New Insight on the Increasing Seismicity during Tenerife's 2004 Volcanic Reactivation

TL;DR

This study analyzes the 2004 Tenerife seismic crisis using advanced techniques, revealing two main seismogenic zones and proposing a magma intrusion model consistent with prior geophysical data.

Contribution

It introduces novel seismic analysis methods, including cross-correlation and hypoDD, to better locate and classify earthquakes during the Tenerife crisis.

Findings

Identification of two major seismogenic zones northwest and southwest of Teide-Pico Viejo

Detection of over 800 additional seismic events improving the earthquake catalogue

Revised timing of activity onset, starting three months earlier than previously believed

Abstract

Starting in April 2004, unusual seismic activity was observed in the interior of the island of Tenerife (Canary Islands, Spain) with much evidence pointing to a reawakening of volcanic activity. This seismicity is now analyzed with techniques unprecedented in previous studies of this crisis. The 200 earthquakes located onshore during 2004 and 2005 have been classified by cross-correlation, resulting in a small number of significant families. The application of a relative location algorithm (hypoDD) revealed important features about the spatial distribution of the earthquakes. The seismic catalogue has been enhanced with more than 800 additional events, detected only by the closest seismic station. These events were assigned to families by correlation and as a consequence their hypocentral location and magnitude were estimated by comparing them to the earthquakes of each family. The new catalogue obtained by these methods identifies two major seismogenic zones, one to the northwest and the other to the southwest of the Teide-Pico Viejo complex and having a separation of at least 10 km between them. These regions alternate their activity starting in January 2004, i.e., three months earlier than previously thought. We propose a simple model based on the results of this work which will also concur with all previous geophysical and geochemical studies of the 2004 crisis. The model proposes a single magma intrusion affecting the central part of the island with lateral dikes driven by the rifts to the northwest and southwest.