U N I V E R S I D A D E D O S A Ç O R E S S I C U T A U R O R A S C I E N T I A L U C E T Ponta Delgada 2018 The use of infrasound in volcano monitoring. Contribution for future application in the Azores Islands Dissertação de Mestrado Sandro Branquinho de Matos Vulcanologia e Riscos Geológicos Mestrado em
22
Embed
The use of infrasound in volcano monitoring : contribution ...€¦ · The use of infrasound in volcano monitoring. Contribution for future applic ation in the Azores Islands Dissertação
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
UN
IVERSIDADE DOS AÇ
OR
ES
SIC
UT A
URORA SCIENTIA LUCE
T
Ponta Delgada 2018
The use of infrasound in volcano monitoring.
Contribution for future application in the Azores Islands
Contribution for future application in the Azores Islands Dissertação de Mestrado
Orientadores
Doutor Nicolau Maria Berquó de Aguiar Wallenstein Professor Auxiliar, Universidade dos Açores Doutor Maurizio Ripepe Professor in Geophysics, UniFi -Università degli Studi di Firenze
Dissertação de Mestrado submetida como requisito parcial para obtenção do grau de Mestre em Vulcanologia e Riscos Geológicos
Sandro Branquinho de Matos
Table of Contents
I
TABLE OF CONTENTS
LIST OF FIGURES …………………………………………………………..……………………………………………………… V
LIST OF TABLES …..………………………………………………………………………………………………………….….. X
LIST OF PHOTOGRAPHIES ………………………………………………………………………………………………..… XI
LIST OF ACRONYMS ……………………………………………………………………………………………………….… XII
ACKNOWLEDGEMENTS ………………………………………………………………………………………………….. XIV
ABSTRACT ………………………………………………………………………………………………………………………. XVI
RESUMO …………………………………………………………………………………………………………………….…. XVII
CHAPTER 1. INTRODUCTION
1.1. Framework and objectives of the work ……………………………….……………………………………………...... 1
1.1.1. Motivation ………………………………………………………………………………………………………………….……………….….. 1 1.1.2. Study relevance …………………………………………………………………………………………………………………………..….. 1 1.1.3. Research objectives …………………………………………………………………………………………………………………………. 2 1.1.4. Dissertation structure and organization …………………………………………………………………………………………..… 2
2.4. Atmosphere and Infrasound propagation ……………………………………………………………………………..…..….. 17
2.4.1. General concepts …………………………………………………………………………………..……………………………….…….. 17
2.4.1.1. Chemical composition of the atmosphere …………………………………………………………………….……….. 17 2.4.1.2. Thermal structure of the atmosphere ……………………………………………………………………………………. 18
2.4.2. Effects of winds in the propagation of infrasound …………………………………………………………………………….. 20 2.4.3. Waveguides ………………………………………………………………………………………………..……………………………….. 22 2.4.4. Infrasonic phases ……………………………………………………………………………..…………………………………….…….. 23
Table of Contents
II
CHAPTER 3. IMS INFRASOUND STATIONS
3.1. The Background ………………………………………………….…………………………………………………………………………... 26
4.2.3.1.1.1. Microbarometer …………………………………………………………..……………………….….. 56 4.2.3.2. The Central recording Facility (CRF) ……………………………………………………..…………………………..….. 57
4.3. The ETN infrasound station ……………………………………..……………………………………………………..…………….… 57 4.3.1. The ETN infrasonic array ……………………………………………………………………………………………………………….... 58
4.4. Data Processing ……………………………………………………………………………………………………………………….…….… 58
4.4.1. Data preparation …………………………………………………………………………………………………………………………... 59 4.4.2. Processed data files organization ………………………………………………………..………………………………………...… 59 4.4.3. The use of GPMCC and MATLAB software in data analysis …………………….……………………………………….… 59
5.2.1.1. Geographic location ………………………………………………………………………………………………………….….. 74 5.2.1.2. Geological Framework ………………………………………………………………………………………………………….. 75 5.2.1.3. The Mount Etna Volcano …………………………………………………………………………………………….………... 75
5.2.2. The 2011 May – August lava fountaining activity detections …………………………………………………………...... 78
5.2.2.1. Data collection ……………………………………………………………………………………………………………………… 78 5.2.2.2. Framework of volcano and local infrasonic activity …………………………………………..………………….….. 79 5.2.2.3. Data analysis ………………………………………………………………………………………………………………………... 83
5.2.3. The 16th to 26th May 2016 eruptive activity ………………………………………………………….…….…………………….. 92
5.2.3.1. Data collection ……………………………………………………………………………………………………………….…….. 92 5.2.3.2. Framework of volcano and local infrasonic activity …………………………………………………………………... 92 5.2.3.3. Data analysis …………………………………………………………………………………………………………………….….. 96
APPENDIX 05 - PMCC_conf_file used in GPMCC ...................................................................................................................... A-9
APPENDIX 06 - Some infrasound studies about volcanoes ...................................................................................................... A-13
Fig. 2.6 - a) Two explosions recorded at IS42 (elements H1-H4); and b) Spectrogram of the two explosions (elements H1 to H4) (Wallenstein & Campus, 2017). ……………………………………………………………………………..………………………………...…….. 12
Fig. 2.7 - Diagram illustrating that compressions and rarefactions are respectively regions of higher and lower than normal atmospheric pressure (https://www.physicsforums.com, adapted). .………………………………...…………..……………………….. 14
Fig. 2.8 - Temperature profile of a standard atmosphere (http://pangeaplusgeo.weebly.com/a-layers.html). ………... 18
Fig. 2.9 - a) The sound speed in the atmosphere that results from the temperature profile is shown vs. Altitude. b) Northern hemisphere typical atmospheric profile with the primary layers of the atmosphere and (b, c) their seasonal variation (adapted from Waxler, 2016). …………………………………………………………………………………………………….……....…….………….. 21
Fig. 2.10- Directions of zonal wind in North Hemisphere (e.g.over Europe) depending on the season (Mialle, 2007). …. 21
Fig. 2.11- Waveguide is any region in which a layer of smaller sound velocity is bounded above or below by regions of higher velocity and the Earth’s surface (CTBTO, 2009). ………………………………….………………………………………..……………………..….. 22
Fig. 2.12 - Simulations of the propagation of infrasound in the atmosphere (CTBTO, 2009). ……………………………...…..….. 25
Fig. 3.1 - CTBT treaty book and text on the establishment of a Preparatory Commission for the CTBTO (image from https://www.ctbto.org/the-treaty/treaty-text/). …………………………………………………………………..……..…………………….….. 27
Fig. 3.2 - IMS infrasound stations network on 01 October 2018 (adapt. from https://www.ctbto.org). …………….…….….. 28
Fig. 3.3 - Basic Infrasound station elements (CTBTO, 2017). See text for description of the different components of the station. ………………………………………………………………………………………………………………………………………………...………….….. 30
Fig. 3.4 - Possible configurations of Infrasound arrays. They depend on local conditions and logistical issues. Stations located in high wind areas or on islands often require more array elements to improve their detection capability (CTBTO, 2009). …………………………………………………………………………………………………..……………………………………………………………....…….….. 32
Fig. 3.5 - Array layout and array response of a 4-Element station (1st and 2nd images from the left), and an array layout and response for an eight-element pentagon main array with a triangular subarray (3rd and 4th images from the left) (CTBTO, 2009). ……………………………………………………………………………………………………………………..…………………………...………….….. 34
Fig. 3.7 - Temperature profiles during the day (BCD; inversion between CB) and night (AB; inversion). The temperature increase during the day in the surface layer is one mechanism for driving wind (Walker & Hedlin, 2010). ………..…….…... 36
Fig. 3.8 - Regional influences affect the wind in the interior of the continents during the day, due to variations of solar heating near the surface, (Walker & Hedlin, 2010). …………………………………………………………………………………………………….…...….. 36
Fig. 3.9 - Regional influences on coastal winds during the day lead to convective systems at night. (Walker & Hedlin, 2010). ………………………………………………………………………………………………………………………………………………………………………..…….. 37
Fig. 3.10 - Examples of some of the wind-noise-reducing systems (WNRS) used at stations in the IMS infrasound network (adapted from Christie & Campus, 2010). ……………………………………………………………………………………………………………….. 38
Fig. 3.14 - Example of a signal pictured in time-domain graphic (left) with amplitude (vertical axis) versus time (horizontal axis) (https://www.erzetich-audio.com/knowledgebase-05-time-vs-frequency.html) …………………………..…………….….... 42
Fig. 4.6 - Frequency response of the MB2005 sensor (CEA-DASE, 2017). …..…………………………………………….………….….. 57
Fig. 4.7 - A) ETN position map (white star), geometry (inset) of the array and B) back-azimuth of the five main ative vents and effusive fracture (EF) of 2008 (Uliveri et al., 2013). ..………………………………………………………………….………………….………….. 58
Fig. 4.8 - DTK-GPMCC main window display: (1) toolbar, where can access to general tools; (2) Station Tabs (can be more than one); (3) Detection Atributte Pixels panels, where processed PMCC detection atributes are displayed; (4) Waveform and Arrival Picks, where recorded waveform and detected arrival time are displayed. ………………………………………………. 62
Fig. 4.9 - Fiftheen-bands with logarithmically spaced filter parameters configuration (0.07 Hz-4 Hz) with variable window length. On the left side the frequency bands attributes are displayed. On the right side the frequency response (magnitude and phase) filters are shown. …………………………………………………………………………………………..…………………………………….. 63
List of Figures
VII
Fig. 4.10 - List of mat files examples of that resulted from the conversion of wfdisk files to be readable by the MatLab software (in this case related to Grímsvötn activity). …………………………………………………..…………..……………………………….. 65
Fig. 4.11 - a) m-file script example for H4, H7 and H8, and b) final image plot correlation signal between H4, H7 and H8 IS42 array sensors recorded on 19/05/2016. ……………………………………………………………………………………………………………….... 66
Fig. 4.12 - Example of plot back-azimuths detections on 17-23 May 2016 from station IS42 filtered between 50° and 150 ° degrees. ……………………………………………………………………………………………………………………………….……………………………... 66
Fig. 5.1 - Grimsvötn and Mt. Etna locations relative to IS42 (Matos et al., 2017). ………………………………………………………. 67
Fig. 5.2 - Sicily Island location (Esri®). …………………………………………………………………….……………………………………………..…. 74
Fig. 5.3 - Mount Etna location and Central Mediterranean geological-structural scheme: 1) Regional overthrust of the Sardinia-Corsica block upon Calabride units; 2) Regional overthrust of the Kabilo-Calabride units upon the Apenninic- Maghrebian chain; 3) External front of the Apenninic-Maghrebian chain upon the Foreland units and the External Thrust System; 4) Thrust front of the External Thrust System; 5) Main normal and strike-slip faults (Branca et al., 2011a). ....….. 75
Fig. 5.4 - a) Sicily island and Etna region (red square); b) Schematic map of Mt Etna main faults (modified from Azzaro et al., 2012): PPFS - Pernicana Provenzana Fault System; TFS - Timpe Fault System; VdB - Valle del Bove; c) The central craters (orange square on b): NEC - Northeast Crater; BN - Bocca Nuova crater; VOR - Voragine crater; SEC - Southeast crater; NSEC - New Southeast crater (PIT crater); and the new Southeast 3 (SEC3 or Cono della sella). The yellow dots indicate the location of degassing apertures of BN, VOR, NSEC and SEC3 (INGV, 2017); d) Eruptive fissures and pyroclastic cones distribution on Mt. Etna Volcano (Azzaro et al., 2012). ……………………………………………………………………………..……………………………………. 76
Fig. 5.5- IS42 detections on 11th and 12th May, based on the expected travel time and back-azimuth. …..…………….……. 83
Fig. 5.6 - Infrasonic parameter (IP) timeline on 11th and 12th May. …………………………………..……………………………………….. 83
Fig. 5.7 - IS42 detections on 9th July, based on the expected travel time and back-azimuth. ………………………….………..….. 84
Fig. 5.21 - IS42 detections on 29th August, based on the expected travel time and back-azimuth. ………..…………..…..…….. 91
Fig. 5.22 - Infrasonic parameter (IP) on 28th and 29th August. ……………………………………….…………………………………….…….. 91
Fig. 5.23 - PMCC back-azimuths results between 16th and 26th May 2016. …………………….………………………………………….. 96
Fig. 5.24 - IS42 detections on 17th and 18th May, based on the expected travel time and back-azimuth. …………….…….….. 96
Fig. 5.25 - IS42 detections on 17th and 18th May, associated to selected back-azimuths and clusters of detections. ……... 97
Fig. 5.26 -ETN IP parameter on 17th and 18th May, associated to selected back-azimuths and clusters of detections. ……. 97
Fig. 5.27 - IS42 detections on 19th May, based on the expected travel time and back-azimuth. ………………………………….. 98
Fig. 5.28 - a) IS42 detections on 19th May, related to selected back-azimuths and b) ETN IP parameter on 19th May. ….... 98
Fig. 5.29 - Iceland main topographic and batimetric map features (Esri®). …………………………………………………………..…….. 99
Fig. 5.30 - Orographic map of Iceland with the main glaciers. Smaller glaciers are on the icecaps. 1-Vatnajökull (8.160 km2); 2 - Langjökull (950 km2); 3 - Hofsjökull (925 km2); 4 - Mýrdalsjökull (596 km2); 5 - Eyjafjallajökull (77 km2); 6 - Drangajökull (160 km2); 7 - Snæfellsjökul (7 km2). lnlet: Geological map showing the active volcanic zone and the central volcanoes. Adapt from Bjornsson & Pálsson, 2008. ………………………………………………………………………………………………………………………………….. 100
Fig. 5.31 - Iceland Basalt Plateau lies at the junction between submarine segments of the Middle Atlantic Ridge, the Reykjanes Ridge to the south and the Kolbeisey Ridge to the north. The line with the small circles shows the progressive position of the Iceland mantle plume from 65 million years until the actuality. Modified by Sauders et al., 1997 and adapted from Thordarson and Larsen, 2007. ……………………………………………………………………………………………………………..……….. 101
Fig. 5.32 - Geological map of Iceland with 30 volcanic systems. Main geological formation divisions and rift zones. RR, Reykjanes Ridge; KR, Kolbeinsey Ridge; RVB, Reykjanes Volcanic Belt; SISZ, South Iceland Seismic Zone; WVZ, West Volcanic Zone; MIB, Mid-Iceland Belt; NVZ, Northern Volcanic Zone; ÖVB, Örœfi Volcanic Belt; EVZ, Eastern Volcanic Zone; SVB, Snœfellsnes Volcanic Belt; TFZ, Tjörnes Fracture Zone. The Grímsvötn volcanic system (19) is located near the vertical axis of the current mantle plume. (Based on Jóhannesson and Sæmundsson (1998b) and Thordarson & Hoskuldsson, 2008). .. 103
Fig. 5.33 - 2011 IS42 detections between 21th and 28th May, based on the expected travel time and back-azimuth. …... 108
Fig. 5.34 - IS42 detections 21st May, based on the expected travel time and back-azimuth. …………………………………….… 108
Fig. 5.35 - 21st May detections between 21:59 UTC and 23:59 UTC, with 19 families selected, a speed of 372 m/s, a mean back-azimuth of 18° and a mean frequency of 0.70 Hz b) polar plot according to back-azimuth (polar angle) and trace velocity (polar radius) related to detections time; c) polar plot of pixels families detections related to back-azimuth, speed and frequency. ……………………………………………………………………………………………………………………………………………..……….….. 109
Fig. 5.36 - IS42 detections on 22nd May, based on the expected travel time and back-azimuth. ……………………..……...…... 109
List of Figures
IX
Fig. 5.37 - 22nd May detections between 21:59 UTC and 23:59 UTC, with 19 families selected, a speed of 372 m/s, a mean back-azimuth of 18° and a mean frequency of 0.70 Hz b) polar plot according to back-azimuth (polar angle) and trace velocity (polar radius) related to detections time; c) polar plot of pixels families detections related to back-azimuth, speed and frequency. ……………………………………………………………………………………………………………………………………………..…………... 110
Fig. 5.38 - IS42 detections on 23rd May, based on the expected travel time and back-azimuth. …..…………...................….. 111
Fig. 5.39 - 23rd May detections between 00:00 UTC and 23:05 UTC, with 21 families selected, a speed of 375 m/s, a mean back-azimuth of 14.82° and a mean frequency of 0.74 Hz b) polar plot according to back-azimuth (polar angle) and trace velocity (polar radius) related to detections time; c) polar plot of pixels families detections related to back-azimuth, speed and frequency. ………………………………………………………………………………………………………………………………………………...….. 111
Fig. 5.40 - IS42 detections on 24th May, based on the expected travel time and back-azimuth …………………………....…….. 112
Fig. 5.41 - 24th May detections between 00:00 UTC and 23:05 UTC, with 4 families selected, a speed of 375 m/s, a mean back-azimuth of 14.82° and a mean frequency of 0.74 Hz b) polar plot according to back-azimuth (polar angle) and trace velocity (polar radius) related to detections time; c) polar plot of pixels families detections related to back-azimuth, speed and frequency. ……………………………………………………………………………………………………………………………………………….….. 112
Fig. 5.42 - IS42 detections on 25th May, based on the expected travel time and back-azimuth. ……….…………………....….. 113
Fig. 5.43 - May 25th detections between 00:00 UTC and 23:05 UTC, with 4 families selected, a speed of 375 m/s, a mean back-azimuth of 14.82° and a mean frequency of 0.74 Hz b) polar plot acording to back-azimuth (polar angle) and trace velocity (polar radius) related to detections time; c) polar plot of Pixels Families detections related to back-azimuth, speed and frequency. …………………………………………….……………………………………………………………………………………………….….... 113
Fig. 6.1 - Volcanic activity in REB (IDC-CTBTO) on 19th and 25th July 2011 in the Sicily region. 19th - Red line: stations that recorded the 00:51 UTC event; 25th - Yellow line: stations that recorded the 04:25 UTC event (Matos et al., 2017). ………………………………………………………………………………………………………………………………………………………..……………….…. 115
Fig. 6.2. - a) I42PT back-azimuth detections between 16th and 25th May 2016 showing the Mount Etna back-azimuth (red line) and the three analysed clusters of detections; b) Early-Warning System principal stages; c) ETN array IP-Infrasonic parameter timeline: Strombolian phase (1), Lava-fountain activity (2,3,5), strong explosive activity (4) (Matos et al., 2017). …………………………………………………………………………………………………………………………………………………………………….….….. 119
Fig. 6.3 - Volcanic activity in REB (IDC) on 21st to 22nd May 2011 in Grímsvötn region activity. Day 21st, Orange line: stations that recorded the 19:16 UTC event; Blue line: stations that recorded the 21:25 UTC event; Day 22nd , Green line: stations that recorded the 01:40 UTC event; Red line: stations that recorded the 04:49 UTC event; Yellow line: stations that recorded the 05:49 UTC event (Matos et al., 2017). ………………………………………………………………………………………………………………...... 122
Fig. 6.4 - Example of microbaroms recorded at IS42 on 2017/09/08 (Wallenstein & Campus, 2017). ………………………… 124
Fig. 6.5 – Signal recorded during a strong geomagnetic storm, showing a large perturbation with frequencies between 0.01 and 0.1 Hz (compatible to aurora-genetated infrasound (Wallenstein & Campus, 2017). …………………………………………… 125
Fig. 6.6 – Example of an event with a local magnitude of 5.9 occurred in Azores Archipelago showing seismic arrivals at IS42 recorded on 2013/04/30 and compatible with surface waves propagation. Data was filtered between 0.4 and 4 Hz (Wallenstein & Campus, 2017). …………………………………………………………………………………………………………………………… 125
List of Tables
X
LIST OF TABLES
Table 2.1 - Sound propagation velocity in various types of materials. …………………………………………………………………….. 15
Table 2.2 - Composition of the Atmosphere near the Earth´s surface. ……………………………..…………………………………….. 18
Table 2.3 - Phases designations, maximum infrasound refraction altitudes to the ground by phase type and characteristic values of celerity. …………………………………………………………………………………….……………………………………………………….... 23
Table 4.1 - Name and sources locations of study volcanoes. ………………………………………..………..……………………………... 49
Table 5.1 - Mount Etna activity cronology from May to August 2011 used in this study. .……………………………………...… 78
Table 5.2 - IS42 main detection parameters on 11th and 12th May. ……………….…………………………..…………………….…….. 83
Table 5.3 - IS42 main detection parameters on 9th July. …………………………………………………..…………………………...…..….. 84
Table 5.4 - IS42 main detection parameters on 19th July. …………………………………………………………………………….…....….. 85
Table 5.5 - IS42 main detection parameters on 24th and 25th July. …………..…………………………..……………………………..….. 86
Table 5.6 - IS42 main detection parameters on 30th July. ……………………………………….……………………………..………...…….. 87
Table 5.7 - IS42 main detection parameters on 5th and 6th August. ………………..………………………………………………...…….. 88
Table 5.8 - IS42 main detection parameters on 12th August. …………………………………..……………………………………..…….... 89
Table 5.9 - IS42 main detection parameters on 20th August. ………………………..………………………………………………….……. 90
Table 5.10 - IS42 main detection parameters on 29th August. ………………………………………………………………………..…….... 91
Table 5.11 - Etna activity chronology in May 2016 used in this study. …………………………………………………………………….. 92
Table 5.12 -ETN IP parameter on May 17th and 18th related to selected back-azimuths. ………………………………………..... 97
Table 5.13 - 30 volcanic systems of Iceland. ModifiedThordarson & Höskuldsson (2008). ……………………………………..….. 104
Table 5.14 - Grimsvötn activity chronology in May 2011 used in this work. ………………………………………………………….. 107
Table 5.15 - IS42 main detection parameters on 22nd May (Grimsvötn activity). ….…..……………..……………………….…... 110
Table 5.16 - IS42 main detection parameters on 23rd May (Grimsvötn activity). ……………….…………………………..…….... 111
Table 5.17 - IS42 main detection parameters on 24th May (Grimsvötn activity). …….…………………………………….……….. 112
Table 6.1– Resume of the comparison between 2011 May – August detections on IS42 with ETN station and UniFi/ Protezione Civile Nazionale bulletins. ………………………………………………………………………………………………….…………...… 116
Table 6.2 –Resume of the comparison between May 2016 detections on IS42 with ETN array and UniFi/ Protezione Civile Nazionale bulletins. ……………………………………………………………………………………………………………………………………..…... 120
Table 6.3 - May 2011 resume table of comparison between IS42 detections with IMO bulletins …………………………... 123
List of Photographies
XI
LIST OF PHOTOGRAPHIES
Photo 1.1 - Frank Perret (1867-1943) at the Campi Flegrei in Pozzuoli, Italy, with an improvised "geophone” in hopes of detecting magma’s subterranean movements. Here, using a microphone to amplify the sounds from the earth interior, he connected a cable from the geophone to the loudspeaker on his ear. …………………………………………………………………..…... 1
Photo 3.1 - IS42 Infrasound station in Graciosa Island, Acores, Portugal, I42H7 element. ……………………..…………………... 26
Photo 4.1 – Detail of I42H1 (Photo IVAR). …………………………………………………………………………………..……………………….….. 48
Photo 4.2 – IS42 was installed in heavily forested area. Pico do Timão scoria cone in the background (photo from Nicolau Wallenstein). ………………………..……………………………………………………………………………………………………………………….…….. 51
Photo 4.3- WNRS pipes and manifold. ………………………..…………………………………………………………………………………..….….. 55
Photo 4.4- I42H8 station element before and after putting gravel on stainless steel pipes and on inlet ports. …………………………………………………………………………………………………………………………………………………………………………………55