Multidisciplinary monitoring of Mt. Mayon, Luzon, Philippines

Part 1 – Overview and Geochemical Monitoring

F M Schwandner1, D Hidayat1, S Marcial1, C Newhall1, E Laguerta2, R Vaquilar2, A Baloloy2, R Valerio2

1. Mayon volcano: Background activity2. Geochemical Monitoring3. Tectonic settings4. Geophysical Monitoring5. Self-made low-cost data logger6. Preliminary results

• Research collaboration: Earth Observatory of Singapore, Philippine Institute of Volcanology and Seismology (PHIVOLCS) since 2010

• Objective: Develop a multi-disciplinary monitoring system around Mayon

• geophysical & gas geochemical monitoring, and petrologic studies.

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Mayon is an openly-degassed basaltic-andesitic volcano, rises to 2,462m above Albay Gulf in the Philippines.

Considered the most active volcano in the Philippines, Mayon produce small eruptions every few years with two large (VEI 4) historical eruptions in 1814 and 1897. The two recent eruptions in 2006 and 2009 were largely effusive, produced lava flow and pyroclastic flows.

In the spectrum from openly-degassed to plugged volcanoes, Mayon is near the openly-degassing end, producing mostly small and frequent eruptions.

1. Mayon volcano: Background activity

Relatively short and modest seismic and gas precursors to recent eruptions of Mayon.

Data courtesy of (PHIVOLCS).

1. Mayon volcano: Background activity

SO2 flux in t/dSDH: emergent “tremor”, including rock fallsLF- and HF- VQ: low and high frequency volcanic earthquakes

In the latest eruption, a small explosion on early Dec 11, 2009 was followed by spilling of incandescent blocks over the crater rim. Both the 2006 and 2009 eruptions started slowly with rock falls and increased SO2. Extrusion rate peaked within 1-2 weeks and died away within 3-6 weeks. Only minor explosive activity occurred.

SO2 flux in t/dSDH: emergent “tremor”, including rock fallsLF- and HF- VQ: low and high frequency volcanic earthquakes

Data courtesy of (PHIVOLCS).

1. Mayon volcano: Background activity

Mayon volcano status is level-1 with low seismicity dominated mostly by local and regional tectonic earthquakes with continuous emission of SO2 from its crater.

Reported volcanic earthquakes and seismically detected rock fall events per month (dark and light gray bars, respectively, left axis) and SO2 flux (open triangles and dashed line) averaged per month (right axis) at Mayon from 1 January 2010 to July 2011. Background colors indicate the Alert Level corresponding to the scale to the right of the figure. Little if any data are available from March through December 2010, presumably due to low activity during this interval. Data courtesy of (PHIVOLCS).

1. Mayon volcano: Background activity

• Research collaboration: Earth Observatory of Singapore, Philippine Institute of Volcanology and Seismology (PHIVOLCS) since 2010

• Objective: Develop a multi-disciplinary monitoring system around Mayon

• geophysical & gas geochemical monitoring, and petrologic studies.

Mayon monitoring network design

Mayon monitoring network

Mayon hazard zonation:6-km no settlement zone

Mayon hazard zonation:6-km no settlement zone

…and lahars

FTIR

GOSATOMI, TOMS, …

Mayon conceptual geochemical monitoring design

2. Geochemical monitoring

Gas Geochemistry: flank CO2 as early unrest indicator

• Ground/flank gas network:– Low cost, low maintenance = networkable, (+ solar power, telemetry)– Chamber: US$45k/ea; high wear, strongly affected by wind & rain– Pipe: US$05k/ea; low-flow $1k only, minimum wear & noise

Gas Geochemistry: flank CO2 as early unrest indicator

Options:• Continuous (recirculation) mode,• Pump Test mode

Gas Geochemistry: flank CO2 as early unrest indicator: toward real-time flux fields

Place, cal, val time series sensors

Temporal population variation loadingsEnd: Flux field variations with time

Refine operational parameters

Invert

Spatial population variation loadings

Measure time series, apply met corrections

Extract population statistics: PDF (permeability distribution function)

Start: Measure flux grid or mesh

Gas Geochemistry: flank CO2 as early unrest indicator

Multisensor gas stations design (6 Mayon, 2 Gede)• Prototype built, copies being built in Nov-Dec 2011, at Mayon since Nov 2011. • Include each: Vaisala met station, soil CO2 concentration

and derived CO2 flux, heat flux, soil moisture & soil temperature. • Telemetry pending repeaters finalization. • Supporting data acquired July 2011 (flux & permeability mapping campaigns).

Gas permeability / flux mapping with EOS students, PHIVOLCS colleagues. Mayon 7/2011.

Multi-sensors box designed for volcano monitoring stations. Schwandner & Marcial 2011. Inset photo displays how wall installation will appear like, inside the shelters, in January 2011.

Gas Geochemistry:Conduit degassing monitoring (NOVAC SO2)

NOVAC SO2 monitoring stations (2 Mayon) • April/May 2011 installed. First in Asia, of global network >50 sites.• Collaboration with NOVAC (Bo Galle, Sweden).• Telemetry pending repeaters completion. • PHIVOLCS scientists trained. • Data streams being finalized: node -> observatory -> NOVAC -> EOS & PHIVOLCS HQ

Installation in May 2011

Control box including spectrometer, batteries, solar charge controllers.

Scanner optics

Lightning rod

Sample 180 degree scan in 5 degree slant column absorption measurement intervals. Highlighted is edge of plume just outside the scan range.

One of two NOVAC stations at Mayon (Calbayog station)

Hydrology / Geochemistry:Strain and flank degassing monitoring

Wells multi-sensors (2 at Mayon) • Sensors: depth (strain), pH, conductivity, salinity, chloride, temperature, ORP.• 2 stations installed: 1 spring box (Padang, June ‘11), 1 shallow well (Bonga, March ‘11).

PHIVOLCS scientists trained. • Bimonthly data downloads, battery service (soon solar), calibration.• Telemetry pending completion of antenna masts (under way, contracted),

and installation of solar panels (delivered) & GSM modem.

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Calibration offset

Multidisciplinary monitoring of Mt. Mayon, Luzon, Philippines

Part 2 – Geophysical Monitoring

D Hidayat1, F M Schwandner1, S Marcial1, C Newhall1, E Laguerta2, R Vaquilar2, A Baloloy2, R Valerio2

GPS data from PHIVOLCS-GPS working group have yielded phases of precursory ground displacement prior to eruptive activity in 2006 and 2009.

Plots of relative distance changes between stations suggest inflation due to magma intrusion in late 2005; followed by apparent deflation in early to mid 2006.Renewed inflation began again in late 2007 to early 2008; followed by extrusion of magma in the December 2009 eruption.Besides showing evidence of surface ground deformation from volcanic origin, the observed GPS signal around Mayon also showing local tectonic origin (Bacolcol, pers. comm.).

Data courtesy of (PHIVOLCS).

1. Mayon volcano: Background activity

3. Tectonic settings

The Oas Graben bounded by Legaspi Lineament to the north and San Vicente Linao Fault to the south. The Legazpi Lineament (N70oW) is seismically active and is a left-lateral fault with a normal component to the east (Le Rouzic, 1999). GPS data analysis (Rangin et al., 1999) derived a left-lateral motion of 13 mm/yr along the Legaspi Fault with 13 mm/yr of extension perpendicular to it.

Tectonically, Mayon is located in the Bicol Basin (Oas Graben), a northwest trending structural depression. Structural analysis of previous study reveals a regional transtensional stress regime in the Bicol basin, which induced the northwest striking left-lateral faults to have a normal slip component (Lagmay et al., 2005).

4. Geophysical Monitoring

Currently there are 4 broadband seismographs, 3 short period instruments (PHIVOLCS-NEID; which recently upgraded to broadband instrument), and 5 tiltmeters. These instruments will be telemetered to the Lignon Hill Volcano Observatory through radio and 3G broadband internet.

4. Geophysical Monitoring

5. Self-made low-cost data loggerWe also make use of our self-made low-cost tiltmeter datalogger which has been operating since Jan 2011, performing data acquisition with sampling rate of 20 minute/sample and transmitted through gsm network as text message.We also designed and assembled a high data-rate datalogger and tested it with short period seismic and tilt instrument at Mayon, Gede and Salak volcanoes. The datalogger can also be used for other analog sensors such as microphones, microbarographs and others. It is equipped with GPS for accurate time. We are using one type of 5.8 GHz radio telemetry in our volcano laboratories. The 5.8 GHz is growing in use due to low cost, versatility, and no frequency license requirement compared to 900 MHz, but it does not have the flexibility of a lower-frequency system to shoot through vegetation and around corners.An alternative solution for telemetry from remote location to EOS data center without to worry about line of sight is using a new device: a 3G modem integrated with a router that can link to internet service provided by cellular companies.

Monitoring Data Schema

Trimble NetR8Geospace

Mini Seis-monitorTrilliumcompact

Applied Geomechanics701-(4X)

Earthworm

Earth Observatory of Singapore

PHIVOLCSManila

Seiscomp

Lignon Hill Volcano Observatory

Earthworm

swarm

PICOTCO2 & met

INTERNET

NOVACSO2

HydrolabMS5: Wells

Currently there are 4 broadband seismographs, 3 short period instruments (PHIVOLCS-NEID; which recently upgraded to broadband instrument), and 5 tiltmeters. These instruments will be telemetered to the Lignon Hill Volcano Observatory through radio and 3G broadband internet.

6. Preliminary Results

6. Preliminary Results

6. Preliminary Results

Understanding on what structures active deformation is occurring and how deformation signal is currently partitioned between tectonic and volcanic origin is a key for characterizing magma movement in the time of unrest.

Preliminary analysis of the tangential components of tiltmeters (particularly the stations VMDB and VMAB, NE of the volcano) shows gradual inflation movement over several months period. The tangential components for tiltmeters are roughly perpendicular to the fault north of Mayon. This may suggest downward tilting of the graben in the northern side of Mayon. Another possibility is that the magmatic system under Mayon is asymmetrical.

With the additional 2 instruments recently installed, we have better azimuthal tiltmeter coverage around the volcano, which permitted us to monitor any possible surface ground deformation coming from either volcanic and tectonic origin.

This hypothesis can be verified later.

6. Preliminary Results

We perform 3D forward modeling (flat surface/no topo) of a left-lateral strike slip fault with normal component (mimicking Legaspi lineament movement as describe by GPS solution of Rangin et al.1999). Parameters: strike N65W; dip 80 (westward); left lateral motion: 13mm; dip-slip: 13mm.The main idea was to check whether the observed tangential tilt is compatible with the movement of Legaspi Lineament. We can see consistency of the observed tangential tilt to the model .Note: positive tangential-tilt trend = counterclockwise movement. VMDB and VMAB positive trend = downward movement of the block northwestward of these stations (footwall of Legaspi Lineament downward)

6. Preliminary Results

Earthquakes in the area reflect both Mayon volcanic activity and its adjacent tectonic activity. High quality of hypocenter location is essential. Before detailed study of volcano-related seismic events, our broadband seismograph study will refine a velocity model underneath the volcano with the analysis of receiver functions of teleseismic earthquakes. Such information can be also used to better formulate a coherent regional tectonic model and help characterize the seismic sources in the region. Our study presents the depth of Moho and crustal velocity structure including low velocity zones, which hint the depth of magma bodies.

6. Preliminary Results

In the spectrum from openly-degassed to plugged volcanoes, Mayon is near the openly-degassing end, producing mostly small and frequent eruption.

An EOS-PHIVOLCS collaboration is initiated in 2010 with effort to develop a multi-disciplinary monitoring system around Mayon includes geophysical monitoring, gas geochemical monitoring, and petrologic studies.

Short and modest seismic and gas precursors to recent eruptions of Mayon. GPS data analysis yielded precursory inflation for 2006 and 2009 eruption. However, the deformation signals were affected much by the deformation due to tectonics.

Combined analysis of multi-parameter geophysical data will enable the possibility to locate and quantified the fault movement adjacent to Mayon, isolate seismic and deformation signal related to volcanic origin, for better understanding magmatic system of Mayon volcano.

EOS-CVGHM geophysical monitoring networkFY2011

1. Established geophysical network (3 broadband, 3 short-period, and 2 tiltmeter stations installed and operating)

2. Data connection through GSM and radio telemetry; continuous data stream to Gede observatory with sampling rate: 100sps (BB & SP) and 1 sample per 20 minutes (Tilt)

3. Self-made low cost data logger was tested and now functioning permanently for tiltmeter and short period

4. In progress: real time data display (observatories, CVGHM-Bandung and EOS)

Gede and Salak Monitoring Status

Gede-2 broadband stations are installed, permanent house already built-1 repeater stations is built, 1 repeater housed in Telkomsel cellular tower-1 short period station is installed-2 short period stations are planned: 1 will be in SW of Gede (before 31/03/12), 1 will be at the summit (~May 2012)-2 tiltmeterS are installed and co-located with broadband seismometers: 1 will be relocate from north to south station by 31/03/12.

Salak-2 short period stations are installed: 1 with permanent house is recently built-1 broadband station is installed between Salak and Pangrango; this can serve data for Gede as well

Telemetry-Radio network is built for both Gede and Salak-for station with difficult line of sight, 3G internet is used for data telemetry-Each at the observatory post there is a server where data are accessible via internet for CVGHM and EOS. Realtime data display can be achieved, delayed data backup at EOS is being implemented. Enhancement of internet speed will be implemented by 31/03/12 for realtime data display and backup at EOS.

Temporary seismic and tilt installation at station N of Gede Volcano

Permanent seismic and tilt installation at station S of Gede Volcano

Repeater station installation for Gede and Salak Volcanoes

Earthquake Locations at and around Gede Volcano

Earthquake Locations at and around Gede Volcano, cont.

-These are locatable tectonic and volcanic earthquakes from May-Oct 2011 with S-P less than 5 sec.-Several earthquakes occurred beneath Gede crater with depth 0-5km-Several earthquake occurred along Cimandiri fault-Sequences of small earthquakes (depth range 0-15 km) occurred NE Gede and SW of Gede (Cluster 1 and 2), over the time of recordings, many occurred along SW-NE across Gede and Pangrango.-We postulates that there is (are) faults running across Gede-Pangrango connecting Cimandiri fault and Lembang fault (NE or Gede). Similar swarms occurred in 1997 were located between Gede and Pangrango.-Earthquake hypocenters are still preliminary, velocity structure refinement will improve locations probably clustered more than currently shown.