ~10 km from town, where the amplitude of the waves are still relatively large. The same effect can be seen when throwing a rock in the water: ripples are high near where the rock landed, but as the ripples travel away, their amplitude decreases. The distance of this earthquake to the other stations in the Rū network is so large that you probably did not feel its seismic waves, but your TC1 seismometer is sensitive enough to record it. Have a look when you get back to school on Monday!

Lake Taupō is a large caldera volcano. From time to time, Taupō-nui-a-Tia and the surrounding areas see increases in the amount of earthquakes. They often come from a distinct spot. We call this an “earthquake swarm.” Swarms over the years have come from different spots under the lake, and sometimes swarms will stop and start years later in the same location. Exactly why this happens is an area of active research. This particular earthquake is part of a recent swarm from the last weeks. You can read more details about this swarm and seismicity near Taupō here.