Part II: The new Malargüe seismic array Workshop, Cambridge, April 19 th 2011 Elmer Ruigrok, Deyan Draganov and Kees Wapenaar

MalaRRgue MalaRRgue: A large seismic array in the Malargüe department Partial collocation with Pierre Auger Observatory 2012: temporary array of 80 stations >=2013: ‘permanent’ array Monitoring and imaging the subsurface Application of recently developed techniques International team of geophysicists ICES

Why a seismic array in Malargüe? Outline How will we achieve high-resolution subsurface images?

Why a seismic array in Malargüe? How will we achieve high-resolution subsurface images?

The missing seismic array … Swell Local waves Oceanic -> seismic waves Beamforming seismic waves -> sea state Ocean waves Seismic arrays (Koper et al., 2010) MalaRRgue, aim 1: monitoring the southern oceans

Peteroa volcano MalaRRgue, aim 2: imaging and monitoring the Peteroa volcano Volcano activity, September 2010

Tectonic setting

Volcanism features

Imaging challenges still to be addressed (Gilbert et al., 2006) Malargüe Known –Moho depth Our imaging targets –Moho topography –Basin topography –Nazca slab depth –Magma intrusions –Major faults MalaRRgue, aim 3: detailed imaging of the lithosphere

Local seismicity MalaRRgue, aim 4: localizing local seismic activity Malargüe Regional seismicity

Preliminary array design

Positioning with Pierre Auger stations Seismic station PA particle detector

Why a seismic array in Malargüe? How will we achieve high-resolution subsurface images?

A method using teleseismic arrivals Illumination for passive seismology I

Crust and upper mantle Illumination for passive seismology II A method using teleseismic arrivals

Crust and upper mantle Conventional method: receiver function

Receiver function image Malargüe

Crust and upper mantle ~3km New method: seismic interferometry, input

Example response selection Time-window and separate pre-processing P and reverberations PP and reverberations

Further processing Subsurface reflectivity image (example) New method: seismic interferometry, output

A dense sensor network Malargüe T-array –2 orthogonal linear subarrays –3 km inline spacing –42 stations –‘Basin’ setting

Illumination by earthquakes and storms I: Inline earthquakes II: Inline oceanic storms (Landes et al., 2010)

High-resolution subsurface imaging 1.Reflection imaging instead of conversion imaging 2.Dense sensor network 3.Using not only earthquake responses, but also storm-induced waves

Summary Large seismic array (80 stations) planned in the Malargüe department 1.Imaging subsurface 2.Monitoring the sea state in the SH 3.Monitoring volcanic activity 4.Monitoring local seismicity

PAO synergies Facility and expertise exchange Coupling atmospheric gravity waves with seismic waves? Coupling lightening to seismic waves?

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