gns science report 2013-046.pdf · the gns science ggw database contains a number of locations in...

© Institute of Geological and Nuclear Sciences Limited, 2013

ISSN 1177-2425 ISBN 978-1-972192-93-1

J. Rose, GNS Science, Private Bag 2000, Taupo 3352 (current address: 4544 County Road 25 SW, Hoffman, Minnesota, USA 56339). G. Zemansky, GNS Science, Private Bag 2000, Taupo 3352 (current address: Prime Hydrogeology Ltd., 119 Lakewood Drive, Taupo)

BIBLIOGRAPHIC REFERENCE

Rose, J., Zemansky, G. 2013. Potential effects of volcanic activity on level and quality of associated groundwater, GNS Science Report 2013/46. 22 p.

GNS Science Report 2013/46 i

CONTENTS

ABSTRACT ........................................................................................................................... II

KEYWORDS .......................................................................................................................... II

1.0 INTRODUCTION ........................................................................................................ 1

2.0 LITERATURE REVIEW .............................................................................................. 2

2.1 Groundwater Level Monitoring Around Volcanoes ........................................................ 2 2.2 Groundwater Chemistry Monitoring Around Volcanoes ................................................ 3

3.0 EXISTING MONITORING DATASETS WITHIN NEW ZEALAND ............................... 6

3.1 Ruapehu ........................................................................................................................ 6 3.1.1 Well Information................................................................................................. 6 3.1.2 Water Quality Data ............................................................................................ 8

3.2 Tongariro ....................................................................................................................... 9 3.2.1 Well Information................................................................................................. 9 3.2.2 Water Quality Data .......................................................................................... 10

3.3 Taranaki ....................................................................................................................... 10 3.3.1 Well Information............................................................................................... 10 3.3.2 Water Quality Data .......................................................................................... 11

3.4 White Island ................................................................................................................. 12 3.4.1 Well Information............................................................................................... 12 3.4.2 Water Quality Data .......................................................................................... 12

3.5 Raoul Island ................................................................................................................. 13 3.5.1 Well Information............................................................................................... 13 3.5.2 Water Quality Data .......................................................................................... 13

4.0 SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS .................................... 14

5.0 REFERENCES CITED .............................................................................................. 15

FIGURES

Figure 1: Locations of sampling sites, wells, and springs near Ruapehu and Tongariro. ............................ 7 Figure 2: Silica Rapids chemistry plots. Solid bar lines represent eruptions from Ruapehu. ...................... 9 Figure 3: Locations of wells, springs, and a seepage near Taranaki. ........................................................ 11 Figure 4: Water sampling and record locations at White Island. ................................................................ 12

APPENDICES

APPENDIX 1: GGW WATER QUALITY DATA ELECTRONIC FILES (ENCLOSED ON CD)18

ENCLOSURES CD Containing: A. Chemdata Formatted for NGMP Calc.xls; B. Detailed Chem Data.xlsx; C. GNS GGW Existing Chem Datasets.xls; D. NGMP Stats Calculator Output File.xlsx; E. Silica Rapids Chem Data.xls; F. Soda Springs Chem Data.xlx

GNS Science Report 2013/46 ii

ABSTRACT

Groundwater level and quality changes preceding eruptive volcanic activity could potentially have predictive value if closely monitored. Groundwater levels have been reported in the scientific literature to change (both rise and fall) in conjunction with volcanic activity in Japan and in the Philippines.

There are also reports of changes in the quality of groundwater in wells, springs, and crater lakes in a number of other places in the world in association with volcanic activity as well as New Zealand. However, there is some inconsistency in the data with changes sometimes being documented while at other times either being in the opposite direction or not seen at all. These include increases in B, Ca2+, Mg2+, Na+, and SiO2 of springs in advance of eruptive activity at Popocatepetl volcano in Mexico, an increase in SO4

2- concentrations for a thermal spring on the flank of Tacana volcano in Mexico prior to an eruption as well as variations in B, total Fe, and Mg2+. In New Zealand, these include increases prior to the 1995 eruption in levels of Al, Ca2+, Fe, Mg2+, Na, SO4, Cl, and conductivity, decreases in SO4 and Cl prior to the September 2007 eruption, and increases in spring-fed Silica Rapids concentrations of Ca2+, Mg2+, Na+, HCO3

-, Cl-, SO42-, and conductivity and decreases in Al,

Fe, and temperature in association with the 1995 and 1996 Ruapehu eruptions and a decrease Al in association with the September 2007 Ruapehu eruption.

The GNS Science GGW database contains a number of locations in proximity to volcanoes. These data and a statistical analysis output sheet are provided in an Appendix to this report. Both of the authors of this report have left employment at GNS Science before they could comprehensively evaluate these data. We recommend that such an evaluation occur as the next step in this programme.

We also recommend that an effort be made to develop a number of real groundwater monitoring sites, including wells and springs, in relatively close proximity to the most active volcanoes in New Zealand. Mt. Ruapehu, Mt. Tongariro, and White Island are candidates for such monitoring. Monitoring should include continuous water level and conductivity measurements and frequent sampling for major ions and other selected water quality variables (e.g., Al, B, Fe, and SiO2). Continuous water level and conductivity measurements could be telemetered for real-time monitoring to the Wairakei Research Centre. Annual sampling to analyse for major ions and other selected water quality variables is insufficient for the purpose. Quarterly or possibly monthly with an increase in frequency if changes are detected that warrant it are recommended. This list could be fleshed out with reference to known indicators of geothermal geochemistry in New Zealand. There is a rich literature in that regard.

KEYWORDS

Groundwater, volcanoes, water levels, water quality

GNS Science Report 2013/46 1

1.0 INTRODUCTION

In the latest international review of the volcanology programme of the Institute of Geological and Nuclear Sciences (GNS Science), it was recommended that the relationship between volcanic activity and groundwater and the potential for groundwater monitoring as an indicator of volcanic activity be assessed. Groundwater level and quality monitoring have been used internationally to monitor volcanic activity elsewhere for some time, but this has not been done in a formalized way in New Zealand.

This report documents a literature review of what groundwater level and water quality changes have been attributed to volcanic activity internationally and describes the existing monitoring datasets that are available within New Zealand related to groundwater. Recommendations for a groundwater monitoring program within New Zealand are then presented.


2.0 LITERATURE REVIEW

2.1 GROUNDWATER LEVEL MONITORING AROUND VOLCANOES

“Rising magma and groundwater invariably interact” (Newhall et al., 2001). Groundwater level changes prior to volcanic eruptions have been studied, but few observations have been recorded over time. Newhall et al. (2001) cited examples of water level changes before eruptions observed at numerous volcanoes dating from the 1500’s to the present. Sparks (2003) noted that groundwater emissions and changes in water tables prior to eruptions are likely caused by rising magma opening up fracture systems and disturbing groundwater systems. Groundwater level and spring discharge changes may occur when pore water pressure is raised by heating from rising magma or raised/lowered by mechanical strain in confined aquifers (Newhall et al., 2001).

Groundwater level changes prior to volcanic activity have been observed at Mayon Volcano, Philippines and Miyake-jima, Usu, and Meakan-dake volcanoes, Japan as follows:

• Mayon Volcano, Philippines - Residents approximately 8 to 15 km away from the summit of Mayon observed groundwater levels drop (up to 5 m) in wells in a shallow unconfined aquifer prior to the 1993 eruption (Newhall et al., 2001; Albano et al., 2001; and Jentzsch et al., 2001). Modeling of the groundwater system using MODFLOW by Albano et al. (2002) indicated that the water level changes were likely caused by enhanced permeability (opening of fractures) and rainfall pattern changes. Spring discharge in the Mayon Volcano area also decreased prior to eruptions in 1999, 2000, and 2011 (Albano et al., 2001).

• Miyake-jima Volcano, Japan - Groundwater level measurements collected hourly from a well within an unconfined aquifer at Miyake-jima Volcano showed tens of centimeter rises and drops during seismic activity associated with a caldera forming event in 2000. The water level changes were consistent with uplift and subsidence of the ground surface (Albano et al., 2002).

• Usu Volcano, Japan - Water levels in a thermal aquifer on the northern foot of Usu decreased 6 months prior to eruption (31 March 2000) with the decline accelerating starting in January 2000 (Shibata and Akita, 2001). The groundwater level rose (> 100 m) 2.5 days after the start of phreatic explosions. Water level changes were observed in two wells using pressure transducers. Water levels in Lake Toya varied with groundwater levels after time lags of 46 hours and 23 hours in the wells (Shibata et al., 2008).

Water level changes in deep confined aquifers at Usu Volcano were compared with the tidal response of the aquifers. GPS data showed that crustal deformation accounted for the changes. Water level changes in unconfined aquifers six months prior to an eruption at Usu were caused by opening of fractures (Albano et al., 2002).

• Meakan-dake Volcano, Japan - Groundwater levels measured on Meakan-dake dropped approximately 21 hours prior an earthquake swarm (Takahashi et al., 2012). Wells were located 8 km from the volcano summit and consisted of one deep (AK1; 1,061 m below ground level [BGL]) and two shallower wells (AK4; 57 m BGL and AK3; 92 m BGL). Water levels were measured using pressure transducers that were transmitted in real time to the data center at Hokkaido University. Barometric pressure was also measured at the site. An earthquake swarm began on 9 January 2008.


Groundwater levels at the three wells lowered simultaneously approximately 21 hours prior the earthquake swarm which indicated a decrease in volumetric strain. Water levels did not recover until at least 20 January. Total water decrease was 25 cm, 4 cm, and 3 cm in AK1, AK4, and AK3, respectively.

2.2 GROUNDWATER CHEMISTRY MONITORING AROUND VOLCANOES

Groundwater chemistry in an active volcanic setting may change in composition as a result of interaction with volcanic products, mainly through dissolution of volcanic gas (Armienta et al., 2008). Groundwater absorbs water-soluble gases such as SO2, HCl, HF, and CO2 and concentrations of such ions as SO4

2-, Cl-, F-, and HCO3- may increase (Newhall et al., 2001

and Armienta et al., 2008).

Changes in groundwater and spring chemistry prior to, during, and following volcanic activity have been documented at several active and quiescent volcanoes including Usu volcano, Japan; Popocatepetl volcano, Mexico; Vesuvius volcano, Italy; Azores archipelago; Karysmsky volcano, Kamchatka (Russia); Mt. Etna, Italy; and Tacana volcano, Mexico as follows:

• Usu Volcano, Japan - Water temperature and chemical composition of samples collected near Usu Volcano showed temporal variations; however, there were no precursory changes related to eruptions (Shibata et al., 2008). Water temperatures measured for 28 years showed that increases occurred after eruptions. Chemical composition measured since May 1999 showed no significant changes in the concentrations of major dissolved ions prior to the 2000 eruption; however, concentrations of Na+, K+, Cl-, and SO4

2- increased following the eruption and then decreased again. Concentrations of HCO3

-, Ca2+, and Mg2+ ions showed limited variation after the 2000 eruption. Shibata et al. (2008) concluded that shallow water was affected by the 2000 eruption. They found that water temperature and concentrations of Na+, K+, Cl-, and SO4

2- increased due to increased injection of the deep hydrothermal liquid.

• Popocatepetl Volcano, Mexico— Spring water chemistry monitored monthly for 7 years (1994 – 2000) at Popocatepetl Volcano, Mexico showed response to volcanic activity before and during eruptions (Martin-Del Pozzo et al., 2002). Popocatepetl is a large stratovolcano that rises to 5,452 m above MSL within deposits covering more than 3,000 km2. Spring water was monitored at five sites located on the eastern and southern flanks of the volcano. Samples were analysed for pH, temperature, conductivity, SiO2, Mg2+, Ca2+, Na+, K+, SO4

2- , Cl-, F-, B, and HCO3- at each site.

Springs were mainly characterised with low temperatures (3 – 22 °C) and conductivity. SO4

2-, Cl-, F-, HCO3-, B, and the SO4

2-/Cl- ratio varied prior to main eruptive activity and were related to ascending magma pulses which supplied acidic fluids to the springs. Na+, Ca2+, SiO2, and Mg2+ concentrations increased before eruptive activity, apparently as a function of temperature changes. Boron was also detected prior to larger events. Temperature and pH did not show large changes with eruptions.

Another spring water chemistry study at Popocatepetl volcano by Armienta et al. (2008) showed variations in concentrations of major ion and other chemical species from 1995 to 2004 prior to, during, and following eruptive activity. New eruptive activity commenced in December 1994 and continued irregularly until April 2003, the largest dome growth coming in late-2000. Water samples were collected at seven sites (6 springs and 1 shallow well) on the eastern and southern sides of the volcano. Water was sampled from 1995 to 2004 and analysed for major ions and selected chemical


species including silica, boron, fluoride and sulfide. pH and temperature were also measured at the field sites. Spring water corresponded to a bicarbonate water type. Chemistry results indicated:

˗ Cations including calcium, sodium, and potassium showed no correlation to volcanic activity;

˗ Chloride and sulphate concentrations varied slightly prior to and during episodes of increased activity;

˗ Sulphate concentrations also increased slightly through the entire eruptive period;

˗ Magnesium showed a slight increasing trend at one of the sampling sites;

˗ Boron levels were low during the entire observation period; however, concentrations peaked prior to and during volcanic activity;

˗ Calculated CO2 concentrations showed two episodes of partial pressure CO2 increase and decrease;

˗ pH varied throughout the eruptive period; and

˗ Fluoride concentrations remained stable until the second stage of magma output when fluoride increased. Fluoride concentrations decreased sharply after the extrusion of the last dome, likely related to the temperature drop in the magma chamber.

Overall, Armienta et al. (2008) found that boron, chloride, sulphate, fluoride, and CO2 were more sensitive to changes in volcanic activity. They also found extreme care must be taken while collecting pH and temperature field measurements in order to accurately calculate CO2 in water. They also found concentrations of chemical species could be “derived from a direct interaction of diffuse volcanic gases with the aquifers, or from the opening of new pathways for water and gases owing to the reactivation of the fault system.”

• Vesuvius volcano, Italy - Groundwater monitoring from 1998 to 2001 provided a baseline for temporal changes of groundwater chemistry in the current dormant state of Vesuvius volcano, Italy (Federico et al., 2004). Two springs and eleven wells used for irrigation, predominantly located on the southern flanks of Vesuvius, were periodically monitored. Water samples of were collected for field measurement of temperature, pH, Eh, and alkalinity. Samples were analysed for major ions, total dissolved solids (TDS), delta O, CO2, He, and Ra. Analytical results showed constant chemical composition of the aquifer over the period sampled. There were temporary changes in shallower water bodies related to seasonal and anthropogenic effects whereas deeper wells (> 100 m depth) displayed stable values of temperature, pH, HCO3, and dissolved CO2. Federico et al. (2004) noted that careful assessment of non-volcanic processes affecting groundwater chemistry must be identified in order to relate geochemical variations with volcanic activity.

• Azores archipelago - Groundwater chemistry has been monitored from mineral and thermal water discharges at the Azores archipelago since the 19th century. Groundwater occurs in a basal aquifer system that floats on underlying saltwater and perched-water bodies. Water types are mainly sodium bicarbonate. The dataset provided baseline values and trends for pH, temperature, CO2, and major-element composition. pH and temperature are measured weekly and show a stable behaviour (Cruz, 2003).


• Karysmsky volcano, Kamchatka (Russia)— A deep well (2,542 m BGL) located 100 km in a north-northeastern direction from the Karymsky volcano showed clear variations in geochemical data relating to the beginning of a strong eruption and a magnitude 6.9 earthquake in 1996 (Biagi et al., 2004). Another earthquake (magnitude 7.7) occurred in December 1997 approximately 350 km away from the well in the same direction. There were also pre-seismic variations and permanent modifications in geochemical data associated with it. Water samples are collected every three days from the deep well and measured for ion content (Na+, Ca2+, Cl-, HCO3

-, SO42-), gas content (total,

CO2, Ar, N2), and pH. Data showed variations in all parameters starting three months prior to the events. These generally lasted no more than a few weeks. Biagi et al. (2004) found that geochemical variations were consistent with a flux of new water in the aquifer and the release of carbon dioxide gas from the ground.

• Mt. Etna, Italy— Dissolved CO2 in groundwater monitored for 20 months using a new device at Mt. Etna showed variations induced by volcanic activity (De Gregorio et al., 2011). The new sampling device was placed in a drainage gallery within a cabin on the northeastern portion of Mt Etna. The station measured CO2 concentration, water temperature, total dissolved gas pressure (TDGP), air temperature, and atmospheric pressure every four hours. Data were transmitted daily. A strong linear correlation between conventional sampling methods and the new device was seen. Volcanic eruptions began in May 2008 and ended July 2009. Data showed an overall decrease in dissolved CO2 from November 2008 to April 2009, which was interpreted as the depletion of magma in the system known to occur at the end of eruptive activity.

• Tacana volcano, Mexico—A thermal spring on the flank of Tacana Volcano showed an increase in SO4

2- concentrations 2 months prior to a seismic swarm and a small phreatic explosion (De la Reyna-Cruz et al., 1989). Two days following the eruption sulphate concentrations decreased. Total iron, Mg2+, B, bicarbonate also varied prior to the eruption.


3.0 EXISTING MONITORING DATASETS WITHIN NEW ZEALAND

Information on groundwater wells and springs and water quality data in the vicinity of major North Island volcanos were gathered from regional councils, Geonet, and the GNS Science Groundwater and Geothermal databases (GGW).

Groundwater well and spring information was requested from regional council groundwater databases. Waikato Regional Council and Horizons Regional Council provided well and spring data around the central plateau volcanoes (Ruapehu, Ngauruhoe, and Tongariro). Taranaki Regional Council provided well and spring data around Mt. Taranaki.

Geonet continuously monitors New Zealand’s active volcanoes. There are approximately 105 sampling locations associated with geothermal features and volcano monitoring within New Zealand, Whale Island, White Island, and Raoul Island. Note that some of the locations are confidential due to industrial use therefore the locations may not be identified outside of GNS Science.

The Groundwater and Geothermal Database (GGW) was accessed by Moreau-Fournier (GNS Science) on 21 September 2012 to retrieve all existing data related to volcano monitoring. GGW holds a collection of hydrologic, geochemical, geologic, and geophysical data from over 1,500 sites within New Zealand for research purposes including Geonet sites. GGW also stores some of the water and gas chemistry data collected on volcanoes and geothermal fields. Data was available for volcanoes including Raoul, Ruapehu, Tarawera, Taupo, Tongariro-Ngauruhoe, and White Island and geothermal fields including Ngatamariki, Rotoma, Rotorua, Tikitere/Rotoiti, Waikite, and Rotoma. Chemistry data were available at several sampling locations including 7 pools, 16 lakes, 10 seepages, 47 springs, 15 streams, 1 river, and 1 volcanic vent. GPS measurements taken at benchmarks around Lake Taupo were also available. Data have been collected from crater lakes and springs on the flanks of various volcanoes, including Ngauruhoe, Ruapehu, Taranaki, Tongariro, White Island, and Raoul Island, were selected for this project.

3.1 RUAPEHU

Ruapehu is considered an active volcano and has had several major eruptions. Major eruptive episodes since 1990 have occurred at the following times:

• May to October 1995;

• June to October 1996;

• 4 October 2006; and

• 25 September 2007.

3.1.1 Well Information

Horizon’s Regional Council conducted a well search based on a 21 km radius of Mt. Ruapehu. Records of 11 wells were found and information on them provided. Wells are located in the south, southwest, and northwest directions from the summit of Mt. Ruapehu (Figure 1). The closet well to the summit is approximately 14.5 km to the northwest. Wells within this region are used for industrial, stock, and domestic purposes. Well depths ranged from 6.4 to 144.8 m depth. Well logs were available for most wells. Lithology consisted of volcanic alluvial materials (sand, gravel, clay, and silt), volcanic ash and rock, shells, and siltstone (colloquially referred to as “papa”). A groundwater level measurement was


available for six of the wells. Depth to groundwater ranged from 10 to 28.1 m (~690 to 776 m above MSL). Groundwater chemistry data were available for two of the wells (713002 and 725001) that are used for industrial purposes.

Figure 1: Locations of sampling sites, wells, and springs near Ruapehu and Tongariro.


3.1.2 Water Quality Data

There are a number of sites located in proximity to volcanoes in New Zealand for which data is available within the GNS Science GGW database. Such data downloaded from the GGW database are provided in Appendix 1 of this report. Also provided are the output results of a statistical analysis of these data using the GNS Science NGMP calculator. However, these data have not been evaluated by the authors of this report due to lack of time. Water quality data for the Ruapehu crater lake was assessed by Christenson and his work is referred to herein. We also present time series plots of data for silica rapids. Other sites require additional evaluation. Geonet currently monitors four sites on Mt. Ruapehu including the crater lake north and central vents, crater lake outlet, and Silica Rapids. Silica Rapids is a spring fed stream on the northwestern flank of Mt. Ruapehu. The Silica Rapids sampling location is at an elevation of 1,290 m ASL and approximately 7.2 km from the crater lake. Chemistry data are available in the GGW database from 1998 to the present for the central vent of Ruapehu (101 samples), the crater lake outlet (92 samples), and Silica Rapids (11 samples). Britten provided additional annual monitoring data for Silica Rapids for 1990, 1992, and 1995. Sampling at the crater lake north (31 analyses) began in 2008.

Mt. Ruapheu crater lake water composition was assessed in relation to the 1995 to 1996 eruptions and September 2007 eruption by Christenson (2000) and Christenson et al. (2010), respectively. Christenson (2000) found that the thermal and chemical character of the crater lake was impacted as early as January 1995 from the degassing of the ascending magma column. The first eruption was on 23 September 1995. It expelled the crater lake. Christenson (2000) presented cation, anion, pH and temperature time series plots for the crater lake outlet water which showed concentrations of Al, Ca, Fe, Na, Mg, SO4, and Cl increasing prior to the September 1995 eruption. Christenson et al. (2010) examined lake composition data from 2006 to 2008 and found that SO4 and Cl concentrations showed strong dilution trends 20 months prior to the September 2007 eruption.

Silica Rapids chemistry data was not assessed in relation to the 1995 to 1996 eruptions or the September 2007 event by Christenson (2000) or by Christenson et al. (2010). Therefore, it was plotted in Figure 2. The most noticeable changes in Figure 2 are increases in major ions (the cations Ca, Mg, and Na and the anions HCO3, Cl, and SO4) and conductivity and decreases in Al, Fe, and temperature in association with the 1995 and 1996 eruptions. However, the sampling frequency was infrequent (annually or less frequently). In contrast, there were relatively small decreases for some of the same major cations in association with the 2006 and 2007 eruptions and essentially no changes for major anions; however, there appears to have been a substantial decrease in Al at that time.


Figure 2: Silica Rapids chemistry plots. Solid bar lines represent eruptions from Ruapehu.

The GGW database also held data for nine additional sampling locations on Mt. Ruapehu. Four of these locations were one-off sampling points in 2007 associated with tephra dam seepage. The other five were near the Whangaehu River waterfall from 2004 to 2006.

3.2 TONGARIRO

The Tongariro complex contains multiple volcanic cones including Mt. Ngauruhoe. Tongariro had eruptive episodes recently from July to August 2012 and on 21 November 2012.


Well information was gathered from both Horizons and Waikato regional councils as the boundary between the regions is near Tongariro. Waikato Regional Council provided information on 17 wells within 20 km of Tongariro (Figure 1). Wells were predominantly located to the northeast of Tongariro. Well depths ranged from 7.3 m to 36.1 m. Well logs were available for all of these wells except three. Lithology consisted of gravel, sand, silt, clay, and andesite. Only one water level measurement was recorded for one well. That was 3.5 m BGL in 1993. Horizons Regional Council provided information on two wells within 20 km of Tongariro. Both wells are located to the west of Tongariro and owned by Landcorp Farming Ltd. The wells are used for stock and house supply and are 39 and 41 m deep (714002 and 714001, respectively). Groundwater levels were recorded at 28.1 BGL (714002; 776.9 m MSL) and 10.77 m BGL (714001; 894.23 m MSL).


Two geothermal wells are located on Tongariro. WRC 72_2090 is located at the Ketetahi Hot Springs on the northern slopes of Mt. Tongariro (north crater) at the head of Mangatipua Valley. WRC 72_3971 is located at No Name Spring, above Lower Emerald Lake, to the south of the central crater. No well log or water level information was available for these wells however, these are Geonet sampling locations and chemistry data for them is discussed below.


Geonet has 24 sampling locations within the Tongariro complex. This includes 6 lake locations, 2 springs, 15 fumaroles, and 2 streams. GGW has records of 15 water chemistry sampling points relating to five water features including the Upper and Lower Tama lakes, Soda Springs, Emerald Lakes, Blue Lake, and Ketetahi Hot Springs and Stream.

Upper Tama and Lower Tama lakes are situated between Mt. Ruapehu and Mt. Ngauruhoe. Water chemistry data in GGW database shows that the lakes were sampled periodically from 1981 to 2003 and annually from 2006 to the present.

Soda Springs is located approximately 2 km north of the summit of Mt. Ngauruhoe and 1.3 km west of the Tongariro’s south crater. GGW holds three sampling location records for Soda Springs. One sampling location holds annual chemistry from 2003 to 2011. The other sampling locations were collected at the waterfall and in the flat part of the stream randomly from 1989 to 1999.

The Emerald Lakes are located to the south of Tongariro’s central crater. The lakes are sampled at four locations Upper, Middle, and Lower Emerald Lakes and at a spring (No Name Spring) by Lower Emerald Lake. Chemistry data for the lakes have been collected annually from 1993 to present. A sample was also collected in 1981, 1983, and 1984. Sampling at the spring was undertaken annually from 1998 to present. Blue Lake is located to the east of Tongariro’s central crater. Annual water chemistry samples were collected from 1998 to present. A single sample was collected in 1981, 1983, and 1994.

Ketetahi Hot Springs are located on the northern slope of Mt. Tongariro. Five sampling locations were recorded in the GGW database including three points within the Ketetahi Stream and two springs (Iron and Black Cauldron springs). None of the sites are monitored annually. Chemistry data are randomly available for 1984 to 2007.

3.3 TARANAKI

The last major eruption of Taranaki occurred around 1854.


The Taranaki Regional Council (TRC) provided locations of 26 wells, 3 springs, and 1 seepage within 12.5 km of Taranaki (Figure 3). Limited information on the wells including use, depth, water levels, and logs is available and was accessed. Well depths ranged from 19.8 m to 367 m BGL. Groundwater use is predominantly for stock and domestic purposes. Groundwater level measurements were provided for 4 wells. These ranged from 4.6 m to 13.7 m BGL.


Figure 3: Locations of wells, springs, and a seepage near Taranaki.

The spring locations are associated with the Kapuni Stream and Patea River on the southeastern flank of Taranaki. TRC noted that these springs were used for a groundwater isotope study. More information regarding this study is believed to exist but was not available as a part of this project.


No water chemistry data were available from TRC, Geonet, or GGW near for any of the locations in the Taranaki region.


3.4 WHITE ISLAND

White Island is New Zealand’s most active volcano. It was in a state of frequent eruptions of various styles and sizes from December 1975 to July 2000. Recently, it was eruptive from July to August 2012 and again in 2013.


There are no wells located on White Island.


Geonet samples 29 locations at White Island within the crater lake and water features running from the crater. These locations are indicated in Figure 4. GGW has chemistry records for 36 water features including the crater lake, streams, pools, and springs. The majority of the water features were sampled for a limited time period while 11 locations have longer records that were sampled quarterly.

Figure 4: Water sampling and record locations at White Island.


3.5 RAOUL ISLAND

Raoul Island is located approximately 1,000 km northeast of New Zealand in the Kermadec Islands. Raoul Island erupted on 17 March 2006.


Well information was not obtained for Raoul Island.


Geonet has records of 10 sampling locations on Raoul Island including lakes, seepage at a beach, pools, and fumaroles. GGW has records for 13 sampling locations some of the locations were only sampled once post the 2006 eruption. However, 7 of the sampling locations have larger records of at least 29 sampling events.


4.0 SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS

Groundwater level and quality changes preceding eruptive volcanic activity could potentially have predictive value if closely monitored. Groundwater levels have been reported in the scientific literature to change (both rise and fall) in conjunction with volcanic activity in Japan and in the Philippines.

There are also reports of changes in the quality of groundwater in wells, springs, and crater lakes in a number of other places in the world in association with volcanic activity as well as New Zealand. However, there is some inconsistency in the data with changes sometimes being documented while at other times either being in the opposite direction or not seen at all. These include increases in B, Ca2+, Mg2+, Na+, and SiO2 of springs in advance of eruptive activity at Popocatepetl volcano in Mexico, an increase in SO4

2- concentrations for a thermal spring on the flank of Tacana volcano in Mexico prior to an eruption as well as variations in B, total Fe, and Mg2+. In New Zealand, these include increases prior to the 1995 eruption in levels of Al, Ca2+, Fe, Mg2+, Na, SO4, Cl, and conductivity, decreases in SO4 and Cl prior to the September 2007 eruption, and increases in spring-fed Silica Rapids concentrations of Ca2+, Mg2+, Na+, HCO3

-, Cl-, SO42-, and conductivity and decreases in Al,

Fe, and temperature in association with the 1995 and 1996 Ruapehu eruptions and a decrease Al in association with the September 2007 Ruapehu eruption.

The GNS Science GGW database contains a number of locations in proximity to volcanoes. These data and a statistical analysis output sheet are provided in an Appendix to this report. Both of the authors of this report have left employment at GNS Science before they could comprehensively evaluate these data. We recommend that such an evaluation occur as the next step in this programme.

We also recommend that an effort be made to develop a number of real groundwater monitoring sites, including wells and springs, in relatively close proximity to the most active volcanoes in New Zealand. Mt. Ruapehu, Mt. Tongariro, and White Island are candidates for such monitoring. Monitoring should include continuous water level and conductivity measurements and frequent sampling for major ions and other selected water quality variables (e.g., Al, B, Fe, and SiO2). Continuous water level and conductivity measurements could be telemetered for real-time monitoring to the Wairakei Research Centre. Annual sampling to analyse for major ions and other selected water quality variables is insufficient for the purpose. Quarterly or possibly monthly with an increase in frequency if changes are detected that warrant it are recommended. This list could be fleshed out with reference to known indicators of geothermal geochemistry in New Zealand. There is a rich literature in that regard.


5.0 REFERENCES CITED

Albano, S.E.; Matsumoto, N.; Newhall, C.G.; Koizumi, N.; Sato, T. 2002. Mechanisms of groundwater level changes at volcanoes. Abstract V21A-1177 IN: 2002 AGU Fall Meeting, 6 - 10 December, San Francisco, California, USA: abstracts. Washington, DC: American Geophysical Union

Albano, S.E.; Sandoval, T.; Toldeo, R. 2001. Groundwater at Mayon, Volcano. Abstract V42B-1017 IN: 2001 AGU Fall Meeting, 10 – 14 December, San Francisco, California, USA: abstracts. Washington, DC: American Geophysical Union

Armienta, M.A.; De la Cruz-Reyan, S.; Gomez, A.; Ramos, E.; Ceniceros, N.; Cruz, O.; Aguayo, A.; Martinez, A. 2008. Hydrogeochemical indicators of the Popocatepetl volcano activity. Journal of Volcanology and Geothermal Research, 170: 35 – 50

Biagi, P.F.; Castellana, L.; Piccolo, R.; Minafra, A.; Maggipinto, G.; Ermini, A.; Capozzi, V.; Perna, G.; Khatkevich, Y.M.; Gordeev, E.I. 2004. Disturbances in groundwater chemical parameters related to seismic and volcanic activity in Kamchatka (Russia). Natural Hazards and Earth System Science, 4: 535 - 539

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APPENDICES


APPENDIX 1: GGW WATER QUALITY DATA ELECTRONIC FILES (ENCLOSED ON CD)

A. Chemdata Formatted for NGMP Calc.xls

B. Detailed Chem Data.xlsx

C. GNS GGW Existing Chem Datasets.xls

D. NGMP Stats Calculator Output File.xlsx

E. Silica Rapids Chem Data.xls

F. Soda Springs Chem Data.xlx

gns science report 2013-046.pdf · the gns science ggw database contains a number of locations in...

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