Locations of families of repeating events at Telica Volcano, Nicaragua Mel Rodgers1, Mitch Hastings1, Glenn Thompson1, Diana Roman2 1. University of South Florida. 2. Carnegie Institution of Washington −88.00˚ −86.00˚ −84.00˚ −82.00˚ 12.00˚ 1. Introduction Honduras 3. Results 14.00˚ −87.00˚ −86.00˚ Cosiguina 13.00˚ Nicaragua Telica is a Persistently Restless Volcano with ☀ San Cristobal Telica 12.00˚ 3.1 Multiplet “1” stack high rates of seismicity (>100s Cerro Negro Momotombo 12.65˚ events/day), high levels of degassing and Costa Rica10.00˚ 12.00˚ frequent small explosions. Locating events is dicult due to the ☀ TBHS low-amplitude, low-frequency and Telica TBTN 12.60˚ TBCF emergent nature of the waveforms. TBHY TBMR ☀ Telica has a high rate of multiplet km occurrence. Between 2010-2013 ~25% of TBCA 0 2 4 events belonged to a multiplet. 12.55˚ In this study we locate multiplets using TESAND seismic (broad band) ☀ Active vent STACK STACK waveform cross-correlation stacking to −86.90˚ −86.85˚ −86.80˚ TBHS TBHY obtain rst arrivals. Figure 1. Location of Telica & TESAND network stations. 2. Methods Prior work: • TESAND network deployed between 2010-2013. • STA/LTA event detection and catalogue creation in Antelope ->200,000 events. • Full cross-correlation using Peakmatch (Rodgers et al., 2015a) at single station TBTN of all events -> ~9000 multiplets (51,000 events) correlated above xcorr threshold 0.8. STACK STACK This study: TBMR TBTN 1. Using the multiplets previously identied on TBTN we select the 51 multiplets that contained more than 50 events per family (Ranging from ~5,000 to 50 events). Figure 5. Multiplet “1” (below). 16 waveforms correlate with each other above a cross-correlation threshold of 0.8 at 4 stations. Only 8 2. We nd these events on other stations in the network and identify a subset of events waveforms shown here. Stack is shown in bottom panel on all that correlate with each other on all other stations. stations. The TBTN stack is the same as shown in Figure 4. Figure 2. Multiplet 3.2 Preliminary locations TBTN Final subset selection TBHS TBHY TBMR Multiplet 1 Group criteria diagram Figure 6. Preliminary locations of Waveform A A A A A Multiplet 1 a subset of events from two Waveform B B Multiplet 2 Multiplets. 12.62˚ TESAND Station Waveform C C C C C TBHS - Multiplet “1” (blue): Master Waveform D D D event from May 2012. Events Waveform E E spanning December 2011 - Waveform F F F F F February 2013. The 8 located 12.61˚ events have an average rms of Xcorr > 0.8 Xcorr > 0.8 TBTN 0.8, azimuthal gap of 157, average horizontal error of xxx TBCF km and vertical error of xxxx km - Multiplet “2” (red): Master 3. From this nal group we stack the waveforms on each station 12.60˚ TBHY event from September 2011. Figure 3. Multiplet Events spanning from August TBTN TBHS TBHY TBMR 2011 to September 2012. The 3 A A A A stack diagram TBMR km located events have an average C C C C 12.59˚ rms of 0.42, azimuthal gap of 163, 0 0.5 1 F F F F average horizontal error of xxx −86.85˚ −86.84˚ −86.83˚ km and vertical error of xxx km STACK STACK STACK STACK 4. Pick the rst arrival on the stacked waveform and calculate an arrival 4. GISMO framework time for each waveform at each station. - This workow and code has been developed in the GISMO toolbox framework. 10 6 TBTN - stack (BHZ) - starting 2012-05-11 15:47:51.960 4 - GISMO is a seismic data analysis toolbox for MATLAB: https://geoscience-community-codes.github.io/GISMO 3 Figure 4. Stacked - This code will be available in the repository of GISMO 2 Stack waveform for Pick contributed code. 1 nm Multiplet “1” 0 (Figure 6) at TBTN 5. Future Work -1 (BHZ) showing - Integrate GISMO workow into Antelope -2 example pick. - Run for all multiplets! 5 10 15 20 25 30 35 40 Seconds References & Data Acknowledgements: Lienert, B.R., Havskov, J., 1995. A Computer Program for Locating Earthquakes Both Locally and Globally. Seismol. Res. Lett. 66, 26–36. 5. Locate events using picks from these rst arrivals. Horizontal component can be Rodgers, M., Rodgers, S., Roman, D.C., 2015a. Peakmatch: A Java Program for Multiplet Analysis of Large Seismic Datasets. Seismol. Res. Lett. 86, 1208–1218. Rodgers, M., Roman, D.C., Geirsson, H., LaFemina, P., McNutt, S.R., Muñoz, A., Tenorio, V., 2015b. Stable and unstable phases of elevated seismic activity at the used for S-wave pick. persistently restless Telica Volcano, Nicaragua. J. Volcanol. Geotherm. Res. 290, 63–74. -> Preliminary locations obtained using HYPOCENTER (Lienert and Havskov, Thompson G. and Reyes, C., (2018) GISMO - a seismic data analysis toolbox for MATLAB [software package], http://geoscience-community-codes.github.io/GISMO/. Accessed August 2018. 1995) using the velocity model of Rodgers et al. 2015b. Telica data was collected by the TESAND network (NSF EAR-0911366 to D.Roman and P.LaFemina) .