Volcanoes and Volcanic Rocks II

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Volcanoes and Volcanic Rocks II
Volcanoes and Volcanic Rocks II
Photo credit G. Mattioli
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Lava Floods

• Submarine Eruptions
• Pillow Basalts  

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Flood Basalts, Columbia River
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Columnar Jointing, Devils Postpile, CA
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Columnar Jointing
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Empty Lava Tube
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Pillow Basalts, Iceland
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Composite Volcano
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Popocatépetl, Mexico, 1960
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Recent Global Volcanic Activity
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Introduction to Pyroclastic Volcanism

• Volcanic rocks and tectonics
• Island arcs as sites for pyroclastic rocks
• Pyroclastic rock generation modes
• Effusive vs. explosive volcanism
• Some characteristics of pyroclastic rocks
• Soufriere Hills Volcano, Montserrat

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Volatile Control on Eruption Style
From Sparks, 1978
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Pressure Effects on Volatile-rich Systems
From Best, 2003
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Volatiles and Eruptions
From Best, 2003
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Dome Formation
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1993 Dome MSH
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circum-Caribbean seismicity
Caribbean
epicenters lt 30 km depth from USGS
Modified from Jansma et al., 2000
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Caribbean bathymetry
BR Beata Ridge HE Hess Escarpment NPDB North
Panama Deformed Belt SCDB South Caribbean
deformed belt
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Montserrat Location Map
From Mattioli et al., 1998
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1995 Tar River Valley
Tar River Valley - Looking ENE October 1995
English Crater 4 Ka Sector Collapse
Photo credit G. Wadge
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1995 earthquakes
Harmonic Tremor
VT Eqs -gt
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Destroyed Hermitage CGPS Site, 1996
Photo credit G. Mattioli
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Kinematic Flow Models

• Theoretical background
• Data required
• Parameterization of the models
• Results from Montserrat
• Implications

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Required data

• Accurate DEMs - required adding a synthetic
  dome to generate current topopgraphy not on
  available maps
• Previous direct measurements at other similar
  volcanoes Mt. St. Helens and Mt. Unzen

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Kinematic Flow Models
From Hooper Mattioli, 2001
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Tar River Valley, Spring 1996
Burnt Zone - Initial channelization of small PFs
Photo credit G. Mattioli
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Simulated Flow Velocities
From Hooper Mattioli, 2001
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SHV Pyroclastic Deposits to 1998
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New Tar River Delta
July 12th 2003 eruption
From http//www.bgs.ac.uk/news/montserrat.html
Photo credit Steve OMeara Volcano Watch
International
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Plymouth, Montserrat - Oct. 1997
Photo credit G. Mattioli
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Sub-surface magmatic processes

• Campaign and continuous GPS geodesy done from
  1995-2003
• Several CGPS sites destroyed over the years
  current network was 6 sites WTYD site destroyed
  on July 12th, but will be replaced.
• Data processed in absolute point positioning mode
  with final JPL orbits, clocks, and earth
  orientation parameters
• CALIPSO Project recently added 4 additional sites

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Hermitage CGPS site, Jul. 1996
Photo credit G. Mattioli
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General CGPS Schematic
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Vulcanian Explosions, Oct. 1997
No Surface Flux
Renewed Dome Growth
Explosions -gt
lt-Dome Growth
13 km
Subsidence Again! -gt
lt- Subsidence
Inflation -gt
Photo credits G. Mattioli
Data from Mattioli et al., 2001 Sparks et al.,
1998
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GPS Data and Elastic Model
From Mattioli et al., 2002
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GPS Vertical Velocity Field
From Mattioli et al., 1998 Mattioli et al., 2002
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CALIPSO Borehole Observatory

• Sacks-Evertson single component dilatometer (10-9
  strain)
• Nearly broadband 3 component seismometer (2 Hz
  to 1 kHz)
• Pinnacle Systems short-baseline electronic
  tiltmeter
• Ashtech µ-Z code-phase CGPS w/ choke ring antenna

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Unloading DOSECC Drill Rig
Photo credits G. Mattioli
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SHV Dome - Dec. 2002
Photo of dome in Dec. 02 on a rare clear day. By
July 2003 the dome had grown to gt230 M m3 and
had not collapsed significantly for 2 years!!
Photo credit G. Mattioli
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Drilling Operations Core Logging
Photo credits G. Mattioli
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Grouting Strainmeter at Air Studios
Photo credit G. Mattioli
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Trants Construction
Photo credit G. Mattioli
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Trants Instrument Crypt GPS Monument
Photo credit G. Mattioli
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Reftek Downloads
Photo credit G. Mattioli
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July 12th PFs
July 12th, 2003 - Dome collapse begins at 9 AM
AST By sunset, pyroclastic flows are getting
more energetic and now routinely reach the sea
at the Tar River delta. NB white is steam while
gray is co-ignimbrite ash cloud.
Photo credit G. Mattioli
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July 12 Data
Trants Borehole Seismic and Strain Records for
July 12th Sub-plinian to Plinian event at 11 PM
AST
Seismometer 200 Hz (803 PM to 1213AM AST)
Strainmeter 50 Hz (842 PM to 1242AM AST)
Although Trants site was impacted by ash during
the culminating event of the July12th dome
collapse, the CALIPSO BH instruments
functioned throughout the eruption.
Photo credit G. Mattioli
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Air Studios on July 14th
First visit to Air Studios on July 14th - 12.5 cm
of ash and 6 cm mud in crypt NB infrasound
microphone under ash, but CALIPSO was still up!
Photo credits G. Mattioli
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Ash in Olveston - July 13th
The morning after at Sea Dreams in Olveston 12
cm of ash and 6.5 cm pumice fragments!
Photo credits G. Mattioli