A reappraisal of seismicity recorded during the 1996 Gjalp eruption in Iceland using modern seismological methods

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游佳美(Ika Wahyu Utami) 查詢紙本館藏

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論文名稱

A reappraisal of seismicity recorded during the 1996 Gjalp eruption in Iceland using modern seismological methods
(A reappraisal of seismicity recorded during the 1996 Gjalp eruption in Iceland using modern seismological methods)

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摘要(中)

1996年9月30日，在冰島的兩個火山中心 Grimsvotn和 Barearbunga之間的7公里長的裂縫發生冰川底火山噴發 (Gjalp噴發)。在噴發的一天半前，巴達本加火山發生了強烈的地震（Mw 5.6）。爆發持續了13天，隨之而來的是大量而密集的小地震（ML <4）和火山震顫。為了詳細研究這些事件，我們使用現代地震學方法分析了由臨時地震網絡HOTSPOT記錄的火山地震信號。為了獲得高度準確的位置，我們採用具有伴隨站校正項的可靠的一維速度模型。然後通過使用新推導的模型計算非線性概率位置來定位所有這些事件。我們將這301個事件的波形相關聯，根據地震目錄和他們記錄的地震圖的相似性來定義關聯事件。接著，我們計算了事件對之間的相對行程時間差，並使用雙差分定位法來解決這些事件之間的震源分離。我們以這種方法，將其中 192個事件重新定位並提高定位精準度，而緊密的火山群集也顯示我們將相對水平位置的不確定性控制於1公里內，垂直定位則小於 2公里。在這項研究中，我們還計算了一個光譜參數，即所有地震信號的質心頻率。此外，我們也計算了主要事件和接下來十個事件的矩張量以了解它們的震源過程。震源機制解顯示這些地震特性為非雙力偶源，而且等向分量不明顯。沿Barearbunga火山口邊緣發生的事件為逆斷層，而位於裂縫中的事件則以平移斷層為主。從地震活動模式來看，震央從 Barearbunga火山口向噴發地點轉移，可看出有一個橫向遷移穿過 Barearbunga火山下方的淺岩漿室延伸的堤壩。質心頻率表明沿Barearbunga環斷層和裂縫沿線的大多數事件，其起因有極高的可能是和岩石碎裂有關，而非流體。因此，我們將此結果視為本研究中地震矩張量等向分量不明顯的解釋。

摘要(英)

In September 30, 1996, a subglacial eruption, the Gjalp eruption, occurred along a 7-km-long fissure between two volcanic centres, Grimsvotn and Barearbunga in Iceland. A strong earthquake in Barearbunga (Mw 5.6) preceded the eruption, one and a half days before. The eruption continued for 13 days and it was followed by an intense earthquake swarm with a large number of small earthquakes (ML < 4) and volcanic tremor. To study these events in detail, we analyzed the volcanoseismic signals that were recorded by the temporary seismic network, HOTSPOT, using modern seismological methods. In order to obtain highly accurate
locations, a reliable minimum 1D velocity model with accompanying station correction terms was computed. All these events were then located by calculating non-linear, probabilistic locations using the newly derived model. We correlated the waveforms of these 301 events to define linked events based on the catalogue and the similarity of their recorded seismograms. Subsequently, we calculated the relative travel time difference between event pairs and solved the hypocentral separation between these events using the double-difference method. With this approach, 192 events were successfully relocated and we were able to improve the
location accuracy by showing a tight clustering and producing relative horizontal location uncertainties of less than 1 km and less than 2 km for the vertical location uncertainties. In this study, we also calculated a spectral parameter, known as the centroid frequency for all earthquake signals. Furthermore, the moment tensor for the main event and 10 events that followed were calculated in order to understand their source processes. All of events we
analyzed in this study were best characterized with non-double-couple solutions and insignificant isotropic components. The events along the Barearbunga caldera rim show thrust mechanisms while the events located in the fissure are dominated by strike-slip mechanisms. From the seismicity patterns, the shift of epicentres from the Barearbunga caldera towards the eruption site was an indication that there was a lateral migration through a dyke extending from the shallow magma chamber underneath the Barearbunga volcano. Centroid frequencies indicate that most events along the Barearbunga ring fault and along the fissure contained high-frequencies implying rupture of rock, rather than fluid-related source processes. This result thus we consider as an explanation for the insignificant isotropic component of the moment tensors derived in this study.

關鍵字(中)

★ Gjalp 噴發
★ 冰島

關鍵字(英)

★ Gjalp eruption
★ Iceland

論文目次

摘要 ............................................................................................................................................ i ABSTRACT .............................................................................................................................. ii ACKNOWLEDGEMENTS .................................................................................................... iii TABLE OF CONTENTS ........................................................................................................ iv LIST OF FIGURES ................................................................................................................. vi LIST OF TABLES .................................................................................................................. vii Chapter 1 INTRODUCTION ................................................................................................................... 1 1.1 Tectonic setting of Iceland ............................................................................................... 1 1.2 Volcanoes beneath the Vatnajokull glacier ...................................................................... 2 1.3 Aims and structure of this thesis....................................................................................... 5 Chapter 2 DATA DESCRIPTION .......................................................................................................... 11 2.1 The HOTSPOT seismic network .................................................................................... 11 2.2 Data pre-processing ........................................................................................................ 11 2.3 Calculation of centroid frequency .................................................................................. 12 Chapter 3 VELOCITY MODEL, EARTHQUAKE LOCATIONS AND MOMENT TENSOR INVERSION ........................................................................................................................... 16 3.1 Estimation of minimum 1D velocity model ................................................................... 16 3.2 Absolute locations .......................................................................................................... 18 3.2.1 Method .................................................................................................................. 18 3.2.2 Results ................................................................................................................... 20 3.3 Relative locations ........................................................................................................... 21 3.3.1 Method .................................................................................................................. 21
3.3.2 Results ................................................................................................................... 24
3.4 Moment tensor inversions .............................................................................................. 25
3.4.1 Method .................................................................................................................. 25
3.4.2 Results ................................................................................................................... 26
Chapter 4
DISCUSSION AND CONCLUSIONS .................................................................................. 43
4.1 Interpretation of seismicity ............................................................................................. 43
4.2 Conclusions .................................................................................................................... 45
REFERENCES ....................................................................................................................... 48
Appendix A.............................................................................................................................. 53
Appendix B .............................................................................................................................. 54
Appendix C.............................................................................................................................. 64
Appendix D.............................................................................................................................. 71

參考文獻

Agustsdottir, T., Woods, J., Greenfield, T., Green, R. G., White, R. S., Winder, T.,
Brandsdottir, B., Steinthorsson, S., & Soosalu, H., (2016). Strike-slip faulting
during the 2014 Barearbunga-Holuhraun dike intrusion, central Iceland. Geophys.
Res. Lett., 43, 1495-1503 pp. doi:101.1002/201GL067423.
Alfaro, R., Brandsdottir, B., Rowlands, D. P., White, R. S., & Gudmundsson, M. T.,
(2007). Structure of the Grimsvotn volcano under the Vatnajokull icecap.
Geophys. J. Int., 168, 863-876 pp.
Allen, R. M., Nolet, G., Morgan, W. J., Vogjord, K., Nettles, M., Ekstrom, G., Bergsson,
B. H., Erlendsson, P., Foulger, G. R., Jakobsdottir, S., Julian, B. R., Pritchard, M.,
Ragnarsson, S., & Stefansson, R., (2002). Plume-driven plumbing and crustal
formation in Iceland. J. Geophys. Res., 107, B8. doi: 1029/2001JB000584.
Bjarnason, I.T., Menke, M., Flovenz, O. G., & Caress, D., (1993). Tomographic image
of the Mid-Atlantic plate boundary in southwestern Iceland. J. Geophys. Res., 98,
6607-6622 pp.
Bjarnason, I. T., & Schmeling, H., (2009). The lithosphere and asthenosphere of the
Iceland hotspot from surface waves. Geophys. J. Int., 178, 394-418 pp.
doi:10.1111/j.1365-246X.2009.04155.x.
Bjornsson, H., (1988). Hydrology of ice caps in volcanic regions. Soc. Sci. Isl.
Reykjavik., 45, 139.
Bjornsson, H., & Einarsson, P., (1990). Volcanoes beneath Vatnajokull, Iceland:
Evidence from radio echo-sounding, earthquakes, and jokulhlaups. Jokull., 40,
147-167 pp.
Bjornsson, H., & Gudmundsson, M. T., (1993). Variations in thermal outputs of the
subglacial Grimsvotn caldera, Iceland. Geophys. Res. Lett., 20, 2127-2130 pp.
Bjornsson, H., Gudmundsson, M. T., Palsson, F., & Flowers, G. E., (2001). The
extraordinary jokulhlaups from Grimsvotn, Vatnajokull, Iceland. AGU Fall
Meeting Abstracts., 1, 0667.
Einarsson, P., (2001). Structure and evolution of the Iceland hotspot. Deutsche
Geophysikalische Gesellschaft., 1/2001, 11-14 pp.
Einarsson, P., (2008). Plate boundaries, rifts and transforms in Iceland. Jokull., 58, 35-
58 pp.
Einarsson, P., Brandsdottir, B., Gudmundsson, M. T., Bjornsson, H., Gronvold, K., &
Sigmundsson, F., (1997). Center of the Iceland hotspot experiences volcanic
unrest. EOS. Transactions. AGU., 78, 369, 374-375 pp.
Glynn, C. C., & Konstantinou, K. I., (2016). Reduction of randomness in seismic noise
as a short-term precursor to a volcanic eruption. Sci. Rep., 6, 3773. doi:
10.1038/srep37733.
Gomberg, J. S., Shedlock, K. M., & Roecker S. W., (1990). The effect of S-wave arrival
times on the accuracy of hypocentre estimation. Bull. Seism. Soc. Am., 80, 6,
1605-1628 pp.
Got, J., Frechet, J., & Klein, F. W., (1994). Deep fault plane geometry inferred from
multiplet relative relocation beneath south flank of Kilauea. J. Geophys. Res., 99,
375-386 pp.
Gudmundsson, A., (1995). Infrastructure and mechanics of volcanic systems in Iceland.
J. Volcanol. Geotherm. Res., 64, 1-22 pp.
Gudmundsson, A., (2007). Conceptual and numerical models of ring-fault formation.
Volcanol. Geotherm. Res., 164, 142-160 pp.
Gudmundsson, M. T., Bjornsson, H., & Palsson, F., (1995). Changes in jokulhlaups
sizes in Grimsvotn, Vatnajokull, Iceland, 1934-1991, deduced from in-situ
measurements of subglacial lake volume. J. Glaciology., 41, 263-272 pp.
Gudmundsson, M. T., & Hognadottir, T., (2007). Volcanic systems and calderas in the
Vatnajokull region, central Iceland: Constraints on crustal structure from gravity
data. J. Geodyn., 43, 1, 153-169 pp. doi: 10.1016/j/jog.2006.09.015.
Gudmundsson, M. T., Sigmundsson, F., Bjornsson, H., & Hognadottir, T., (2004). The
1996 eruption at Gjalp, Vatnajokull ice cap, Icecland: Efficiency of heat transfer,
ice deformation and subglacial water pressure. Bull. Volcanol., 66, 1, 46-65 pp.
doi: 10.1007/s00445-003-0295-9.
Gudmundsson, M. T., Sigmundsson, F., & Bjornsson, H., (1997). Ice volcano
interaction of the 1996 Gjalp eruption, Vatnajokull, Iceland. Nature., 389, 954-957
pp.
Hermann, R., & Ammon, C. J., (2002). Computer programs in seismology user′s guide. Department of Earth and Atmospheric Sciences, Saint Louis University, United
States.
Jakobsson, S., (1979). Petrology of recent basalts of the eastern volcanic zone, Iceland.
Acta Nat. Isl., 26, 103 pp.
Johannesson, H., Jakobsson, S. P., & Samundsson, K., (1990). Geological map of
Iceland, sheet 6, South Iceland, 3rd edn, Icelandic Museum of Natural History and
Iceland Geodetic Survey, Reykjavik.
Johannesson, H., & Samundsson, K., (1998). Jardfraedikort af Islandi. Hoggun
(Geological map of Iceland. Tectonics). Reykjavk: Natturfraedistofunu Islands
(Icelandic Institute of Natural History).
Jost, M. L., & Hermann, R. B., (1989). A student′s guide to and review of moment
tensors. Seism. Res. Lett., 60, 37-57 pp.
Kissling, E., (1988). Geotomography with local earthquake data. Rev. Geophys., 26,
659-698 pp.
Kissling, E., (1995). Program VELEST user’s guide-short introduction. Institute of
Geophysics, ETH Zurich, Zurich, 25 pp.
Kissling, E., Ellsworth, W. L., Eberhart-Phillips, D., & Kradolfer, U., (1994). Initial
reference models in local earthquake tomography. J. Geophys. Res., 99, 19 635-19
646 pp.
Konstantinou, K. I., Kao, H., Lin, C., & Liang, W., (2003). Analysis of broad-band
regional waveforms of the 1996 September 29 earthquake at Bardarbunga
volcano, central Iceland: inverstigation of the magma injection hypothesis.
Geophys. J. Int., 154, 134-145 pp.
Konstantinou, K. I., Nolet, G., Morgan, W. J., Allen, R. M., & Pritchard, M. J., (2000).
Seismic phenomena asssociated with the 1996 Vatnajokull eruption, central
Iceland. J. Volcanol. Geotherm. Res., 102, 169-187 pp. doi: 10.1016/s0377-
0273(00)00187-6.
Larsen, G., (2002). A brief overview of eruptions from ice-covered and ice-capped
volcanic systems in Iceland during the past 11 centuries: Frequency, periodicity
and implications. Geological Society., 202, 1, 81-90 pp.
doi:10.1144/gsl.sp.2002.202.01.05.
Lomax, A., & Curtis, A., (2001). Fast, probabilistic earthquake location in 3D models using oct-tree importance sampling. Geophys. Res. Abstr., 3.
Lomax, A., Virieux, J., Volcant, P., & Thierry-Berge, C., (2000). Probabilistic
earthquake location in 3D and layered models, in Advances in seismic events
location. 101-134 pp. Eds: Thurber, C. H., Rabinowitz, N., & Kluwer Acad.,
Norwell, MA, USA.
Martin, H., Simone, C., Sebastian, H., Eleonora, R., Vala, H., Kristin, J., Kristin V., &
Torsten, D., (2015). Earthquake focal mechanisms associated with dyke
propagation and caldera collapse at the Barearbunga volcano, Iceland. Geophys.
Res., 17, EGU2015-5854-1.
Menke, W., (1989). Geophysical data analysis: Discrete inverse theory. 1St Edition. San
Diego: Academic Press, 289 pp.
Nettles, M., & Ekstrom, G., (1998). Faulting mechanism of anomalous earthquake near
Barearbunga Volcano, Iceland. J. Geophys. Res., 103(B8), 17 973-17 983 pp.
Oskarsson, N., Sigvalason, G. E., & Steinthorsson, S., (1982). A dynamic model of rift
zone petrogenesis and the regional petrology of Iceland. J. Petr. Special Issue., 23,
28-74 pp.
Oskarsson, N., Steinthorsson, S., & Sigvaldason, G. E., (1985). Iceland geochemical
anomaly: Origin, volcanotectonics, chemical fractionation and isotope evolution
of the crust. J. Geophys. Res., 90, B12. doi: 10.1029/jb090ib12p10011.
Paige, C. C., & Saunders, M. A., (1982). LSQR: An algorithm for sparse linear
equations and sparse least squares. ACM Transactions on Mathematical Software,
8, 1, 43-71 pp.
Torbjarnardottir, B. S., Bjarnason, I. T., & Einarsson, P., (1997). Seismic tremor in the
Vatnajokull Region in 1995–1996. Report., Science Institute, University of
Iceland, RH-03–97, 37 pp
Pritchard, M. J., (2000). A seismological study of the mantle beneath
Iceland. PhD Thesis. University of Durham.
Riel, B., Milillo, P., Simons, M., Lundgren, P., Kanamori, H., & Samsonov, S., (2015).
The collapse of the Barearbunga caldera, Iceland. Geophys. J. Int., 202, 446-453
pp.
Ruch, J., Wang, T., Xu, W., Hensch, M., & Jonsson, S., (2016). Oblique rift opening
revealed by reoccuring magma injetion in central Iceland. Nature., 7, 12352. doi: 10.1038/ncomms12352.
Samundsson, K., (1978). Fissure swarm and central volcanoes of the neovolcanic zones
of Iceland. Geol. J. Special Issue., 19, 415-432 pp.
Shen, Y., Solomon, S. C., Bjarnason, I. T., & Wolfe, C. J., (1998). Seismic evidence for
a lower-mantle origin of the Iceland plume. Nature., 395, 62-65 pp.
Steinthorsson, S., Hardaeson, B., Ellam, R., & Larse, G., (2000). Petrochemistry of the
Gjalp-1996 subglacial eruption, Vatnajokull, SE Iceland. JVGR., 98, 79-90 pp.
Tarantola, A., & Valette, B., (1982). Inverse problems = Quest for information, J.
Geophys., 50, 159-170 pp.
Tarraga, M., Carniel, R., Ortiz, R., Marrero, J. M., & Garcia, A., (2006). On the
predictability of volcano-tectonic events by low frequency seismic noise analysis
at Teide-Pico Viejo volcanic complex, Canary Islands. Natural Hazards and Earth
System Science, 6, 3, 365-376 pp. doi:10.5194/nhess-6-365-2006.
Thordarson, T., & Hoskuldsson, A., (2002). Iceland. Hertfordshire: Terra Publishing.
Thordarson, T., & Larsen, G., (2007). Volcanism in Iceland in historical time: Volcano
types, eruption styles and eruptive history. J. Geodyn., 43, 1, 118-152 pp.
doi:10.1016/j.jog.2006.09.005.
Tkal?i?, H., Dreger, D., Foulger, G. R., & Julian, B. R., (2009). The puzzle of the 1996
Bardarbunga, Iceland, earthquake: No volumetric component in the source
mechanism. Bull. Seis. Soc., 99, 5, 3077-3085 pp.
Tkal?i?., H., & Fichtner, A., (2010). Insights into the kinematics of a volcanic caldera
drop: Probabilistic finite-source inversion of the 1996 Barearbunga, Iceland,
earthquake. Earth. Planet. Sci. Lett., 297, 607-615 pp.
Tryggvason K., Husubye, E. S., & Stefansson, R., (1983). Seismic image of the
hypothesized Icelandic hotspot. Tectonophysics., 100, 97-118 pp.
Waldhauser, F., (2001). HypoDD: A program to compute double-difference hypocentre
locations. U.S geological survey., Open file report., 1, 113.
Waldhauser, F., & Ellsworth, W. L., (2000). A double difference earthquake location
algorithm: Method and application to the northern Hayward fault, California,
Bull. Seism. Soc. Am., 90, 6, 1353-1368 pp.
Wolfe, C. J., Bjarnason, I., Vandecar, J., & Solomon, S. C., (1997). Seismic structure of
the Iceland mantle plume. Nature., 385, 6613, 245-247 pp. doi:10.1038/385245a.

指導教授

柯士達(K. I. Konstantinou)

審核日期

2018-7-18

推文