The 2001 Taupō Fault Belt Seismicity as Evidence of Magma-Tectonic Interaction at Taupō Volcano

The Taupō Volcanic Zone (TVZ) is the southern extent of the Tonga-Kermadec volcanic arc and encompasses the Taupō Rift, with the two structures accommodating extension through the central North Island of New Zealand via magmatic and tectonic processes, respectively. Interplay between components of the TVZ and Taupō Rift are evident at Taupō volcano, which exhibits periods of increased seismicity on a decadal scale. One period of increased seismicity occurred in 2001 outside the caldera in the adjacent Taupō Fault Belt. We use seismological analysis to detect and characterize the Taupō Fault Belt seismicity, which aligns in clusters close to active faults, and was preceded by a large cluster of earthquakes beneath Lake Taupō's Western Bay. This cluster and a temporal change in the local stress field imply that a magmatic intrusion beneath the Western Bay initiated the unrest in the fault belt. Our analysis suggests this intrusion may have occurred outside the silicic reservoir at Taupō and that it represents an example of interaction between the regional tectonic and deep mafic magmatic systems at Taupō.