Downhole seismometers lead to a refined velocity model

As the magma rises for the next eruption, we want to know!

One of the ways we detect rising magma is seismology, and knowing how quickly seismic waves move through the ground below Auckland is important to determine how much time we have before the magma reaches the surface.

By refining the velocity model used to locate earthquakes, Auckland can be better prepared for an eruption from the volcanic field that lies beneath the region in New Zealand’s upper North Island.

In the past, high levels of background seismic noise and extremely low levels of historical seismicity have made monitoring particularly challenging in the area.

In order to improve volcanic field monitoring, recent steps include the installation of downhole seismometers and a seismic refraction study to refine the velocity model.

An evaluation of the performance of a newly installed downhole seismometer shows that downhole instrumentation in a volcano monitoring network allows for improved earthquake detection.

However, several downhole sensors are required across the network to achieve the best results.

The seismic refraction study used surface explosions at Auckland quarries as a source of seismic waves, and revealed that improvements to the velocity model for Auckland can help define earthquake locations and depths.

However, further refinements are required before the model is incorporated into the GeoNet earthquake location system so that the region is better prepared for an eruption.

Tags:Auckland Volcanic Fielddownhole seismometerEmergency ManagementGeoNetmonitoringpublicationsvelocity model