## 2 Materials and Methods
### Data
#### 2.2.2 Typhoon and Rainfall Data  
The International Best Track Archive for Climate Stewardship (IBTrACS) data repository [63] compiles the hurricane/typhoon best-track position and intensity from different data sources and makes them available in one consolidated archive. We obtained the fourth version of this data in shapefile format to extract the spatial information corresponding to 19 typhoon events that had an impact on the landslide area or had a SSHWS category three (H3) or higher within a 100 km radius from the Butangbunasi landslide (Table 2). \begin{table}
\begin{tabular}{c c c} \hline \hline
**Sensor** & **Acquisition Date** & **Scene ID** \\ \hline Landsat 8 & 8 November 2018 & LCS1170442018312 LGN00 \\ Landsat 8 & 4 December 2016 & LCS1170442016339 LGN01 \\ Landsat 8 & 16 November 2015 & LCS1170442015320 LGN01 \\ Landsat 8 & 03 June 2013 & LCS1170442013154 LGN01 \\ Landsat 5 & 20 December 2010 & LTS1170442010354 BKT00 \\ Landsat 5 & 12 September 2009 & LTS1170442009255 BKT00 \\ Landsat 5 & 24 August 2008 & LTS1170442008237 BKT00 \\ Landsat 5 & 17 March 2008 & LTS1170442008077 BKT00 \\ Landsat 5 & 3 October 2005 & LTS11704420052576 BJC00 \\ Landsat 5 & 17 September 2005 & LTS117044200256B0 RT02 \\ Landsat 5 & 12 July 2004 & LTS1170442004194 BKT02 \\ Landsat 7 & 14 September 2001 & LTS1170442001257 EDC00 \\ Landsat 7 & 27 September 2000 & LTS11704420002715 GS00 \\ Landsat 5 & 1 November 1998 & LTS1170441998305 BJC00 \\ Landsat 5 & 23 August 1996 & LTS1170441996236 CLT00 \\ Landsat 5 & 3 September 1994 & LTS1170441994246 CLT00 \\ Landsat 5 & 31 October 1992 & LTS1170441992305 BJC00 \\ Landsat 5 & 10 October 1990 & LTS1170441990283 BJC00 \\ Landsat 5 & 23 October 1989 & LTS1170441989296 BJC00 \\ Landsat 5 & 12 December 1984 & LTS1170441984347 HAJ00 \\ \hline \hline \end{tabular} Note. – 1 variables selected from the closest point in the typhoon track to the centroid of the Butangbunasi landslide area; 2 Maximum Saffir-Simpson hurricane wind scale (SHWS) category reached by the typhoon when passing over Taiwan. H = Hurricane, TS = Tropical Storm.  
\end{table} 
Table 1: Landsat satellite images for the study area. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Name** & **Year** & **Date and Time 1** & **Maximum SSHWS** & **SSHWS** & **Distance to Butangbunasi** \\  & & & **Category 2** & **Category 1** & **Landslide (km) 1** \\ \hline Megi & 2016 & 27 September 2016 12:00 & H3 & H1 & 74 \\ Neperatk & 2016 & 8 July 2016 03:00 & H4 & H1 & 58 \\ Soudler & 2015 & 8 August 2015 00:00 & H3 & H2 & 78 \\ Talim & 2012 & 20 June 2012 12:00 & TS & TS & 151 \\ Fanapi & 2010 & 19 September 2010 06:00 & H3 & H1 & 16 \\ Morakot & 2009 & 7 August 2009 18:00 & H1 & TS & 108 \\ Fung-Wong & 2008 & 28 July 2008 0:00 & H2 & H2 & 64 \\ Sepat & 2007 & 18 August 2007 00:00 & H3 & H3 & 46 \\ Longwang & 2005 & 2 October 2005 00:00 & H4 & H2 & 85 \\ Haitang & 2005 & 18 July 2005 0:00 & H4 & H3 & 106 \\ Mindulie & 2004 & 1 July 2004 12:00 & H1 & H1 & 81 \\ Torai & 2001 & 29 July 2001 18:00 & H3 & H3 & 80 \\ Blis & 2002 & 22 August 2000 15:00 & H5 & H4 & 47 \\ Otto & 1998 & 4 August 1998 06:00 & H1 & H1 & 48 \\ Gloria & 1996 & 26 July 1996 09:00 & H2 & H2 & 87 \\ [PERSON] & 1994 & 10 July 1994 12:00 & H4 & H4 & 70 \\ [PERSON] & 1992 & 4 September 1992 15:00 & TS & TS & 56 \\ Dot & 1990 & 7 September 1990 15:00 & H1 & H1 & 33 \\ [PERSON] & 1989 & 11 September 1989 18:00 & H4 & H2 & 51 \\ \hline \hline \end{tabular} Note. – 1 variables selected from the closest point in the typhoon track to the centroid of the Butangbunasi landslide area; 2 Maximum Saffir-Simpson hurricane wind scale (SHWS) category reached by the typhoon when passing over Taiwan. H = Hurricane, TS = Tropical Storm.  
\end{table} 
Table 2: Selected typhoon and tropical storm events for the study. As for the rainfall data, Taiwan's Central Weather Bureau (CWB) provides the open Typhoon Database [64], which compiles various sources of information relevant to the study and the monitoring of typhoon events in the western North Pacific.