Capturing Mauna Loa's Current Reawakening

3-80 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH Magmatic Systems terferograms areterferograms dominatedby large agree well. Stacks of individualin general, theInSAR andCGPSdata ments over thepastseveral years. In has grown tomore than20instru network ofcontinuousstationsthat measurements anda periodic survey to mid-2006.TheGPSdatainclude from149 interferograms mid-1999 that togethercomprise77scenesand RADARSAT andENVISAT images the volcano. The InSAR datainclude magmatic-tectonic deformationof mit andriftzones toexplore recent collected over Mauna Loa’s sum We analyze InSAR andGPSdata transient detailsoftheseevents. gated inorder toresolve thesubtleor errors that mustbeassessedandmiti present themostsignificantsource of that atmosphericheterogeneities from this processing stream suggest investigation. Preliminary solutions quickly identifiedformore detailed so thatdeformationevents canbe using thePAGES GPSsoftware a nearreal-time processing approach Additionally, we have implemented anddynamic controls. into structural on Mauna Loaandgiveinsights new should imagefuture volcanic events two flankingrift zones. Thisnetwork coverage ofthesummitregion and (CGPS) receivers toprovide denser stalled 11additionalcontinuousGPS Mauna Loareinflation, we have in In response totheonsetofrecent volcano, hasbeenrelatively sparse. age forMauna Loa, Earth’s largest network ofGPSstations,thecover neighbor, Kilauea,hasanextensive Although itsmore recently active James Foster » Benjamin A.Brooks » Processes, Mauna Loa,Hawaii and Numerical Investigations ofMagmatic and Volcanotectonic Capturing Mauna Loa’s Current Reawakening -Integrated Geodetic School of Ocean and Earth Science and School ofOcean andEarth Technology, University ofHawaii School of Ocean and Earth Science and School ofOcean andEarth Technology, University ofHawaii ------Patrick, M.R.,Brooks, B.A.,Poland, M.,and Foster, J.,Brooks, B.,Cherubini, T., Shacat, Brooks, B.A.,Foster, J.H.,Miklius, A.,andSche References for thesubsidence. favor avolcano-tectonic explanation from theregion, andwe are ledto of high-resolution weather models data is not reproduced by our analysis toured intheInSAR feature observed the region, thetypeofclosed-con largein anomalies are very certainly Although atmosphericwatervapor flank ofneighboringKilauea volcano. to explaindeformationofthesouth similar tothemechanisminvoked SWRZ openingandflankmobility, or d)acombinationofdeep-seated translation above adecollement, flank mobility related toSE-directed b) deep-seatedSWRZopening,c) a) persistentatmosphericartifacts, to explainthisanomalyincluding: mit inflation. We explore hypotheses periods priortotheinitiationofsum grams, includingthosethatspantime The feature ispresent inallinterfero Loa’s Southwest RiftZone (SWRZ). (apparent subsidence)alongMauna ~0.5 cm/yrline-of-sightlengthening sults alsodetecta9×15kmregion of Mauna Loa’s summitregion. Our re recent (2002topresent) inflationof (cm scale)motionsassociatedwith Associated withMauna Loa’s Southwest Rift Foster, J.H.,2006,Recent Deformation 2006GL026781. Geophys. Res. Lett.,v. 33,p. doi:10.1029/ with ahighresolution weather model: Mitigating atmosphericnoiseforInSAR C., Businger, S.,and Werner, C.L.,2006, Fall Meet. Suppl., Abstract G52A-06. Volcano, Hawai’i: Eos Trans. AGU, v. 86,p. and Near Real-Time Processing, Mauna Loa newerk, M.,2006,Extended GPSNetwork - - - - - Work by NSFaward supported EAR-0440433. Brooks, B.,Foster, J.,Miklius, A.,Poland, M., Brooks, B.A.,Foster, J.H.,Bevis, M.F., L.N., ScienceLetters246(2006)207-216. etary Jan. 2005(F).B.A.Brooks andPlan etal./Earth (C); 9Nov. 2000(D); 16Dec. 2002(E);and26 Slow displacementsfor20Sept, earthquake 1998 indicates thepositionofHilina Pali scarp. (C-F) site atNational Park (C)HP headquarters. service shown. Inverted whitetriangleistheraingauge the HSvolume andatdepthslessthan20kmare occurringin time period.Only thoseearthquakes Data Centerforthesame California Earthquake from theHVO catalogarchived attheNorthern ellipses indicate2 rows) from GPSstations(red text)for1997-2005, panels C-F. (B)Average yearly velocities (grey ar zones. White boxes are GPSstationsshown in the HS-boundingsouth-west andeastKilauearift slump. SWRZandERZare northward limitsof Kea volcano; K,Kilaueavolcano; HS,Hilina by grey box. ML,Mauna Loavolcano; MK,Mauna network. (A)Locationmapwithstudyarea shown Figure 1. S53E-05. AGU, v. 87,p. Fall Meet. Suppl., Abstract Islandearthquakes, ofHawai`i: Eos Trans. the October 15,2006KiholoBay/Mahukona seismic continuousGPSmeasurements from Johanson, I., and Wicks, C., 2006,Post- Letters, v. 246,p. 207-216. volcano, Hawai’i Science andPlanetary Earth slow ontheflankofKilauea earthquakes Wolfe, C.J.,andBehn, M.,2006,Periodic Suppl., Abstract G53A-0872. Zone?: Eos Trans. AGU, v. 87,p. Fall Meet. ContinuousGPSdatafrom Kilauea σ errors. White dotsare seismicity - - 3-81 Magmatic Systems Accelerated Uplift of the Yellowstone Caldera, 2004-2006, from GPS and InSAR Observations

Wu-Lung Chang » Department of Geology and Geophysics, University of Utah Robert B. Smith » Department of Geology and Geophysics, University of Utah Christine M. Puskas » Department of Geology and Geophysics, University of Utah Jamie J. Farrell » Department of Geology and Geophysics, University of Utah Chuck Wicks » U.S. Geological Survey, Menlo Park, CA 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH Geodetic techniques have been employed to monitor the crustal motion evidence, we propose that a new intru- of Yellowstone beginning with the precise leveling of benchmarks in- sion of magma into the mid-crustal or stalled in 1923. Since 1997, the University of Utah has installed six per- pressurization of a deep hydrothermal manent GPS stations inside Yellowstone National Park for continuously system likely caused the uplift within monitoring the ground deformation associated with seismic, volcanic, the Yellowstone caldera. The Norris and hydrothermal activities. Starting in mid-2004, the GPS network subsidence, in contrast, may be induced recorded an episode of unprecedented uplift of the Yellowstone caldera by the crystallization and contraction concomitant with subsidence of the northeast caldera area including of crustal magmatic bodies and the Norris Geyser Basin. The deformation continues into 2007, with nearly associated loss of dissolved fluid and constant inflation rates of ~6 cm/yr and 4 cm/yr at the Sour Creek and gas to shallow fault and hydrothermal Mallard Lake resurgent domes, respectively (Figure 1). These rates are systems. up to three times faster than preceding caldera uplift rate from 1923 and Figure 1. (a) Locations of measured uplift in the Yellowstone caldera. (b) Time series of vertical motion 1984. The horizontal velocities, in addition, are 7 to 21 mm/yr outward measured at six sites. from both domes. Meanwhile, Norris Geyser Basin experienced subsidence at ~4 cm/yr that is two times higher than the 1996-2002 uplift rate. Incorporating GPS data from the University of Utah and five new PBO stations, we evaluated source models by inverting the GPS and InSAR data for the geometry and expansion (contraction) of dislocations in an elastic half-space [Chang et al., 2007]. The results indicate two horizontal sill-like structures ~8 km beneath the caldera with a total volumetric expansion rate of 0.11 km3/yr, and a northwest-dipping tabular body 16 km beneath the Norris Geyser Basin with a volumetric contraction rate of 0.018 km3/yr. Incorporating seismic, hydrothermal, and geochemical

References Chang, W., R.B. Smith, C. Wicks, C. Puskas, and J. Farrell, 2007, Acceler- ated uplift and source modeling of the Yellowstone caldera, 2004-2007, From GPS and InSAR observations, in preparation. This research was supported by NSF Grants #0314298, #9725431, and #9316289.

3-80 3-81 3-82 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH Magmatic Systems hr, respectively, forbaselinesbetween 10mand~1000km. (rms) horizontal velocity andvertical errors were lessthan0.2and0.9mm/ lengths. For example,for24-hourdatatimespans,theroot-mean-square periodandthebaseline velocity esti-mates wasdependentontheobserving straight linetothestochasticestimates,theyshowed thattheaccuracyof By modelingthetime-dependent positionasarandomwalkandfitting GPS antennainthehorizon-tal planeat1mm/hrformore than 24hours. This work isanextensionof Elosegui etal.[1996],inwhich we translateda applications (Figure 1). curacy canbeachieved forGPSpositiondeterminationsinhigh-sample-rate be measured. In Elosegui etal.[2006],we reported thatmillimeter-level ac be compared andtheresultant totheground truth, can GPSerror spectrum rate GPSdata.Analysisofthetime-dependentpositionestimatescanthen lated (seismicorother)motionsoftheEarth’s whilecollecting high- surface GPS. TheGPSantennaattachedtothispositioningtableundergoessimu truth” displacementsforassessingthetechniqueofhigh-sample-rate(~1Hz) is accuratetobetterthan0.1mminposition,andthusprovides the“ground built anapparatusfortranslatingaGPSantennaonpositioningtablethat theseismicmotionsassociatedwithearthquakes. Wenoes, andinparticular as thoseassociatedwithglacialflow, active surges,glacialearthquakes, volca motions,such (secondstodays)surface GPS todetecttransient,short-term We approach toassesstheaccuracyofhigh-rate adoptedan instrumental J. L.Davis » P. Elosegui » Short-Term Motions Accuracy AssessmentofHigh-rate GPSforDetection of Institute forSpace Sciences,CSIC-IEEC,Barcelona, Spain Harvard-Smithsonian CenterforAstrophysics, Cambridge,MA - - - This work was supported This workby NASA,the wassupported Smithson Elosegui, P., J.L.Davis, D.Oberlander, R. Elosegui, P., J.L.Davis, J.M.Johansson, andI. References value of10mmandanrmsvalue of2.5mm. has a maximum span ofthesimulatedearthquake overposition estimate(green curve) the15-min position, shown by thered dots.Theerror inthe to provide time-dependentdeterminationsofsite wereduring thesimulatedearthquake analyzed the figure by theblueline.TheGPSdataacquired Theprogrammed motionisshownearthquake. in which wasthenusedtosimulatethemotionsofan installed onahigh-accuracypositioningtable, of Elosegui etal.[2006].AGPSantennawas the accuracyofGPS-seismologytechnique Figure 1. Education andScience. ian Institution, andtheSpanish of Ministry 2006GL026065. Res. Lett.,33,L11308,doi:10.1029/ of high-rateGPSforseismol-ogy, Geophys. Baena, andG.Ekström (2006),Accuracy Geophys. Res., 101,11,249–11,261. tions withtheGlobal Positioning System, J. Shapiro (1996),Detection oftransientmo Results from studiesof ground-truth - - 3-83 Magmatic Systems Augustine Volcano: PBO Data

Jeff Freymueller »Geophysical Institute, University of Alaska Fairbanks

PBO data recorded before and during the eruption of Augustine Volcano provided new insights into the magmatic plumbing system at Augustine volcano, as well as

surprises that will require further 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH research to understand. These results give an example of the future gains expected from measuring deformation at other PBO volcanoes. The first sign of unrest at Augustine appeared in early summer 2005, with an increase in seismicity accom- panied by a small inflation signal. Surprisingly, from the beginning the inflation signal indicated a source at shallow depth, roughly at sea level. Campaign GPS measurements over the 15 years prior to the eruption indicated no previous accumulation of magma at such shallow depth. The initial inflation source was small, Figure 1. Time series of geodetic data and earthquake occurrence. (Top) The line length between GPS stations AV02 and AV03 as a function of time. (Bottom) A temporal histogram of located earthquakes, detectable only by high-quality with the inset showing epicentral locations. The red line denotes the cumulative number of located continuous GPS, and it may be that earthquakes. The green vertical line marks November 17, 2005, the purported beginning of dike ascent. deformation associated with the rise From Cervelli et al. [2006]. of this small initial pod of magma was simply too small to record with from temporary sites deployed just before the volcano became too dangerous GPS – strainmeters or tiltmeters to visit helped constrain the source depth to mid-crustal depths. Together such as those that PBO plans to with the lack of pre-eruptive deformation prior to 2005, these observations install might have provided further lead to a model for the magma rise in which small leading pods ascended important data about the initial rise from mid-crustal depths, eventually reaching the surface. After there was a of magma. continuous magma column from the surface to mid-crustal depths, sus- Once significant extrusion of magma tained extrusion began. began, about two weeks after the The destruction of some sites in the initial explosions and the first major first major explosions, the surviving pyroclastic flow also illustrated the need for redundancy in network design. PBO sites recorded a deflation signal Additional instrumentation installed on Augustine since the eruption ad- with a different spatial pattern than dresses that need. The value of additional temporary continuous sites also the inflation. Although only weakly suggests a future use for part of the PBO campaign instrument pool, as long constrained by PBO data because as funding and approval for rapid response can be obtained. two sites were destroyed quickly, the References deflation source clearly came from Cervelli, P. F., T. Fournier, J. Freymueller, and J. A. Power (2006), Ground deformation associated with a significantly greater depth than the precursory unrest and early phases of the January 2006 eruption of Augustine Volcano, Alaska, the inflation source. Additional data Geophys. Res. Lett., 33, L18304, doi:10.1029/2006GL027219.

3-82 3-83 3-84 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH Magmatic Systems additional simplifiedantennamastsbasedonthesame AVCO (Figure 1),andhadourmachineshopmakeup We borrowed Tech-2000 antennamastsfrom UN found theanswer intheUNAVCO web pages. alternative thatwouldallow a quickinstallation,and PBO-style installationwasimpossible. We soughtan lack ofdaylight,andby safetyconcerns,soafull-blown the island. We were constrainedby winterweather and continuoussiteson decision toinstallseveral temporary In December, Alaska Volcano madethe Observatory from thesummitlimitedresolution ofdeepersource. low deformationsource, butthelackofstationsfarther sensitiveThese locationsmadethenetworktoshal very trated nearthesummitandupperflanksof volcano. GPS sitesontheisland,PBOnetwork wasconcen (PBO)continuous fiveObservatory Plate Boundary explosions inmid-December 2005.Althoughthere were mation, Augustine volcano begantoexperiencesmall After monthsofincreasing unrest defor andprecursory Peter Cervelli » Jeff Freymueller » Monitoring theAugustine Volcano U.S.Geological Survey, Alaska Volcano Observatory Geophysical Institute, University ofAlaskaFairbanks - - - - temporary continuoussiteonthesouthflankof temporary Augustine volcano, usinga Figure 1. the eruption. in source observed constraining thedeeperdeflationary a periodofseveral months,andprovided usefuldata available toanchorthechains,mastswere stableover work ontheisland.At thethree siteswhere bedrock was cal–soon afterourinstallationsitbecametoounsafeto installed duetobadweather. Moving quicklywascriti power.ing onlybattery Asixthplannedsitecouldnotbe the lower flanksofthe volcano, recording locallyandus be setupinaboutanhour, andwe setup5sitesaround design. Theseantennamastsallowed acompletesiteto sites are deflationsource. consistentwithadeep(mid-crustal) around 2006.1. Datato thesouthduringeruption, from thisand other Figure 2. borrowed UNAVCO Tech-2000 mast. University ofAlaskaFairbanks student Tom Fournier setsupa Site AUGB coastofAugustine onthenorth Island moved abruptly - - 3-85 Magmatic Systems Tectonic Controls on Magmatism at Taal Volcano, Philippines

Gerald A. Galgana » Indiana University Michael W. Hamburger » Indiana University Ernesto Corpuz » PHIVOLCS, C.P. Garcia Avenue, Quezon City, 1101 Philippines Beth A. Bartel » UNAVCO, Boulder, CO

Space geodetic methods combined with imaging are used to inspect active tectonics and magmatism within

the Macolod Corridor and the Taal Caldera, a geologi- 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH cally complex area in Southwestern Luzon. This area is characterized by extensive volcanism and widespread faulting. Radar and multispectral imageries subjected through analytical shading and image filtering techniques and combined with digital terrain models are used to analyze fault orientations and detailed geomor- phic features of the area. Campaign geodetic observations (1996-2002) from GPS stations within Luzon are used in combination with remote sensing and earthquake slip vectors to derive the kinematics of Luzon. We use an elastic block modeling approach, which characterizes crustal deformation as a result of rotation of discrete elastic microplates around Euler poles. The resulting best-fit model indicates that the Luzon area is composed of six microplates. The vicinity Macolod area in SW Luzon is best represented with three mobile microplates. Active tectonics of the Philippine mobile belt is dominated by eastward subduction along the Manila Trench (~20 to 100 mm y-1), westward subduc- -1 tion along the Philippine Trench (~29 to 34 mm y ), Figure 1. Time series showing relative position of continuous GPS stations and sinistral strike-slip faulting along the Philippine around Taal Volcano with respect to station KAYT. Inset focuses on most re- Fault (~10 to 40 mm y-1). The velocity field indicates cent inflationary event that started around June 2004 lasting to March 2005. localized transpression along the N-S trending Marikina for the earlier inflation and deflation events indicate -1 Fault (~10 to 12 mm y ), and transtensional motion that a Mogi point source 4 to 5 km deep centered at the along the NE-SW trending Macolod Corridor fault zone Volcano Island describes the deformation effectively. -1 (~5 to 10 mm y ) (Galgana, 2005). Observations from The inflationary trends are interpreted to be episodes of the continuous single- and dual-frequency GPS stations magma intrusion to a shallow reservoir beneath Volcano of the Taal Volcano network from 1998-2005 indicate a Island, which is significantly affected by regional tecto- sequence of inflationary and deflationary events, which nism (Bartel, 2002). include several periods of rapid volcanic inflation (~120 References: mm uplift from February to November 2000) and rapid Bartel, B., 2002. Magma Dynamics at Taal Volcano, Philippines from deflation (~33 mm subsidence from June to December Continuous GPS Measurements. Master’s Thesis, Indiana University, 1999). The most recent episode of inflation extended Bloomington, Indiana. from June 2004 to March 2005 indicated ~73 mm y-1 Galgana, Gerald A., 2005. Kinematics of an Active Plate Boundary Zone: extension across the volcanic edifice, with about 50 mm Insights on the Tectonics of Luzon, Philippines Using Terrain Models, Focal Mechanisms, and GPS Observations. Master’s thesis, Indiana uplift with respect to the caldera wall. A recent deflation- University, Bloomington, Indiana. ary pattern starting April 2005 is also detected. Models This work is supported by NSF grant EAR-0307524.

3-84 3-85 3-86 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH Magmatic Systems eruption thatbeganon 22 October 2005.Thecontinu eruption pressurization ofan~2-km-deepsilleventually ledtoan of thisgeodeticmonitoringshow thatthefillingand The ing ratesupuntilthetimeoferuption. results uplifting. Thecalderafloortheninflatedataccelerat ence continueduntil2003,whenthecalderafloorbegan detail by a six-stationcontinuousGPSnetwork. Subsid deformation ofthevolcano hasbeencaptured ingreat although there From wasnoeruption. 2002onward, the 2005. From 2001-2002,thecalderafloorsubsided, before whichbeganon22October itslatesteruption, Sierra Negra displayed more complicatedbehavior being processed. thosedataarebenchmarks only500mapart; currently tive fissure serendipitously directly intruded between 2 dina network inJune 2005andfoundthattheerup inMayin aneruption 2005. We reoccupied theFernan km beneaththecalderafloor. Thisinflationculminated eled aspressurization ofasubcalderasillthatliesabout2 et al.,2006).Regular expansionofFernandina ismod magma intoshallow (Geist between reservoirs eruptions of of thevolcanoes, undoubtedlyduetotheintrusion extents ofdeformationthecalderafloorsandflanks Negra calderasfrom 2000-2002revealed extraordinary Campaign GPSmeasurements atFernandina andSierra » Beth Bartel Charles Meertens » William Chadwick» Dennis Geist » Magma Movement atGalápagos Shield Volcanoes UNAVCO, Boulder, CO University ofIdaho UNAVCO, Boulder, CO Oregon State University/NOAA, Newport ------can relieve accumulatedstrainandeffectively postpone onstrate thatfaultingabove magmabody anintruding at abasalticvolcano, anddem faulting, anderuption These results highlightthefeedbacksbetween inflation, strong constraintsforimproved deformationmodels. trapdoor faulting,andcoseismicCGPSdataprovide uplift traordinary was byaccommodated in part repeated inflationever recordedsory atabasalticcaldera.Thisex nearly 5moftotalupliftsince1992,thelargestprecur andcontributedto inflation leadinguptotheeruption ous GPSmonitoringmeasured >2mofaccelerating relative toGV03. Vertical dashedlinesinEand Fshow timesof16 April for displacementsatGV06during16April 2005trapdoorfaultingevent, F: Vertical displacementtimeseries,asinE.Inset shows kinematicsolution lated (dashedline)andGV04,GV05,GV06are shown relative toGV03. andGLPSwereGALA alsodown; thereafter movement atGV03isextrapo frequency receivers hadfailed(GV01andGV02).After1September 2005, on Isla Santa Noise Cruz. level increases after10June 2005,whenbothdual at CGPSstationsfrom 2002to2006,relative and GLPS tostationsGALA areeruption indicated.E:Horizontal componentonly) displacements(north amounting tonearly5m. Times ofmajortrapdoorfaultingevents and2005 Uplift ofthecentercalderaatSierra Negra history from 1992to2006 included (seeFigure 2). C: Vertical displacementsduringinflation,asinB.D: only to10June 2005).Fault-related displacementson16April 2005are not 1 April 2003to21October 2005(GV01onlyto3December 2004;GV02 cation ofCGPSstations,andhorizontal displacementsduringinflationfrom al. (2006).B:Summit ofSierra Negra, showing sinuousridgefaultsystem,lo deformationatSierraeruption Negra volcano. A:Locationmapafter Yun el Figure 1. eruption. Continuous globalpositioningsystem(CGPS)results showing pre- Chadwick, WW, Geist, D.,Jonsson, S,Poland, Geist, D.,Chadwick, WW, andJohnson, D, References The collaborative work withUNAVCO hasbeen aperture radar;GPS—global positioningsystem. October 2005.InSAR—inferometric synthetic on22 2005 trapdoorfaultingevent anderuption Geology, inpress, 2006. atSierraeruption Negra volcano, Galapagos, bursting at the seams: Inflation, faulting, and M, Johnson, DandMeertens, C, Volcano Research 150,79-97,2006. Journal of Volcanology andGeothermal Negra Volcanoes, Galápagos, 2000-2002, toring Networks atFernandina andSierra Results fromGPSAndGravity new Moni EAR-0538205. by NSFgrantsEAR-0004067and supported ------3-87 Magmatic Systems Recent Seismicity and Surface Deformation at Lake Tahoe: An Update on Lower Crustal Magma Movement

William C. Hammond » Nevada Bureau of Mines and Geology, University of Nevada Geoff Blewitt »Nevada Bureau of Mines and Geology, University of Nevada Corne Kreemer » Nevada Bureau of Mines and Geology, University of Nevada Hans-Peter Plag » Nevada Bureau of Mines and Geology, University of Nevada John Anderson » Nevada Seismological Laboratory, University of Nevada

Ken Smith » Nevada Seismological Laboratory, University of Nevada 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH

Figure 1. Cumulative seismic moment as a function of time for deep and Figure 2. GPS time series (longitude) for site SLID which is ~15-20 km east shallow earthquakes the Tahoe seismic swarm. of the epicenters.

In late 2003 a lower crustal seismic swarm (29-33 km transition zone, and may provide some clues about the depth) occurred beneath the north end of Lake Tahoe state of stress in this active transtensional system. We on the California-Nevada border. This swarm was ac- have established nine new GPS sites around the Tahoe companied by an ~1 cm northeastward motion of the region that will help constrain the depth and location continuous GPS site SLID on Slide Mountain, Nevada. of future fluid motions should they occur [Hammond The position and motion of SLID with respect to the et al., 2006]. Planned installations for PBO will further northeast-dipping planar cluster of seismicity suggested enhance our ability to monitor this motion. that the earthquakes and surface motion were caused by a progressive filling of a crack with magma, injected References from below [Blewitt, 2004; Smith et al., 2004]. This Blewitt, G., 2004, Lower crustal transients and surface mass transport: Time series filtering for signal detection at two spatial extremes, Eos Trans. activity began again in mid-2005 when another move- AGU, 85(47), Abstract G51D-02. ment, of size and direction nearly equal to the 2003 Hammond, W.C., G. Blewitt, C. Kreemer, H.-P. Plag, J.G. Anderson, and event, was observed with GPS at SLID. However, this K.D. Smith, 2006, Recent seismicity and surface deformation at Lake Tahoe: An update on lower crustal magma movement, in UNAVCO, time the associated cluster of seismic activity was shal- Inc. Annual Meeting, Denver, CO, March 13-16, 2006. lower and more energetic (Figure 1). The distribution Smith, K.D., D. von Seggern, G. Blewitt, L. Preston, J.G. Anderson, B.P. of shallow seismicity follows a spatial pattern that is Wernicke, and J.L. Davis, 2004, Evidence for Deep Magma injection strongly focused to the north of the original swarm, and beneath Lake Tahoe, Nevada-California, Science, 305, 1277-1280. divided into separate northwest and northeast trending clusters. This distribution suggests some influence by the tectonic structures of the Great Basin/Sierra Nevada

3-86 3-87 3-88 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH Magmatic Systems simple elastichalfspacemodel, includingrelatively tion. Thecouplingmodelconfirms results from the WVZ isdeactivating inthedirection ofEVZ propaga tent withasimplepropagating ridgemodel whereby the equal tothetotalplaterate,~1820mm/yr, consis across thetworiftzones are approximately constantand direction ofridgepropagation. Summed extension rates to11.0±0.8mm/yrinthesouthwest, the the northeast ing ratesintheEVZ decrease from 19.0±2.0mm/yrin 7.0 ±0.4mm/yrinthesouthwest. Conversely, spread WVZ increase to from 2.6±0.9mm/yrinthenortheast Spreadingwithin theuncertainties. ratesacross the between the WVZ andEVZ, fitarigidblockmodel Zones EVZ). (WVZ, GPSdatafrom theHreppar block, rift zones, representing the Western and Eastern Volcanic space andviscoelasticcouplingmodelsfortwoparallel 2003 are compared withtwo-dimensionalelastichalf insouthIcelandGPS observations between 1994and P. Einarsson » F. Sigmundsson » E. Sturkell » T. Árnadóttir » » R. Malservisi T.H. Dixon » P.C. LaFemina » Geodetic GPS Measurements inSouth Iceland SISZ earthquakes. Thelocationsofthe profiles modeledinthisstudy SISZ earthquakes. are shown byblackdashedlines(LaFemina etal.,2005). Figure 1. Nordic Volcanological Center, Institute Sciences,University ofEarth ofIceland, Reykjavik, Iceland Rosenstiel Schoolof Marine andAtmospheric Sciences,University ofMiami Science Institute, University ofIceland, Reykjavik, Iceland Ludwig-Maximilian University, Munich, Germany Nordic Volcanological Center, Institute Sciences,University ofEarth ofIceland, Reykjavik, Iceland Department ofGeosciences,Department Penn State University GPS velocity field relative tostable AmericacorrectedNorth forco-seismicoffsets from the17and21 June2000 Nordic Volcanological Center, Institute of Sciences, Earth University of Iceland, Reykjavik, Iceland - - - Hekla CGPSnetwork. (CGPS) andsemi-CGPSacross theEVZ ofthe aspart andtheinstallationof continuous GPS observations We are continuing thisresearch withadditionalEGPS tion in1477AD. in1862-64,andamajorerup small volume eruption the Bárðabunga-Veidivötn fissure swarm.Thissitehada Lakagígar fissure butis20kmtothe west on eruption, and future rifting,doesnotcoincidewiththe1783-84 magmaaccumulation sumably thelocusofsub-surface velocity gradientintheEVZ,maximum surface pre –to 10 LaFemina, P., Dixon, T., R.,Arnadottir, Malservisi, T., Sturkell, E.,Sigmunds Reference and allows foranestimateofmeanviscosity(~10 shallow lockingdepths(<5km)beneaththeriftzones, System, J.Geophys. Res., v110,B11405,doi:10.1029/2005JB003675. Iceland: Strain Accumulation andPartitioning inaPropagating Ridge son, F. andEinarsson, P. (2005),Geodetic GPSMeasurements inSouth 20 Pa s)beneaththeelasticlayer. Thelocationof 19

- - - 3-89 Magmatic Systems High Rate CGPS Instrumentation on Cotopaxi Volcano

P. LaFemina » Department of Geosciences, Penn State University P. Mothes » Instituto Geofísico, Escuela Politécnica Nacional, Quito, Ecuador T. Dixon » Rosenstiel School of Marine and Atmospheric Sciences, University of Miami C. Connor » Dept of Geology, University of South Florida D. Rivero » Instituto Geofísico, Escuela Politécnica Nacional, Quito, Ecuador C. Ramos » Instituto Geofísico, Escuela Politécnica Nacional, Quito, Ecuador L. Troncoso » Instituto Geofísico, Escuela Politécnica Nacional, Quito, Ecuador W. Enríquez » Instituto Geofísico, Escuela Politécnica Nacional, Quito, Ecuador 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH

Cotopaxi volcano, Ecuador, is a large stratovolcano the vigorous seismic swarms and increased gas exhala- located approximately 60 km south of the capitol city tions from the crater, which are observed by a permanent Quito. The last important eruption (VEI 4) occurred in video camera on the crater rim (5890 m), with possible 1877 and mild eruptive activity continued into the early inflationary/deflationary cycles related to the migration 1900s. In an effort to improve the deformation monitor- of magma and/or magmatic volatiles. This new instru- ing of Cotopaxi volcano, two dual frequency (L1/L2) mentation compliments the data obtained from two GPS receivers (Trimble NetRS receivers with Zephyr L1 GPS instruments operating since 2002 (installed by Geodetic antennas with ground planes) were installed UNAVCO), six EDM arrays measured since 1987, and in early 2005 on the NE and SW flanks of Cotopaxi two telemetered tiltmeters. at 4400 m elevation, with a baseline length of approximately 8 km. Data arrives to the Instituto Geofisico- Figure 1. Photograph of CGPS site CONE on the northeast flank of Coto- paxi volcano. This CGPS site along with CGPS site MORU span the edifice Quito in real time via telemetry/ethernet connection. with a baseline length of 8 km. The CONE monument is 0.5 m spike mount, Data processing will assess probable correlations between epoxied into a glaciated lava flow.

3-88 3-89 3-90 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH Magmatic Systems Figure 2. extreme environments. scale. Thisnetworkandpower alsoallows fortestingoftelemetry systemsin for investigation ofavolcano’s magma-tectoniccontextatamore regional Duringcasting ofavolcanic eruption. quiescentperiodsCGPSdataallows ity, includingmagmamigrationthrough theedifice,andprediction/fore activ 2004). Thismonitoringleadstothepotentialfordetectingprecursory activityandquiescence(e.g., edifice duringperiodsoferuptive Mattia etal., the dynamicandstaticprocesses thatoccurwithinandaround avolcanic Monitoring volcano deformationwith1-HzCGPS allows ustoinvestigate LaFemina etal.,2005). we mustunderstand thebackground tectonicsignalincludinguplift(e.g., across the SISZandEVZ. To betterunderstanddeformationofthevolcano, spreading direction, andtherefore maybeinfluenced by strainaccumulation inthelast34 years. Thetrenderuptions ofthe volcano isobliquetothe zone (EVZ) seven timesinthelastcentury, andhaserupted includingfour tersection oftheSouth Iceland Seismic Zone (SISZ)andtheeasternvolcanic and the Torfajokull volcano since2000.Hekla volcano islocatedatthein and Torfajokull volcano. The Hekla volcano hasbeenmeasured since 1996 This network isimbeddedwithinanepisodicGPSnetwork at Hekla volcano improve volcano. themonitoringandunderstandingofthisplateboundary We have installedsix(6)CGPSstationsatHekla volcano, Iceland, to T. Dixon » T. Árnadóttir » H. Geirsson » E. Sturkell » P.C. LaFemina » Dynamic Monitoring ofHekla Volcano, Iceland with1HzCGPS Topographic CGPS(red mapofthesixnew hexagons)andEGPS (whitehexagons)networks atHekla and Torfajokull volcanoes, Iceland. Rosenstiel Schoolof Marine andAtmospheric Sciences,University ofMiami Nordic Volcanological Center, Institute Science,University ofEarth ofIceland, Reykjavik, Iceland Iceland Meteorological Office, Reykjavik, Iceland Nordic Volcanological Center, Institute Science,University ofEarth ofIceland Department ofGeosciences, Department Penn State University - - - Mattia, M.,Rossi, M.,Guglielmino, F., Aloisi,M. LaFemina, P., Dixon, T., R.,Arna Malservisi, References powered by bothsolarandwindgenerators. tion andmigrationthrough theedifice.Thesiteis allow ustoinvestigate thedynamicsofdikeforma the northwest flank of Hekla volcano. This site will Figure 1. 2004GL021281. Res. Lett.,31,L24610,doi:10.1029/ Hz instantaneousGPSpositions,Geophys. system ofStromboli Island asimagedfrom 1 and Bock, Y. (2004),Theshallow plumbing ing RidgeSystem, J.Geophys. Res., inpress. cumulation andPartitioning inaPropagat Measurements inSouth Iceland: Strain Ac and Einarsson, P. (2005),Geodetic GPS dottir, T., Sturkell, E.,Sigmundsson, F. Photograph ofsiteHEKRlocatedon - - - - 3-91 Magmatic Systems Deformation Associated with Eruptive Activity at Mount St. Helens, Washington

Michael Lisowski » U.S. Geological Survey, Cascades Volcano Observatory Larry Mastin » U.S. Geological Survey, Cascades Volcano Observatory Daniel Dzurisin » U.S. Geological Survey, Cascades Volcano Observatory Michael Poland » U.S. Geological Survey, Hawaiian Volcano Observatory

On September 23, 2004, a seismic swarm marked the onset of

eruptive activity at Mount St. Helens, Washington, after 18 years 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH of quiescence. A few days later, an intensely deforming, uplifted welt was recognized in the southeast part of the crater, and a series of phreatic explosions lasting five days began on October 1, 2004. The USGS Cascades Volcano Observatory and Plate Boundary Observatory responded by deploying 18 continuous GPS stations on and around the flanks of the volcano, in addition to other stations elsewhere in the region. The network has measured remarkably little deformation. Prior to the eruption, only one continuous GPS station, JRO1, was operating, 8 km north of the volcano. JRO1 recorded about 2 cm of displacement towards the volcano during the first two weeks of the unrest. Be- tween mid-October 2004 and the end of 2005, the GPS network detected only a few cm of deflation of the volcano. Deforma- Figure 2. Top: Average observed (black) and modeled (red) GPS tion from Interferometric Synthetic Aperture Radar (InSAR) is displacements from Mount St. Helens between October 15, 2004 and December 31, 2005. The model assumes a vertical prolate el- similarly muted; a stack of 9 RADARSAT interferograms span- lipsoid between 6 and 12 km depth beneath the volcano with a vol- ning 2004-2005 shows only about 2 cm of line-of-sight deflation ume loss of 20 × 106 m3/yr. Bottom: Time series of displacements centered on Mount St. Helens. from continuous GPS stations on the flanks of Mount St. Helens. Red line marks the onset of seismic unrest on September 23 2004. Deformation from InSAR and GPS can be approximated by a volume loss of 20-30 × 106 m3/yr at depths of 6 to 12 km (de- pending on the model geometry). Interestingly, during this time period at least 70 × 106 m3/yr of lava was extruded. This discrep- ancy in volume does not necessarily imply recharge to the magma reservoir at depth. The difference can also be explained by the expansion of bubbles in the reservoir as volume is removed. Con- tinued geodetic research at Mount St. Helens offers the chance to further investigate a variety of important issues in volcanology, including the relationship between erupted volume and modeled volume loss, the geometry and size of the magma reservoir, and the relationship between deformation rates and eruptive activity (e.g., explosive activity, effusion rate, magma chemistry, etc.). Figure 1. InSAR results from Mount St. Helens showing (A) observed, (B) modeled, and (C) residual deformation. Observed line-of-sight displacements are from a stack of 9 RADARSAT standard model 2 interferograms spanning 2004-2005. The model assumes a point source at 12 km depth with a volume loss of 27 × 106 m3/yr.

3-90 3-91 3-92 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH Magmatic Systems has revealed characteristicsoftheHRGPS signalthat mented inareal-time system. Furthermore, ouranalysis to improve themeasurement accuracyandcanbeimple tide effects.These “noise” sources canbefiltered in order elastic effectsonthepillars of GPSstations,and3)earth the positionofsatellites(Bocketal.,2000),2)thermo of frequencies related to1)sidereal effectsattributedto domains. We have beenabletocharacterize typicalpeaks software toolsforanalysisinbothtimeandfrequency HRGPS signalinvolcanic areas, we have developed new In order toimprove ourabilityto fullyexplore the Stromboli Island (Italy) (Mattia eruption etal.,2004). already revealed duringthe2002-2003 itsimportance their potentialfordamageestimated.Thistechniquehas and otherdangerous phenomenacanbemonitored and opening ofvents, migrationoffractures fields,landslides slopes ofvolcanoes. During largeexplosions, eruption, ties tomonitortheopeningoffractures fieldsonthe rate GPSdatacanbeusedby civilprotection authori the realphases ofaneruption timeprocessing ofhigh sis ofhighrateGPS(HRGPS) data.Infirst thevery activitycanberevealederuptive through acareful analy dynamics ofmagmaticfluidsaspossibleprecursors to Transient episodesofground displacement related tothe Ida M.» Cecil H.» Yehuda » Bock Mario Mattia » High RateGPSonActive Volcanoes Green Institute Physics, ofGeophysicsUniversity andPlanetary of California, San Diego Green Institute Physics, ofGeophysicsUniversity andPlanetary of California, San Diego Istituto Nazionale diGeofisica e Vulcanologia - diCatania, Sez. P.zza Roma 2,Catania(Italy) Green Institute Physics, ofGeophysicsUniversity andPlanetary ofCalifornia, San Diego - - - - This work was (partially) funded This workby the was(partially) Italian della Dipartimento Protezione Puglisi G.,BonaccorsoA.,Mattia A.,CampisiO., M.,AloisiBonforte Mattia M.,Rossi M.,AloisiGuglielmino F., Bock, Y. (2004).The Bonaccorso A.,AloisiM.,Mattia M.(2002):Dike emplacementforerunning Bock, Y., R.Nikolaidis, P. J.deJonge, andM.Bevis (2000)Instantaneous Aloisi M.,A.Bonaccorso,S.Gambino, M.Mattia, G.Puglisi, Etna 2002 References: (Italy) andAugustine (Alaska,USA)volcanoes. during therecent ofStromboli eruptions (Italy), Etna activity. We have appliedthisapproach todatacollected may indicateapossibleprecursor ofrenewed volcanic UNAVCO fortheGPSdata. di Geofisica e Vulcanologia –INGV. We thankthePBOproject and Civile intheframeof2004-2006 agreement withIstituto Nazionale Geology, No.79, 13 geodetic monitoringsystematStromboli volcano (Italy), Engineering Cantarero M.,Falzone G.,Puglisi B.,Rossi M.(2005)New integrated doi:10.1029/2004GL021281. instantaneous GPSpositionsGeophys. Res. Lett.,31,No. 24,L24610 shallow plumbingsystemofStromboli Island asimagedfrom 1Hz data. Geophys. Res. Lett.,29,13. the Etna July modeledthrough continuous tilt andGPS 2001eruption System, J.Geophys. Res., 105,28,223-28,254. geodetic positioningatmediumdistanceswiththeGlobal Positioning Res. Lett.,30(23),2214,doi:10.1029/2003GL018896. imagedfrom continuoustiltandGPS data(2003).Geophys.eruption Geodetics RTDNet software. stantaneous positioning[Bocketal.,2000]using 15-minute median.Data were processed by in Everythe stillongoing2006eruption. “dot” isa station onAugustine volcano (Alaska)during Figure 1. Deformation patternoftheAV05 GPS - 3-93 Magmatic Systems The CALIPSO Project at Soufrière Hills Volcano, Montserrat, BWI: Using Integrated Deformation Data to Constrain Magmatic Processes

Glen Mattioli » Department of Geosciences, University of Arkansas Barry Voight » Department of Geosciences, Penn State University Derek Elsworth » Department of Geosciences, Penn State University Dannie Hidayat » Department of Geosciences, Penn State University Alan Linde » Department of Terrestrial Magnetism, Carnegie Institution of Washington, DC Peter Malin » Division of Earth Sciences, Duke University 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH Jurgen Nueberg » School of the Earth and Environment, University of Leeds, Leeds, UK Selwyn Sacks » Department of Terrestrial Magnetism, Carnegie Institution of Washington, DC Eylon Shalev » Division of Earth Sciences, Duke University Steve Sparks » Department of Earth Sciences, University of Bristol, Bristol, UK The staff of the MVO » Montserrat Volcano Observatory, Flemmings, Montserrat, British West Indies

The “Caribbean Andesite Lava Island Precision Seismo- geodetic Observatory,” (i.e. CALIPSO) has greatly enhanced the geophysical infrastructure at the Soufriere Hills Volcano (SHV), Montserrat with installation of an integrated array of borehole and surface instrumentation at four sites. Each site has a Sacks-Evertson dilatometer, a three-component seismometer (~Hz to 1 kHz), a Pin- nacle Technologies tiltmeter, and an Ashtech u-Z CGPS receiver with choke ring antenna, similar to volcano sites in western North America as part of EarthScope. CALIPSO sensors recorded the collapse of the SHV lava dome on Montserrat in July 2003, the largest such event worldwide in the historical record (Mattioli et al., 2004). Dilatometer data show remarkable and unprecedented favoring a deeper source. These measurements support a rapid (~600s) pressurization of a deep source. Voight temporal evolution of the mid-crustal pre-eruption stor- et al. (2006) inferred an oblate spheroidal source with age zone from 1995 to 2005. average radius ~1 km centered at 5.5 to 6 km depth. An overpressure of ~1 MPa was attributed to growth of 1 to References 3% of gas bubbles in supersaturated magma, triggered Mattioli, G.S., S.R. Young, B. Voight, and others, 2004, Prototype PBO Instrumentation of CALIPSO Captures World-Record Lava Dome by the dynamics of dome unloading. Collapse of July 2003 on Soufrière Hills Volcano, Montserrat (Feature Pyroclastic flows entering the sea may cause tsunami article), EOS transactions, American Geophysical Union, 85, 317-328. generation at coastal volcanoes worldwide, but geophysi- Voight, B., A.T. Linde, I.S. Sacks, G.S., Mattioli, and others, 2006, Un- cally monitored field occurrences are very rare. Mattioli precedented pressure increase in deep magma reservoir triggered by lava-dome collapse, Geophysical Research Letters 33, doi:10.1029/ et al. (2007) reconstructed the process of tsunami gen- 2005GL024870. eration and propagation during the prolonged, gigantic Mattioli, G.S., A.T. Linde, I. S. Sacks, P. Watts, and others, 2007, Unique collapse of the SHV in 2003 using a combination of and remarkable strainmeter measurements of pyroclastic flow-generated data from the CALIPSO array. Mattioli (2005) also tsunami, Geology, 35 (1), 25-28, DOI: 10.1130/G22931A.1. reported that periods of surface uplift recorded by GPS Mattioli, G.S., 2005, CALIPSO, and a decade of GPS surface deformation: what we have learned from Soufrière Hills volcano (Invited), Montser- at SHV correspond to an inflating, while subsidence rat, Proc. of “Soufriere Hills Volcano – Ten Years On.” Seismic Research corresponds to a deflating Mogi source. Inverted depths Unit, Univ. West Indies Press, in press. are between 6 and 13 km, with the recent observations This work was supported by NSF-EAR Awards 0116485, 0507334, 0523097, and 0607782 to UARK.

3-92 3-93 3-94 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH Kilauea’s southflank. Major signalsincludeinflationof Mauna Loa volcano andseaward motionof off thetopoffigure) has been removed tocorrect for Pacificplatemotion. the Island ofHawaii. The velocity ofthecontinuoussiteon Mauna Kea (just Figure 1. Magmatic Systems recognized. Miklius(2003)speculatedthat andCervelli both volcanoes allowed suchamazingbehaviortobe volcano. Thepresence ofcontinuousGPSnetworks on in lava effusion from the Puù Òò vent onKilauea began inflatingin May 2002,atthesametimeasasurge Mauna Loahadbeendeflatingsince1994butabruptly al. (2006). etal.(2002),BrooksCervelli etal.(2006)andSegall et cations documentingthe“slow earthquakes” include flank ofthe volcano between 1998and2005. Publi have been several aseismicfaultslipevents onthesouth inflation marking theendof2005. In addition,there system. Theupliftratehas varied over time,whichrapid to anincrease inmagmasupplytotheshallow volcanic slowed andgraduallyturnedtouplift,apparently related at Kilauea’s summit.Starting in2000,thesubsidence of the1983-present deflationhasoccurred eruption, University (Miklius etal.,2005).For thevast majority by theUSGS,University ofHawaii, andStanford a GPSnetwork installedandoperatedcollaboratively in Hawaii. Thisdeformationwas well characterized by ety ofdeformationatMauna LoaandKilaueavolcanoes The pastfive years have brought anunprecedented vari Michael Poland » MikliusAsta » Magmatic Deformation inHawaii Average horizontal displacementratesform2002through 2004on U.S.Geological Survey, Hawaiian Volcano Observatory U.S.Geological Survey, Hawaiian Volcano Observatory - - Brooks, B.A.,Foster, J.H.,Bevis, M.F., L.N., Wolfe, C.J.,andBehn, M., References beneath thecaldera. caldera rimandinadike-likebodyalignedSW-NE point source locatedbeneathMauna Loa’s southeast deformation canbemodeledasvolume increase ina increase inratebetween mid-2004andmid-2005.The tinued tothepresent, andwaspunctuatedby afive-fold the effusive episode. Inflation of MaunaLoahascon magma system,providing totrigger thestress necessary ing systemaffectedKilauea’s already pressurized shallow a pulseofmagmaintroduced intoMauna Loa’s plumb indicating volcano inflation. Insets show stationlocationsonthe volcano. Mauna Loa’s caldera (right). Extension is positive, with increases in line-length Figure 2. Segall, P., Desmaris, E.K.,Shelly, D.,Miklius,P., A.,andCervelli, 2006, Miklius, P., A.,Cervelli, Sako, M.,Lisowski, M.,Owen, S.,Segall, P., Foster, Milius, P., A.andCervelli, 2003,Interaction between Mauna Loaand P.,Cervelli, Segall, P., Johnson, K.,Lisowski, M.,andMiklius, A.,2002,Sud 2006, Periodic slow ontheflankofKilauea volcano, earthquakes waii, Nature, 442,2006. Earthquakes Triggered by Silent Slip Events onKilauea Volcano, Ha Geological Survey Open-File Report 2005-1425, 46p. measurements ontheIsland ofHawaiì: 1997through 2004,U.S. J., Kamibayashi,K.,andBrooks, B.,2005,Global Positioning System Kilauea, Nature, 421,p.229. 415, p. 1014-1018. den aseismicfaultsliponthesouthflankofKilauea volcano, Nature, Hawai’i, ScienceLetters,246,p. andPlanetary 207-216. Earth Time seriesofline-lengthchangeacross Kilaueacaldera(left)and - - - - 3-95 Magmatic Systems Reoccupation of the Riobamba (RIOP) Monument, Ecuador

P. Mothes » Instituto Geofísico, Escuela Politécnica Nacional, Quito Ecuador P. LaFemina » Department of Geosciences, Penn State University D. Rivero » Instituto Geofísico, Escuela Politécnica Nacional, Quito Ecuador C. Ramos » Instituto Geofísico, Escuela Politécnica Nacional, Quito Ecuador J. Pozo » Instituto Geofísico, Escuela Politécnica Nacional, Quito Ecuador D. Cisneros » Dept de Geodesia, Instituto Geográfico Militar, Quito, Ecuador

The Riobamba (RIOP) site was established during the Since early January 2007, the station has been operat- 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH CASA project in 1996 and operated from 1996 to 2001, ing on a permanent basis. Instrumentation includes a functioning as a permanent station, hosting a Rogue Trimble SSI receiver and a Trimble chokering antenna. SNR-8000 receiver and a TuboRogue Dorn Margo- Data access via modem/phone line is being arranged; lin with chokering antenna. Its cement monument is however at the moment the data are being downloaded located on a military base in Riobamba, Ecuador. Data every two weeks and are being temporarily stored at the were sent via a fixed modem/phone line to a computer Instituto Geofísico, before transferal to UNAVCO. at the Instituto Geografico Militar in Quito, and then The data will be used to help constrain deformation pat- transferred via FTP to UNAVCO. About 500 days of terns on the nearby erupting Tungurahua volcano and data are shared at the UNAVCO facility. also serve as a control point in the InterAndean Valley to determine local and regional deformation.

Figure 1: Reoccupation of the RIOP monument in Riobamba, Ecuador. The station had been abandoned for six years.

3-94 3-95 3-96 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH Magmatic Systems Caldera wallandoverlooks thetown ofFira. Convention Centernearthevolcanolgical observatory, sitsontheEastern Manager Jim Normandeau. Thesite,whichisinstalledatopofthe Santronini Figure 1. Stathis Stiros » Andrew V. Newman » GPS Study ofOngoing Deformation atSantorini Caldera,Greece islets Palea andNea Kameni,andThira (background). Figure 2. Station KERA,wasinstalledonThirasianearacliff overlooking the Station NOMI,beinginstalledby UNAVCO Engineer andProject Geodesy Lab, Dept ofCivilEngineering, Patras University, Greece Earth andAtmospheric Sciences, Georgia Earth Institute of Technology spread andlocallylargetsunamiwaves across theAegean zation. Additionally, likelycausedwide theeruption possibly contributingtothedemiseofMinoan civili theprevious and islandsurface, et al.,2006],burying expelled some60km 1650 B.C.inamassive that seriesofPlinean eruptions system haditsmostrecent caldera-formingevent around sea level, composingagroup offive smallislands.The flanks andcentralpost-calderalavas exposedabove the submerged,withonlypiecesofcalderawall, is partially fueled by subduction along the Hellenic arc. The caldera well active developedvolcanic but still very system Santorini ofa Calderain thesouthernAegean ispart This work was supported This workby wassupported Georgia Institute of Technology, CollegeofSci Sirgudsson, H.,S.Carey, M.Alexandri,G. Vougioukalakis, K.Croff, C. References ing future regional volcanic crises. be usefulforearlyhazard awareness andmitigationdur submerged environment. Aswell, thisinformationmay standing theearlypost-calderaresurgence inamostly This informationmayadditionallybeusefulforunder mation aboutnearsource rheologyandpressure history. transient deformationthatwouldyieldvaluable infor deformation anddetermineifthere existsanysignificant measurements we hopetoestablishtherateofongoing summer 2007.Through thecontinuousandcampaign are planningasecondsetofmeasurements forspring- sitesacrossnew thefive-island group. Currently, we a firstGPScampaignof18previously establishedand one oftheyoung centralislets.Aswell, we performed across the caldera,andwillsoonfinishathird siteatop we establishedanetworkport, oftwocontinuous GPS In late-spring2006,withUNAVCO engineeringsup of thesubmergedcalderafloor. most recent inthe1950s,formingcentralisletsatop ongoing smallerpyroclastic andphreatic the eruptions, and Mediterranean Seas. Thesystem remains active with ences. (34), 2006. of Greece’s Santorini Volcanic Field, Eos, Trans. Am.Geoph. Un.I, 87 Gogou, D.Ballas, T. Misaridis, andP. Nomikou, Marine Investigations Roman, D.Sakellariou, C.Anagnostou,G.Rousakis, C.Ioakim, A. 3 ofvolcanic material[Sirgudsson ------3-97 Magmatic Systems Ongoing Transient Deformation from a Shallow Socorro Magma Body?

Andrew V. Newman » Earth and Atmospheric Sciences, Georgia Institute of Technology Dave Love » New Mexico Bureau of Geology and Mineral Resources Richard Chamberlain » New Mexico Bureau of Geology and Mineral Resources Timothy H. Dixon » Marine Geology and Geophysics-RSMAS, University of Miami Peter LaFemina » Marine Geology and Geophysics-RSMAS, University of Miami Susan L. Bilek » Earth and Environmental Sciences, New Mexico Tech Richard Aster » Earth and Environmental Sciences, New Mexico Tech 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH The Socorro Magma Body (SMB), between Socorro and Belen, New Mexico, lies within the central portion of the Rio Grande Rift Valley and is one of the largest known magma bodies in Earth’s continental crust. The SMB is expressed in several geophysical anomalies, including increased local seismicity, low electric conduc- tivity, and surface uplift. Studies of local microseismicity and deep seismic soundings revealed an unusual crustal reflector about 50 to 70 km wide, and about 19 km in depth, and were interpreted as requiring fluids, most likely melt, in the middle crust beneath Socorro. These data have led to a general acceptance of the Socorro reflector as the prime example of a large active sill-like Figure 1: GPS results across Socorro Magma Body, New Mexico. Measure- magma intrusion. Using precision leveling and Interfero- ments from new campaign sites (blue diamonds) suggest 0 to 2 cm of uplift, with horizontal spreading. Vertical changes occur rapidly with > 1 cm change metric Synthetic Aperture Radar, previous studies have over 10 km. Errors at this stage are still large. found averaged uplift of about 2 to 4 mm/yr centered on the Socorro seismic reflector at 19 km depth. We performed three GPS campaigns over 9 to 12 bedrock sites in 2002, 2003, and 2005. Vertical GPS over the southern SMB switch from between +10 and 20 mm with the maximum uplift (20 mm) in 2002, to a similar level deflation the following year. Currently, these data suggest a significant and smaller body transiently inflating at about 5km depth and corresponding to 0.5-5 million m3 between 2002 and 2003. These results indicate that the SMB may have considerable variation in the spatio-temporal pattern of deformation averaging to a slower long-term inflation. Figure2: UNAVCO field engineers Beth Bartel and Nicole Feldl after the In fall of 2005, with the help of UNAVCO field engi- completion of short-brace continuous installation of PDBG GPS within the Socorro Magma Body. neers, we installed two new continuous GPS sites near References: the center of transient inflation. In collaboration with Newman, A. V., D. Love, R. Chamberlin, P. LaFemina & T. H. Dixon, Rapid Los Alamos National Laboratory and New Mexico Tech, inflation across the central Socorro Magma Body?, Trans. Amer. Geo- these sites are collocated with two continuously record- phys. Un. (EOS), 85, Fall 2004. ing broadband seismometers aimed at identifying low- Newman, A. V., D. Love, R. Chamberlin, P. LaFemina & T. H. Dixon, Rapid inflation across the central Socorro Magma Body?, Geoph. Res. Lett. frequency tremors associated with migrating fluids. [In Prep]. The work was supported by LANL-NMT MOU Grant; Georgia Tech, Col- lege of Sciences.

3-96 3-97 3-98 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH Magmatic Systems pressures thatmaylead toafuture eruption. tion thatwillhelpultimately identifythepossiblesource develop realistic rheologicmodelsof ground deforma tous,thereforeis important we have beenworking to the source processes uplift thatcontrolled thissurface remains.but thepotentialforeruption Understanding Fortunately, thisevent didnotculminateinan eruption, curring duringtheperiod. cm. Alsoshown are between MW4.3and4.9 (opencircles) earthquakes oc data). Total inflationtothecenterofdeformation(bull’s surface eye) is~10 1/2 wavelength oftheradarfrequency (28.3mmforC-bandERS-2satellite color ``fringe’’ represents across line-of-sightlengthchange(23ooff-vertical) 1997 and19MAY, 1998)from theERS-2descendingsatellite orbit.Each Figure 1: period ofupliftinthelate1990swasmeasured. data, thespatialandtemporalextentofasignificant UNAVCO), aswell aselectronic distancemeter(EDM) thetic Aperture Radar(InSAR) data(botharchived at years. With theaidofGPSandInterferometric Syn overthe largestvolcanic eruptions thepast1million expelledmoreeruption than600km3andwasoneof This ~760,000 years agoinalargeignimbriteeruption. Scope Project. The20×30km2calderawascreated major volcanic focussitefortheongoingNSF-Earth on theeasternedgeofSierra Nevada rangeandisa Long Valley Calderaissituatedineast-centralCalifornia Goodluck Ofoegbu » Noel Gourmelen » Jacqueline Dixon » Timothy Dixon » Andrew V. Newman » Incorporating Viscoelastic Near-Source Rheology Source Processes ofSurface Deformation atLong Valley Caldera InSAR imageofLong Valley caldera(SARimagesfrom 12AUG, Rosenstiel Schoolof Marine andAtmospheric Sciences,University ofMiami Rosenstiel Schoolof Marine andAtmospheric Sciences,University ofMiami Rosenstiel Schoolof Marine andAtmospheric Sciences,University ofMiami Earth andAtmospheric Sciences, Georgia Earth Institute of Technology Southwest Research Center, San Antonio, TX - - - - This work was supported This workby LosAlamos wassupported National Lab(IGPPand Directors Newman, A. V., T. H.Dixon, G.Ofoegbu &J.E.Dixon, Geodetic and Seis Newman, A. V., T. H.Dixon &N.Gourmelen, AFour-Dimensional Visco References: sode alongwithanynear-future episodeshoulditoccur. be invaluable forfuture modelingofthe1997-98epi data, alongwithSARdataattheUNAVCO facilitywill continued availability ofearlierandPBO-installedGPS fluids surrounding apurely fluidmagmaticsource. The vestigate the time-dependenteffectofviscoussemi-solid In ourmodelingofdeformationatLong Valley, we in The source issurrounded(VE)shell. by a0.5-1kmthickviscoelastic dippingprolatevertically spheroid pressure source modelcentered at6km. et al.,2003],andpetrologic interpretations [Bailey 1989].Alsoshown isthe vectors (arrows), highprecision South Moat seismicity(smalldots)[Prejean exaggeration (afterHill etal.,[1998]),includingCASAandKRAKgeodetic Figure 2: publication #3). Fellowship) toAVN andNASAONR grants to THD (CSTARS 105 3,183-206,February 2001. Evidence for Viscoelastic Rheology Jour. of Volcan. andGeoth. Res., mic ConstraintsonRecent Activity atLong Valley Caldera,California: doi:10.1016/j.jvolgeores.2005.07.017, 244-269,2006. between 1995and2000,Journ. of Volcan. andGeoth. Res., 150(1), elastic Model forDeformation oftheLong Valley Caldera,California, Schematiccross sectionofLong Valley calderawithnovertical - - - - 3-99 Magmatic Systems Kinematics and Crustal Deformation of the Yellowstone Hotspot from GPS Measurements: 1987-2006 C. M. Puskas » Dept of Geology and Geophysics, University of Utah R. B. Smith » Dept of Geology and Geophysics, University of Utah W. L. Chang » Dept of Geology and Geophysics, University of Utah D. Drobeck » Dept of Geology and Geophysics, University of Utah C. M. Meertens » UNAVCO, Boulder, CO

Campaign and continuous GPS data caldera. Continuous GPS observa- [Chang and Smith, 2006]. This 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH were acquired from 1987 to 2005 to tions revealed a reversal to rapid model predicted post-seismic hori- measure deformation of the Yellow- caldera-wide uplift up to ~6 cm/yr zontal motion of 1 mm/yr within stone-Snake River Plain volcano-tec- from 2004 to 2006. 40 km of the fault and uplift up to tonic province [Puskas et al., 2006]. These deformation episodes have 2 mm/yr to the north of the fault. The University of Utah, supported been modeled [Vasco et al., 2007] by Using the rheology model, all of by UNAVCO and with collabora- volumetric strain inversion revealing our data were corrected for time-de- tors, conducted seven campaigns a mid-crustal source (6-10 km deep) pendent deformation caused by the between 1987 and 2003, occupying of compression and expansion that M7.5 earthquake. 140 stations and installing and op- coincides with the top of the tomo- erating 15 permanent GPS stations. graphically imaged crustal magma References The University of Utah permanent body. Deformation is likely a result Chang, W. L. and R. B. Smith, (2007), Lithospheric rheology from post-seismic stations will be incorporated into an of accumulation and/or migration deformation of a M=7.5 normal-fault- expanded EarthScope PBO network, of hydrothermal fluids or magmatic ing earthquake with implications for improving coverage of Yellowstone. continental kinematics, J. Geophys. Res., crystallization. (in revision). The GPS data revealed large and un- Thirty kilometers west of the Yellow- Meertens, C. M., R. B. Smith, C. M. Puskas, expected episodes of vertical defor- stone caldera, fault-normal extension (2000), Crustal Deformation of the mation of the Yellowstone caldera. continued across the Hebgen Lake Yellowstone Caldera from Campaign and Continuous GPS surveys, 1987 – 2000, The caldera subsided at a maximum fault at 3.1 to 5.3 mm/yr during Eos Trans. AGU, 81(48), Fall Meet. rate of 14 ± 3 mm/yr in 1987-1995. the period 30 to 46 years follow- Suppl. Abstract V22F-19. Vertical deformation shifted to the ing the 1959 M7.5 earthquake. Puskas, C. M., R. B. Smith, C. M. Meertens, NW caldera boundary uplift at 5 ± 4 Baseline data for 16 years of GPS W. L. Chang, (2007), Crustal Deforma- tion of the Yellowstone-Snake River Plain mm/yr for 1995-2000. For 2000- observations combined with USGS volcanic system: campaign and continu- 2003, caldera deformation switched trilateration data were used to model ous GPS observations, 1987-2004, J. Geophys. Res., 112 doi:10.1029/ to subsidence of up to 9 ± 6 mm/yr, crustal rheology from the viscoelastic 2006JB004325, in press. yielding direct evidence of a restless relaxation following this large event Puskas, C. M., R. B. Smith, G. Waite, L. Flesch, (2004), Kinematic Deformation of the Interior Western U.S. Extensional Regime with Mantle Flow, Eos Trans. AGU, 85(47), Fall Meet. Suppl. Abstract T31A-1247. Vasco, D. W., C. M. Puskas, R. B. Smith, and C. M. Meertens, (2006), Crustal deformation and source models of the Yellowstone volcanic field from geodetic data, J. Geophys. Res., (in revision). The research was supported by NSF Grants 0314298, 9725431, and 9316289.

3-98 3-99 3-100 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH This work was supported This workby NSFgrantsEAR-9902875andEAR-0537920. wassupported Segall, P., etal.,Earthquakes Triggered by Silent Slip Events onKilauea Volcano, P.,Cervelli, etal.,Sudden aseismicfaultslipon thesouthflankofKilauea volcano, References 2005 event withdepthconstrainedby seismicity. from inversion ofGPSdata.Thesolid red lineindicatesthe event. (b)Cross-section. Dashed linesrepresent dislocations indicate relocated accompanyingthe2005slip earthquakes fitting dislocationsfound by non-linearoptimization.Circles Rectanglesdence intervals. show projections ofbest- surface (a) Vectors show displacements foreachevent with95%confi have thepotentialtogrow earthquakes. intodestructive the increased hazard duringslow-slip events, astriggered events depth ofslow slip, andcouldleadtoamethodforquantifying are low. Detection ofsuchevents wouldhelpconstrainthe elsewhere mightgoundetectedifbackground seismicityrates change. Triggered accompanyingslow-slip earthquakes events because theymustfallinzones ofpositive Coulombstress 7 to8km,constraintheslow sliptobeatcomparabledepths, areearthquakes triggered. locatedatdepthsof Theearthquakes, by increased stressing causedby slow slip, implyingthatthe micity. is Thetemporalevolutionwell explained ofearthquakes in January 2005,theslow slipbeganbefore theincrease inseis slips onKilaueavolcano, Hawaii. For themostenergeticevent, silent high-frequency thataccompanyotherwise earthquakes whichareearthquakes, easilylocated. We report onswarmsof slip events have notyet been associated withhigh-frequency range. Except forsomeevents ontheSan Andreas fault,slow- is difficulttolocateandmaybedistributed over a broad depth tion zones isassociatedwithnon-volcanic tremor, buttremor this hypothesishasnotbeenproven. Slow slipinsomesubduc are these silentearthquakes locatedalongtheplatemegathrust, deformationmeasurements.surface Althoughitisassumedthat depths oftheseevents have beendifficulttodetermine from trough inJapan, Cascadia,andGuerrero inMexico, butthe covered inanumberofsubductionzones includingtheNankai Slow-slip events, or‘silent earthquakes’, have recently beendis Magmatic Systems Peter Cervelli » MikliusAsta » David Shelley » Emily Desmarais » Paul Segall » Earthquakes Triggered by Silent Slip Events onKilauea Volcano Hawaii, Nature, 442,2006. Nature, 415,2002. Stanford University Hawaiian Volcano Observatory Alaska Volcano Observatory Stanford University Stanford University - - - - during periodsofrapiddisplacement. day (blackhistogram).Note thattheseismicityrateincreases per circles) andnumberofKilaueasouth-flankearthquakes North componentofdisplacementGPSstationKAEP(gray Figure 2. events. Figure 1. Temporal associationofdeformationand seismicity. Displacements andslipzones forfoursilentslip 3-101 Magmatic Systems Crustal Deformation Near Yucca Mountain, Nevada

B. P. Wernicke » Division of Geological & Planetary Sciences, California Institute of Technology J. L. Davis » Harvard-Smithsonian Center for Astrophysics, Cambridge, MA R A. Bennett » Department of Geosciences, University of Arizona J. E. Normandeau » UNAVCO, Boulder, CO A. M. Friedrich » Institute for Geology, University of Hanover, Germany N. A. Niemi » Department of Geological Sciences, University of Michigan

As part of the BARGEN GPS network, we established a were in part transients associated with the 1992 Ms 5.4 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH dense cluster of GPS sites in the Yucca Mountain area. Little Skull Mountain earthquake. Postseismic motions The cluster was installed in 1999 to provide the most do not appear to affect the 1999–2003 velocity field in reliable measurements possible of geodetic strain patterns either campaign or continuous data. The observed mag- across the nation’s only proposed permanent repository nitude of the velocity contrast across the area, the overall for high-level radioactive waste. The accuracy of the linearity of the gradient, and the large area of undeform- measured horizontal velocities is ~0.2 mm/yr [Davis et ing crust to the east of Yucca Mountain are difficult to al., 2003]. The network lies astride a boundary between explain by elastic bending of the crust associated with the geodetically stable central Great Basin and the ac- the Death Valley fault zone, a major right-lateral strike- tive western Great Basin, which at the latitude of Yucca slip fault about 50 km west of the repository site. These Mountain is undergoing distributed right-lateral shear at observations, along with apparent local variations in the a rate of ~60 nstrain/yr. The GPS solution (1999–2003) velocity gradient, suggest that significant right-lateral from the Yucca Mountain cluster (Figure 1) yields a ve- strain accumulation, with displacement rate ~1 mm/yr, locity field characterized by nearly homogenous N20°W may be associated with structures in the Yucca Mountain right-lateral shear of 20 ± 2 nstrain/yr (net velocity area (Figure 2). The absence of structures in the area with contrast of 1.2 mm/yr across a 60 km aperture) in the equivalent late Quaternary displacement rates under- vicinity of the proposed repository site [Wernicke et al., scores the problem of reconciling discrepancies between 2004]. Comparison of time series of continuous results geologic and geodetic estimates of deformation rates. with earlier campaign surveys [Wernicke et al., 1998] indicating 50 nstrain/yr of west-northwest extension from 1991 to 1997 suggests that the more rapid rates

References Davis, J. L., R. A. Bennett, and B. P. Wernicke, Assessment of GPS velocity accuracy for the Basin and Range Geodetic Network (BARGEN), Geophys. Res. Lett., 30, 1411, doi:10.1029/2003GL016961, 2003. Wernicke, B., J. L. Davis, R. A. Bennett, P. Elósegui, M. Abolins, R. J. Brady, M. A. House, N. A. Niemi, and J. K. Snow, Anomalous strain accumulation in the Yucca Mountain area, Nevada, Science, 279, 2096– 2100, 1998. Wernicke, B., J. L. Davis, R. A. Bennett, J. E. Normandeau, A. M. Friedrich, and N. A. Niemi, Tectonic implications of a dense continuous GPS velocity field at Yucca Mountain, Ne- vada, J. Geophys. Res., 109, B12404, doi:10.1029/2003JB002832, 2004. This work was supported by the U.S. Department of Energy and the National Science Founda- tion. Figure 1. Horizontal velocity field (in a local reference frame) for the Yucca Mountain cluster of BARGEN. Locations of sites MILE and WAHO [Wernicke et al., 1998] are indicated by white triangles. The star indicates the epicenter of the 29 June 1992 Ms 5.4 Little Skull Mountain earthquake. The dashed line indicates the location of the model Death Valley fault of Figure 2 [Wernicke et al., 2004].

Figure 2. N20°W projection of velocities and the two-fault model of Wernicke et al. [2004] (solid curve). The second fault is located at x = +54 km. The dotted curve shows effects of a single fault at x = 0, representing the Death Valley Fault.

3-100 3-101 3-102 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH transport through anearlyhorizontaltransport conduit. andmagma alonganinterface between magma transport tion source fortheuplift.Thus, we cannotdistinguish narrow shallow-dipping prolate ellipsoidasadeforma tween adeep shallow dipping sill(Figure 1)andadeep the 95%confidencelevel we couldnotdistinguishbe Incorporation oftheGPSdataledustoconcludethatat episode (Figure 2). model theInSAR andGPSmeasurements oftheuplift collected by theUniversity ofUtah) tosimultaneously campaign GPSmeasurements (Meertens etal.,2000, appropriate deformationsource, sowe incorporated measurements allow betterdeterminationofthemost (LOS, Figure 2)tothesatellite.Horizontal deformation one dimensional,inthedirection oftheline-of-sight is system. Thedeformationdatainaninterferograms tion atamagmaoutletbeneaththe Yellowstone volcanic source. We interpreted thissource asmagmaaccumula the databetterthanapointsource oraprolate ellipsoid deep narrow shallow dippingsillmodel(Figure 1)fits 1998) wasmostlycontainedwithinthecalderarim.A a previous InSAR studyof Yellowstone etal., (Wicks etal.,2006).Thedeformation signalin 2002 (Wicks lowstone, shown inFigure 1,lastedfrom 1996through deformationin An anomalousmodeofsurface Yel Magmatic Systems Charles Wicks » the Rimof Yellowstone Caldera InSAR ofAnomalousUplift andGPSObservations Under U.S. Geological Survey, Menlo Park, CA - - - - Meertens, C.M.,R.B.Smith, andC.M.Puskas, Eos Trans. AGU, 81(48) Wicks, C.,Thatcher, W. &Dzurisin,D. Migration offluids beneath Yellow Wicks, C.,Thatcher, W. &Dzurisin,D. Uplift, thermal unrest andmagma REFERENCES Collection oftheGPSdata,archived atUNAVCO, wasfunded by anNSF shows theflighttrackofsatellite. inthecenterofscene.Thearrowvertical perpendiculartothe LOS vector the line-of-sightdirection tothesatellite,whichisabout23degrees from culated values dofallwithinthe95%ellipses.Thearrow labeled“LOS” shows values donotfallwithinthe95%ellipsesandgrayshow where thecal data (alongnarrow sill,Figure 1).Black ellipsesshow where thecalculated the calculateddisplacementfrom themodelthatbestfitsGPSand InSAR 2000) are shown inblackwith95%confidenceellipses.The red vectorsshow vectors from Univ. ofUtah GPScampaignsin1995and2000(Meertens, frominterferogram etal.,2006).GPS summer1995to2000(Wicks Figure 2. white box shows thelocationofbest-fitsillmodel. calderarim. under thenorth Yellow linesshow theroads inthepark area. The Yellowstone National Park. shows Theinterferograms over 70mmofuplift formed ~640,000years ago. ofthe Thedouble-dashlineshows theboundary linemarks thelocationofrim the short-dash Yellowstone calderathat ERS2 satelliteimagesacquired duringthesummersof1996and2000. The Figure 1. V22F-19 (2000). 458-462 (1998). stone Calderainferred from satelliteradar interferometry. Science282, at intrusion Yellowstone Caldera.Nature 440,72-75(2006). grant toDr. Robert Smith (University ofUtah). Thecolored squares are dataparsedfrom anunwrappedstacked calculatedfrom Aninterferogram twoEuropean Space Agency - - 3-103 Magmatic Systems Mechanical Modeling of Volcanic Deformation: Application to Mauna Loa

Sang-Ho Yun » Department of Geophysics, Stanford University Paul Segall » Department of Geophysics, Stanford University Howard Zebker » Department of Geophysics, Stanford University Falk Amelung » Division of Marine Geology and Geophysics, University of Miami

We model crustal deformation at Mauna Loa volcano 2008-2012 UNAVCO PROPOSAL: GEODESY ADVANCING EARTH SCIENCE RESEARCH using boundary element methods constrained by In- terferometric Synthetic Aperture Radar (InSAR) data. A total of thirty interferograms are stacked to reduce atmospheric noise for four different look angles (two as- cending and two descending with look angles from 23.5 to 43.5 degrees) from the Radarsat satellite. The overall time span of the interferograms is November 2001–Sep- tember 2005, and the maximum stacked line-of-sight velocities (range decrease) are from 5.1 cm/year (ascend- ing beam 3) to 7.9 cm/year (descending beam 6). We fit the four interferograms with one planar dike-like and one finite spherical magma chamber that are intercon- nected and share the same excess magma pressure. Simulated annealing inversion with binary parameters Figure 1. Best-fit dike and spherical magma chamber model that are hydrauli- cally connected to each other (a) Map view and (b) dike-plane view. The (Yun et al., 2006) allows solving for the excess pressure geometries of the two magma bodies and their excess magma pressure are and the geometry of the deformation source. Topogra- estimated simultaneously. phy correction (Williams and Wadge, 2000) was applied during the inversion. The estimated excess pressure is about 1.76 MPa, and the spherical magma chamber is estimated to be at a depth of about 4.66 km below the summit of Mauna Loa. The excess pressure constrains the radius of the spherical chamber, which is estimated to be about 1.15 km. The dike plane aligns with Mauna Loa’s southwest rift zone, and the maximum dike opening rate is about 30 cm/year. The volume increase rates of the dike and the spherical magma chamber are 24.7 x 106 m3/year and 0.3 x 106 m3/year respectively. This model explains 96% of data variance with an RMS error of 2.40 mm/year.

References Williams, C. A. and Wadge, G., 2000, An accurate and efficient method for including the effects of topography in three-dimensional elastic models of ground deformation with applications to radar interferometry, Jour- nal of Geophysical Research, v105 (B4), 8103 - 20. Yun, S., Segall, P., and Zebker, H., 2006. Constraints on magma chamber geometry at Sierra Negra volcano, Galápagos Islands, based on InSAR observations, Journal of Volcanology and Geothermal Research, v150 This work was supported by NSF Grants EAR-0511035 and EAR-0346240. (1-3), p.232-243.

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