Stress control of deep rift intrusion at Mauna Loa volcano, Hawaii - - PowerPoint PPT Presentation

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Stress control of deep rift intrusion at Mauna Loa volcano, Hawaii - - PowerPoint PPT Presentation

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Stress control of deep rift intrusion at Mauna Loa volcano, Hawaii Outline: - past earthquake-volcano interaction at - 2002-2005 intrusion - effects on the volcano - Kilauea deformation Falk Amelung*, Sang-Ho Yun, Thomas Walter, Paul

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SLIDE 1

Stress control of deep rift intrusion at Mauna Loa volcano, Hawaii

Falk Amelung*, Sang-Ho Yun, Thomas Walter, Paul Segall, Sang-Wan Kim (*) Rosenstiel School of Marine and Atmospheric Sciences (RSMAS) University of Miami, Florida, USA Outline:

  • past earthquake-volcano

interaction at

  • 2002-2005 intrusion
  • effects on the volcano
  • Kilauea deformation
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SLIDE 2

The Hawaiian Volcanoes

Kilauea: continuous eruption since 1983

Photos: HVO

The Hawaiian volcanoes

Pu’u O’o 1983

Mauna Loa: eruptions in 1950, 1975, 1984

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SLIDE 3

The Hawaiian Volcanoes

Photos: HVO

The Hawaiian volcanoes

The modes of deformation:  rift intrusion  seismic/aseismic decollement slip  flank motion  magma chamber inflation/deflation

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SLIDE 4

The Hawaiian Volcanoes

Photos: HVO

The Hawaiian volcanoes

The modes of deformation:  rift intrusion  seismic/aseismic decollement slip  flank motion  magma chamber inflation/deflation 1975 M7.2 Kalapana earthquake

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SLIDE 5

The Hawaiian Volcanoes

Photos: HVO

The Hawaiian volcanoes

The modes of deformation:  rift intrusion  seismic/aseismic decollement slip  flank motion  magma chamber inflation/deflation 1975 M7.2 Kalapana earthquake

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SLIDE 6

The Hawaiian Volcanoes

Photos: HVO

The Hawaiian volcanoes

The modes of deformation:  rift intrusion  seismic/aseismic decollement slip  flank motion  magma chamber inflation/deflation Did the 1974 earthquake trigger the 1975 eruption ?

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SLIDE 7

The Hawaiian Volcanoes

Photos: HVO

The Hawaiian volcanoes

The modes of deformation:  rift intrusion  seismic/aseismic decollement slip  flank motion  magma chamber inflation/deflation Did the 1974 earthquake trigger the 1975 eruption ?

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SLIDE 8

Earthquakes and eruptions at Mauna Loa

Walter and Amelung, JGR, 2006

  • 17 eruptions since 1850
  • 15 earthquakes sin 1850 (M>6)
  • 75% of eruptions and earthquakes

are part of 2-yr sequences (random probability is 20%)

earthquake-volcano interaction !

  • pairs of NERZ eruptions and

Kaoiki earthquakes.

  • pairs of SWRZ eruptions and

Kona or Hilea earthquakes

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SLIDE 9

Stress changes due to earthquakes

Normal stress along the rift zone due to 1950 Kona earthquake The 1950 dike intruded in a section

  • f the rift zone unclamped by the earthquake !

Walter and Amelung, JGR, 2006

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SLIDE 10

Stress changes due to earthquakes

Normal stress along the rift zone due to 1983 Kaoiki earthquake The 1984 dike intruded in a section

  • f the rift zone unclamped by the earthquake !

Walter and Amelung, JGR, 2006

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SLIDE 11

Stress changes due to dike intrusions

Coulomb failure stress along decollement due to dike intrusion into the North East Rift Zone NERZ intrusions encourage Kaoiki earthquakes !

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SLIDE 12

Stress changes due to dike intrusions

Coulomb failure stress along decollement due to dike intrusion into the South West Rift Zone SWRZ intrusions encourage Hilea and Kona earthquakes !

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SLIDE 13

Stress changes at magma body due to earthquakes

All earthquake types cause extension.

magma chamber

Conclusion:

magma chamber decompression encourages eruptions

Walter and Amelung, JGR, 2006 Walter and Amelung, Geology, 2007

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SLIDE 14

Mauna Loa inflation 2002-2005

MOKP MLSP ELEP

GPS-measured baseline length

MLSP-MOKP: 10 cm lengthening during 2002-2005 ELEP-MOKP: 25 cm lengthening during 2002-2005

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SLIDE 15

Interferograms

Radarsat

  • Jan 2002 – Dec 2005
  • 4 beams (23.5° - 43.5°)
  • 5-8 interferograms stacked per beam
  • repeat cycle of 24 days -> 60 images/yr

D1: 23.5° A3: 30.5° A6: 43.5° D6: 43.5°

Descending Standard Beam 1 Ascending Standard Beam 6 incidence angle 43.5° incidence angle 23.5°

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SLIDE 16

Stacked Interferograms

Ascending, Beam 3

Mauna Loa volcano, Hawaii

Descending S6

LOS velocity [m/yr]

Interferogram stack

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SLIDE 17

Stacked Interferograms

Ascending, Beam 3

Mauna Loa volcano, Hawaii

Descending S1

LOS velocity [m/yr]

Interferogram stack

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SLIDE 18

Stacked Interferograms

Ascending, Beam 3

Mauna Loa volcano, Hawaii

Ascending A3

LOS velocity [m/yr]

Interferogram stack

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SLIDE 19

Stacked Interferograms

Ascending, Beam 3

Mauna Loa volcano, Hawaii

Ascending A6

LOS velocity [m/yr]

Interferogram stack

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SLIDE 20

Stacked Interferograms

Mauna Loa volcano, 2002-2005 2-D velocity field

based on ~60 SAR images

Amelung et al., Science, 2007

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SLIDE 21

Magma source model: Distributed dike opening + Mogi

this model: independent dislocation and point sources. next model: account for interaction between dike and magma chamber using a constant magma excess pressure model

  • -> inferred parameter: excess pressure, chamber radius
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SLIDE 22

Magma source model: Distributed dike opening + Mogi

this model: independent dislocation and point sources. next model: account for interaction between dike and magma chamber using a constant magma excess pressure model

  • -> inferred parameter: excess pressure, chamber radius
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SLIDE 23

Magma source model: Distributed dike opening + Mogi

?

this model: independent dislocation and point sources. next model: account for interaction between dike and magma chamber using a constant magma excess pressure model

  • -> inferred parameter: excess pressure, chamber radius
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SLIDE 24

Magmatic system modelling approach

B

Coupled constant excess pressure dike-chamber model (binary dike)

Dike opening depends on how open elements are connected (Yun et al., 2005)

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SLIDE 25

Geophysical Inversion: Boundary Element Approach

  • Dike divided into elements, either open or closed, subject to constant pressure
  • Simulated Annealing Procedure used to find optimal parameters.
  • Invert for :

excess pressure dike geometry sphere geometry

Simulation: Sang-Ho Yun

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SLIDE 26

Geophysical Inversion: Boundary Element Approach

  • Dike divided into elements, either open or closed, subject to constant pressure
  • Simulated Annealing Procedure used to find optimal parameters.
  • Invert for :

excess pressure dike geometry sphere geometry

Simulation: Sang-Ho Yun

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SLIDE 27

Preferred model

Amelung et al., Science, 2007

Model features:

Dike opening under summit and uppermost SWRZ Intrusion along 20 km of SWRZ/summit riftzone

  • Max. opening 30 cm/yr (--> 1.3 m 2002-2007)

Magma chamber at 4.8 km depth Chamber diameter 1.3 km 1.8 MPa/yr excess pressure (--> 8 MPa 2002-2007)

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SLIDE 28

Mauna Loa: Model Fit

, Differences are due to

  • simplified chamber model
  • unmodelled decollement slip.

Preferred model

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SLIDE 29

Why did the intrusion occur in the SWRZ ?

Proposed answer: Stress transfer

2002-2005 intrusion

  • ccurred into section
  • f rift zone unclamped

by 1983 earthquake and 1984 eruption.

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SLIDE 30

Where would we expect the next intrusion?

2002-2005 caused strongest unclamping next to it.

  • current intrusion continues and next eruption occurs from SWRZ
  • current intrusion stops, next intrusion occurs into rift sections of strongest unclamping
  • intrusion triggers earthquake (or aseismic slip)

Forecast: one of three scenarios will occur (stress model based):

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SLIDE 31

Coulomb stress

  • Coulomb stress for seaward motion along horizontal fault planes increased by > 0.5 MPa.
  • Intrusion encouraged seismic or aseismic decollement motion
  • Aseismic slip may already be occurring
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SLIDE 32

Opening along Rift Zone

  • maximum dike inflation south of caldera beneath summit reservoir
  • rift intrusion at depth under summit and SWRZ
  • magma chamber at 4.5 km below summit
  • magma chamber 1.3 km radius
  • magma excess pressure ~2 MPa/yr

Conclusions:

  • 1. Magmatic system (2002-2005):
  • 2. Stress transfer:
  • intrusion occurred in rift section unclamped by

1983/84 earthquake and intrusion.

  • intrusion encouraged new intrusions into parts of SWRZ
  • intrusion encouraged decollement faulting (seismic or aseismic)
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SLIDE 33

The dynamic Hawaiian volcanoes

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SLIDE 34

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Kilauea volcano

Total Time: 32.6 yr Total Time: 22.2 yr Total Time: 45.6 yr Total Time: 19.3 yr −155.4 −155.35 −155.3 −155.25 −155.2 −155.15 −155.1 −155.05 −155 19.2 19.25 19.3 19.35 19.4 19.45 −155.4 −155.35 −155.3 −155.25 −155.2 −155.15 −155.1 −155.05 −155 19.2 19.25 19.3 19.35 19.4 19.45 −155.4 −155.35 −155.3 −155.25 −155.2 −155.15 −155.1 −155.05 −155 19.2 19.25 19.3 19.35 19.4 19.45 −155.4 −155.35 −155.3 −155.25 −155.2 −155.15 −155.1 −155.05 −155 19.2 19.25 19.3 19.35 19.4 19.45

RsatD1 1999-2005 RsatD4 2000-2004 RsatA3 2000-2005 RsatA6 1998-2005

−0.03 −0.015 0.015 0.03 LOS velocity [m/yr]
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SLIDE 35

29

Kilauea volcano

Total Time: 32.6 yr Total Time: 22.2 yr Total Time: 45.6 yr Total Time: 19.3 yr −155.4 −155.35 −155.3 −155.25 −155.2 −155.15 −155.1 −155.05 −155 19.2 19.25 19.3 19.35 19.4 19.45 −155.4 −155.35 −155.3 −155.25 −155.2 −155.15 −155.1 −155.05 −155 19.2 19.25 19.3 19.35 19.4 19.45 −155.4 −155.35 −155.3 −155.25 −155.2 −155.15 −155.1 −155.05 −155 19.2 19.25 19.3 19.35 19.4 19.45 −155.4 −155.35 −155.3 −155.25 −155.2 −155.15 −155.1 −155.05 −155 19.2 19.25 19.3 19.35 19.4 19.45

RsatD1 1999-2005 RsatD4 2000-2004 RsatA3 2000-2005 RsatA6 1998-2005

−0.03 −0.015 0.015 0.03 LOS velocity [m/yr]

Text

Southflank seaward motion explained by decollement slip and rift intrusion (Owen et al.,2000)

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SLIDE 36

30

Kilauea volcano

Total Time: 32.6 yr Total Time: 22.2 yr Total Time: 45.6 yr Total Time: 19.3 yr −155.4 −155.35 −155.3 −155.25 −155.2 −155.15 −155.1 −155.05 −155 19.2 19.25 19.3 19.35 19.4 19.45 −155.4 −155.35 −155.3 −155.25 −155.2 −155.15 −155.1 −155.05 −155 19.2 19.25 19.3 19.35 19.4 19.45 −155.4 −155.35 −155.3 −155.25 −155.2 −155.15 −155.1 −155.05 −155 19.2 19.25 19.3 19.35 19.4 19.45 −155.4 −155.35 −155.3 −155.25 −155.2 −155.15 −155.1 −155.05 −155 19.2 19.25 19.3 19.35 19.4 19.45

RsatD1 1999-2005 RsatD4 2000-2004 RsatA3 2000-2005 RsatA6 1998-2005

−0.03 −0.015 0.015 0.03 LOS velocity [m/yr]

Total Time: 119.8 yr

155.4 −155.30 −155.20 19.20 19.30 19.35 19.40

−0.03 −0.015 0.015 0.03 ground velocity [m/yr]

−155.1 −155.0

maximum uplift !

uplift

tical deformation

LOS-velocity uplift

exaggerated colorscale

Text Text

  • Southwest rift zone subsiding at 6-7 cm/yr
  • South flank uplifting at 1.5 cm/yr
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SLIDE 37

31

Kilauea volcano

Total Time: 119.8 yr

155.4 −155.30 −155.20 19.20 19.30 19.35 19.40

−0.03 −0.015 0.015 0.03 ground velocity [m/yr]

−155.1 −155.0

maximum uplift !

uplift

tical deformation

uplift

exaggerated colorscale

Text Text

  • Southwest rift zone subsiding at 6-7 cm/yr
  • South flank uplifting at 1.5 cm/yr
  • ceanic crust

detachement Olivine cumulates subsidence uplift

?

1.5 km

  • 12 km

Text

uplift subsidence

Southwest rift zone

  • ceanic crust

detachement deep dike subsidence uplift

?

1.5 km

  • 12 km

East rift zone

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SLIDE 38

32

19.3 19.4

4 km

Kilauea caldera

1cycle = 12 cm look direction

JERS, 4.5 yr , Oct 1993 - Mar 1998

5 cm/yr 1990-1996 GPS

Total Time: 19.3 yr 19.25 19.3 19.35 19.4 19.45

RsatD4 2000-2004

Continuity with time

JERS 1993-1998 Radarsat 2000-2004

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SLIDE 39

921020−930301

−155.3 −155.25 −155.2 −155.15 19.2 19.25 19.3 19.35 19.4 19.45

1999 80o

  • 60

50-80 1993 1997

33

JERS 1992-1993

ALOS 2007 JERS 1992-1993

Intrusions

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SLIDE 40

magma intrusion into rift zone and shallow magma reservoir intrusion occurrs into a section of the rift zone that was unclamped by the 1983 earthquake stress change modelling is a tool for intrusion forecasting

34

Conclusions

Mauna Loa: Kilauea very dynamic with secular subsidence and uplift in the summit area, repectively intrusions into east rift zone and summit area time-series analysis needed

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SLIDE 41