Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , and during 4 1 − ´ an s 3 Solid Earth Discussions to 0.02 m ´ 1 A. Reyes Davila − a, Universidad de Colima, s ı ´ ected by partial collapses. 3 , G. ff usion rate, interrupted inter- 3 ff , P. Lesage 1 2 1 as well as the seismic energy. By calibrating again in March 2011. In June 2011, magma ff 1 ´ ´ e de Savoie, CNRS, Le Bourget-du-Lac, France an de Colima, Mexico, started in 1998 and was − s 3 , U. Kueppers 2 , N. R. Varley 1 1,* This discussion paper is/has been under review for the journal Solid Earth (SE). Please refer to the corresponding final paper in SE if available. Centro Universitario de Estudios e Investigaciones en Vulcanolog Earth and Environmental Sciences, Ludwig-Maximilians-UniversityFacultad (LMU), de Munich, Ciencias, Germany University of Colima,Institut Colima, des Mexico Sciences de la Terre, Universit now at: Lancaster Environment Centre, Lancaster University, UK ume. Thus it is possible to calibrate the seismic records associated with the rockfalls the seismic signals using thefalls over volumes a estimated certain from period photographs, wasinvestigated. the Over used the to count course estimate of of the rock- the magmaserved measurement extrusion in period, flux number significant for changes of the were period rockfalls,extrusion ob- rockfall rate volume and was hence not averaged2010 constant: extrusion and it rate. dropped The increased down fromextrusion to had 0.008 0.008 m m come to aconstrain halt. the The methodology growth presented rateThere represents of a is domes reliable a tool that to good are correlation repeatedly between a thermal and seismic energies and rockfall vol- investigated. Larger events exhibitedvolume a of correlation a between rockfallface the and as previously well the estimated as surfaceWe the showed temperature that mean of for temperature the largermum of temperature freshly events, at rockfall the exposed the masses volume newly dome of formed distributed cli sur- the over rockfall the correlates slope. with the maxi- overflowing the crater rim, leadingno to significant the increase generation in dome of volumea rockfall was crucial events. perceivable This parameter and for meant the volcano that rate monitoringquantified of and magma via hazard ascent, measurements assessment, could of noapproaches the longer to dome’s be quantify dimensions. the Here,rockfalls magma we through ascent present the rate. alternative detailed We analysisual estimate of rockfall the events). sets The of volume relationship photographs of betweenexposed (before volume individual and and dome infrared after surface images individ- and of the the freshly seismic signals related to the rockfall events was then The most recent eruptive phasecharacterized of by Volc episodic dome growthmittently with by a explosive variable eruptions. e the Between dome November 2009 was and limited June to 2011, a growth lobe at on the western side where it had previously started Abstract 4 Quantification of magma ascent rate through rockfall monitoring at the growing/collapsing lava dome of Volc Solid Earth Discuss., 5, 1–39,www.solid-earth-discuss.net/5/1/2013/ 2013 doi:10.5194/sed-5-1-2013 © Author(s) 2013. CC Attribution 3.0 License. de Colima, Mexico S. B. Mueller D. B. Dingwell 1 2 3 Colima, Mexico * Received: 11 December 2012 – Accepted: 12Correspondence December to: 2012 S. – B. Published: Mueller 15 ([email protected]) JanuaryPublished 2013 by Copernicus Publications on behalf of the European Geosciences Union. 5 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | in 2008 ` ere Hills 1 − s erent orders ` ere Hills Vol- ff 3 ecting the rheo- usive (lava flows ff ff W (Fig. 1). The altitude 0 64 ◦ ) whereas it was low in 2001–2003 1 − N and 103 s 0 3 51 ◦ 5 m 4 3 (Ryan, 2010). The Mount St. Helens extrusion > 1 − s usive events formed summit domes with the first 3 ff ´ erences with the surrounding country rock. At high an de Colima has frequently varied: 1998–1999 and ´ an de Colima since 1998 has been followed by more ff ecting the cooling history and thereby the viscosity) and usion rate. Varley et al. (2010) studied in detail these ff ff ) (Varley et al., 2010). In comparison to other volcanoes, 1 − s ´ an de Colima has shown cyclicity over several di 3 1 m ´ an de Colima has been characterized by daily Vulcanian explosions < usion rate at Volc ff in 2004) and then gradually decreased to less than 1 m 1 − s 3 ´ an de Colima extrusion rate between 2007 and 2011 was unusually low: the ´ an de Colima is located in Mexico at 19 set from the centre (Fig. 2). Since 2003, Volc The magma e Many other lava domes have been observed to grow in cycles. At Soufri The behaviour of Volc ff logical properties). Degassing, cooling and compaction may lead to the formation of a 2 Dome growth and rockfalls Magma rises due toviscosities, buoyancy the di erupted magmalava tends flows, to leading remain to close smallthe to aspect interplay the of ratio ascent vent bodies. rate The rathermagma (a shape than properties of forming (composition, a bubble dome and is crystal controlled content, by each a acute explosive activity. In 2005,ing a series a of period larger Vulcanianevents with eruptions that took elevated occurred place e dur- betweenflows February were and produced from September column 2005;a collapse. preceding at Each swarm least eruption of event 30 low was magnitude pyroclastic characterized long-period by events. average magma extrusion rate at Soufriere2008 Hills dome Volcano, growth Montserrat, period during was 5.6 the m rate 2005– during the 2004–2008fast dome growth (6 m period describes(Smith, a 2011). typical dome that started as a result of2010). crystallization, Each pressurization eruptive event and at subsequent Volc explosions (Varley et al., showed cyclic behaviour (Barmin et al., 2002). 2004 were characterized byand a fast 2007–2011 rate ( ( the Volc 1922 (Rose, 1972). Also Mount Unzen, Japan, and Shiveluch volcano, Kamtchatka tween 2004 and 2008 (Smith etstudied al., at 2011). the Further Santiaguito periodic dome, dome Guatemala, growth behaviour which was has been continuously active since extent the southern and northerno rims. This is due to the growth within the cratercano being on Montserrat, Westthree Indies, and episodes four of years since growth 1995,2010). were when monitored A the to last detailed period last case ofVolcano between study activity was started of carried (Loughlin out the et both 2005–2008 al., case by dome of Ryan growth et cyclic al. dome cycle (2010) growth on and and Soufri collapse Loughlin was et observed al. at (2010). Mount Another St. Helens, USA, be- The most recent eruptive periodand started domes). in It 1998 and hasdome was started shown primarily growing a e in greathas early been variability 2007 characterized (Varley in by et exceptionally magma al., slowreached extrusion growth the 2010) rates crater and rates. throughout. rim stopped Once The it in the began current dome June to 2011. overflow mainly It down the western flank and to minor Volc of the dome duringThe the volcano observation is period locatedand January at is 2010 the characterized to by western calc-alkalineof June extreme the magma, 2011 of Riviera generated was the – as 3850 Cocos Trans m. a Plates – result beneath Mexican of the Volcanic the North Belt of subduction American magnitude Plate. of time. The lasta eruptive cycle period ended with of a Plinian quiescence,flank eruption lava discrete in flows 1913. e commencing After in 1961 and ending in 1962 (Luhr and Carmichael, 1980). active dome growth and hazard management associated with rockfalls specifically. 1 Introduction (a continuous monitoring tool) to improve both volcano monitoring at volcanoes with 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ) of a lava dome ◦ 38 ected, block-and-ash ∼ ff ) of low lava domes is not ◦ ´ an de Colima, can fluctuate usion rate. ff ´ an de Colima dome would not fit in any ´ an de Colima, pyroclastic flows in Octo- 6 5 ´ an de Colima during the last period (1998 on- c. At Volc ffi ected air tra ´ an de Colima though was from 2009 to 2011, during which the ff ´ an de Colima itself is shaped as a truncated cone that has filled ´ . After Blake (1990), who describes four kinds of domes (upheaved plugs, an de Colima dome has the typical dome slope angle ( ◦ Monitoring rockfalls is important because this can contribute to real time hazard as- Rockfalls can lead to many threatening situations to mankind or the environment. Domes can lose volume by Eq. (1) gravitational instabilities, Eq. (2) explosive erup- The dome of Volc The four dome growth episodes at Volc Dome growth can take place either endogenously or exogenously. Endogenous (Varley et al., 2010). At Merapi Volcano, Indonesia, continuous monitoring of dome rockfall activity at volcanoes correlates directly with the e Moran et al. (2008)occurred describe in May an 2006. unusuallycould The large possibly rockfall have rockfall resulted a at inber Mount an 2004 St. column travelled that Helens, asthat far rose which as large to 6.1 dome 6000 km m, collapses incano which would the (Sulpizio threaten La et many Lumbre of al., ravine.plosion the 2010). Simulations in ranches The have September that last shown surround 2005 major the and pyroclastic vol- marked flow was the generated end by of an the ex- 2004–2005 period of activity ties may change ascoarse a material response and/or entrainment to of the ambientof air morphology the will density along significantly current. increase the the path. mobility The deposition of sessment and help in examining the activity of a volcano. Increasing or decreasing tions or Eq. (3)the collapsing other. vesicles (Kennedy The et styleof al., with gravitational 2012). which instabilities Obviously, one material issure can is a trigger and transported function temperature away of distribution)collapses from the or and the growth collapses the dome conditions from volumefall in of slowly events. of case the Larger growing dome volumes dome domes or collapse.flows (pres- will if may Small be most larger generated. volume portions commonly If the of leaddome, collapse a pyroclastic event to flows takes dome rock- place will are from likely a an take active place. or Generally fast speaking, growing the transport proper- domes. On the otherat hand, Mount it St. doesn’t Helens; have alsodemonstrated. a the A typical typical typical flat spine low lava slope like domeIndies. angle the was (10–15 most the dome current at dome Soufriere de St. Vincent, West and was usually observed to be degas through the dome, which is typical for low lava dome. Volc mainly endogenous growth atgrowing Mount period St. at Helens, Volc USA.dome The was overflowing most the recent Western exogenously crater rim and a lobemost formed. of the summitcooled and crater crystallized (Fig. lava. 2).imately The Its 38 flanks carapace of the consistslava dome domes, of low exhibit variably lava a domes sized slope andof blocks coulees), the angle Volc of four, of typical approx- categories. It is positioned between the lava dome and the low lava and exogenous growth was2002) observed and during was the explained by 1991–1995 variations eruption in the (Kaneko rate et ofwards) al., extrusion. mainly took placescribed endogenously, partly by Major exogenously; a et similar al. situation (2009) is who de- describe the 2004–2008 lava spine extrusion and and more unstable domes;rockfalls and this makes can them more lead proneon to to collapse the the (Nakada, other 1996). generation Endogenous hand, growth, ofthe may block-and-ash chance increase of flows gas violent, or accumulation explosiveet eruptions within al., (Rose the et 1995). edifice, al., Activity thus 1977;between at enhancing Fink exogenous lobate et and domes, endogenous; al., this like 1990; was Nakada the1986 observed one Mount for example St. at during Helens Volc the dome 1980– study has growth been period carried (Fink out et at al., Unzen 1990). volcano, A Japan; similar, fluctuation more between recent endogenous potential leads to an increased risk of explosions. growth happens by magma intrudingtrusion into as the new dome surface interior, lobes exogenouslyimportant (Fink growth by et bearing ex- al., on volcanic 1990). hazard The issues. type Exogenous of growth dome usually growth builds may steeper have an dense plug with a greatly reduced permeability. The consequent reduction of degassing 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ´ on emission; 2 and the approx- ` ere Hills Volcano ff ´ eunion. Signals were ´ an de Colima: finding waves could not be dis- S and P 8 7 ` ere Hills lava dome was assessed for the pe- erent approaches: terrestrial photos, ground based ff ´ an de Colima during the recent activity were small, due to a very usion rate was larger. erent types of dome instabilities: those of purely gravitational nature ff ff usion rate and occurred up to 20 times a day within the monitored timeframe for ff Active domes have been investigated by seismic, Doppler – radar and photographic Feasibility and validity of using seismicity for detection, localization and size determi- Rockfalls at Volc More general studies regarding relations between rockfall properties and seismic- Several studies have recently investigated the characteristics of the seismicity gen- methods; e.g. the growthriod rate of of 2005–2008 Soufri usingLIDAR, ground four based di radar andfiles an (Ryan empirical et method al., usingmost photographs 2010). simple. of Only However, as dome the it pro- was photographicthe only method dome, possible was to systematic take errors used photos arose. regularly fromby Photo-based two being dome Sparks locations the monitoring around et was al. firsteruption carried at (1998), out Soufriere for Hills the Volcano. first episode of lava dome growth within the current low e this paper (March and Aprilobservation 2011). point The to section the ofwhich the West had dome of not observed the varied from volcano since2010, the has the when Play end a the of e diameter 2009. of Up approximately to 298 60 m, rockfalls a day were recorded in the beginning and the end of the extrusion. nation of rockfalls at Montserrat,al. Catalonia, (2008). Spain Rockfall has volume been was in describedthen a by first correlated Vilajosana instance to et obtained the by using seismicbeen a signals. laser done One scanner by and step Jongmans furtherimaging and to methods Garambois, laser for (2007) investigating scanner structures who methods of used has rockfall 2-D areas. and 3-D geophysical ried out during thea 2004 link andesitic between block seismic – signalvariations lava in duration extrusion the of at number rockfalls, Volc of energyal. rockfalls of (2008). and They explosions explosions compared and was it the temporal withthe field both rockfall of the appearance interest rate of of and Zobin magma subsequent discharge et disappearance and SO was found to clearly indicate duration determined using the seismic signals. A similar study to this was also car- 1995–1997 lava dome and both the frequency of occurrence of rockfalls and their envelope area, risetime and averageof ground rockslide velocity) and volume, runout used them distance,slope. for drop Norris an height, (1994) estimation studied potential Mount energy St.noes and Helens, in gradient Mount the of Adams Cascade and the Range Mountparameters and Rainier like characterized volca- source the volume, link source betweenrockfalls. materials, seismicity track and materials rockfall and failure modes for ity have been doneby by Calder various et others: al. a (2005), rockfall analysis describes at a Soufri link between changing rate of growth of the crater. A link between deflation ofrockfall the activity summit was dome, following found. cratering The floor fundamental collapse, feasibility rockslide and event and parametersal. validity has of (2011). also been using They described characterized seismicitysimple by the for Dammeier metrics estimat- seismic et (signal signals duration, of peak alpine value rockslides of by the taking ground five velocity envelope, velocity and gravitational instabilities immediately followed by explosions. erated by rockfalls. Hibert etfrequency) al. associated (2011), analysed with seismic rockfallscigar signals at shaped, (shape, Piton did duration and de not show latinguished. clear Their Fournaise, peak duration R amplitude varied and betweenranged 50 s between 2 and and more 10 than Hzon 200 and s; four was short frequency centred usually period at stations 5 Hz. located Rockfall between signals 600 m were and registered 2100 m from the centre of the the dome activity status iscrowave crucial Doppler for system hazard which mitigation. iscoverage. Hort They not et determined hampered al. by both (2005), weatherimate set the conditions up amount velocity a such of of mi- as material material cloud described passing breaking two through o di the radar beam. As a result, these authors activity has been carried out since 2001. Due to its proximity to the City of Yogyakarta, 5 5 25 20 10 15 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ´ ambula ´ an de Col- usion rates ff erent dome pro- ff ´ an de Colima by Ar erent; since growth of the dome essen- ff 9 10 cient. The network consists of four short-period ffi ´ an de Colima was di ´ an de Colima ´ an de Colima can be readily identified by their seismic signal; sur- ´ an de Colima for this period mainly contained LP’s, tremor, explosion ´ an de Colima Volcano Tectonic (VT) swarms, Long Period (LP) events 5 Hz) (Shearer, 2009). For accurate rockfall monitoring at Volc > ´ an de Colima, thermal images are obtained from flights, handheld ground- usive eruption; however, during and after the eruption the seismicity changed ff erent approach to determine the magma extrusion rate had to be developed. A ff At Volc A seismic signal study has already been carried out at Volc Beneath Volc Rockfalls at Volc The situation at Volc based observations and temporary fixed stations. These images are not only used for Thermography is applicable fortemperatures many related monitoring to problems: degassinglies the and/or spatial eruptive in activity distribution time or of series;(Hutchinson the and et detection they of al., can anoma- 2012;more be intense Calvari used magmatic et for activity; al.,commonly deriving an observed 2007). increase heat prior Higher of to fluxes gas eruptions fumarolesal., and or 1986). flux gas e shallow temperature is magma has usually intrusions been (e.g. caused Menyailov by et signals, rockfalls or pyroclastic flowsclearly and few identifiable lahars. seismic Rockfall waveform signals15. and always showed had a a high frequency range between 1 and 4 Thermography used in volcano monitoring broadband sensor is using a 24a bit A/D sampling converter frequency and of digital transmission. 100rockfalls Hz. Signals originated have During at the the visualdence same observation of location period the from of seismic the this signal dome. was study, Accordingly, all considered the minor path and depen- et not taken al. into (2011). consideration. They investigateding the cross 2004–2005 correlation period of of LP’smic large and activity autoregressive eruptive at analysis activity, Volc includ- of monochromatic LP’s. Seis- frequency ( ima the seismic network RESCO isand su four broadband stations.closest The signals station of to the thetelemetered EZV4 to volcano station the (1.9 were km observatory used, from and it digitized the being with crater). the a The 16 bit short-period A/D signals converter, are whereas the duration seismic waveform. They can last up to several minutes and have a high peak face processes at volcanoesduce in seismic general, signals like that lahars, typically show pyroclastic a flows slowly or increasing rockfalls and pro- then decreasing, long and Hybrids have been detected.1999 VT e swarms were mainlyto detected LP prior and to Hybrid thetypes 1998– events of (Zobin signals et dominated: al., tremor,LP 2002). which events, During sometimes larger the was magnitude recent harmonic,(Varley isolated eruptive small et LP episode, magnitude events four al., or 2010),Chouet, LP similar 1997) events and to with explosion a tornillos quakes. diminishing which coda are defined for Galeras (Gil Cruz and et al. (2005), examinedSoufriere rockfall frequencies Hills during Volcano, an Montserratcorrelating andesite and with lava described log dome logistic repose eruption survivor intervalssignals at distributions. has between A not detailed rockfalls been seismic included analysis in of this rockfall paper. to removal of material through rockfalls. 3 Seismicity at Volc In general, limited work on rockfall(Hibert seismicity has et been done. al., Much 2011; of2012) Dammeier the previous deals et work mainly al., with 2011;Even the DeRoin less seismic and work analysis McNutt, has of 2012; DeRoin been rockfall or et done block-and-ash al., on flow the events. analyses of the frequency of rockfalls, Calder tially stopped after Novemberand 2009, magma input when into the thea dome dome was di reached immediately compensated the inphotographic western the form method crater of is rockfalls, rim stillfiles, applicable, but by though examination not of by dome images correlating showing di variation of the surface features due 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | (1) ´ an de ´ an de Colima the line between b along the y-axis can be h ected by the sun position ff ´ an de Colima was conducted in 2010 and 12 11 ´ an de Colima since 2004 (Stevenson and Var- , estimated from photos from flights obtained at ◦ 3 ± as shown in Fig. 4a and b. The thick, black line on the ◦ l can be calculated as follows: 38 l , = h γ . (2) 2300 1050 ) γ = − σ h σ ( being the line between observer and the top of the rock, sin a = and tan ´ on, the relatively flat floor of a collapse caldera (Figs. 1 and 2), about 2.3 km δ β h ≈ sin β A Nikon D90 SLR (single lens reflex camera) with a resolution of 12.2 megapixels In order to calculate the volume of a block on the dome, one needs to define three is the real length of the rock, but what is measured using the photos taken before and = s a same gradient as the domeare angular slope. due Rocks to on dome thel growth dome and cooling carapace processes. of Figure Volc after 4 is shows the the apparent geometry; length l dome represents the block inallel; question. with Lines a andobserver b and (Fig. the 4b) are bottoman approximately of average par- the slope angle rock. of Thethe rock same itself altitude as is the part dome. of As the rocks dome are surface supposed with to be cuboids, they show the ent; axis z is perpendicularrocks to are the assumed surface to of the havethe slope an x-axis (Fig. ideal 4). could cuboid For be shapeviewer further with simply and calculations, 6 rock measured faces. did because The notsurement the true influence of length the geometrical it. length along The line along linedome the of of y-axis. was sight The sight 2300 horizontal between did, m; distance however, betweenview the influence observer had vertical the and to mea- be distance taken wasused into to 1050 consideration. m. calculate The the Therefore apparent true length the length oblique angle of and a 300 mm lens wasblocks larger used. than The 20 raw cm photos to bein were easily digitally question recognized sharpened, were and which defined. marked Where allowed on possible, the the rocks before and after picturesorthogonal (Fig. axes 3). (Fig. 4c): axis y is parallel to the slope; x is perpendicular to the gradi- events for this study. The volume of individual rockfall eventshigh-resolution was photos estimated through of a the comparisonblocks dome of or sets before entire of and dome after sectionsbeen (Fig. that removed 3). during were The an quantifiable event. goal indaylight. For was size obvious Additionally, before to reasons, the a identify this rockfall image techniquebehind and only the quality had works volcano was during (morning) negativelydegassing and conditions. a reduced As visibility a due consequence, to we meteorological used or the volcano data of 23 out of 86 recorded to April 2011. Observationsthe were made Play from a basefrom the to crater. the west of the volcano, within 5.1 Direct observation decrease in the explosivitythermal images of were the used to volcanoColima. investigate the (Varley thermal and signature Reyes, of rockfalls 2013). at Volc For this study, 5 Methodology A field campaign to monitor2011. rockfalls This at paper Volc presents data of a total of 86 rockfall events, from the period March the thermal gradient ofmonitored ash from plumes. a Fumaroles fixed onley, location the 2008). at crater Trends Volc like rim a havegence sharp been of routinely drop a in lavaof fumarole dome fumarole heat in temperatures fluxes the coincided between with summit January the crater 2006 emer- in and 2007. August Also 2007 a coincided with general, a long term drop rockfall monitoring, but also for thermal surveys of growing domes, fumaroles or for 5 5 25 15 20 10 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | er- 480 ff × C. C2 ◦ C hotter than the ◦ erence of 199.3 ff C. Furthermore, for every rockfall ◦ GmbH (Germany) with a 640 ) as each pixel had the dimensions 0 C whilst the rocks were within the re- ® 2 ◦ = T ∆ 14 13 1.3) (3) = ρ ( z C after the rockfall, giving a di ◦ 3.02 = ). Results were obtained for all 86 rockfalls events within the y 2 . Finally the length of the block along the z-axis, normal to the dome ◦ 0.9) and C before and 305 of the exposed face and the mean temperature of the rockfall masses, = ◦ T ρ ( ; those events were noted with a ∆ z 4.5 m (20.25 m T being Standard Deviation SD. These ratios provide an alternative method to being 27 × ∆ ρ δ 2.11 Figure 5 shows a series of three images of the dome (a) prior to, (b) during and (c) By correlating the estimated rockfall volume derived from the photographic images Here we demonstrate the approach for defining the temperature of the exposed face. Every rockfall exposed a new surface with a specific mean and maximum tempera- The camera was set up at the observation site, where it recorded an image of the Taking the average values of the axes of the rocks in the photos, the following empir- = ing each rockfall event. This created a barrier reducing measured temperatures. The after the rockfall event. Onwhere the the images exposed are face two willslope, circles, be where C1 generated the and during rockfall C2; will therefers C1 pass rockfall, to marks during C2 the the the marks pixel event. spot a withit The the spot was maximum maximum on 105.7 temperature temperature the for within C1 shows the a maximum circle temperature C1 of and moregion. than in In 400 this picture (b), case C1which and occured C2 show due relatively to low a temperatures combination due to of ash impacts generation on the slope and from the dome dur- it was possible tovolume solely obtain by a using relationship thermal images which in could the end. beThe used rockfall to event estimate of(21:07 8 the and March rockfall 21:11 2011 GMT) will between be 15:07 used and as 15:11 an example. Colima Standard Time ence the number of pixels ating elevated temperatures thermal on image the could slope beThe of quantified mean the by a temperatures volcano pixel in of precise the the edgingin result- analyzed of mass Irbis the distributed and areas on compared of the to interest. when slope the the were estimated calculated hottest volumes. pixels The where mean revealed temperatures on where the taken slope. with the mal images were analysed with the software IRBIS Professional fromture; InfraTec large GmbH. volume rockfallslocal produced pre-rockfall pixel dome temperatures exterior. up Inof contrast, to only in 200 a the few case cubic meters) of it very was small not rockfalls always (volume possible to constrain a temperature di stated are the average temperatures within the pixels of the infrared image. The ther- area on the domerockfall surface masses after spread a over rockfall the and to volcano investigate slope. the It mean should temperature be of noted that temperatures For thermal imagery, a VarioCam hrarray from was InfraTec used inysis this of study. Based the on entireof the visible 4.5 distance, dome this surface (28 allowedobservation 000 for m period. a detailed anal- dome every two seconds continuously, leadingfall to during an the excellent 12 database for field every days. rock- The thermal images were used for analysing the exposed of each individual z-axis.calculation The of rock all volumefrom three the was lengths observation estimated base and based in using the upon West) the as the known a5.2 resulting scale. dome diameter Thermal (298 imagery m viewed ical relationships were found: x with estimate the lengthnear-vertical of face the that z-axis.scaling was For this generated calculating face with during the the the volume ratios of of rockfall the was individual axes measured gives blocks, us a if the possible; most accurate possible length surface and in somebe cases determined. hard to Photos detect fromcould in flights be the were seen. pictures evaluated, We takenThe when found from length all that Playon pointing three the needs downwards along length axes to axis of along y the the is z-axis rocks always the is longest always one. the shortest one. with 5 5 25 15 20 10 20 25 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 0 0 T T E E (6) (4) (5) ∆ and volume T ∆ at the NW edge ff (Fig. 9) meaning that vs. mean temperature and pseudo – energy V V V and 0 E ´ an de Colima. cult due to strong ash generation. A ffi at Volc 16 15 V 0.88, Fig. 6): = 2 was estimated for the signals associated with 15 rockfalls. A R 0 0.85; Fig. 7) was observed with the exception of two events. The (Lesage, 2009). Figure 8 shows a typical seismic rockfall signal E in arbitrary units of the seismic network. This analysis was only 0 = 2 E R erences of the exposed dome area before and after each rockfall were ff and 0 3 E T 7 T ∆ − volcanalysis in m ´ an de Colima together with its spectrogram. ) yields the result ( V 3 1.21 1.25 0.84 The correlation between estimated volume of rockfalls The ratio between volume and mean temperature of rockfall traces has been calcu- Because rockfall signals are complex, it is not possible to calculate precisely the In Fig. 5c, the hot trace of the rockfall moving down the slope can be seen. The ther- = = = (m with possible for rockfalls without simultaneous eruptive or ash-venting events. The proxy of energy remarkably good correlation was observedcan between be used to estimate rockfall volume gives the following empirical relationship: V V Using this relationship, an estimation ofon the thermal volume images. of rockfalls is possible based solely 5.5 Comparison between rockfall volume and seismic energy outlier (a) represents ait rockfall started that occurred in an shortly areatemperatures. after of The another the large second dome rockfall. outlier withof Thus (b) lava the exposed marks that dome a is wherecooled hotter rockfall rockfall over than that a activity average broke more surface was substantial o low time. and accordingly thelated and involved the blocks following had relationship has been found: volume of theof event. 15 Figure rockfall 7 events. Onlybecause shows 15 the of estimated 8 remaining the volume rockfalls total weremeasurement 23 associated of with estimated an rockfalls the explosive were event; meannew easily in temperature correlation this compared case ( was di The mean temperature of the rockfall mass on the slope correlated very well with the V 5.4 Comparison between the rockfall volumeThe and thermal volume monitoring estimated fromvalues of the the photographs exposed wasmasses face compared distributed on with the over the dome theV and measured slope. to A the first mean order temperature correlation of between the rockfall of Volc corresponding energy release. Thus wesum used of the the integral squares of of theenergy the samples squared release. multiplied signal, by Analysis or the and the samplingSeismo interval, calculations as were a proxy carried of the out with the Matlab package 5.3 Energy of associated seismic signals The seismic investigation offact that rockfalls, however, some brought rockfallsrockfall occur an and together additional with eruption challenge: small signalsvolume the eruptive were estimated events. superimposed. using In these pairs 15with cases of an out the eruption, photographs, of allowing however, the straightforward occurred analysis 23 not of the events simultaneously seismic with signal. their then correlated to volume of rockfalls estimated from the photographicmal pairs emission from (Fig. hot 6). rocks rollingmean down the temperatures slope of was the measured asto analyzed a the rockfall time rockfall traces series. volume The in (Fig. Irbis 7), were as estimated then from again photographs. compared temperature di 5 5 25 20 15 10 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | C, their ◦ . As shown 1 − s in 2010 with an 3 of pure rockfalls 0 1 − C, the hottest tem- cient, though more E C and 100 ◦ s ◦ ffi 3 giving an average magma C. The volume of five large 3 ◦ and 0.014 m ; the average volume of this ◦ 1 − s erences in frequency content be- 3 and 0.019 m ff . These events are relatively rare. 1 3 − s 3 18 17 erence was 20 ff per rockfall. The three categories were: small, 3 ) has been established; taking the error of 31 % (see 1 − were estimated for March 2011 events. After analysing h . The volume of 12 medium events was estimated and . In comparison, taking the mean volume of all 23 calcu- 0 3 3 . 1 3 E − s 3 proved to be much more accurate and e ´ an de Colima started overflowing the western crater rim in . 0 3 ) instead of classifying them by size, the magma extrusion rate 3 E or 90 % greater. For the year 2010, an average magma extrusion (40.68 m 3 1 − s erence of these events usually was between 20 3 ff erence measured for the 23 rockfalls was 200 ff of the seismic signal was calculated, which as discussed, is related to the 0 E at the exposed face of these events is always more than 100 For the second and more accurate method of extrusion rate calculation, rockfalls oc- Taking July 2010 as an example, there were in total 897 rockfall events recorded. 591 Large rockfalls can last for at least 5 min and the seismograms can reach saturation. The first step in this approach was evaluating the seismic records of each day in Medium rockfalls were defined by duration (less than 3 min) and an amplitude be- For the first method, the average volumes of rockfalls for the three classes were Two approaches for constraining the magma extrusion rate were employed using the T explosion signal prevents an estimationvalue of the volume. The integratedenergy velocity squared of the rockfall.with In explosions, an the duration attempt of tospectrogram the include of rockfalls was the a considered. seismic consideration Employingtween signals of the explosion and frequency rockfalls and by rockfall coinciding allowed using afor di precise the determination majority of the of durationshowed superimposed parameter only events. a Plotting moderate duration correlation against (Fig. 12). discussion) into account, it rangesin between Fig. 0.008 11, m theinitial variation increase was in February between followed 0.008 by m a general decline. curring during an eruption have been excluded as the superposition of the rockfall and events was estimated, giving an average of 147 m of them were oftotal the volume small of magma type, extruded 222 inextrusion medium July rate 2010 and of was 84 0.010 27 m 000 oflated m the events (56.59 large m rockfall type.resulted So at 0.019 the m rate of 0.011 m volume was less thanthe 100 average m value was 43 m ∆ perature di temperature di tween 33 % and 66 % of the maximum from the seismic signal. The exposed face 2010 to obtain thesmall total rockfalls number usually ofthe is rockfalls saturation less that threshold than yearestimated of one (Fig. amongst the minute the 10). seismic photographic and The events.from signal. the Clearly duration the The estimating amplitude photographs of missing volume is is the rockmaximum far of volumes about exposed less six 33 accurate face % small for temperaturerockfall of small events di type volumes. was was For 8.7 m those six events the assigned while counting theestimated volumes number resulted of in rockfallsmedium 56.6 m per and day. large. Taking Avolumes the volume from mean the was of photographs. assignedsmall It all to volume needs 23 when each to compared type be to based emphasized other volcanoes that upon with all the higher rockfalls rates estimated were of of extrusion. a calibrated seismic data. In theinto first, three rockfalls classes depending for upon the the wholeindividual associated year level seismic of of energies seismic 2010 signal. were Inand classified the comparing second, the results ofual the seismic two methods, energies unsurprisingly thetime estimation consuming. of individ- After the domeNovember at 2009, Volc no significantrockfalls increase generated at in the volume lobeto was between be perceivable. November equivalent For 2009 in and this their June volume reason, to 2011 represent are the assumed total extrusion of magma. 5.6 Magma extrusion rate 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | (7) ´ an de cient and ffi ects the re- ff 1 mm of measured rock ± for the slope angle, 1 mm ◦ value of 0.8; for this analysis, 2 R error of dome slope angle produces ◦ 3 ected by this correlation coe ± ff of rockfall volume generated during an . There were 701 rockfalls in March 2011, ´ 0 an de Colima during March 2011 was es- (0.8, Fig. 13) is worse. However, only 5 % 3 E 2 erent parts of the dome; the manually mea- 20 19 ff R . This result agrees reasonably with the result 1 − s 3 0.0027 m is high; it is assumed that there are no significant systematic ± 2 1 − R s . Also observations, both in the field and of the seismicity, showed . The total magma extrusion rate can be divided between 1 3 3 − s cient 3 ffi 7000 m for isolated rockfalls and 1000 m D ± 3 3 usive activity gradually decreased after November 2010 until it finally stopped in ff 0.1 21 Calculations using correlations can be assumed to have a minimal error when the Volume estimation from photographs and subsequent magma extrusion rate calcu- Applying Eq. (4) and Eq. (5), the total magma extruded in March 2011 was After applying Eq. (4), Eq. (5) results, which allowed the constraint of the volume of = applying the Volcanalysis script. For explosion related rockfalls the volume – duration of the total extruded volume inthus March the 2011 overall is impact a shouldenergy be estimations: minimal. seismic Finally, errors rockfallminimal arise signals due errors are to regarding picked uncertainties manually, thesulting on hence picked energy. there The and can Highpass true be filterbut length removes it of background can’t rockfalls noise be which (mainlyerage regarded a oceanic as error noise) a of filter 16estimations. % which After deletes is everything application assumed except and here ofmum consideration and rockfalls. possible of An has error all av- been of possible added 35 error % to sources, in the a the photographic maxi- magma error extrusion rate has been determined when we get 31 %. correlation coe errors. In the caseand explosion) of with estimating the rockfall seismic records, volume from superimposed events (rockfall and took into accounterror that is rocks the are minimum usually rock notrock size all of detectable, parallelepiped. these which A is dimensions furthersmall estimated is source rocks, to still of be the quite 20 impact cm. small,for on However, and the a the volume even volume estiamted considering estimation fromlengths a would translates photographs large to be is an number negligible. the average of error12 The following: %, of final the 25 %; minimum error detectable rockrocks size to might be lead a to cuboid a results further in 3 % an error error and of assuming 13 %. Then calculating the root mean square lations include some inherent error:due to possible a error large sources variation aresured of the rock the dome slope dimensions slope on angle, fromcuboids. di For photographs; our or calculations, the(20 cm we assumption true assumed of length) an for rocks error the being of length perfect 3 of individual rock axes (in the zoomed photograph) recorded visually, 23 werecomparison with suitable other for measured parameters. volume estimates; these were then used for 5.7 Discussion Rockfalls occur frequently during lavaColima emplacement the at number active volcanoes; andand at June magnitude 2011 Volc when increased the significantly summitan dome between estimation overflowed the November of western 2009 craterAt rockfall rim. the In volume this outset study, through wequirement photographic note of observation thermal that images whereas was currently seismic performed. requires stations operator are intervention. running Of constantly, 86 the rockfalls ac- timated at 0.0078 m shown in Fig. 11,2010 at where 0.009 the m magmathat extrusion e rate showsJune a 2011. decrease at the end of eruption, the duration was used togiving estimate an average of 23day per were day. During observed, the a nine reducedout field number the days since an night. observation average was of not 11 carried rockfalls a out through- 21 000 m 20 000 m explosion. The magma extrusion rate at Volc eruption related rockfalls using their duration: V The plot of volumenine days versus of duration observation in resulted March in 2011 an were used. When rockfalls occurred during an 5 5 25 15 20 10 20 25 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | u- ff erent ´ ´ an de an de ff . The relationship 0 ´ ee et al. (2012). In E for March 2011 and a (Ryan et al., 2010), the 1 − usion rate would lead to 1 s ff − 3 s 3 erent e 0.9 m is dependent on volcano-specific ff 0 ± 0.0027 m E ± erent flanks would introduce further com- ff 22 21 usion rates for the 2005–2007 active dome growth ff for February 2010 have been constrained. This result erent magma properties (volatile-contents, tempera- ff 1 − s 3 ´ an de Colima because 0.007 m ´ an de Colima. In particular the correlation between seismicity and ± erent relative position within theerent summit characteristics because crater, the of recorded new parameters seismicity (slope would gradient, have distance to EZV4 erent dome growth characteristics and hence variation in the generation of rockfalls. The relationship between pseudo–energy and volume of rockfalls has, in a di The methodology developed in this study could be used for future periods of e Of course photographic methods for dome monitoring have already been used (e.g. For estimating rockfall volumes over long periods the continuous seismic data stream ff ff ff ters (thermal and seismic data)ume was shown once and calibrated proven by suitable using to a estimate number rockfall vol- of direct estimates from photographic images. 6 Conclusions We propose a methodologythe for magma the extrusion detailed rate monitoringColima of of illustrates volcanoes that rockfall with if volume active dome to domes. growthin is estimate yielding The limited the example to extrusion of rockfalls, rate. the Volc tographic Rockfall method images volume alone before itself succeeds and was after obtained the from comparing events. The pho- relationship with two other parame- to freshly calibrate the associatedColima, seismic almost signal. all During rockfalls late descendedpath. 2009–2011 the Rockfalls at descending western Volc a flank volcanoplications following on for an interpretation di almost of identical theright seismicity. circumstances, But the with presented careful methodology calibration could and prove suitable. under the method at Colima requireswhich produces a small decentralized rockfalls slow ondi growing the dome western flank in ofdi the the summit volcano. If crater theseismic dome station). has Furthermore, a di ture, chemical composition, crystal-contents)di or a di If direct observation is possible, further rockfall volume estimation could be performed parameters such as domeslope slope angle, angle density and of thetechnique rock material, distance itself run-out between is distance seismicvided applicable and station a for calibration and other is dome.if obtained volcanoes Nevertheless, rockfalls in exhibiting were the each to similar case. occur A phenomena in further more pro- than complication one would direction. be The inherent applicability for the presented volume is limited to Volc sive activity at Volc period at Soufriere Hills, theabsolute extrusion rate error was was 5.6 much larger. way, also been described byseismic Hibert and et al. potential (2011). energywith By in experimental studying work granular the on connection flowtimating moving between and granular rockfall combining flows, volumes they an atmethod defined analytical Piton could a approach de be methodology used la for for Fournaise, es- real-time Reunion. rockfall volume They monitoring also at active suggest volcanoes. their which represented the onlyRyan et new al. material (2010) beingto estimated emplaced. be their noted Sparks error that etthan in they al. our volume concentrate presented (1998) calculations on three to and domethey dimensional be were profile calculations observing 15 lines %, on much which two but larger e dimensional can it images. be has Since more accurate a final minimum magma extrusion ratemaximum of of 0.019 0.0078 fits very well withMarch observations 2011 of the rate the decreased period and 2007–2010 finally reached by zero Lavall inat June Soufriere 2011. Hills;changes Sparks in et the dome al., profileconditions was 1998; monitored. permitted In Ryan an our et unprecedented study, the opportunity al., extraordinary observation to 2010), look however, in in detail these at small cases rockfalls, between rockfall volume andor the the thermal material emission onsources. of the flank either was the less exposed precise, dome and face canis easily available. With contain the additional relations error between rockfall volume, duration and pseudo – energy, relation is useful, although less precise than the estimation using 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , ´ avila, G., and doi:10.1130/2010.2464(12) , 2010. ` , 2005. ere Hills Volcano, Montserrat, usion rates using thermal infrared ff usive and explosive eruptions during ff 24 23 , 2011. showed an astonishingly good correlation coef- ´ ez-Gonzales, C., Varley, N. R., Reyes-D V doi:10.1029/2009JB006478 doi:10.1029/2005GL023594 ´ an de Colima, Mexico, J. Volcanol. Geoth. Res., 205, 30–46, as, J. L., Navarro-Ochoa, C., Komorowski, J. C., Saucedo, R., ı ´ , 2011. ke, A., Cristaldi, A., Harris, A. J. L., Spampinato, L., and Boschi, ff ´ an de Colima. Seismic monitoring can thus be used as a powerful We thank all the CIIV interns who helped in the data collection needed ´ es, J. A., Palma, J. L., and Luckett, R.: Probalistic analysis of rockfall fre- ˜ no, V. H., Mac doi:10.1029/2011JF002038 and the rockfall volume 0 ´ eunion Island: From seismic signals to rockfall characteristics, J. Geophys. Res., ¨ oge, M., Seyfried, R., and Ratdomopurbo, A.: In situ observation of dome instabilities ´ an de Colima (Mexico) Lava Dome from 2007 to 2010, Remote sensing of volcanoes E ´ es, A., Gardu usion rate at Volc ´ 116, F04032, at Merapi Volcano, Indonesia: a new301–312, tool 2006. for hazard mitigation, J. Volcanol. Geoth. Res., 153, the Volc J. Volcanol. Geoth. Res., 77, 121–158, 1997. crater, R Helens lava dome, Nature, 348, 435–437, 1990. nying the emplacement and extrusion of a lava dome in Galeras Volcano, Colombia in 1991, Res., 211–212, 61–75, 2012. occurring during the 2006213–214, eruption 14–26, of 2012. Augustine Volcano, Alaska, J. Volcanol. Geoth. Res., slides usingdoi:10.1029/2011JF002037 statistical analysis ofprecursors and seismic seasonal signals, factors on Geophys. occurrence patterns Res., 1997–2009, J. 116, Volcanol. Geoth. F04024, E.: The 2007 Stromboli eruption:data, event Geophys. chronology Res., and 115, e B04201, and Gavilanes, J. C.: Geologiccations mapping for of hazard the assessment, Colima Geol.2010. S. volcanic Am. complex S., (Mexico) 464, and 249–264, impli- quencies during an andesiteGeophys. Res. lava Lett., dome 32, eruption: L16309, The Soufri J. H. and Wagner, G., Berlin, Springer, 88–126, 1990. Sparks, R. S. J.,Hills and Volcano, Young, Montserrat, S. Geophys. R.: Res. Mobility Lett., of 26, pyroclastic 537–540, 1999. flows and surges at the Soufriere Navarro, C.: Seismic activity thatthe accompagnied 2004–2005 the period e at2011. Volc Planet. Sc. Lett., 199, 173–184, 2002. ambula-Mendoza, R., Lesage, P., Vald ff Hutchinson, W., Varley, N., Pyle, D. M., and Mather, T. A.: Airborne Thermal Remote Sensing of Hibert, C., Mangeney, A., Grandjean, G., and Shapiro, N. M.: SlopeHort, M., instabilities V in Dolomieu Gil Cruz, F. and Chouet, B. A.: Long-period events, the most characteristic seismicity accompa- Fink, J. H., Malin, M., and Anderson, S. W.: Intrusive and extrusive growth of the Mount St. DeRoin, N., McNutt, S. R., Sentman, D. D., and Reyes, C.: Seismicity of block and ash flows DeRoin, N. and McNutt, S. R.: Rockfalls at Augustine Volcano, Alaska: The influence of eruption Dammeier, F., Moore, J. R., Haslinger, F., Loew, S.: Characterization of alpine rock- Calvari, S., Lodato, L., Ste Cort Calder, E. S., Cort Blake, S.: Viscoplastic models of lava domes, 1990, in: LavaCalder, flows E. and S., domes, Cole, edited by: P. D., Fink, Dade, W. B., Druitt, T. H., Hoblitt, R. P., Huppert, H. E., Ritchie, L., Barmin, A., Melnik, O., and Sparks, R. S. J.: Periodic behavior in lava dome eruptions, Earth. Ar cellent) and the(247076). EVOKES advanced researcher grant of the EuropeanReferences Research Council ficient (0.92). For this reason,e seismic signals have beentool used to for estimate extrusion the rate magma these monitoring methods be of considered certain for risk erupting assessment volcanoes. atAcknowledgements. We dome-building recommend eruptive centres. that for this study, particularly Magret668/10 Damaschke. and Varley was 768/11. supported by UdeCDingwell FRABA was projects supported by a research professorship of the Bundesexzellenzinitiative (LMUex- posed face on the domethe slope directly of after the the volcano. A rockfallmean better or rockfall correlation slope the was temperature. mean obtained The between rockfall secondused the temperature and volume to more on and important estimate the relationship rockfall thatbetween volumes was was that with the seismic signals. The relationship The thermal emission recorded was either the mean temperature at the freshly ex- 5 5 30 25 20 15 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ` ere Hills Volcano, Montserrat, West 26 25 ´ e ardent eruption from the foot of a dacite lava flow, ´ es, M. A., Hedlin, M. A. H., Bowers, D., Scott, W. ¨ uengoitia, M. A., Hess, K. U., Kueppers, U., Mueller, S., , 1986. en, H., and Meredith, P. G.: Evolution of the mechanics of the ff , 2010. , 2010. , 2008. ´ an de Colima, Mexico, B. Volcanol., 74, 249–260, 2012. ´ an de Colima, Mexico, J. Volcanol. Geoth. Res., 191, 149–166, 2010. as, J. L., Gavilanes, J. C., Arce, J. L., Komorowski, J. C., Gardener, J. E., and ı ´ ´ e de France, 178, 101–112, 2007. ´ ´ ´ et ez-Moreno, G.: Eyewitness, stratigraphy, chemistry, and eruptive dynamics of the 1913 an de Colima, Mexico, 2006–2007, J. Volcanol. Geoth. Res., 177, 911–924, 2008. ´ ee, Y., Varley, N., Alatorre-Ibarg A., Druitt, T. H.,Skerrit, Harford, C., G., Herd, Stasiuk, R., M.production James, M., V., and Stevens, Lejeune, growth N. A.Indies: of M., S., November the Loughlin, 1995 Toothill, to S., lava J., December Norton, dome Wadge, 1997, G., G., of Geophys. Res. and the Lett., Watts,Volc 25, Soufri 3421–3424, R.: 1998. Magma cameras, Earth-Sci. Rev., 106, 63–91, 2011. 2004–2008 Mt. St. Helens lava dome191–200, with 2011. time and temperature, Earth Planet Sci. Lett., 307, doi:10.1029/JB091iB12p12199 E., Sherrod, D. R., and Vallance, J. W.: Seismic and acoustic recordings of an unusu- Vald Plinian eruption of Volc (ocean-island basalt type) and calc-alkalicplume-related volcanism in magmatism the and Mexican propagating volcanic1999. belt: rifting A at case an for active margin, Geology, 27, 51–54, and chemical change1985: of Are fumarolic gases these at indicators Momotombo of Volcano, Nicaragua, a in: possible 1982– eruption?, J. Geophys. Res., 91, 199–214, Strutt, M. H.,Hills and Wadge, Volcano, G.: Montserrat,doi:10.1029/2009GL041477 Growth West of Indies: the lava 2005–2008, dome Geophys. and Res. extrusion rates Lett., at 37, Soufriere L00E08, Santiaguite Volcano Guatemala, B. Volcanol., 40, 53–70, 1977. 343–372, 1980. the 2004–2008 Mount St.phy, Earth Helens, Planet Washington, Sci. eruption Lett., using 286, oblique 243–254, 2009. terrestrial photogra- dome at Unzen Volcano (Japan), Geology, 23, 157–160, 1995. plications for seismic detection of1925–1939, hazardous 1994. mass movements, Bull. Seismol. Soc. Am., 84, Guatemala, B. Volcanol., 36, 73–94, 1972. doi:10.1029/2010GL042547 (in Japanese with English abstract), Mem. Geol. Soc. Jpn., 46, 139–148, 1996. building eruptions at Volc Geosci., 35, 2137–2144, 2009. L., andat Strutt, Soufriere M.: Hills An Volcano, overview Montserrat, of 2005–2007, lava Geophys. dome Res. evolution, Lett., dome 37, collapse L00E16, and cyclicity ally large rockfalldoi:10.1029/2008GL035176 at Mount St. Helens, Washington, Geophys. Res. Lett., 35, L19302, formation of volcanic plugs and domes by collapsing foam,Richard, COV Abstract, D., 2012. Scheu, B., Spieler, O., and Dingwell, D. B.: Magmatic architecture of dome- lava dome examined by satellite infrared160, image 2002. analysis, J. Volcanol. Geoth. Res., 116, 151– Soci & volcanic processes: integratingpress, observation 2013. & modelling, Geological Society, London, in ´ arquez, A., Ferrari, L., Rosas-Elguera, J., Oyarzun, R., Doblas, M., and Verma, S. P.: Alkalic Stevenson, J. A. and Varley, N. R.: Fumarole monitoring with a handheld infrared camera: Sparks, R. S. J., Young, S. R. , Barclay, J., Calder, E. S., Cole, P., Darroux, B., Davies, M. Spaminato, L., Calvari, S., Oppenheimer, C., and Boschi, E.: Volcano surveillance using infrared Moran, S. C., Matoza, R. S., Garc Smith, R., Sammonds, P. R., Tu Saucedo, R., Mac Menyailov, I. A., Nikitina, L. P., Shapar, V. N., and Pilipenko, V. P.: Temperature increase M Ryan, G. A., Loughlin, S. C., James, M. R., Jones, L. D., Calder, E. S., Christopher, T., Rose, W. I., Pearson, T., and Bonis, S.: Nue Major, J. J., Dzurisin, D., Schilling, S. P., and Poland, M. P.: Monitoring lava-dome growth during Rose, W. I.: Pattern and mechanism of volcanic activity at the Santiaguito volcanic dome, Luhr, J. and Carmichael, I.: The Colima Volcanic Complex, Mexico, Contrib. Mineral. Petr., 71, Norris, R. D.: Seismicity of rockfalls and avalanches at three Cascade Range volcanoes: Im- Nakada, S., Myake, Y., Sato, H., Oshima, O., and Fujinawa, A.: Endogenous growth of dacite Nakada, S.: Characteristics of lava dome eruption and dome growth model at Unzen Volcano Lesage, P.: Interactive Matlab software for the analysisLoughlin, of S. seismic C., volcanic signals, Luckett, Comput. R., Ryan, G., Christopher, T., Hards, V., De Angelis, S., Jones, Lavall Kennedy, B. M., Jellinek, M., Lavallee, Y., Von Aulock, F., Russell, K., and Wadsworth, F.: The Kaneko, T., Wooster, M. J., and Nakada, S.: Exogenous and endogenous growth of the Unzen Jongmans, D. and Garambois, D.: Geophysical investigation of landslides: A review, Bulletin 5 5 30 25 30 20 15 25 10 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ´ an ´ ua, nguez, ı ´

(red

´ an de Colima ´ on to the west hand drawing shows the (b) ´ an de Colima, Mexico, J. Vol- ´ antaro and Nevado de Colima rez, J. J., Reyes, G. A., Urs ı ´ ´ an de Colima (Colima, Mexico)

. ´ an de C lue star) and and the active volcano Volcán de Colima

(b

Hand drawing shows the Colima Volcanic Complex ´

es, A., De La Cruz-Reyna, S., Dom ); (b) de de Colima

´ avila, G., Stevenson, J., and Harwood, R.: Gen- the two main theBarrancas twoleading towardsmain the City inColima; of , 2008. 27 28 Red box pyroclastic pyroclastic flows. Also the observation point in Playón the west of ( ´ on, M., Cort guide guide z, J. J., Navarro, C., Ram ı ´ ˜ n ´ an de Colima, B. Volcanol., 72, 1093–1107, 2010b. ntaro ntaro and Nevado á ´ an, A., Khazaradze, G., Garcia, D., and Llosa, J.: Rockfall Barrancas Barrancas

such , ´ s ´ an de Colima: managing the threat, edited by: Varley, N. R. and an de Colima in Mexico (Red box); cán de Colima in Mexico ´ an de Colima (red triangles). Two black lines south of Volc volcanoes volcanoes Volcán de C emission, J. Volcanol. Geoth. Res., 177, 367–377, 2008. ˜

nach, E., Abell 2 osition osition of Vol ´ ´ ambula-Mendoza, R., Reyes-D ambula, R., Reyes, G., Stevenson, J., and Harwood, R.: Long-period seismicity doi:10.5194/nhess-8-805-2008 extinct (a) P . Two black lines . de south black Two ColimaVolcán of show : 1 Position of Volc Figure Figure with the triangles) case of a dome collapse event is whereshown been collected for this has study de data Colima Volcán ´ an de Colima where data for this study has been collected is shown (blue star).

Monitoring the 2004 andesitic block-lava extrusionactivity at and Volcan SO de Colima, Mexico from seismic induced seismic signals: case study8, in 805–812, Montserrat, Catalonia, Nat. Hazards Earth Syst. Sci., T., Galindo, I., Gavilanes, J. C.,M., Mu Velasco, J., Alatorre, E.,de and Colima, Santiago, Mexico, H.: J. Overview Volcanol. of Geoth. the Res., 1997–2000 117, activity 1–19, of 2002. Volc eration of Vulcanian activity andcanol. long-period Geoth. Res., seismicity 198, at 45–46, Volc 2010a. during magma movement at Volc tive Mechanism, in:Komorowski, Volc J. C., Springer, in preparation, 2013. Predicting the block-and-ash flowbased inundation on areas the at2010. present Volc day (February 2010) status, J. Volcanol. Geoth. Res., 193, 49–66, 597 598 599 600 601 602 596 and the active Volc show the two mainevents, Barrancas twice leading barrancas towards guide the pyroclasticof City flows. Volc of Also Colima; the in observation case point of Play a dome collapse Colima Volcanic Complex with the extinct volcanoes Volc Fig. 1. (a) Zobin, V. M., Varley, N. R., Gonzalez, M., Orzco, J., Reyes, G. A., Navarro, C., and Breton, M.: Vilajosana, I., Suri Zobin, V. M., Luhr, J. F., Taran, Y. A., Bret Varley, N. R., Ar Varley, N. R., Ar Varley, N. R. and Reyes, G. A.: Monitoring the Recent Activity: Trying to Understand the Erup- Sulpizio, R., Capra, L., Sarocchi, D., Saucedo, R., Gavilanes-Ruiz, J. C., and Varley, N. R.: 5 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

´

on to the Local Local Time

n be n used olcano. olcano. v olima olima m and ca m and

2011, 15:02 C the West the of

th to n ó Play with the before the rockfall on 8 March 2011, 15:02 . The dome has diametera .has dome The 298 of (a) 30 29 before the rockfall on March 08 after the rockfall. Rocks that are missing after the triggered by an ongoing rockfall. ongoing triggered by an

a) a) was (b) ´ an de Colima ´ an de Colima and the observation camp within the Play Volcán de Colima of of

after the rockfall. Rocks that after are arecircle. Rocks missing with themarked red a rockfall. rockfall theafter b) b)

. the whiteThe slope down track dust : Photograph shows Volcán de Colima and the observation the shows observation camp and de Colima Volcán : Photograph 2 View of the dome

: 3 GMT) GMT) and

Figure Figure de Colima ImageVolcán of theshows growing dome decentralized scale as a View of the dome of Volc Photograph shows Volc

Figure Figure (21:02 603 604 605 606

rockfall are marked with a red circle. Colima Local Time (21:02 GMT) and Fig. 3. West of the volcano. Imageof shows 298 the m decentralized and growing can dome.triggered be The by used dome an as ongoing has a rockfall. a scale diameter in photographs. The white dust track down the slope was Fig. 2. 609 607 608 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

´ an de erence ff

(b)

, during , (a)

.

at Volcán de Colima before de Colima Volcán at

Shows rock axes x, y and z. the dome; C2 marks a spot the on slope where the

(c) rature of each circle which is the base for the temperature , 2011, 21:07 GMT at th exposed face on on March 9 on March

32 31 c) shows rock axes x, y and z y and x, axes rock c) shows

of a rockfall a of

. a rockfall. The black circle C1 marks the exposed

images (c) Each Each picture shows the tempe maximum a rockfall.a The black circle C1 themarks

(c)

: Series of thermal : Series thermal of 5 Figure Figure and after will rockfall pass by. difference measurements. and after

612 613 614 615 616 (b) , during (a) Geometry between observer and rock on dome on rock betweenand Geometry observer

: Series of thermal images of a rockfall on 9 March 2011 at 21:07 GMT at Volc 4 Geometry between observer and rock on dome. Figure Figure measurements. face on the dome;shows C2 the marks maximum temperature a of spot each circle on which the is slope the base where for the the temperature rockfall di will pass by. Each picture Colima before Fig. 5. Fig. 4.

610 611

so

from the distributed

Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

is

2 R marks is is 0.88.

2 (a) ; R of the related deposits for the observed small b) b) marks a rockfall that broke off T from the NW edge of the ff . Point . Point an temperature e me . measured at measured the area origin of th

T accordingly theaccordingly involved mass had had more time for cooling,

and and Point a) marks a rockfall Point thatrockfall a a) marks shortly happened after one big a

low; 34 33 is not representative temperature

. marks a rockfall that broke o (b) volume and volume and

small volume ers can be observed: i the volume of rockfalls

of rockfall of Two outl Two . Here activity rockfall was very for for the observed T Relationship Relationship

: 6 Relationship of rockfall volume and temperature measured at the area of origin; Relationship between the volume of rockfalls and the mean temperature of the related Relationship between Figure Figure : 7 Fig. 7. deposits distributed over thea volcano’s rockfall slope. that Two happened outliersvolume shortly is can after not be a representative. observed: Point bigdome. Here Point one rockfall so activity the wascooling, very high leading low; average accordingly to the the involved observed mass low had value had of more average time for 0.88. Fig. 6.

edge theof dome high high average

617 618 619

over the volcano’s slope.over the volcano’s the NW to the leading T observed average low of value Figure Figure

629 627 628 621 622 623 624 625 626 620 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | that that is approximately

frequency

– the seismogram time (a) its which is a pseudo –

0 b)

E and and rockfall volume is 0.92. rockfall and

E’ the averaged periodogram of energy and stands for a number

Filter was with applied low a corner

– (c) seismogram between between the

2 Highpass

a) a) R – :48 GMT on 9 March 2011.9 GMT on March :48 n order 2n Shown Shown are A

36 35 ’ which is a pseudo station at 17station

Colima with its frequency.

recorded at SOMArecorded

´ an de Colima with its frequency. Shown are and rockfall volume is 0.92. 0 E ockfall was ockfall the averaged periodogram the theof averaged periodogram event.

c)

The r The

. and

between 2 R : Rockfall : volume Rockfall vs. seismic signal related energy with averaged trendline. Good correlation between estimated : Rockfall signal : Rockfall de at Volcán 9 8 its time – frequency spectrogram representation and Figure Figure representation 1of frequency Hz Rockfall volume vs. seismic signal related energy with averaged trendline. Good cor- Rockfall signal at Volc proportional to the actual seismic energy seismic to theunits. without proportional actual Figure Figure volume and seismic signal energy value E

(b)

632 633 634 635 630 631 energy and stands for a numberwithout that units. is approximately proportional to the actual seismic energy Fig. 9. relation between estimated volume and seismic signal energy value Fig. 8. and the event. An orderrockfall 2 was – recorded Highpass at Filter SOMA station was at applied 17:48 with GMT on a 9 low March corner 2011. frequency of 1 Hz. The 640 641 642 636 637 638 639 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

. – 1 - s 3 m

,008 the

for

helicorder helicorder records ´

an de Colima seismic network. ; calculated with the amplitudeseismic . The average extrusion rate in 1 − s 3 /sec, the minimum in/sec, the Juneminimum 2010 with 0 3 m

, with , error 35%of 38 37 de Colima seismic network. seismic de Colima

´ ´ an de Colima in 2010. The blue bar shows the monthly an de Colima in 2010, with error of 31 %; calculated . In November 2010 the decrease of activity starts and will finally stop rockfalls. rockfalls. The small category is defined by seismic amplitude smaller than

1 - s 3 large m

duration duration usually never exceeds 180 seconds. All rockfalls with greater amplitude . They are also usually shorter than 60 seconds in duration. The medium one have mm, mm, their

rockfalls. rockfalls. All the data shown in this figure is gained from the daily

. In November 2010 the decrease of activity starts and will finally stop 1 large − s 3 . The ismaximum in February 2010 with 0,019 smaller than 7

s : Total amount of rockfalls at Volcán de Colima in 2010. The blue bar shows the monthly total, red shows the een the medium and purple the , the minimum in June 2010 with 0.008 m 0 1 1 on on the helicorder output − s Magma extrusion rate of Volc

Total amount of rockfalls at Volc 3 Figure Figure grsmall, 3mm amplitude than 7mm count as thein RESCO Volcán yearthe 2010EZV4/SOMA station of : Magma extrusion : rateMagma Volcánof in de Colima 2010 1

1 647 648 649 650 651 643 644 645 646 in June 2011. Fig. 11. with the seismic amplitude0.019 m – photographic method.2010 The is maximum 0.0113 m is in February 2010 with total, red shows the small,is green the defined medium and by purpleusually seismic the large shorter amplitude rockfalls. The than smaller smalltheir 60 category than s duration 3 usually in mm never exceeds duration. on 180as s. The the large All medium rockfalls. rockfalls helicorder with All one greater output.for the have amplitude the They data than year amplitudes 7 shown 2010 are mm smaller of in count also the than this EZV4/SOMA 7 figure station mm, in is the gained RESCO from Volc the daily helicorder records Fig. 10. photographic method photographic The average extrusion rate in 2010 is 0,0113 2011. June in Figure Figure

655 656 652 653 654

Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | is 0.8. 2 R is is 0.8.

2 R

; 39 vs. duration of rockfalls in seconds; 0 E vs. duration of rockfalls in seconds in rockfalls of duration vs. E’ E’ nergy e

– Pseudo – energy Pseudo Pseudo : 2 1 Fig. 12. Figure Figure

658 659 657