subsidence at southern andes volcanoes induced...interferograms were power-spectrum ﬁltered using...

SUPPLEMENTARY INFORMATIONDOI: 10.1038/NGEO1855

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SUPPLEMENTAL INFORMATION:SUBSIDENCE AT SOUTHERN ANDEAN VOLCANOES INDUCED

BY THE 2010 MAULE EARTHQUAKE

1. InSAR processing

We use ROI_PAC software (Rosen et al., 2004) to process the Envisat, ERS-2and ALOS data. ALOS data were provided by the Japaese Space Agency (JAXA)through the Alaska Satellite Facility and Envisat and ERS data from the EuropeanSpace Agency. Data are restricted by agreements from the data providers, but userscan apply for access through the following URL’s:

http://www.asf.alaska.edu/program/sdc/proposals#alospalsarhttps://earth.esa.int/web/guest/pi-community/apply-for-data/full-proposal

Interferograms were power-spectrum filtered using the algorithm of Goldstein andWerner (1998) and unwrapped using the branch-cut algorithm of Goldstein et al.(1988). Digital Elevation Models from the Shuttle Radar Topography Mission with90 m pixel spacing are used to remove the topographic signature from the InSARphase (Farr et al., 2007).

To isolate the signature of the localized volcanic deformation within the large-scaledeformation pattern of the Maule earthquake, we process only small interferogramregions near the volcanoes of interest. Interferograms with ionospheric disturbances(identified by a distinctive phase anomalies parallel to the local magnetic field lines(Fournier et al., 2010)) are not further analyzed if the entire interferogram is cor-rupted. Once the orbital and topographic effects are removed from the interfero-grams, we then remove the remaining best fitting quadratic function from the phasesignature of the entire interferogram. While this procedure does not completely re-move the effects of the earthquake (particularly potential signals with a long spatiallength scale of 50 km or more), it is usually sufficient to identify any residual local-ized deformation. Several independent interferograms are examined for each volcanicregion so that atmospheric signals may be ruled out and interferograms are stackedtogether to reduce atmospheric noise (Figures 1 and 2).

Profiles through the semi-major and semi-minor axes of the subsidence patternsare shown in Supplemental Figures 1, 2, 3, 4, and 5. No clear pattern of upliftis observed in any of the profiles, except for a putative small earthquake south ofCaldera del Atuel.

1

Subsidence at southern Andes volcanoes induced by the 2010 Maule, Chile earthquake

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2SUPPLEMENTAL INFORMATION: * SUBSIDENCE AT SOUTHERN ANDEAN VOLCANOES INDUCED BY THE 2010 MAULE EARTHQUAKE

2. Response of other deforming volcanoes

Prior to the 2010 Maule earthquake, there were six volcanoes in the SVZ known tobe deforming due to subsurface magmatic or hydrothermal activity. These volcanoesare: Cerro Hudson, Chaitén, Cordón Caulle, Llaima, Copahue, and Laguna delMaule (Pritchard and Simons, 2004; Fournier et al., 2010; Wicks et al., 2011; Bathkeet al., 2011; Velez et al., 2011). We have examined interferograms of these and othervolcanoes for changes in the deformation before and after the Maule earthquake.Cordón Caulle volcano exhibits an episode of uplift in a co-seismic interferogramspanning 13 February to 31 March 2010 (Supplemental Figure 6). We did not findany robust change at Cerro Hudson (Supplemental Figure 7) and other volcanoesgiven the noise and few interferograms available. Laguna del Maule is of specialinterest because it is located within the Maule earthquake rupture area, is deformingrapidly, and does not appear to have been affected by the earthquake (SupplementalFigure 8). Copahue volcano is located just south of the earthquake rupture area andalso is not obviously affected by the Maule earthquake (Supplemental Table 1).

3. Co-seismic static stress field along the volcanic arc

We use the Coulomb 3.2 software (Lin and Stein, 2004; Toda et al., 2005) togenerate forward models of the static internal stress field from the Maule earthquake,resolved on optimally oriented extensional structures over horizontal grids at 2.5 kmdepth. We use the value of the normal component of the stress tensor, ∆σn, to assesswhich of the volcanic centers along the Maule rupture area would be most likely todevelop structural permeability. The magnitude of ∆σn is shown in Figure 3 in mainmanuscript and Supplemental Figure 9.

Extensional structures can represent the orientation of a Mode I crack or normalfault according to the Anderson criterion of faulting. The strike of these optimallyoriented structures is orthogonal to the minimum principal stress vector ∆σ3 at eachgrid element, which is horizontal over most of the upper plate. The dip is determinedbased on the Coulomb rock fracture criterion which depends on the orientation ofthe maximum principal stress, ∆σ1, at each grid node (King et al., 1995).

We test multiple published finite fault slip models of the Maule earthquake (Delouiset al., 2010; Lorito et al., 2011; Vigny et al., 2011; Moreno et al., 2012). We useslip models based on geodetic data because models for great earthquake rupturesthat are based only on teleseismic data do not reliably solve for the slip distribution(Pritchard et al., 2007). We assume linear elasticity with Lamé constants determinedusing average values for upper crustal materials of Elastic modulus (E=75 GPa) andPoisson’s ratio (ν=0.25) (Turcotte and Schubert, 2002). We assume no external stressacting on the elastic half-space to assess exclusively the co-seismic deformation.


SUPPLEMENTAL INFORMATION:SUBSIDENCE AT SOUTHERN ANDEAN VOLCANOES INDUCED BY THE 2010 MAULE EARTHQUAKE3

The five deforming areas are within regions with the maximum values of ∆σn where∆σ3 is oriented approximately perpendicular to the semi-major axis of the observedsubsidence (Figure 3 and Supplemental Figure 9). There are some volcanoes with noobserved subsidence that have similar values and orientation of ∆σn to the volcanoesthat are subsiding. For example, volcanoes between Calabozos and Nevados deChillán (including Nevado de Longaví, San Pedro-Pellado, and Laguna del Maulethat have geothermal features), volcanoes north of Caldera del Atuel (including SanJosé and Maipo with historic eruptions) and south of Nevados de Chillán (includingAntuco which has a historic eruption) (Siebert and Simkin, 2012; González-Ferrán,1995). It is possible that the volcanoes that did not deform did not have sufficienthydrothermal fluids to be mobilized by the co-seismic stress change and shaking –there are few published reports about the geothermal systems at these volcanoes, sofuture field studies may be necessary to test this hypothesis. For the volcanoes northof Caldera del Atuel and south of Nevados de Chillán, it might be relevant that thedeforming volcanoes are geochemically different, belonging to the Transitional SVZinstead of the Northern or Central SVZ (Stern, 2004). Alternatively, it is possiblethat subtle changes in the amplitude of ∆σn and orientation of ∆σ3 control thegeographic limits of deforming volcanoes.

4. Unlikely deformation mechanisms

4.1. Poro-elastic response. The co-seismic stress change can cause the post-seismicmovement of pore fluids and continued deformation that can modeled by subtractingthe co-seismic deformation field calculated using undrained Poisson’s ratio from theco-seismic deformation field calculated using the drained Poisson’s ratio (e.g., Peltzeret al., 1998; Hughes et al., 2010). This post-seismic poro-elastic effect of a large sub-duction earthquake within the volcanic arc should cause ground uplift of severalcm (assuming undrained Poisson’s ratio is larger than the drained value). Whilethis deformation may have occurred, it is not the dominant cause of the observedsubsidence.

4.2. Surficial deposit compaction. Earthquakes have caused compaction andsubsidence of surficial volcanic deposits (e.g., Whelley et al., 2012). We think thismechanism is unlikely because the observed deformation is not obviously limited tocertain types of volcanic deposits.

4.3. Aseismic fault slip. Induced aseismic fault slip has been triggered in vol-canic areas by distant earthquakes (Hill and Prejean, 2007). Detailed fault mapsdo not exist for all five of the deforming areas, but the regional faults trend withthe orientation of deformation (Cembrano and Lara, 2009). We have examined theOkada model of pure dip-slip motion over a range of dips and compared results to



InSAR data covering Caldera de Atuel. We constrain all model parameters exceptfor dip through the Neighborhood Algorithm inversion (strike=350, width=4km,length=14km, depth=6km, ν=0.25km, slip=-0.45m) (Sambridge, 1999). We thencompute forward Okada models for a range of dips (Supplemental Figure 10). Nor-mal faults dipping 20-40 degrees provide a reasonable fit to the width and amplitudeof subsidence while giving rise to relative uplift that would be obscured in the levelof background noise in the InSAR data. However, these dips are unrealisticallyshallow, and it is unlikely that five of such shallow-dipping normal faults would besimultaneously triggered along 200km of the volcanic arc.

4.4. Enhanced elastic deformation. Volcanic and geothermal regions are ex-pected to have weakened rocks due to the presence of high temperatures, fractures,and fluids and possible higher Poisson’s ratio than surrounding rocks. Enhancedelastic deformation could have been triggered in mechanically weak volcanic zones(as seen in fault zones) causing local subsidence (Fialko et al., 2002). Regional re-duction in elastic moduli was seen in Japan after the 2011 earthquake (Nakata andSnieder, 2011), but this proposed deformation mechanism would require enhance-ment at volcanoes that could be confirmed by using Japanese seismometers near thesubsiding areas. But, we do not think the mechanical variations at the volcanoes isa dominant effect for three reasons. First, given the large size of this earthquake, ifthese damage zones are ubiquitous at the volcanoes, we should see more than fivedeforming (including Laguna del Maule). Second, the magnitude of the deforma-tion predicted using reasonable elastic properties in a finite element model (FEM)is smaller than the observed by almost an order of magnitude. Finally, the FEMpredicts uplift around the regions of subsidence that we do not observe.

Our FEM consists of a domain 100km x 100km x 50km with a spherical reservoir(r = 10km) centered between 10km to 5.5km depth. The top surface of the domainis free, the bottom surface has a roller boundary condition, and the sides of thedomain have applied tractions of 0.6 MPa as predicted by our co-seismic static stresschange analysis. We use PyLith1.7.1 software to perform finite element calculationson our mesh (Aagaard et al., 2011). We have tested a range of material constantsfor the crust and reservoir (E=10-84 GPa, G=1-33GPa) consistent with regionalseismic properties (Zandt, 1995) and effective rigidities commonly used in volcanodeformation models (e.g. Trasatti et al. (2005); Bonafede and Ferrari (2009)).

Subsurface stresses resulting from deformation around the reservoir are accommo-dated on the surface via NS-elongated subsidence bordered by symmetrical upliftinglobes to the east and west. This pattern is robust no matter what mesh or combi-nations of material properties are used, it only differs in amplitude (Supplemental



Figure 11). While this simple model underestimates observed subsidence, it is possi-ble that accounting for co-seismic damage could enhance subsidence by subsequentgravitational collapse (Hearn and Fialko, 2009).

5. Plausible deformation mechanisms

5.1. Release of magmatic gases. If there was a large gas accumulation in thethree years before the earthquake, we would expect to see ground uplift at the fivedeforming volcanoes, but we do not detect this. On the other hand, if the volume ofgas is small, the rates of pressurization are small, or the magma is compressible, thepre-event deformation might have been non-detectable.

We have examined nighttime ASTER Product 8 (Surface kinetic temperature)data over the deforming regions for the months of February, March, and April 2010(Supplemental Table 4). For regions in which the lastest pre-Maule ASTER scene wasprior to January 2010, we examined that scene as well. Caldera del Atuel, Calabozos,and Cerro Azul have hotspots neither before nor after the earthquake; Planchón andNevados de Chillán have hotspots both before and after the earthquake but with notemporal variability in hotspot temperature above background (Supplemental Figure12); and Tinguiririca has no ASTER data. The precision of the temperature mea-surements from the temperature-emissivity separation algorithm is 1.5 C (Gillespieet al., 1998), so temperature variations above this threshold should be measurable.The infrequency of ASTER acquisitions over the deforming regions limits our abilityto assess whether the Maule earthquake triggered an increase in thermal output atthese volcanoes.

We also examined raw MODIS data to detect hotspots that were missed by MOD-VOLC, an automatic hotspot detection algorithm that sets a high detection thresholdto avoid false positives (Wright et al., 2004). We examined nighttime MODIS datafrom the Aqua and Terra satellites covering the 5 subsiding volcanoes from 30 daysbefore to 30 days after the earthquake. Though the spatial resolution of MODIS ismuch lower than that of ASTER (from 1 km at nadir to 2x5 km at the edge of theswath), its temporal resolution is much higher, acquiring an image about once perday. For each volcano, we calculated the MODIS Normalized Thermal Index [NTI= (band21-band32)/(band21+band32) using band 21] for each pixel in a 0.1 x 0.1degree box centered on the volcano and used the pixel with the highest NTI in ouranalysis. We found no significant increase (within a 95% confidence interval) in NTIfrom before and after the earthquake (Supplemental Figure 13). Our method detectshotspots with NTI lower than the MODVOLC detection threshold of -0.8 but stillsignificantly higher than average. The low spatial resolution of MODIS does notallow us to detect small-scale changes in thermal behavior at the deforming regions.



MODIS data (Product MODIS Calibrated Radiances 5-Min L1B Swath 1km V005)from the NASA Aqua and Terra satellites and ASTER data (AST08 Surface KineticTemperature) from the NASA Terra satellite were accessed through the followingURL:

http://reverb.echo.nasa.gov/reverb.

Data are restricted by agreements from the data providers, but users can apply foraccess.

5.2. Release of hydrothermal fluids. For each volcanic region, we model the sub-sidence with a collapsing spherical point source embedded in a homogeneous elastichalf-space (a.k.a. “Mogi” model) in order to estimate the depth and volume of fluidwithdrawal to an order of magnitude. Using the inversion method of Fournier et al.(2010), we employ an iterative least squares inversion to solve for the 3-D locationand volume change of the point source. This simple modeling gives source depthsbetween 3 and 10 km, and volume changes between 0.01 and 0.04 km3 (SupplementalTable 2).

We have analyzed stream discharge data collected by the Chilean Dirección Gen-eral de Aguas at stations surrounding the deforming volcanic regions. The spatialand temporal coverage of the data that we were able to access is not ideal. Wewere able to access 7 streamflow stations spanning a one month time period from 15February to 15 March 2010 (Supplemental Figure 14). Chilean streamflow data wereprovided by the Chilean Ministerio de Obras Públicas Direcciión General de AguasDivisiión de Hidrologiía. Free access to the data is available to registered users atthe following URL:

http://dgasatel.mop.cl

At 6 of the 7 stations for which we have stream discharge data, there is a clearincrease in discharge immediately following the Maule earthquake. Additional datafrom stations outside of the deforming regions would be necessary to determine if thisobserved increase in stream discharge could be attributed to the escape of subsurfacefluids and thus related to the volcanic subsidence observed by InSAR. Also, chemicalanalysis of the streamflow before and after the earthquake would help determine ifthe post-Maule streamflow was coming from a different source. In a study area southof Nevados de Chillán and west of the volcanic arc yet still within the rupture zoneof the Maule earthquake, Mohr et al. (2012) found that streamflow experienced animmediate co-seismic decline followed by a significant increase of up to 400%. Thisincrease is attributed to release of water from a shallow saprolite layer at 6 m depthand increased vertical permeability.



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Supplemental Table 1. Interferograms of volcanoes that had de-formation triggered by the Maule earthquake. Interferograms used instacks in Figures 1 and 2 are identified with by ’**’. ALOS data is finebeam single or dual polarization. When dual we use the HH channeland converted to the single polarization pixel size by padding with ze-ros.*These interferograms show subsidence inferred to be due to the Mauleearthquake.

Time Span Baseline(m)

Satellite(track/path)

Result*

Caldera del Atuel23 Dec. 2008-7 Feb. 2007 1370 ALOS (110) noisy, but no obvious deformation12 Feb. 2009-7 Feb. 2007 1040 ALOS (110) no deformation15 Feb. 2010-10 Nov. 2007 70 ALOS (110) Ionosphere15 Feb. 2010-7 Feb. 2007 1280 ALOS (110) Ionosphere**2 Apr. 2010-10 Feb. 2008 350 ALOS (110) ionosphere, subsidence at Caldera del Atuel*, landslide**2 Apr. 2010-10 Nov. 2007 800 ALOS (110) noisy, but Caldera del Atuel subsidence***2 Apr. 2010-15 Feb. 2010 750 ALOS (110) ionosphere, Caldera del Atuel* subsidence and "earth-

quake"**3 Oct. 2010-27 Mar. 2008 720 ALOS (110) subsidence at Caldera del Atuel*, landslides3 Oct. 2011-10 Feb. 2008 80 ALOS (110) some ionosphere, subsidence at Caldera del Atuel*3 Oct. 2011-2 Apr. 2010 1340 ALOS (110) Ionosphere3 Oct. 2011-27 Mar. 2008 140 ALOS (110) IonosphereCaldera del Atuel, Tinguiririca17 Oct. 2009-11 Apr. 2007 590 ALOS (111) no obvious deformation besides anthropogenic4 Mar. 2010-27 Feb. 2008 1080 ALOS (111) Caldera del Atuel, Tinguiririca, landslide, anthropogenic*4 Mar. 2010-17 Oct. 2009 1560 ALOS (111) too noisy20 Oct. 2010-4 Mar. 2010 1130 ALOS (111) noisy, but no obvious deformation20 Oct. 2010-27 Feb. 2008 50 ALOS (111) Caldera del Atuel, Tinguiririca, landslide, anthropogenic*20 Oct. 2010-13 Apr. 2008 250 ALOS (111) Caldera del Atuel, Tinguiririca, landslide, anthropogenic*20 Jan. 2011-4 Mar. 2010 2050 ALOS (111) noisy, but no obvious deformation20 Jan. 2011-13 Apr. 2008 670 ALOS (111) Caldera del Atuel, Tinguiririca, landslide, anthropogenic*Laguna del Maule, Calabozos, Tinguiririca, Cerro Azul29 Oct. 2007-26 Jan. 2007 750 ALOS (112) No obvious deformation, but maybe troposphere signature30 Apr. 2008-29 Jan. 2008 480 ALOS (112) No obvious deformation, but maybe troposphere signature31 Jan. 2009-26 Jan. 2007 1720 ALOS (112) Laguna del Maule but no other obvious deformation3 Feb. 2010-29 Oct. 2007 200 ALOS (112) noisy but no obvious deformation besides Laguna del Maule3 Feb. 2010-26 Jan. 2007 700 ALOS (112) Laguna del Maule but no other obvious deformation3 Feb. 2010-29 Jan. 2008 1030 ALOS (112) No obvious deformation, but maybe troposphere signature**21 Mar. 2010-29 Jan. 2008 500 ALOS (112) Laguna del Maule, Calabozos, Tinguiririca, Cerro Azul***21 Mar. 2010-3 Feb. 2010 560 ALOS (112) some ionospheric signature, Tinguiririca, Calabozos,*Cerro

Azul subsidence, but nothing obvious at Laguna del Maule,**22 Dec. 2010-30 Apr. 2008 580 ALOS (112) Laguna del Maule, Calabozos, Tinguiririca, Cerro Azul***22 Dec.2010-15 Mar. 2008 360 ALOS (112) Laguna del Maule, Calabozos, Tinguiririca, Cerro Azul***22 Dec.2010-3 Feb. 2010 2090 ALOS (112) Laguna del Maule, Calabozos, Tinguiririca, Cerro Azul?*Laguna del Maule, Calabozos, Cerro Azul20 Feb. 2010-15 Feb. 2008 1010 ALOS (113) Laguna del Maule and ionosphere



7 Apr. 2010-2- Feb. 2010 670 ALOS (113) Cerro Azul, Edge of Calabozos, noise at Laguna del Maule*8 Jan. 2011-7 Apr. 2010 1500 ALOS (113) Laguna del Maule – nothing else obvious8 Jan. 2011-8 Oct. 2010 1040 ALOS (113) Laguna del Maule – nothing else obviousNevados de Chillán22 Oct. 2009-1 Mar. 2007 90 ALOS (114) no deformation6 Mar. 2009-1 Mar. 2007 980 ALOS (114) Small inflation at Chillán or troposphere?6 Mar. 2009-10 Jan. 2009 680 ALOS (114) no deformation**9 Mar. 2010-1 Mar. 2007 1330 ALOS (114) Chillán and Copahue subsidence*9 Mar. 2010-2 Dec. 2007 340 ALOS (114) Ionosphere, but Chillán subsidence still visible?***24 Apr. 2010-3 Mar. 2008 590 ALOS (114) Chillán subsidence*9 Mar. 2010-6 Mar. 2009 2300 ALOS (114) Chillán subsidence*25 Oct. 2010-18 Apr. 2008 90 ALOS (114) Chillán subsidence*25 Jan. 2011-9 Mar. 2010 2230 ALOS (114) Small inflation at Chillán or troposphere?25 Jan. 2011-25 Oct. 2010 960 ALOS (114) Small inflation at Chillán or troposphere?**12 Mar. 2011-18 Apr. 2008 1120 ALOS (114) Chillán subsidence*6 Feb. 2009-31 Jan. 2007 1180 ALOS (115) Copahue subsidence, inflation or tropospheric at Chillán8 Feb. 2010-31 Jan. 2007 1180 ALOS (115) Copahue subsidence, inflation or tropospheric at Chillán8 Feb. 2010-3 Feb. 2008 1020 ALOS (115) tropospheric – nothing obvious, even Copahue is subtle8 Feb. 2010-5 Feb. 2009 2460 ALOS (115) noisy – nothing obvious, even Copahue is subtle26 Mar. 2010-3 Feb. 2008 530 ALOS (115) subsidence at Copahue and Chillán* (something at An-

tuco?)26 Mar. 2010-8 Feb. 2010 490 ALOS (115) subsidence at Copahue and Chillán* Tropospheric effects?27 Dec. 2010-3 Feb. 2008 1330 ALOS (115) subsidence at Copahue and Chillán*11 Feb. 2011-26 Mar. 2010 2120 ALOS (115) Only anthropogenic deformation?11 Feb. 2011-27 Dec. 2010 260 ALOS (115) No obvious deformation12 Jan. 2011-24 Feb. 2010 1600 ALOS (419) Chillán subsidence*, maybe Antuco deposits deformation?10 Apr. 2010-30 Jan. 2010 10 ENVISAT

(261)Chillán subsidence*, noisy near Copahue



Supplemental Table 2. Preliminary modeling results for sphericalpoint source inversion

Volcano Path Max. LOSDef (cm)

Dates Depth (km) ∆ V (km3)

Caldera del Atuel 110 15 3 Oct. 2010-10 Feb. 2008 3.5 0.011

110 13 2 Mar. 2010-15 Feb. 2010 5.1 0.011

111 15 20 Oct. 2010-27 Feb. 2008 5.5 0.016

Tinguiririca 112 10 21 Mar. 2010-29 Jan. 2008 8.9 0.034

112 10 21 Mar. 2010-3 Feb. 2010 10.3 0.044

Calabozos 112 8 21 Mar. 2010-29 Jan. 2008 7.2 0.029

Nevados de Chillán ERS 6 10 Apri. 2010-30 Jan. 2010 7.7 0.013

114 10 24 Apr. 2010-3 Mar. 2008 10.1 0.048

Supplemental Table 3. Material properties used in FEM model ofvolcanic weak zone

Description E(GPa) G(GPa) ννν Vp(km/s) Vs(km/s) ρρρ(kg/m3) umaxz (cm)

Average Crust 84 33 0.25 6100 3500 2750 n/a

Geothermal Zone 10 4 0.25 2148 1240 2600 -1.92

"Void" Space 2 1 0.05 1450 1000 1000 -2.77



Supplemental Table 4. Available ASTER cloud-free nighttimescenes covering the deforming volcanic regions

Volcano Date Hotspot?Y/N

HotspotTemp (K)

BackgroundTemp (K)

Diff(K)

Caldera del Atuel 12/7/2009 N

4/14/2010 N

4/30/2010 N

Tinguiririca N/A

Calabozos 1/1/2010 N

2/2/2010 N

2/9/2010 N

4/7/2010 N

4/23/2010 N

Cerro Azul 2/9/2010 N

4/7/2010 N

4/23/2010 N

Planchón 2/2/2010 Y 306 273 33

4/7/2010 Y 305 275 30

4/23/2010 Y 295 266 10

Nevados de Chillán 11/12/2009 Y 276 266 10

3/13/2010 Y 285 278 7

3/29/2010 Y 291 281 10

4/21/2010 Y 274 264 10



70.9˚W

70.9˚W

70.8˚W

70.8˚W

70.7˚W

70.7˚W

70.6˚W

70.6˚W

35.6˚S 35.6˚S

35.5˚S 35.5˚S

35.4˚S 35.4˚S

−8 −6 −4 −2 0 2 4 6 8

A

A’

B

B’

Cerro Azul100321-080129

LOS Deformation (cm)

0 5 10 15 20 25 30−10

−5

0

5

Distance along profile (km)

LOS Deformation (cm

)

Profile A−A’

100321−080129100321−100203101222−080315100407−100220

0 2 4 6 8 10 12 14 16 18−8

−6

−4

−2

0

2

4Profile B−B’

LOS Deformation (cm

)


Supplemental Figure 1. Cerro Azul interferogram and deforma-tion profiles. The shift in profiles is likely due to the different line-of-sight geometries of interferograms from different tracks (see Supple-mental Table 1), atmospheric delays, and incomplete removal of theMaule earthquake signal.



70.8˚W

70.8˚W

70.7˚W

70.7˚W

70.6˚W

70.6˚W

70.5˚W

70.5˚W

70.4˚W

70.4˚W

35.6˚S 35.6˚S

35.5˚S 35.5˚S

35.4˚S 35.4˚S

35.3˚S 35.3˚S

−12−10 −8 −6 −4 −2 0 2 4 6 8

Calabozos100321-100203


A

A’

B

B’0 5 10 15 20 25 30 35

−16

−14

−12

−10

−8

−6

−4

−2

0

2

4


LOS Deformation (cm

)

Profile A−A’

100321−080129100321−100203101222−080315100407−100220101020−080227101222−080430101222−100203

0 5 10 15 20 25−16

−14

−12

−10

−8

−6

−4

−2

0

2

4Profile B−B’

LOS Deformation (cm

)


Supplemental Figure 2. Calabozos interferogram and deformationprofiles. The shift in profiles is likely due to the different line-of-sightgeometries of interferograms from different tracks (see SupplementalTable 1), atmospheric delays, and incomplete removal of the Mauleearthquake signal.




70.1˚W

70.1˚W

70˚W

70˚W

69.9˚W

69.9˚W

69.8˚W

69.8˚W

34.7˚S 34.7˚S

34.6˚S 34.6˚S

34.5˚S 34.5˚S

−14−12−10 −8 −6 −4 −2 0 2 4 6 8

A

A’

B

B’

Caldera del Atuel100402-100215

0 5 10 15 20 25 30 35 40−15

−10

−5

0

5

10


LO

S D

efo

rma

tion

(cm

)

Profile A−A’

100402−100215101003−080210101020−080227101003−080327100304−080227100402−080210101020−080413110120−080413

0 5 10 15 20 25−14

−12

−10

−8

−6

−4

−2

0

2

4

6Profile B−B’

LO

S D

efo

rma

tion

(cm

)


Uplift due to earthquake

Supplemental Figure 3. Caldera del Atuel interferogram and de-formation profiles. The shift in profiles is likely due to the different line-of-sight geometries of interferograms from different tracks (see Supple-mental Table 1), atmospheric delays, and incomplete removal of theMaule earthquake signal. Several interferograms (including 4/2/2010-2/15/2010 shown) show a localized deformation pattern (primarily up-lift) to the south of the main subsidence region that is constrained tobe between 15 Feb. and 4 Mar., 2010 by analysis of multiple interfer-ograms. Preliminary modeling indicates that the deformation mightbe caused by an earthquake about Mw 5.0, less than 2 km deep, andon a thrust fault. Global and Argentine earthquake catalogs do notshow any earthquakes of this size between those dates and within 1230 km of the deformation, but the nearest seismometers were 100’s ofkm away.




71.6˚W

71.6˚W

71.5˚W

71.5˚W

71.4˚W

71.4˚W

71.3˚W

71.3˚W

71.2˚W

71.2˚W

37.1˚S 37.1˚S

37˚S 37˚S

36.9˚S 36.9˚S

36.8˚S 36.8˚S

36.7˚S 36.7˚S

−10 −8 −6 −4 −2 0 2 4 6 8

A

A’

B

B’

Nevados de Chillán100424-080303

0 5 10 15 20 25 30 35 40−12

−10

−8

−6

−4

−2

0

2

4


LO

S D

efo

rma

tion

(cm

)

Profile A−A’

100410−100130100424−080303100309−070301100326−080203100326−100208110312−080418

0 5 10 15 20 25−12

−10

−8

−6

−4

−2

0

2

4Profile B−B’

LO

S D

efo

rma

tion

(cm

)


Supplemental Figure 4. Nevados de Chillán interferogram anddeformation profiles. The shift in profiles is likely due to the differ-ent line-of-sight geometries of interferograms from different tracks (seeSupplemental Table 1), atmospheric delays, and incomplete removal ofthe Maule earthquake signal.




70.6˚W

70.6˚W

70.5˚W

70.5˚W

70.4˚W

70.4˚W

70.3˚W

70.3˚W

35.1˚S 35.1˚S

35˚S 35˚S

34.9˚S 34.9˚S

34.8˚S 34.8˚S

−12−10 −8 −6 −4 −2 0 2 4 6 8

A

A’

B’

B

Tinguiririca100321-100203

0 5 10 15 20 25 30 35 40 45−15

−10

−5

0

5


LO

S D

efo

rma

tion

(cm

)

Profile A−A’

100321−100203101020−080227100321−080129101222−080315100304−080227101003−080327101020−080413101222−080430101222−100203

0 5 10 15 20 25 30 35−14

−12

−10

−8

−6

−4

−2

0

2

4

6Profile B−B’

LO

S D

efo

rma

tion

(cm

)


Supplemental Figure 5. Tinguiririca interferogram and deforma-tion profiles. The shift in profiles is likely due to the different line-of-sight geometries of interferograms from different tracks (see Supple-mental Table 1), atmospheric delays, and incomplete removal of theMaule earthquake signal.



72.3˚W

72.3˚W

72.2˚W

72.2˚W

72.1˚W

72.1˚W

72˚W

72˚W

40.6˚S 40.6˚S

40.5˚S 40.5˚S

40.4˚S 40.4˚S

10 km

Temp (K)350

295

290

280

270

260

285

275

265

a. 22 Apr 2008 b. 17 May 2011

Temp (K)350

295

290

280

270

260

285

275

265

−10 0 10

Deformation (cm)

c. 13 Feb 2010-31 Mar 2010 (ALOS)

Supplemental Figure 6. (a) ASTER thermal imagery over CordónCaulle volcano before and (b) after the Maule earthquake showing nosignificant change in thermal output. (c) Co-seismic interferogramshowing deformation at the eastern side of Cordillera Nevada Caldera.We believe that the adjacent subsidence signal is a tropospheric effectsince it does not appear in other interferograms spanning the sametime period. The black star indicates the location of the 2011 eruptivevent.



Temp (K)

350

295

290

280

270

260

285

275

265

a. 3 Mar 2008

Temp (K)

350

295

290

280

270

260

285

275

265

b. 2 Mar 2010

73.2˚W 73.1˚W 73˚W 72.9˚W 72.8˚W 73.2˚W 73.1˚W 73˚W 72.9˚W 72.8˚W

46.1˚S

46˚S

45.9˚S

45.8˚S

0 5 10

km

c. 14 Mar. 2009 - 3 Apr. 2010 (Envisat)

0

Contours of ground deformation

7 cm

46.1˚S

46˚S

45.9˚S

45.8˚S

d. 25 Jan. 2010-12 Jun 2010 (ALOS)

0 7 cm

Supplemental Figure 7. (a) ASTER thermal imagery over CerroHudson volcano before and (b) after the Maule earthquake showingno significant change in thermal output. (c) Co-seismic interferogramsshowing no observable ground deformation.



A’

A

a. 12 Feb 2007 − 17 Feb 2009

10 cm

Deformation contours

0

70.6˚W 70.4˚W

36.2˚S

36˚S

10 km

A’

A

c. 3 Feb 2010 − 21 Mar 2010

Deformation (cm)

−5 0 5

70.6˚W 70.4˚W

10 km

A’

A

d. 3 Feb 2010 − 22 Dec 2010

10 cm


0

70.6˚W 70.4˚W

10 km

A’

A

b. 16 Feb 2007 − 2 Mar 2010

10 cm


0

70.6˚W 70.4˚W

10 km

0 5 10 15 20 25 30 35 40 45−10

−5

0

5

10

15

20

25

Lin

e−

of−

sig

ht d

efo

rma

tion

ra

te (

cm/y

r)

Distance along profile A−A’ (km)

Laguna del Maule Deformation Profiles

12 Feb 2007 − 17 Feb 200916 Feb 2007 − 2 Mar 20103 Feb 2010 − 21 Mar 20103 Feb 2010 − 22 Dec 2010

Supplemental Figure 8. (a-b) Interferograms showing inflation atLaguna del Maule in the years preceding the 2010 Maule earthquake,(c) a 46-day interferogram showing no measurable co-seismic defor-mation, and (d) a 10 month interferogram showing continued inflationfollowing the earthquake. (e) Profiles A-A’ show that the inflation rateswere not affected by the earthquake. Though the 46-day interferogramprofile (red line) is relatively noisy, it shows no sign of co-seismic sub-sidence - over a 46-day period, a subsidence rate of >50 cm/yr wouldhave been detected assuming 20 cm/yr uplift and 10 cm of co-seismicsubsidence. There is no obvious change in the rate or pattern of defor-mation from the earthquake, although there is a suggestion that therate of deformation might be temporally variable.© 2013 Macmillan Publishers Limited. All rights reserved.


Fig

ure

9.Static

normal

stresschange

(∆σn )

fromthe

modeled

co-seismic

slipresolved

onoptim

allyoriented

extensionalstructuresat

2.5km

depth,overa30

by30

kmgrid.

The

strikeof

thesestructures

isorthogonal

tothe

minim

umprincipal

stressvector

(∆σ3 )

ateach

gridelem

ent.Maps

producedusing

thefollow

ingslip

models:

(a)Delouis

etal.(2010),(b)

Moreno

etal.(2012),(c)

Vigny

etal.(2011).



0 20 40 60 80 100 120−15

−10

−5

0

5

10

distance (km)

disp

lace

men

t (cm

)

East−West profile LOS displacements

data605040302010

Normal fault model LOS displacements (cm)dip=60o

50 100

50

100

−8−6−4−202

dip=50o

50 100

50

100

−8−6−4−202

dip=40o

50 100

50

100

−8−6−4−202

dip=30o

50 100

50

100

−8−6−4−202

dip=20o

50 100

50

100

−8−6−4−202

dip=10o

50 100

50

100

−8−6−4−202

A.

B.

Supplemental Figure 10. (a) Map view line-of-sight displacementsfor Okada model normal faults of various dips. (b) model displace-ments compared to measured displacements at Caldera de Atuel (froman interferogram covering spanning 2010/10/03 to 2008/02/10).



A.

B.

Supplemental Figure 11. (a) Map of vertical surface displace-ments resulting from a weak reservoir at 5.5km depth, embedded inaverage crust. (b) East-West profiles of vertical surface displacementfor reservoirs at various depths. As an end-member scenario, the pro-file for a void space embedded at 5.5km is also shown. Modeled relativedisplacements (<2cm) are consistently less than InSAR measurements.



-35.28 -35.28

-35.26 -35.26

-35.24 -35.24

-35.22 -35.22

-35.20 -35.20

-70.62

-70.62

-70.60

-70.60

-70.58

-70.58

-70.56

-70.56

-70.54

-70.54-35.28 -35.28

-35.26 -35.26

-35.24 -35.24

-35.22 -35.22

-35.20 -35.20

-70.62

-70.62

-70.60

-70.60

-70.58

-70.58

-70.56

-70.56

-70.54

-70.54

2 Feb 2010 7 Apr 2010

Temp (K)350

295

290

280

270

260

285

275

265

Temp (K)350

295

290

280

270

260

285

275

265

A.

B.

Nevados de Chillán

Planchón-Peteroa

-36.92 -36.92

-36.88 -36.88

-36.84 -36.84

-36.80 -36.80

-71.44

-71.44

-71.40

-71.40

-71.36

-71.36

-71.32

-71.32

Temp (K)350

295

290

280

270

260

285

275

265

12 Nov 2009

-36.92 -36.92

-36.88 -36.88

-36.84 -36.84

-36.80 -36.80

-71.44

-71.44

-71.40

-71.40

-71.36

-71.36

-71.32

-71.32

Temp (K)350

295

290

280

270

260

285

275

265

13 Mar 2010

Supplemental Figure 12. (a) ASTER thermal imagery over Neva-dos de Chillán volcano before and after the Maule earthquake. Sea-sonal variations are apparent between the two images. (b) ASTERthermal imagery over Planchón-Peteroa volcano before and after theMaule earthquake.



−1.00

−0.98

−0.96

−0.94

−0.92

−0.90

−0.88

−0.86

−0.84

−0.82

−0.80

NT

I (b

an

d 2

1)

25 30 35 40 45 50 55 60 65 70 75 80 85 90

Day (Julian, in 2010)

TinguiriricaCaldera del AtuelCerro AzulCalabozosNevados de Chillan

Supplemental Figure 13. Maximum MODIS nighttime NTI cal-culated using Band 21 over volcanoes that experienced co-seismic sub-sidence. Blue line denotes date of the Maule earthquake.



73˚W 72˚W 71˚W 70˚W 69˚W38˚S

37˚S

36˚S

35˚S

34˚S

100 km

Feb−11 Feb−16 Feb−21 Feb−26 Mar−03 Mar−08 Mar−13 Mar−186

6.5

7

7.5

8

8.5

906000003−4 RIO LAS LENAS ANTE JUNTA RIO CACHAPOAL

2010

�ow

(m3 /

s)

A.

B.

Supplemental Figure 14. (a) Streamflow station map. Orangecircles indicate stations for which we have data; blue circles indicateother stations whose data we were not able to access. Pink ellipseshows the approximate Maule earthquake rupture zone. Green circleindicates location of streamflow stations used by Mohr et al. (2012).(b) Stream discharge versus time for station 06000003-4 (northernmostorange station). Red line denotes time of the Maule earthquake.


subsidence at southern andes volcanoes induced...interferograms were power-spectrum ﬁltered using...

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