Supplementary Materials for

Supplementary Materials for

Thermal squeezing of the seismogenic zone controlled rupture of the

volcano-rooted Flores Thrust

Karen Lythgoe, Muzli Muzli, Kyle Bradley*, Teng Wang, Andri Dian Nugraha, Zulfakriza Zulfakriza, Sri Widiyantoro, Shengji Wei

*Corresponding author. Email: [email protected] Published 29 January 2021, Sci. Adv. 7, eabe2348 (2021)

DOI: 10.1126/sciadv.abe2348

This PDF file includes:

Figs. S1 to S14 Table S1

Fig. S1 Overview map of seismic data gathered at Lombok, showing stations used for earthquake re-location (triangles) and seismic reflection profiles (grey lines). Seismic lines 920 and 542 are displayed in Fig S5. 115˚00' 115˚30' 116˚00' 116˚30' 117˚00' 117˚30' 118˚00' 118˚30' 9˚00' 8˚30' 8˚00' Reflection lines Temporary Node Temporary Broadband Permanent Broadband Line 920 Sumbawa Bali Lombok Line 542

0 40 Time(s) 808 BKB 6° 96 884 SMKI 7° 97 997 SGKI 9° 96 1166 TOLI2 26° 95 617 PMSI 29° 98 1168 MRSI 33° 96 1241 SMSI 34° 94 1252 GTOI 37° 98 1689 SGSI 38° 94 628 SPSI 39° 99 1313 KMSI 41° 99 1090 LUWI 42° 96 616 BNSI 45° 99 502 MKS 46° 98 541 KAPI 47° 96 1290 SANI 58° 90 534 BSSI 63° 94 924 ALKI 89° 96 749 LRTI 90° 95 665 MMRI 93° 97 232 DBNI 93° 98 605 EDFI 94° 98 899 SOEI 100° 93 662 SBNI 111° 92 522 BASI 113° 99 2336 WRAB 125° 95 1463 MBWA 165° 95 1592 GIRL 187° 98 225 JAGI 267° 99 204 BYJI 275° 98 PnlV Pnl Waves: Velocity (0.01−0.06 Hz) 0 40 Time(s) 95 95 95 95 83 94 87 93 90 84 70 88 98 98 98 82 97 97 71 94 0 98 26 97 95 94 87 92 98 98 PnlR 0 40 80 120 160 Time(s) 96 78 88 92 93 94 89 88 30 92 53 92 94 90 91 12 84 96 82 91 94 90 88 75 76 69 88 96 94 92 Vertical 0 40 80 120 160 Time(s) 92 93 88 79 78 94 81 81 0 0 2 82 91 81 85 63 0 93 75 92 25 79 53 59 67 68 87 96 87 91 Radial Surface Waves: Velocity (0.01−0.035 Hz)

0 40 80 120 160 Time(s) 89 89 86 96 95 95 97 97 90 94 92 99 98 98 97 89 96 98 98 96 70 96 93 92 97 62 61 36 91 91 Tangential a) Event M_w5.9 09/08/2018 05:25 d) Regional waveforms

b) Regional stations c) Teleseismic stations

0 20 40 60 80 100 Relative RMS 4 8 12 16 20 24 Depth (km) e) Event depth 1 2 3 4 5 6 7 8 Source duration (s) 0 10 20 30 Time (s) f) Teleseismic waveforms 57° HIA 3° 80° TIXI 4° 71° YAK 7° 47° INCN 11° 60° YSS 21° 31° CTAO 115° 40° CAN 137° 67° ABPO 253° 85° MBAR 270° 76° ATD 284° 76° RAYN 297° 81° GNI 313° 84° KIV 316° 62° KBL 317° 58° NIL 318° 64° SIMI 320° 63° AAK 327° 60° WUS 328° 45° LSA 329° 63° MAKZ 334° 57° ULN 353° Velocity (0.02 − 0.2 Hz)

Fig. S2 Moment tensor and centroid depth obtained by waveform inversion for a Mw5.9 event on

9th _{August 3018. a) Best fitting moment tensor b) Regional stations used to obtain moment tensor.}

c) Teleseismic stations used to refine centroid depth. d) Regional waveforms (black) and synthetic waveforms (red), separated into Pnl and surface wave phases for 3 components. e) Event depth misfit curve. Errors are normalized by the lowest misfit model, such that the best-fitting model has a relative error of 0. f) Teleseismic waveforms (black) and the best fit synthetic waveforms (red) generated at the preferred depth.

Fig. S3 Teleseismic waveforms (black) and synthetic waveforms (red) for example events with a clear depth phase. Moment tensors are obtained by waveform inversion of regional data and are then fixed for teleseismic waveform modelling. Teleseismic waveforms for events Mw < 6 are shown in velocity at relatively high frequency to highlight the depth phase. Teleseismic waveforms for events Mw > 6 are shown in displacement.

20 0 20 40 Time (s) Displacement 0.02 0.2 Hz CASY58° 183° CASY58° 183° CASY58° 183° CASY58° 183° 0728.2247, Mw6.4, 10.0km 0805.1146, Mw6.9, 12.0km 0819.0410, Mw6.2, 13.0km 0819.1456, Mw6.9, 16.0km 0 10 Time (s) Velocity 0.5 1.5 Hz KURK67° 335° BYRD88° 172° VNDA73° 171° BYRD87° 172° VNDA73° 171° BRVK73° 333° KMBO79° 270° KMBO79° 270° BYRD87° 172° KURK68° 335° KMBO80° 270° BYRD87° 172° 0806.1821, Mw5.2, 9.0km 0810.1557, Mw4.8, 11.0km 1007.1757, Mw5.1, 11.0km 0821.0109, Mw5.2, 11.0km 0805.1649, Mw5.0, 12.0km 0806.0028, Mw5.3, 12.0km 0802.1907, Mw4.9, 12.0km 0809.0525, Mw5.9, 16.0km 0820.0130, Mw5.3, 16.0km 0806.1550, Mw5.1, 18.0km 0826.0354, Mw5.0, 19.0km 0825.1833, Mw5.5, 21.0km

Fig. S4 Comparison of event depths obtained from double difference relocation, waveform inversion and from the GCMT catalogue.

201807282247 201807290150 201808021907 201808051146 201808051649 201808060028 201808061550 201808061821 201808090525 201808101557 201808190410 201808191456 201808192121 201808200130 201808210109 201808251833 201808260354 201808310237 201809060647 201810071757 201903170707 0 5 10 15 20 25 30 Depth (km) Waveform Inversion GCMT Relocation

Fig. S5 Representative time-domain industry reflection profiles from offshore Lombok, showing the picked décollement surface separating deformed sediments of the Bali Basin from underlying continuous reflectors of the subsided Sunda shelf margin. Line locations are given in Fig S1 and Fig S6.

Fig. S6 Construction of the 3D fault model for the Flores Thrust using north-south profiles through the picked décollement at shallow depth and the relocated seismicity at greater depth. Representative profiles A-E are shown. Microseismicity is projected along an east-west line from a maximum distance of 10 km from the profile centerline. Focal mechanisms of large events are projected onto the representative cross sections from a maximum distance of 20 km.

Fig. S7 Teleseismic displacement (P+SH) waveform fits for the A5 event. The observations are in black and the synthetics are in red, the station ID, component, azimuth (upper) and distance (lower) in degree are shown to the left of each waveform pair, the peak displacement amplitude in the data is indicated at the upper right.

Fig. S8 Teleseismic displacement waveform fits for the A19 event. See Fig S7 for the detailed descriptions.

Fig. S9 InSAR data fitting for the A5 event, the descending and ascending fits are shown in the left and right column, respectively.

Fig. S10 InSAR data fitting for the A19 event, the descending and ascending fits are shown in the left and right column, respectively.

Fig. S11 Slip model checkerboard resolution tests. a) Input slip distribution and b) test results. The relocated seismicity is shown as blue dots. The slip models derived from real data (i.e. in Figure 3) are plotted as dashed contours in (a). Note the overlapping region between the real slip models and the best resolutions of the inversion.

Fig. S12 Superposition of geothermal gradient estimates (recalculated from Hall, 2002) onto a

regional geological terrane map (14). The low regional geothermal gradient of 18 °C/km assumed

in this study is consistent with sparse observations of low heat flow along the eastern margin of the East Java – West Sulawesi block.

Fig. S13 Thermal model solution space. The coloured cells are the suite of models for which 5%±0.5% of the relocated seismicity is hotter than 450°C. The cells are coloured according to the total excess temperature (above 450°C), which we define at the sum of temperatures for each hypocentre located in areas hotter than 450°C. There is a trade-off between the maximum geothermal gradient at Rinjani’s crater (g) and the distance over which the geothermal gradient decays to background levels (d), assuming an 18 °C/km regional geothermal gradient. The preferred model is shown as a red plus symbol. We choose this model as the optimum balance between the two parameters that trade-off, while ensuring that the number of events that exceed the 450°C isotherm are not located in excessively hot areas.

Fig. S14 Overview of thermal model. Left: Thermal model in map view showing the radially symmetric pattern of the local geothermal gradient (circular contour lines, °C/km), the resulting temperature of the Flores Thrust 3D fault surface (background colour, °C), and the 80°C, 250°C,

and 450°C isotherms. Right: Isotherms on the Flores Thrust fault surface from the full ensemble

Table S1 SAR images processed. In the second column, AT means ascending tracks, DT means descending tracks.

Satellites Track Date

yyyymmdd spanning event

Sentinel-1 DT32 20180718 20180730 Event1 28 July Sentinel-1 DT32 20180730 20180805 05 AugEvent2 Sentinel-1 DT32 20180817 20180823 19 AugEvent3 ALOS-2 AT129 20180512 20180804 Event128 July ALOS-2 AT129 20180804 20180818 05 AugEvent2 ALOS-2 AT129 20180818 20190105 Event3 19 Aug