DOCSLIB.ORG

Inflation of the Aira Caldera (Japan) Detected Over Kokubu Urban Area Using SAR Interferometry ERS Data D

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Inflation of the Aira Caldera (Japan) Detected Over Kokubu Urban Area Using SAR Interferometry ERS Data D Inflation of the Aira Caldera (Japan) detected over Kokubu urban area using SAR interferometry ERS data D. Rémy, S. Bonvalot, M. Murakami, P. Briole, S. Okuyama To cite this version: D. Rémy, S. Bonvalot, M. Murakami, P. Briole, S. Okuyama. Inflation of the Aira Caldera (Japan) detected over Kokubu urban area using SAR interferometry ERS data. eEarth, 2007, 2 (1), pp.17-25. hal-00330782 HAL Id: hal-00330782 https://hal.archives-ouvertes.fr/hal-00330782 Submitted on 2 Feb 2007 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. eEarth, 2, 17–25, 2007 www.electronic-earth.net/2/17/2007/ eEarth © Author(s) 2007. This work is licensed under a Creative Commons License. Inflation of the Aira Caldera (Japan) detected over Kokubu urban area using SAR interferometry ERS data D. Remy1,2,*, S. Bonvalot1,2, M. Murakami3, P. Briole2, and S. Okuyama4 1Institut de Recherche pour le Developpement´ (IRD), UR154, France 2Institut de Physique du Globe de Paris, 4 Place Jussieu, 75005 Paris, France 3Geographical Survey Institute, Mizusawa Geodetic Observatory, Japan 4Kyoto University, Dept. of Geophysics, Kyoto, 606-8502, Japan *presently at: Dept. of Geophysics, University of Chile, Santiago, Chile Received: 20 July 2006 – Published in eEarth Discuss.: 8 August 2006 Revised: 26 October 2006 – Accepted: 30 January 2007 – Published: 2 February 2007 Abstract. Nine ERS-1 and ERS-2 descending orbit data ac- 1 Introduction quired over Aira Caldera between June 1995 and November 1998 were used to create 36 differential interferograms. Al- Numerous papers have shown the potential of SAR (Syn- though the interferograms exhibit a relatively low level of thetic Aperture Radar) interferometry data for ground defor- coherence, even for couples sampling short time intervals (6 mation studies on volcanoes (Massonnet and Sigmundsson, months), Synthetique Aperture Radar (SAR) observations re- 2000; Zebker et al., 2000; Pritchard and Simons, 2002). Un- veal a distinct range change pattern over Kokubu urban area der optimal conditions a differential interferogram derived whose amplitude increases with the time separation between from two SAR images may monitor topographic changes in- SAR images. The analysis of the ground deformation time duced by internal volcanic processes with an accuracy of a series relative to the earliest ERS images showed a maxi- few cm over periods of time up to several months or years. mum uplift of about 20 mm between the north and the south Furthermore, as satellite systems repeat their orbit on the of the urban area during the period covered by our satellite order of weeks, it is now possible to generate deformation observations. Taking the reduced surface of the coherent area time series which help to better resolve time dependant de- into account, we performed a simple modeling of the defor- formation (Schmidt and Burgmann, 2003). In this paper we mation field assuming an inflating spherical source within use the DinSAR method to examine ground deformation oc- an elastic half-space medium located beneath the centre of curring on the volcanic complex of the Aira Caldera (Japan) the Aira Caldera. This simple model predicts a maximum within the 1995–1998 period (Fig. 1). This Caldera and its volume increase of 20–30×106 m3 between 1995 and 1998, post-caldera volcano, Sakurajima, are among the most ac- which would produce an inflation of about 70 mm at the cen- tive volcanic centers in Japan where significant ground de- tre of the Aira Caldera and 40 mm in the Kokubu south urban formations have been observed from ground monitoring net- area. These results are in good agreement with other geo- works over several decades (Omori, 1916; Yokoyama, 1971; physical observations carried out on the Aira caldera during Aramaki, 1984). The latest precise leveling survey con- this period. Despite the limited spatial extent of the coherent ducted along a coast road at Sakurijima clearly shows that areas around the Aira Caldera, this study shows that Din- the deflation of the ground around the Aira Caldera start- SAR method using data collected in C band can be success- ing in 1974 turned into inflation in 1994 (Ishihara, 1999). fully used to detect subtle ground displacement changes of Using JERS (L band, λ=23.53 cm) data acquired between the volcanic complex and thus provides complementary in- 1993 and 1998, (Okuyama et al., 2001) detected two dis- formation to ground-based geodetic monitoring of dynamic tinct deformation patterns. Figure 2 shows three examples of processes of the Aira Caldera and Sakurajima volcano. JERS interferograms used in their study for various time pe- riods during 1993–1998. The first deformation pattern is lo- Correspondence to: D. Remy cated at the north flank of Sakurajima and it was interpreted ([email protected]) by the authors as related to a volume change of a shallow Published by Copernicus GmbH on behalf of the European Geosciences Union. 18 D. Remy et al.: Inflation of Aira Caldera (Japan) detected using DinSAR 130° 30' 130° 36' 130° 42' 130° 48' riod total weight of volcanic ash ejected from the summit crater was estimated by the Sakurajima Volcano Research Center to about 8.75×109 kg which leads to an estimation of × 6 3 KAJIKI KOKUBU magma in volume to 3.5 10 m (assuming a magma den- sity of 2500 kg/m3). Presumably, this preeruption uplift was 31° 42' 31° 42' caused by accumulation of magma within a reservoir beneath the Aira caldera prior to the 1999 eruption. KAGOSHIMA BAY In this paper, we show a clear evidence of ground deforma- tion of the northern rim of the Aira Caldera using ERS SAR interferometry, which is in good agreement with the previ- 31° 36' 31° 36' ous independent studies. The analysis and interpretation of KAGOSHIMA the interferogram time series are also presented km 2 DinSAR data acquisition and processing 0 5 10 31° 30' 31° 30' 130° 30' 130° 36' 130° 42' 130° 48' We analyzed a series of 36 interferograms produced from 9 ERS-1 and ERS-2 scenes acquired in descending orbits Fig. 1. Geographical setting of Kagoshima bay. The white dotted over the Aira Caldera volcanic complex between June 1995 line is the rim of the Aira Caldera proposed by Matumoto (1943). and November 1998 (see Fig. 3). The differential interfero- The white box located in the northeast (Kokubu urban area) of the grams were produced by the two pass method with DIAPA- caldera shows the area used in this study for SAR data analysis and SON software (CNES, 1996) using precise ERS orbit data modeling. The black box located in the southwest of the caldera shows the area used to perform the analysis of the spatial structure produced by the Delft Institute for Earth-Oriented Space Re- of interferogram noise. search (DEOS)(Sharroo et al., 1998). The topographic con- tribution was removed by subtracting the fringe pattern com- puted from a Digital Elevation Model (DEM) with 45 m pixel spacing and with a height uncertainty of 5–10 m provided by pressure source located beneath the volcano at 4 km depth. the Geographical Survey Institute (Japan). The resulting in- The second one corresponds to an uplift of Kokubu urban terferograms span between 1 and 1261 days, with perpendic- area, which was interpreted by the authors as related to a ular baselines ranging from 2 m to 730 m (see Fig. 3). volume change caused by magmatic injection of a deep pres- Figure 4 shows typical examples of wrapped interfero- sure source roughly located at the center of the Aira Caldera grams constructed using three different master images (orbits at 10 km depth. Assuming a point center of dilatation (Mogi, 20503, 23509 and 0386). It can be noted that the interfero- 1958), these authors estimated a roughly constant inflation grams exhibit a relatively low level of coherence over the × 6 3 rate of about 8–16 10 m /year between 1992–1998. In whole area due to densely vegetated areas and water surface October 98 began an increase in seismic activity until July which disconnects the Sakurajima volcano from the coast. 1999 which has been interpreted as a migration of the magma The comparison between Fig. 2 and 4 clearly shows that the stored in the magma reservoir beneath the caldera to the sum- interferometric coherence is better and persists longer in L mit of Sakurajima volcano, accumulating stress in the rocks band than in the C band, confirming conclusions from In- around the magma reservoir. This increase in seismic ac- SAR investigations at others places (e.g., Murakami et al, tivity was followed by the eruptive activity which reached 1996; Lu et al., 2005). Consequently using C band, suc- its peak between August 1999 and February 2000 (Smithso- cessful measurements of the phase are only possible in three nian Institution, 1999a, b, 2000; Kriswati and Iguchi, 2003). isolated areas located in the northeast (Kokubu urban area) Kriswati and Iguchi (2003) analyzed GPS data acquired in the northwest (Kajiki urban area) and in the southwest of from the Sakurajima Volcano Research Center network (12 the caldera (Kagoshima urban area). The two isolated ar- permanent stations) and from 7 campaigns of Kyoto Univer- eas corresponding to Kajiki urban area and Kagoshima urban sity in South Kyushu during 1996–2002 period in order to area exhibit signals which are not observed in independent investigate characteristics of ground deformation caused by interferograms (i.e.
Load more

Recommended publications
  • Inflation of the Aira Caldera (Japan) Detected Over
    eEarth, 2, 17–25, 2007 www.electronic-earth.net/2/17/2007/ eEarth © Author(s) 2007. This work is licensed under a Creative Commons License. Inflation of the Aira Caldera (Japan) detected over Kokubu urban area using SAR interferometry ERS data D. Remy1,2,*, S. Bonvalot1,2, M. Murakami3, P. Briole2, and S. Okuyama4 1Institut de Recherche pour le Developpement´ (IRD), UR154, France 2Institut de Physique du Globe de Paris, 4 Place Jussieu, 75005 Paris, France 3Geographical Survey Institute, Mizusawa Geodetic Observatory, Japan 4Kyoto University, Dept. of Geophysics, Kyoto, 606-8502, Japan *presently at: Dept. of Geophysics, University of Chile, Santiago, Chile Received: 20 July 2006 – Published in eEarth Discuss.: 8 August 2006 Revised: 26 October 2006 – Accepted: 30 January 2007 – Published: 2 February 2007 Abstract. Nine ERS-1 and ERS-2 descending orbit data ac- 1 Introduction quired over Aira Caldera between June 1995 and November 1998 were used to create 36 differential interferograms. Al- Numerous papers have shown the potential of SAR (Syn- though the interferograms exhibit a relatively low level of thetic Aperture Radar) interferometry data for ground defor- coherence, even for couples sampling short time intervals (6 mation studies on volcanoes (Massonnet and Sigmundsson, months), Synthetique Aperture Radar (SAR) observations re- 2000; Zebker et al., 2000; Pritchard and Simons, 2002). Un- veal a distinct range change pattern over Kokubu urban area der optimal conditions a differential interferogram derived whose amplitude increases with the time separation between from two SAR images may monitor topographic changes in- SAR images. The analysis of the ground deformation time duced by internal volcanic processes with an accuracy of a series relative to the earliest ERS images showed a maxi- few cm over periods of time up to several months or years.
    [Show full text]
  • An Overview of Analogue Models Compared to Natural Calderas ⁎ Valerio Acocella
    Available online at www.sciencedirect.com Earth-Science Reviews 85 (2007) 125–160 www.elsevier.com/locate/earscirev Understanding caldera structure and development: An overview of analogue models compared to natural calderas ⁎ Valerio Acocella Dipartimento Scienze Geologiche Roma Tre, Roma, Italy Received 1 August 2006; accepted 15 August 2007 Available online 28 August 2007 Abstract Understanding the structure and development of calderas is crucial for predicting their behaviour during periods of unrest and to plan geothermal and ore exploitation. Geological data, including that from analysis of deeply eroded examples, allow the overall surface setting of calderas to be defined, whereas deep drillings and geophysical investigations provide insights on their subsurface structure. Collation of this information from calderas worldwide has resulted in the recent literature in five main caldera types (downsag, piston, funnel, piecemeal, trapdoor), being viewed as end-members. Despite its importance, such a classification does not adequately examine: (a) the structure of calderas (particularly the nature of the caldera's bounding faults); and (b) how this is achieved (including the genetic relationships among the five caldera types). Various sets of analogue models, specifically devoted to study caldera architecture and development, have been recently performed, under different conditions (apparatus, materials, scaling parameters, stress conditions). The first part of this study reviews these experiments, which induce collapse as a result of underpressure or overpressure within the chamber analogue. The experiments simulating overpressure display consistent results, but the experimental depressions require an exceptional amount of doming, seldom observed in nature, to form; therefore, these experiments are not appropriate to understand the structure and formation of most natural calderas.
    [Show full text]
  • Tomographic Image of the Crust Beneath the Aira Caldera in Southern Kyushu
    IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan Forecasting Volcanic Activity - Reading and translating the messages of nature for society 4W_1B-P5 Date/Time: July 24 Poster Tomographic image of the crust beneath the Aira caldera in southern Kyushu Hiroki Miyamachi1, Paul Karson Alanis2, Hiroshi Yakiwara1, Takeshi Tameguri3, Masato Iguchi3 1Kagoshima University, Japan, 2Philippine Institute of Volcanology and Seismology, Philippines, 3Kyoto University, Japan E-mail: [email protected] Associated with the Philippine Sea plate subduction, a nearly straight chain of active Quaternary volcanism runs almost parallel to Nankai Trough in the central part of southern Kyushu. In this region, there are four large calderas: the Kakuto, the Aira, the Ata and the Kikai calderas. We applied the tomography method with a fine grid configuration to the P- and S-wave arrival times of 829 local earthquakes well observed at 101 stations in central and southern Kyushu, and revealed the detailed three-dimensional seismic velocity structure of the crust, especially the region beneath the Aira caldera. In a shallow range from 0 to 10 km depth, low velocity zones (LVZs) are found in the eastern part of Kyushu, where basement rocks are made up of uplifted sedimentary marine terraces (Nakada et al., 2002). The LVZs are also distributed along the volcanic front between Kirishima volcano to Kaimon volcano. Meanwhile, the hypocenters occurred in the inland area are obviously concentrated in regions with a relatively higher velocity and a low Poisson’s ratio at a depth of 10 km. At 20 km depth, the most interesting feature is that a distinctly high Poisson’s ratio zone is located exactly beneath the Aira caldera.
    [Show full text]
  • Volcanic Hazards As Components of Complex Systems: the Case of Japan
    Volume 13 | Issue 33 | Number 6 | Article ID 4359 | Aug 17, 2015 The Asia-Pacific Journal | Japan Focus Volcanic Hazards as Components of Complex Systems: The Case of Japan Gregory Smits The past year or so has been a time of the earth’s crust suggested Mt. Fuji is more particularly vigorous volcanic activity in Japan, likely to erupt owing to effects from the 2011 or at least activity that has intruded into public Tōhoku earthquake.3 Well publicized by a press awareness. Perhaps most dramatic was the release on the eve of its publication, mass deadly eruption of Mt. Ontake on September media around the world have reported this 27, 2014, whose 57 fatalities were the first finding, along with speculation regarding volcano-related deaths in Japan since 1991. On possible connections between earthquakes and May 29, 2015, Mt. Shindake, off the southern volcanic eruptions. tip of Kyushu, erupted violently, forcing the evacuation of the island of Kuchinoerabu. That As of June 30, 2015, the Japan Meteorological same day, Sakurajima, located just north in Agency (JMA) designated ten volcanoes in or Kagoshima Bay, erupted more forcefully than near the main Japanese islands as warranting usual. Sakurajima has been erupting in some levels of warning ranging from Mt. Shindake’s fashion almost continuously since 1955, but Level 5 (“Evacuate”), to Level 2 (“Do not since 2006, its activity has become relatively approach the crater”) in seven cases. more vigorous. Indeed, a May 30 Asahi shinbun Sakurajima is at Level 3 (“Do not approach the article characterized these eruptions as “the volcano”), as is Hakoneyama, located near Mt.
    [Show full text]
  • Calderas in Japan
    Calderas in Japan ref Main Post-Caldera Volcano Most Recent Caldera Type of Ejecta ref About Period No. About Formation Caldera Name Document No. Name Eruption Period (Symbol) 番号 14 Kishimoto, T., et al. (2009) Tephrostratigraphy and Eruption Mashu f Yamamoto, T., et al. (2010) C ages for the ejecta from Style of Mashu Volcano, During the Last 14,000 years, Eastern Mashu Kamuinupuri, Kamuisshuto 7.6 ka* 1, 5 1 Kutcharo and Mashu calderas, eastern Hokkaido, Japan. Bull. Geol. 5 (Ma-f) Hokkaido, Japan. Bull.Volcanol.Soc.Japan Surv. Japan, 61, 161-170. , 54, 15-37. 14 Hasegawa, T., et al. (2010) The history of caldera-forming Kutcharo 1 Yamamoto, T., et al. (2010) C ages for the ejecta from Kutcharo Atosanupuri, Nakajima 40 ka* 1, 2 1 Kutcharo and Mashu calderas, eastern Hokkaido, Japan. Bull. Geol. 2 eruptions in eastern Hokkaido, Japan. CHIKYU MONTHLY, 33, (Kp I) Surv. Japan, 61, 161-170. 726-734. Hasegawa, T., et al. (2010) The history of caldera-forming Hasegawa, T., et al. (2010) The history of caldera-forming Akan 1 Akan Meakandake, Oakandake 120←→210 ka 2 2 eruptions in eastern Hokkaido, Japan. CHIKYU MONTHLY, 33, 726- 2 eruptions in eastern Hokkaido, Japan. CHIKYU MONTHLY, 33, (Ak1) 734. 726-734. Yamagata, K (1994) Tephrochronological Study on the Shikotsu No. 1 Hiroshi Machida and Fusao Arai (2003) Atlas of tephra in and 3 6 Shikotsu and Kuttara Volcanoes in Southwestern Hokkaido, Shikotsu Eniwadake, Tarumaesan 40←→45 ka* 3, 6 around Japan. Univ. of Tokyo Press, 336p. (Spfl, Spfa-1) Japan. Jour. Geol. Soc.
    [Show full text]
  • Breaking Volcano News
    Volcano News & Questions from Students VOLCANIC ERUPTIONS Physical Phenomena Causes – movement at plate boundaries Geography – spatial distribution Forms and eruption styles Magnitude Prediction – looking back & monitoring Hazards – quakes, blasts; release of ash, gas & lava Impacts Fatalities Economic Mitigation & Preparedness Begins with understanding vulnerability Recently, eruption of Icelandic volcano halted air travel Breaking Volcano News http://www.volcanolive.com/news.html …and news of breaking volcanoes History shows that when Eyjafjallajökull erupts, it’s larger neighbour Katla is generally not far behind. Katla is overdue. Katla’s eruption may be 10 or more x the size of the Eyjafjallajökull eruption –significant floods of fresh glacial-melt water into the sea (flow equal to Amazon + Mississippi + Nile + Yangtze occurred following 1755 eruption), a column of ash rising Chaiten, Chile 20km, or more, into the jet stream and spread over N Hemisphere. The Laki eruption in Iceland in 1783 resulted in famine across W Met Office, summer 2010 Europe, and as far S as Egypt, one of the longest and coldest ..as ash entrained in the atmosphere moved from winters on record in N America, and the death of 10,000s of Iceland across the Atlantic. people from gas poisoning and famine. 1 Merapi is at a subduction zone, where the Indo-Australian Plate is sliding NEWS beneath the Eurasian Plate and part of the Pacific Ring of Fire Stratigraphic analysis reveals that eruptions in the Merapi area began about Merapi Eruption 400,000 years ago, and from then until about 10,000 years ago, eruptions were effusive, and outflowing lava emitted was basaltic.
    [Show full text]
  • Inflation of the Aira Caldera (Japan) Detected Over Kokubu
    eEarth, 2, 17–25, 2007 www.electronic-earth.net/2/17/2007/ eEarth © Author(s) 2007. This work is licensed under a Creative Commons License. Inflation of the Aira Caldera (Japan) detected over Kokubu urban area using SAR interferometry ERS data D. Remy1,2,*, S. Bonvalot1,2, M. Murakami3, P. Briole2, and S. Okuyama4 1Institut de Recherche pour le Developpement´ (IRD), UR154, France 2Institut de Physique du Globe de Paris, 4 Place Jussieu, 75005 Paris, France 3Geographical Survey Institute, Mizusawa Geodetic Observatory, Japan 4Kyoto University, Dept. of Geophysics, Kyoto, 606-8502, Japan *presently at: Dept. of Geophysics, University of Chile, Santiago, Chile Received: 20 July 2006 – Published in eEarth Discuss.: 8 August 2006 Revised: 26 October 2006 – Accepted: 30 January 2007 – Published: 2 February 2007 Abstract. Nine ERS-1 and ERS-2 descending orbit data ac- 1 Introduction quired over Aira Caldera between June 1995 and November 1998 were used to create 36 differential interferograms. Al- Numerous papers have shown the potential of SAR (Syn- though the interferograms exhibit a relatively low level of thetic Aperture Radar) interferometry data for ground defor- coherence, even for couples sampling short time intervals (6 mation studies on volcanoes (Massonnet and Sigmundsson, months), Synthetique Aperture Radar (SAR) observations re- 2000; Zebker et al., 2000; Pritchard and Simons, 2002). Un- veal a distinct range change pattern over Kokubu urban area der optimal conditions a differential interferogram derived whose amplitude increases with the time separation between from two SAR images may monitor topographic changes in- SAR images. The analysis of the ground deformation time duced by internal volcanic processes with an accuracy of a series relative to the earliest ERS images showed a maxi- few cm over periods of time up to several months or years.
    [Show full text]
  • GNSS Observation of Volcanic Activities in Sakurajima
    Leica Geosystems TruStory GNSS Observation of Volcanic Activities in Sakurajima Objective Volcano monitoring to predict volcanic eruptions Customer/Institution Geosurf Corporation Disaster Prevention Research Institute Kyoto University, Sakurajima Volcanological Observatory Date Start August 1994 Location Kagoshima Prefecture, Japan Sakurajima is a volcano on the permission, within a 2 km range island of Kyushu. It is located of the Minami-dake crater. on the southern edge of the Aira Caldera and erupts from The volcanic explosion in October the summit of Sakurajima. This 1955 (Showa 30) was the starting summit is split into three peaks point for volcanic eruption predictions known as the Kita-dake (the at the Disaster Prevention Research northern peak), the Naka-dake Institute, and transitive volcanic (the central peak) and the Minami- activities have been monitored dake (the southern peak). The attentively ever since. In June 1956 Project Summary volcano is located in close (Showa 31), observation of volcanic Instruments proximity to the densely popu- activity in the mountain summits Leica GMX902GG Receiver lated Kagoshima city area. It is was on a full-scale level and it was Leica GRX1200 Receiver very active and is known to be determined that the duration would Leica AX antenna the largest active volcano in be of a long-term continual nature. Leica AT502 antenna Japan. The crater at Sakurajima’s This prompted the necessity to Software Minami-dake summit erupted in consider the construction of a Leica GNSS Spider October 1955 (Showa
    [Show full text]
  • The Lateral Growth and Coalesence of Magma Systems Royalsocietypublishing.Org/Journal/Rsta Juliet Biggs1 and Catherine Annen1,2
    The lateral growth and coalesence of magma systems royalsocietypublishing.org/journal/rsta Juliet Biggs1 and Catherine Annen1,2 1School of Earth Sciences, University of Bristol, Queen’s Road, Bristol, BS8 1RJ, UK Research 2Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, IFSTTAR, Cite this article: Biggs J, Annen C. 2019 The ISTerre, 38000 Grenoble, France lateral growth and coalesence of magma JB, 0000-0002-4855-039X systems . Phil.Trans.R.Soc.A377: 20180005. http://dx.doi.org/10.1098/rsta.2018.0005 Thermal and mechanical models of magma reservoir growth need to be reconciled with deformation patterns and structural relationships observed at Accepted: 16 October 2018 active magma systems. Geophysical observations provide a series of short time-scale snap-shots (100– One contribution of 15 to a Theo Murphy 102 years) of the long-term growth of magmatic 3 6 meeting issue ‘Magma reservoir architecture bodies (10 –10 years). In this paper, we first review evidence for the growth of magmatic systems along and dynamics’. structural features and the associated deformation patterns. We then define three distinct growth stages, Subject Areas: (1) aligned melt pockets, (2) coalesced reservoirs, (3) volcanology, geophysics highly evolved systems, which can be distinguished using short-term surface observations. We use Keywords: two-dimensional thermal models to provide first- thermal models, surface deformation, order constraints on the time scales and conditions transcrustal magmatic systems associated with coalescence of individual magma bodies into large-scale reservoirs. We find that closely spaced intrusions (less than 1 km apart) can develop Author for correspondence: combined viscoelastic shells over time scales of 10s kyr Juliet Biggs and form laterally extensive mush systems over time e-mail: [email protected] scales of 10–100 kyr.
    [Show full text]
  • Shallow Magma Pre-Charge During Repeated Plinian Eruptions At
    www.nature.com/scientificreports OPEN Shallow magma pre-charge during repeated Plinian eruptions at Sakurajima volcano Received: 19 October 2018 Naoki Araya1, Michihiko Nakamura1, Atsushi Yasuda2, Satoshi Okumura1, Tomoki Sato 1,3, Accepted: 28 December 2018 Masato Iguchi4, Daisuke Miki4 & Nobuo Geshi5 Published: xx xx xxxx Vigorous explosive eruptions that produce continuous high eruption plumes (Plinian eruptions) are generally assumed to tap a magma reservoir. The 1914 Plinian eruption at the Sakurajima volcano located on the Aira caldera rim is one such case, where the main magma reservoir was assumed to be located approximately 10 km beneath the caldera. However, we report that estimated magma storage depths immediately prior to the eruption were much shallower (0.9–3.2 km) on the basis of pressure at which volatiles within the phenocryst melt inclusions and plagioclase rims were fnally equilibrated. The same is observed for two historic Plinian eruptions in 1471 and 1779. This depth is even shallower than the shallowest magma reservoir estimated from the pressure source for geodetic deformation during recent Vulcanian explosions (4 km beneath the crater). We propose that the magmas were fed from a thick conduit pre-charged from deeper reservoirs. The ground subsidence observed after 1914 within the Aira caldera may have been caused by conduit recharge following the eruption. Voluminous conduit recharge could be key to forecasting the next possible large eruption at the Sakurajima volcano. Forecasting the initiation of future eruptions is a challenging but rewarding task in volcanology. A common and promising approach is to learn from pre-eruptive processes of past, similar eruptions1–5.
    [Show full text]
  • Shallow Velocity Structure Beneath the Aira Caldera and Sakurajima Volcano As Inferred from Refraction Analysis of the Seismic Experiment in 2008
    Bull. Volcanol. Soc. Japan Article Vol. 58 (2013) No. 1, pp. 227-237 Shallow Velocity Structure Beneath the Aira Caldera and Sakurajima Volcano as Inferred from Refraction Analysis of the Seismic Experiment in 2008 1） 1） 1） 2） 2） Hiroki MIYAMACHI , Chisato TOMARI , Hiroshi YAKIWARA , Masato IGUCHI , Takeshi TAMEGURI , 2） 3） 3） 4） 5） Keigo YAMAMOTO , Takahiro OHKURA , Takashi ANDO , Kyosuke ONISHI , Hiroshi SHIMIZU , 5） 6） 7） 8） 9） Yusuke YAMASHITA , Haruhisa NAKAMICHI , Teruo YAMAWAKI , Jun OIKAWA ,SadatoUEKI , 10） 11） 12） 12） Tomoki TSUTSUI , Hitoshi MORI ,MakotoNISHIDA , Hideyuki HIRAMATSU , 12） 12） 12） Tomoyuki KOEDA , Yoshirou MASUDA , Kouji KATOU , 12） 1） Kengo HATAKEYAMA and Tetsuo KOBAYASHI (Received December 24, 2010; Accepted July 21, 2011) We performed refraction analysis for the first P-wave arrival time data observed in the seismic experiment in 2008, and estimated a shallow velocity model up to 3 km depth beneath the Aira caldera and Sakurajima volcano. We found that a basement layer with a velocity of 4.6-5.0 km/s, which corresponds to geologically the Shimanto Group, inclines toward the central part of the Aira caldera. A low velocity zone with a velocity of 4.2-4.4 km/s is located in a depth range 1.5-3 km in the central part of the caldera. This low velocity zone suggests high activity of the magma plumbing system from the deep magma reservoir distributed beneath the caldera. It is found that the basement layer steeply falls down from 1 km to 2.5 km in depth along the northwestern boundary of the Kagoshima graben.
    [Show full text]
  • Thermomechanical Controls on Magma Supply And
    www.nature.com/scientificreports OPEN Thermomechanical controls on magma supply and volcanic deformation: application to Aira Received: 10 March 2016 Accepted: 03 August 2016 caldera, Japan Published: 13 September 2016 James Hickey1,†, Joachim Gottsmann1, Haruhisa Nakamichi2 & Masato Iguchi2 Ground deformation often precedes volcanic eruptions, and results from complex interactions between source processes and the thermomechanical behaviour of surrounding rocks. Previous models aiming to constrain source processes were unable to include realistic mechanical and thermal rock properties, and the role of thermomechanical heterogeneity in magma accumulation was unclear. Here we show how spatio-temporal deformation and magma reservoir evolution are fundamentally controlled by three- dimensional thermomechanical heterogeneity. Using the example of continued inflation at Aira caldera, Japan, we demonstrate that magma is accumulating faster than it can be erupted, and the current uplift is approaching the level inferred prior to the violent 1914 Plinian eruption. Magma storage conditions coincide with estimates for the caldera-forming reservoir ~29,000 years ago, and the inferred magma supply rate indicates a ~130-year timeframe to amass enough magma to feed a future 1914-sized eruption. These new inferences are important for eruption forecasting and risk mitigation, and have significant implications for the interpretations of volcanic deformation worldwide. The location and magnitude of crustal magma accumulation has important implications for volcanic hazards, eruption forecasting and risk mitigation1. It is possible to infer first-order estimates of these parameters using spatial patterns in geodetic data and generic models2,3. However, for more informed constraints, that are consist- ent across independent data sets, the inclusion of additional geophysical and geological observables are essential, necessitating the development of more sophisticated models.
    [Show full text]