Recent Inflation of Mauna Loa Volcano, Hawai`i
Abstract
The inflation of Mauna Loa Volcano that began in May 2002 continues. The inflation rate was highest during the first six months, then relatively low over the next year. Continuously recording GPS (CGPS) stations indicate that extension and uplift rates increased again in 2004. The deformation pattern defined by continuous- and survey-GPS data shows a strong asymmetry of motion about the summit, with greater horizontal velocities on the southeast flank. Vertical velocities, however, are higher in the summit area. Modeling of both the continuous- and survey-GPS data suggests two sources of deformation - inflation of a magma reservoir 4-5 km below the southeastern caldera (between the main topographic caldera and the outer ring faults) and slip on a fault beneath the southeast flank. The start of reinflation in 2002 immediately followed a small swarm of deep (30-50 km) short-period earthquakes in late April to early May. Seismicity was not notable thereafter until early July 2004, when a sustained flurry of deep, long-period seismicity began, averaging one located earthquake per day for the first three weeks, and gradually increasing to about 100 locatable events per week as of this writing. The Hawaiian Volcano Observatory has recently performed upgrades of the seismic network and expanded the deformation monitoring network on Mauna Loa. In early 2002, the deformation network on Mauna Loa consisted of 4 CGPS stations, 3 electronic tiltmeters, and 3 strainmeters. Just those few CGPS stations were enough to alert us, with unprecedented timeliness, of the onset of inflation. Survey GPS measurements of a large array of benchmarks confirmed the renewed inflation and helped characterize the deformation sources. Today, we have 13 CGPS stations, 6 tiltmeters, and 3 strainmeters on Mauna Loa, with another tiltmeter to be installed in October. The main expansion in GPS instrumentation occurred in 2004, with the installation of 6 new instruments. Several new GPS stations are positioned to monitor the potential movement of magma into the northeast and southwest rift zones and into the area of radial vents on the northwest flank. The network is also designed to monitor stress changes in the seismically active Ka`oiki fault zone on the southeast flank.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2004
- Bibcode:
- 2004AGUFM.G42A..02M
- Keywords:
-
- 8419 Eruption monitoring (7280);
- 7280 Volcano seismology (8419);
- 1208 Crustal movements: intraplate (8110);
- 1243 Space geodetic surveys