Wendy McCausland Graduate Research Assistant Department of Earth and Space Sciences, University of Washington Advisors

1. Volcanic Seismology and Deep Long Period Earthquakes Introduction- Types, characteristics How relate to volcanic processes? Deep Long Period Earthquakes (DLP) Examples from some Cascade Volcanoes Mt Baker Mt Rainier Mt St. Helens Introduction- Types, characteristics How relate to volcanic processes? Deep Long Period Earthquakes (DLP) Examples from some Cascade Volcanoes Mt Baker Mt Rainier Mt St. Helens

2. Dr. Steve MaloneResearch Professor Department of Earth and Space Sciences Research Interests: Seismicity of the Cascade volcanoes Earthquake and volcanic hazards Strong-motion seismology Computer applications in seismic data acquisition and network analysis Pacific Northwest Seismic Network (PNSN) http://www.ess.washington.edu/SEIS/PNSN/

3. Current Stations Pacific Northwest Seismograph Network 138 Short-period + 15 others 21 Broad-band + 9 others 69 Strong-motion + 35 NSMP sites The map shows the stations of the PNSN (three catagories) and some of the stations from the cooperating networks.The map shows the stations of the PNSN (three catagories) and some of the stations from the cooperating networks.

4. Dr. Chris NewhallAffiliate Professor, Dept of Earth and Space SciencesResearch Scientist, U.S.G.S. Leader of the World Organization of Volcano Observatories (WOVO) http://www.wovo.org Member of the USGS' Volcano Disaster Assistance Team Recent work focuses on: Processes of volcanic unrest (seismicity, ground deformation, gas emission, etc) Applications of this research to eruption forecasting Developing a web-accessible database of volcanic unrest, linked to the Smithsonian database of historical volcanic eruptions � WOVOdat http://www.wovo.org/wovodat.htm Helps colleagues from the Cascades Volcano Observatory (CVO) and a number of countries during volcanic crises

6. Graduate Students Studies of particularly puzzling or previously unrecognized patterns of unrest, Sarah Albano - groundwater response to volcanic strain Wendy McCausland - unusual volcanic seismicity, DLP events Jeff Witter - circulation of magma in volcanic conduits as a mechanism for non-explosive volatile emission at passively degassing volcanoes, excess SO2 degassing Josh Jones � seismicity of Oldoinyo Lengai, Mount Hood Adam Haulter � Avalanche events at Mount Rainier Thesis study of ephemeral processes Cami Apfelbeck - chemical and thermal evolution of the new caldera lake at Pinatubo Shannon Hayes - world-record-setting sediment transport from Pinatubo's pyroclastic deposits

7. What is Volcanic Seismology? Study of Earthquakes At or near volcano (<10km) Generated by volcanic processes Velocity structure of the volcano Seismic attenuation at the volcano

8. Volcanic Seismicity � Why Study? To understand Dynamics of active volcanic systems Physical properties of bubbly magma Map the extent and evolution of source regions Stress conditions, both regional and local Ultimately leads to better Forecasting of eruptive behavior Assessment of volcanic hazards

9. Volcanic Seismicity � Why Different from Tectonic?

10. High Frequency events (volcano-tectonic): - Shear or tensile failure Occur in swarms Clear P and S-waves Dominant frequencies: 5-15 Hz Low frequency or Long period events: - Volumetric sources (gas, liquid, solid interactions) - Nonlinear flow processes in cracks and conduits - Shear/ tensile failure with attenuation and path effects Emergent P- wave, no S-wave Dominant frequencies between 1 - 5 Hz Hybrid events: - combination of high and low frequency - high frequency onset, low frequency coda - mixture of processes: earthquake adjacent to fluid filled crack shallower low frequency event, preserves high frequency Explosion Quakes: - accompany explosive eruptions - presence of airwave on seismograms - energy partitioned into: air/acoustic wave seismic wave Volcanic tremor: - continuous signal - duration of minutes or longer - dominant frequencies: 1- 5 Hz - series of low frequency events - can be harmonic: single low frequency or with overtones - spasmodic higher frequency, pulsating, irregular High Frequency events (volcano-tectonic): - Shear or tensile failure Occur in swarms Clear P and S-waves Dominant frequencies: 5-15 Hz Low frequency or Long period events: - Volumetric sources (gas, liquid, solid interactions) - Nonlinear flow processes in cracks and conduits - Shear/ tensile failure with attenuation and path effects Emergent P- wave, no S-wave Dominant frequencies between 1 - 5 Hz Hybrid events: - combination of high and low frequency - high frequency onset, low frequency coda - mixture of processes: earthquake adjacent to fluid filled crack shallower low frequency event, preserves high frequency Explosion Quakes: - accompany explosive eruptions - presence of airwave on seismograms - energy partitioned into: air/acoustic wave seismic wave Volcanic tremor: - continuous signal - duration of minutes or longer - dominant frequencies: 1- 5 Hz - series of low frequency events - can be harmonic: single low frequency or with overtones - spasmodic higher frequency, pulsating, irregular

11. Recent Eruptive History of Cascade Volcanoes Recent Eruptive History of Cascade VolcanoesRecent Eruptive History of Cascade Volcanoes

12. Relative Seismicity at Cascade Volcanoes Relative Seismicity of Cascade volcanoes Arrows indicate Volcanoes specifically monitored by the Pacific Northwest Seismic Network. Relative Seismicity of Cascade volcanoes Arrows indicate Volcanoes specifically monitored by the Pacific Northwest Seismic Network.

13. Seismicity in the Cascades Region1990-2001 M>0.5

14. Deep Long Period Earthquakes

15. Deep Long Period Earthquakes

16. Deep Long Period Seismicity and Volcano Locations Locations of volcanoes and tectonic and Deep Long Period seismicity in the Cascades Red Dots show the locations of the Deep Long Period Events Green dots show the locations of tectonic and volcano-tectonic events (non-low frequency events)Locations of volcanoes and tectonic and Deep Long Period seismicity in the Cascades Red Dots show the locations of the Deep Long Period Events Green dots show the locations of tectonic and volcano-tectonic events (non-low frequency events)

17. Mount Hood While no DLP�s have been detected at Mt. Hood, their existence is not precluded. This is because the events thus far detected at other Cascades volcanoes have triggered the seismic network. A deliberate search for deep long period events is necessary.While no DLP�s have been detected at Mt. Hood, their existence is not precluded. This is because the events thus far detected at other Cascades volcanoes have triggered the seismic network. A deliberate search for deep long period events is necessary.

18. Mt Hood Earthquakes Red triangles active all along stations Faded, only active for part of time period temporary or recent Blue events directly under or in cone Black are ones that are not. Triggering point.Red triangles active all along stations Faded, only active for part of time period temporary or recent Blue events directly under or in cone Black are ones that are not. Triggering point.

19. Mount St. Helens

20. Mt St Helens Seismicity Red and Pink Triangles are seismic station locations Black circles are earthquakes Blue circles are earthquakesRed and Pink Triangles are seismic station locations Black circles are earthquakes Blue circles are earthquakes

21. Mt St Helens Relocations

22. Mt St Helens Stress Model

23. Mount St. Helens - 2 decades Mount St. Helens time sequences After major explosive eruptions of 1980.Mount St. Helens time sequences After major explosive eruptions of 1980.

24. Current Seismicity atMount St. Helens

25. Deep LPs Mt St Helens

26. Mount Rainier

27. Mt Rainier Seismicity Red triangles indicate seismic stations Pink triangles indicate Black circles are Blue circles areRed triangles indicate seismic stations Pink triangles indicate Black circles are Blue circles are

28. Mt. Rainier Velocity Tomography Mount Rainier p-wave velocity tomography Golden circles indicate some of the earthquakes used Seth Moran (1997)Mount Rainier p-wave velocity tomography Golden circles indicate some of the earthquakes used Seth Moran (1997)

29. Mt Rainier DLP Events

30. Mt Rainier DLP Earthquakes

31. Mt Rainier DLPsFiltered for Low and High Frequencies Same events filtered for less than 6 Hz and greater than 6 Hz Some have more high frequency relative to low.Same events filtered for less than 6 Hz and greater than 6 Hz Some have more high frequency relative to low.

32. Mt Rainier Comparing a Long Period with a High Frequency Event Events not colocated, but within 3-4 km.Events not colocated, but within 3-4 km.

33. Focal Mechanisms for VT events and locations of DLPs Focal Mechanisms for events in 3 different depths ranges Green - shallow - stress inversion show max comp n-s min e-w Blue - mid range - stress inversion show max comp n-s min e-w Red - deep - min stress direction rotates to vertical but max stays N-S. Location of DLP�s spatially distinct Focal Mechanisms for events in 3 different depths ranges Green - shallow - stress inversion show max comp n-s min e-w Blue - mid range - stress inversion show max comp n-s min e-w Red - deep - min stress direction rotates to vertical but max stays N-S. Location of DLP�s spatially distinct

34. Comparison of spectral content of DLP vs VTs at 2 stations Spectra from two events at two stations for Mt Rainier comparing the frequency content of a volcano tectonic event (high frequency) and a Deep Long Period event (low frequency) on two stations. Spectra from two events at two stations for Mt Rainier comparing the frequency content of a volcano tectonic event (high frequency) and a Deep Long Period event (low frequency) on two stations.

35. Spectrogram for High Frequency and Low Frequency Events Station FMW Spectrogram for Volcano Tectonic event (top) and Deep Long Period (DLP) event. Spectrogram for Volcano Tectonic event (top) and Deep Long Period (DLP) event.

36. In Summary