Dynamics of active magmatic and hydrothermal systems at Taal Volcano, Philippines, from continuous GPS measurements

Abstract

A dense network of continuous single‐ and dual‐frequency GPS receivers at Taal Volcano, Philippines, reveals four major stages of volcanogenic deformation: deflation, from installation in June 1998 to December 1998; inflation, from January to March 1999; deflation, from April 1999 to February 2000; and inflation, from February to November 2000. The largest displacements occurred during the February–November 2000 period of inflation, which was characterized by ∼120 mm of uplift of the center of Volcano Island relative to the northern caldera rim at average rates up to 216 mm/yr. Deformation sources were modeled using a constrained least squares inversion algorithm. The source of 1999 deflation and inflation in 2000 were modeled as contractional and dilatational Mogi point sources centered at 4.2 and 5.2 km depth, respectively, beneath Volcano Island. The locations of the inflationary and deflationary sources are indistinguishable within the 95% confidence estimates. Modeling using a running 4‐month time window from June 1999 to March 2001 reveals little evidence for source migration. We suggest that the two periods of inflation observed at Taal result from episodic intrusions of magma into a shallow reservoir centered beneath Volcano Island. Subsequent deflation may result from exsolution of magmatic fluids and/or gases into an overlying, unconfined hydrothermal system.

Volcano deformation monitoring using GPS

“…6) in addition to three continuously operating dual-frequency GPS receivers that had been deployed earlier (Lowry et al 2001), making it one of the densest volcano monitoring networks in the world. Using daily coordinate solutions and the Bernese version 4.2 software (Rothacher & Mervart 2001), this network revealed distinct periods of inflation and deflation with the largest uplift being approximately 12cm (Bartel et al 2003). As expected, the precision of the height component decreases approximately linearly with increasing baseline length, in this case from ±5mm at 2.8km to ±18mm at 13.3km.…”

“…The data can be processed at hourly or shorter intervals in order to provide station deformation estimates. The UNAVCO system was first tested at the Long Valley Caldera, California, in 1998 and has subsequently been deployed on several other volcanoes, including Popocatepetl, Mexico (Cabral-Cano et al 1999), Kilauea/Mauna Loa, Hawaii (Cervelli et al 2002) and Taal volcano, Philippines (Bartel et al 2003). The latter network comprises 11 remote stations located on the flanks of the volcano (Fig.…”

“…As expected, the precision of the height component decreases approximately linearly with increasing baseline length, in this case from ±5mm at 2.8km to ±18mm at 13.3km. (Bartel et al 2003) Rizos et al (2000) and Roberts (2002) describe the prototype of a four-station network of single-frequency GPS receivers installed on Mt. Papandayan, Indonesia.…”

Volcano Deformation and Modeling on Active Volcanoes in the Philippines from ALOS InSAR Time Series

“…Reference [13] estimated a source depth of 5.2 km centered at 14.021°N, 120.999°E for the 2000 inflationary period, with a maximum inflation rate of 22 cm/yr. Reference [14] estimated a source depth of 5.1 km centered at 14.013°N, 121.003°E for the 2005 inflationary period, with a maximum inflation rate of 18 cm/yr.…”

Shear-wave Velocity Structure around Teide Volcano: Results Using Microtremors with the SPAC Method and Implications for Interpretation of Geodetic Results

“…Therefore, traditional monitoring systems based on the use of seismic, hydrologic or fumarolic activity observations are complemented with geodetic observations (e.g., SIGURDSSON et al, 2000), extending the study of volcanic phenomena from seconds (seismic monitoring) to years and providing details on the growth of magma bodies within the volcano (STEIN et al, 2000). Geodetic volcano monitoring includes the deployment of long-term instrumentation, such as clinometers and extensometers, and regular geodetic network surveying campaigns using classic terrestrial techniques or GPS (Global Positional System), the use of gravimetry as well as the more recent techniques PGPS (Permanent GPS observation) and radar interferometry technology (DIXON et al, 1997;SEGALL et al, 2001;BARTEL et al, 2003;DZURISIN, 2003). As an obvious consequence, these long-term geodetic monitoring techniques involve subsequent interpretation of observed deformation and gravity changes.…”