Station PF FOR - Station Sismologique de Chateau Fort

Network: PF - Volcanologic Network of Piton de Fournaise-OVPF

Nearby stations (2 deg radius)

Station Name (Lat, Lon) Start / End Elevation
FOR Station Sismologique de Chateau Fort (-21.26, 55.72) 2011-01-01 / 2599-12-31 2049 m
Crust2 Type:B1,melt affected o.c. and oceanic plateaus, 0.5 km seds.
Thickness Estimate:16 km
Thickness StdDev:2.9 km
Vp/Vs Estimate:1.98
Vp/Vs StdDev:0.09
Vs Estimate:2.395 km/s
Poisson's Ratio:0.33
Peak Value:0.06
Assumed Vp:4.73 km/s
Ps Weight:0.33333334
PpPs Weight:0.33333334
PsPs Weight:0.33333328
Residual Complexity:0.450
Nearby stations H:22 km +- 8.5 km
(2.0 deg) Vp/Vs:1.84 +- 0.20

3 with match > 90% ( 2.3622048 %) and 11 with match > 80% ( 8.661417 %) out of 127.

Download stack as xyz text file.

Azimuth Distribution of Events:

Prior Results for this Station

Study Thickness Vp/Vs Vp Vs Poissons Ratio Extra
EARS 16 km 1.98 4.73 km/s 2.395 km/s 0.33
Crust2.0 16 km 2.06 4.73 km/s 2.3 km/s 0.35 B1,melt affected o.c. and oceanic plateaus, 0.5 km seds.
Global Maxima 16 km 1.98 4.73 km/s 2.395 km/s 0.33 amp=0.064924195
Local Maxima 1 27 km 1.85 4.73 km/s 2.553 km/s 0.29 amp=0.02850517
Local Maxima 2 29 km 1.60 4.73 km/s 2.956 km/s 0.18 amp=0.022262227
Local Maxima 3 55 km 1.87 4.73 km/s 2.536 km/s 0.30 amp=0.016912976
Local Maxima 4 32 km 2.07 4.73 km/s 2.282 km/s 0.35 amp=0.015186789
Predicted Arrivals for vertical incidence
(zero ray parameter)
Ps3.40 SECOND
PpPs10.38 SECOND
PsPs/PpSs13.78 SECOND

Events Processed for this Station

Download zip of receiver functions as SAC

View Record Section

Plot maxima for each earthquake.

Events Used in the Stack

(11 events)
Radial Match Distance Baz FERegion Time Lat/Lon Depth Magnitude
92.81186 57.0 deg 32.272 deg Nepal 2015/05/12 07:05:19 GMT (27.8, 86.1) 15 km 7.3 MWW
90.71703 56.6 deg 350.393 deg Iran-Iraq Border Region 2017/11/12 18:18:17 GMT (34.9, 46.0) 19 km 7.3 Mww
90.31137 96.5 deg 99.2 deg Solomon Islands 2017/01/22 04:30:23 GMT (-6.2, 155.1) 136 km 7.9 mww
89.554985 72.9 deg 80.999 deg Northern Molucca Sea 2014/11/26 14:33:43 GMT (1.9, 126.5) 39 km 6.8 MWW, 6.8 MWC, 6.8 MWB, 7.0 MI
88.97945 70.4 deg 76.997 deg Celebes Sea 2017/01/10 06:13:48 GMT (4.4, 122.7) 622 km 6.9 Mi
87.243004 72.9 deg 81.001 deg Northern Molucca Sea 2014/11/15 02:31:40 GMT (1.9, 126.5) 35 km 7.1 MWW, 7.0 MWW, 7.3 MI
85.92189 68.1 deg 214.001 deg South Sandwich Islands Region 2018/12/11 02:26:32 GMT (-58.6, -26.5) 165 km 7.1 mww
82.18998 74.7 deg 77.468 deg Mindanao, Philippines 2018/12/29 03:39:12 GMT (5.8, 126.9) 49 km 7.2 Mi
81.975044 61.6 deg 88.942 deg Sumbawa Region, Indonesia 2016/12/29 22:30:18 GMT (-9.1, 118.6) 72 km 6.2 Mwp
80.96694 72.3 deg 90.081 deg Banda Sea 2019/06/24 02:53:39 GMT (-6.4, 129.2) 212 km 7.3 mww
80.76436 68.5 deg 216.549 deg South Sandwich Islands Region 2016/05/28 09:46:59 GMT (-56.2, -26.9) 73 km 7.2 MWW, 7.3 MI

Losers

(116 events)
Radial Match Distance Baz FERegion Time Lat/Lon Depth Magnitude Reason
91.259636 95.7 deg 96.95 deg New Ireland Region, P.N.G. 2016/12/17 11:22:39 GMT (-4.4, 153.5) 83 km 5.6 mb
91.07668 35.5 deg 145.125 deg Southeast Indian Ridge 2015/12/04 22:24:54 GMT (-47.7, 85.2) 10 km 7.1 MWP
90.78473 59.1 deg 14.073 deg Hindu Kush Region, Afghanistan 2015/10/26 09:09:32 GMT (36.4, 70.7) 212 km 7.5 MWW, 7.5 MWB
88.2566 94.8 deg 138.887 deg South Island, New Zealand 2016/11/13 13:31:26 GMT (-42.3, 173.7) 8.3 km 6.2 MWW
84.11146 85.1 deg 94.711 deg New Guinea, Papua New Guinea 2018/02/25 17:44:39 GMT (-6.2, 142.8) 10 km 7.6 Mi
84.106636 94.6 deg 97.591 deg New Britain Region, P.N.G. 2015/02/26 23:44:58 GMT (-5.4, 152.8) 37 km 5.0 MW
82.16075 95.3 deg 62.339 deg Bonin Islands, Japan Region 2015/05/30 11:23:02 GMT (27.8, 140.5) 678 km 7.8 MWP, 8.5 MI
79.5945 73.5 deg 80.873 deg Northern Molucca Sea 2014/11/21 10:10:19 GMT (2.3, 127.1) 38 km 6.5 MWC, 6.8 MI, 6.9 MI
79.074585 95.7 deg 97.009 deg New Ireland Region, P.N.G. 2016/12/17 10:51:11 GMT (-4.5, 153.6) 73 km 8.0 Mi
78.82871 52.2 deg 83.181 deg Java, Indonesia 2017/12/15 16:47:56 GMT (-7.7, 108.0) 92 km 6.5 Mww
77.907394 59.3 deg 14.425 deg Afghanistan-Tajikistan Bord Reg. 2015/12/25 19:14:48 GMT (36.5, 71.1) 204 km 6.2 MO
77.25344 96.1 deg 74.302 deg Mariana Islands 2015/02/27 16:24:50 GMT (16.9, 145.8) 20 km 5.7 MB
76.91745 35.7 deg 77.353 deg South Indian Ocean 2014/06/14 11:11:00 GMT (-10.1, 91.1) 7.1 km 6.4 MWP, 6.4 MWB
76.526924 59.8 deg 87.271 deg Sumbawa Region, Indonesia 2018/08/05 11:46:34 GMT (-8.3, 116.5) 10 km 7.0 Mww
76.05356 67.8 deg 83.062 deg Sulawesi, Indonesia 2019/04/12 11:40:49 GMT (-1.9, 122.6) 17 km 6.8 Mww
75.3285 88.0 deg 207.301 deg Drake Passage 2018/10/29 06:54:21 GMT (-57.4, -66.4) 10 km 6.3 Mww
75.00913 96.4 deg 72.7 deg Mariana Islands 2016/07/29 21:18:25 GMT (18.5, 145.5) 212 km 7.7 MWW, 7.7 MWB, 7.7 MI
74.939255 72.9 deg 90.573 deg Banda Sea 2018/03/25 20:14:47 GMT (-6.7, 129.9) 172 km 6.4 Mww
74.60378 56.6 deg 44.661 deg Myanmar 2016/08/24 10:34:55 GMT (20.9, 94.6) 84 km 6.8 MO
74.45536 70.7 deg 90.703 deg Banda Sea 2016/12/21 00:17:15 GMT (-7.5, 127.9) 152 km 6.7 Mww
74.18363 96.6 deg 166.84 deg Pacific-Antarctic Ridge 2015/03/02 02:50:47 GMT (-59.6, -150.7) 13 km 5.5 MWB, 5.5 MWC
73.986336 86.4 deg 93.116 deg New Guinea, Papua New Guinea 2017/11/07 21:26:38 GMT (-4.2, 143.5) 107 km 6.5 mww
73.96168 93.4 deg 97.148 deg New Britain Region, P.N.G. 2018/03/29 21:25:32 GMT (-5.5, 151.4) 10 km 6.9 mww
73.58564 84.5 deg 57.943 deg Ryukyu Islands, Japan 2014/03/02 20:11:23 GMT (27.4, 127.4) 119 km 6.5 MWW, 6.4 MWB, 6.5 MWC, 6.6 MI, 6.7 MI
72.24183 88.6 deg 78.614 deg W. Caroline Islands, Micronesia 2017/12/08 00:22:53 GMT (10.1, 140.2) 7.5 km 6.5 mww
71.57246 90.1 deg 96.497 deg New Britain Region, P.N.G. 2014/11/07 03:33:54 GMT (-6.0, 148.2) 43 km 6.6 MWW, 6.6 MWB, 6.9 MI
71.441246 59.3 deg 14.727 deg Afghanistan-Tajikistan Bord Reg. 2015/11/22 18:16:04 GMT (36.5, 71.5) 92 km 5.9 MB
70.24961 78.4 deg 58.373 deg Taiwan 2018/02/06 15:50:41 GMT (24.2, 121.7) 9.5 km 6.4 Mww
70.14367 47.3 deg 216.239 deg Southwest Of Africa 2018/01/28 16:03:03 GMT (-53.1, 9.7) 10 km 6.6 Mww
69.52728 65.8 deg 81.048 deg Minahassa Peninsula, Sulawesi 2018/09/28 10:16:49 GMT (-0.9, 120.0) 10 km 5.7 mb
69.129585 72.8 deg 81.25 deg Northern Molucca Sea 2015/03/17 22:12:28 GMT (1.7, 126.5) 42 km 6.6 MO
69.077225 93.4 deg 97.168 deg New Britain Region, P.N.G. 2018/03/24 11:23:32 GMT (-5.5, 151.5) 36 km 6.3 mww
68.39912 67.7 deg 90.484 deg Timor Region 2015/11/04 03:44:15 GMT (-8.4, 124.9) 14 km 6.3 MWP
68.317406 31.0 deg 307.322 deg Lake Victoria Region 2016/09/10 12:27:28 GMT (-1.0, 31.5) 10 km 5.9 MWW, 5.8 MWB, 5.9 MWC
68.106804 47.7 deg 72.604 deg Southern Sumatra, Indonesia 2016/06/01 22:56:00 GMT (-2.1, 100.7) 50 km 6.6 MWW, 6.4 MWB, 6.6 MWC, 6.7 MWC
67.54184 63.2 deg 87.65 deg Flores Sea 2018/08/17 15:35:02 GMT (-7.4, 119.8) 539 km 6.5 Mww
66.88118 73.6 deg 90.272 deg Banda Sea 2014/12/06 22:05:10 GMT (-6.1, 130.5) 117 km 6.0 MB
65.72928 75.7 deg 71.092 deg Samar, Philippines 2019/04/23 05:37:52 GMT (11.8, 125.2) 54 km 6.4 Mww
65.385605 56.9 deg 32.351 deg Nepal 2015/05/12 07:17:20 GMT (27.8, 86.1) 10 km 5.6 MB
64.881966 66.7 deg 272.982 deg Ascension Island Region 2018/10/05 14:59:44 GMT (-5.6, -11.5) 10 km 5.6 Mww
64.826775 94.0 deg 97.312 deg New Britain Region, P.N.G. 2015/05/05 02:40:24 GMT (-5.4, 152.1) 45 km 5.3 mb
64.670685 65.7 deg 88.503 deg Flores Sea 2016/08/23 19:39:44 GMT (-7.3, 122.5) 528 km 6.0 MB
64.59886 94.5 deg 97.027 deg New Britain Region, P.N.G. 2015/08/10 12:00:28 GMT (-4.9, 152.5) 55 km 4.9 mb
64.300064 59.2 deg 14.128 deg Hindu Kush Region, Afghanistan 2018/01/31 07:07:00 GMT (36.5, 70.8) 191 km 6.1 Mww
63.97073 69.1 deg 216.771 deg South Sandwich Islands Region 2019/04/05 16:14:16 GMT (-55.9, -27.8) 58 km 6.5 mww
63.42941 78.4 deg 58.529 deg Taiwan 2019/04/18 05:01:06 GMT (24.0, 121.7) 20 km 6.1 Mww
63.260548 66.3 deg 88.674 deg Banda Sea 2017/10/24 10:47:47 GMT (-7.2, 123.0) 549 km 6.7 Mww
63.16802 59.8 deg 14.473 deg Afghanistan-Tajikistan Bord Reg. 2018/05/09 10:41:45 GMT (37.0, 71.4) 112 km 6.2 Mww
62.845825 72.0 deg 81.271 deg Northern Molucca Sea 2016/10/27 08:17:49 GMT (1.3, 125.8) 56 km 5.9 MB, 5.8 MWB
62.774204 53.4 deg 79.92 deg Java Sea 2016/10/19 00:26:01 GMT (-4.9, 108.2) 614 km 6.6 MWW, 6.6 MWC, 6.7 MWB
62.36257 75.6 deg 150.953 deg Balleny Islands Region 2017/10/08 20:48:58 GMT (-61.7, 154.6) 10 km 6.3 Mww
61.36585 84.5 deg 89.966 deg Irian Jaya Region, Indonesia 2016/09/24 11:04:30 GMT (-1.9, 140.6) 10 km 5.6 MB
61.272026 70.8 deg 82.231 deg Northern Molucca Sea 2017/01/13 16:39:25 GMT (0.0, 125.1) 46 km 5.7 mb
60.856804 66.6 deg 88.88 deg Banda Sea 2016/12/05 01:13:04 GMT (-7.3, 123.4) 526 km 6.3 Mww
60.571236 51.7 deg 1.749 deg Northern And Central Iran 2017/12/01 02:32:46 GMT (30.7, 57.3) 9.0 km 6.1 Mww
60.54345 59.5 deg 87.311 deg Sumbawa Region, Indonesia 2018/08/09 05:25:31 GMT (-8.4, 116.2) 10 km 5.9 Mww
60.00163 59.8 deg 87.29 deg Sumbawa Region, Indonesia 2018/07/28 22:47:37 GMT (-8.3, 116.5) 6.4 km 6.4 Mww
59.907673 59.9 deg 87.378 deg Sumbawa Region, Indonesia 2018/08/19 04:10:21 GMT (-8.3, 116.6) 7.9 km 6.3 Mww
59.65839 67.5 deg 214.583 deg South Sandwich Islands Region 2018/08/14 03:29:53 GMT (-58.1, -25.3) 35 km 6.1 Mww
59.492348 47.5 deg 57.243 deg Nicobar Islands, India Region 2019/01/17 02:53:07 GMT (7.4, 94.4) 99 km 5.4 Mww
59.482307 94.5 deg 97.301 deg New Britain Region, P.N.G. 2015/03/30 00:15:30 GMT (-5.2, 152.6) 35 km 5.7 MB
59.20408 90.5 deg 96.714 deg New Britain Region, P.N.G. 2016/11/01 19:03:28 GMT (-6.1, 148.6) 35 km 5.9 MWB
58.631184 73.7 deg 74.887 deg Mindanao, Philippines 2017/09/23 20:47:08 GMT (7.6, 124.9) 31 km 5.7 Mww
58.62502 69.6 deg 86.977 deg Banda Sea 2016/06/05 16:25:33 GMT (-4.6, 125.6) 429 km 6.3 MWB
58.574177 94.7 deg 76.572 deg Mariana Islands 2017/03/13 08:49:06 GMT (14.3, 145.3) 101 km 5.5 Mi
58.14779 73.8 deg 78.87 deg Talaud Islands, Indonesia 2014/05/04 08:53:58 GMT (4.2, 126.6) 100 km 5.2 MW
58.076218 70.1 deg 49.476 deg Southeastern China 2015/03/30 01:47:36 GMT (26.7, 108.8) 20 km 5.4 mb, 5.4 mb, 5.8 MS
57.835762 73.4 deg 90.273 deg Banda Sea 2018/03/02 02:20:12 GMT (-6.2, 130.3) 137 km 5.9 Mww
57.237343 74.6 deg 76.885 deg Mindanao, Philippines 2019/05/31 10:12:32 GMT (6.3, 126.6) 90 km 6.1 Mww
57.233864 49.0 deg 74.282 deg Southern Sumatra, Indonesia 2018/12/30 08:39:12 GMT (-2.7, 102.3) 168 km 5.8 Mww
56.92257 67.8 deg 75.487 deg Sulu Archipelago, Philippines 2015/01/19 17:19:45 GMT (4.6, 119.8) 11 km 5.5 MWB
56.920876 71.8 deg 81.01 deg Northern Molucca Sea 2014/06/17 19:56:23 GMT (1.5, 125.5) 99 km 5.0 MW
56.371502 71.8 deg 90.828 deg Banda Sea 2015/11/11 23:36:18 GMT (-7.2, 128.9) 122 km 5.7 MB
56.204502 55.9 deg 349.937 deg Iran-Iraq Border Region 2019/01/06 13:42:01 GMT (34.1, 45.7) 25 km 5.8 mb
56.193424 72.0 deg 326.792 deg Tyrrhenian Sea 2016/10/28 20:02:48 GMT (39.3, 13.5) 448 km 5.8 MWW, 5.8 MWB
55.945465 61.3 deg 86.33 deg Bali Sea 2014/10/30 12:11:36 GMT (-7.0, 117.6) 546 km 5.7 MB
55.892334 75.0 deg 87.726 deg Seram, Indonesia 2018/03/08 03:51:07 GMT (-3.3, 130.9) 7.9 km 5.7 Mww
55.886547 94.7 deg 95.457 deg New Ireland Region, P.N.G. 2019/02/17 14:35:56 GMT (-3.4, 152.1) 368 km 6.4 Mww
55.847736 91.9 deg 94.181 deg Bismarck Sea 2019/05/15 00:33:45 GMT (-3.2, 149.0) 10 km 5.5 Mww
55.569633 85.6 deg 79.392 deg W. Caroline Islands, Micronesia 2016/12/18 09:47:08 GMT (8.3, 137.7) 29 km 6.5 Mi
55.4995 49.3 deg 12.024 deg Pakistan 2015/08/03 13:16:03 GMT (27.3, 66.0) 25 km 5.4 MW
55.197918 49.7 deg 51.145 deg Andaman Islands, India Region 2018/02/13 02:39:53 GMT (12.4, 93.1) 69 km 5.6 mb
55.098568 93.8 deg 95.945 deg New Britain Region, P.N.G. 2014/07/15 16:39:01 GMT (-4.2, 151.4) 10 km 5.5 MB
54.33413 59.1 deg 14.079 deg Hindu Kush Region, Afghanistan 2014/03/19 14:15:43 GMT (36.5, 70.7) 193 km 4.7 mb
53.8964 74.9 deg 328.948 deg Central Italy 2016/10/30 06:40:19 GMT (42.9, 13.1) 10 km 6.6 MWW, 6.6 MWR
53.15298 72.8 deg 74.285 deg Mindanao, Philippines 2018/11/04 07:55:29 GMT (7.8, 123.9) 598 km 6.0 Mww
52.997864 72.7 deg 91.133 deg Banda Sea 2015/11/21 09:06:12 GMT (-7.2, 129.9) 67 km 6.1 MWP
52.921707 75.2 deg 61.882 deg Philippine Islands Region 2014/11/17 14:13:43 GMT (19.6, 120.5) 23 km 5.2 MW, 5.3 mb, 4.9 MS
52.903206 90.8 deg 96.74 deg New Britain Region, P.N.G. 2016/10/17 06:14:58 GMT (-6.1, 148.9) 35 km 6.9 MO
52.39973 83.5 deg 91.666 deg Irian Jaya, Indonesia 2018/12/16 09:42:37 GMT (-3.9, 140.3) 61 km 6.1 Mww
52.039513 72.5 deg 81.504 deg Northern Molucca Sea 2016/06/07 19:15:15 GMT (1.3, 126.3) 31 km 6.3 MWW, 6.2 MWB, 6.3 MWC, 6.4 MWC, 6.5 MI, 6.6 MI
51.31362 93.1 deg 97.381 deg New Britain Region, P.N.G. 2018/10/10 20:45:26 GMT (-5.8, 151.3) 52 km 5.9 mb
51.03181 71.9 deg 90.828 deg Banda Sea 2015/12/24 23:10:58 GMT (-7.2, 129.0) 128 km 5.8 MB, 5.8 MB
50.910492 30.8 deg 210.398 deg Prince Edward Islands Region 2014/11/17 16:52:46 GMT (-46.4, 33.8) 10 km 6.2 MWB
49.893044 94.7 deg 96.811 deg New Britain Region, P.N.G. 2015/03/30 08:31:46 GMT (-4.7, 152.6) 35 km 5.3 mb, 5.2 mb, 5.7 MS
49.06797 71.7 deg 80.982 deg Northern Molucca Sea 2018/10/13 04:34:15 GMT (1.5, 125.4) 106 km 5.2 Mww
49.01394 75.7 deg 72.982 deg Leyte, Philippines 2015/07/03 06:43:23 GMT (10.2, 125.9) 50 km 6.0 MB
48.989513 66.1 deg 88.449 deg Flores Sea 2018/07/28 17:07:23 GMT (-7.1, 122.7) 577 km 6.0 Mww
48.50811 93.7 deg 76.765 deg Mariana Islands 2014/09/17 06:14:46 GMT (13.8, 144.4) 137 km 6.7 MWC, 7.1 MI
48.443733 52.9 deg 84.19 deg Java, Indonesia 2019/06/09 09:32:25 GMT (-8.2, 109.0) 80 km 5.2 Mww
48.288357 73.6 deg 65.321 deg Luzon, Philippines 2019/02/06 10:25:20 GMT (15.9, 120.6) 130 km 5.5 Mww
48.21494 72.7 deg 90.646 deg Banda Sea 2017/11/29 23:53:50 GMT (-6.8, 129.8) 160 km 5.5 Mww
47.760624 73.4 deg 90.62 deg Banda Sea 2019/01/04 06:22:44 GMT (-6.5, 130.4) 118 km 5.6 Mww
47.21635 47.2 deg 66.007 deg Northern Sumatra, Indonesia 2019/03/11 13:26:24 GMT (1.9, 97.8) 41 km 5.2 Mww
47.103325 67.4 deg 214.624 deg South Sandwich Islands Region 2018/11/01 19:30:20 GMT (-58.1, -25.2) 29 km 5.8 Mww
46.928814 56.3 deg 31.231 deg Nepal-India Border Region 2015/04/25 23:16:15 GMT (27.8, 84.9) 10 km 5.6 MB
46.418995 76.2 deg 73.008 deg Philippine Islands Region 2014/01/02 09:56:17 GMT (10.4, 126.5) 60 km 5.0 mb
46.37051 90.9 deg 96.797 deg New Britain Region, P.N.G. 2019/03/11 16:25:51 GMT (-6.1, 149.0) 31 km 5.8 Mww
45.09918 57.3 deg 17.202 deg Pakistan 2015/07/24 20:59:53 GMT (33.9, 73.1) 15 km 5.0 MW
44.92899 82.6 deg 273.686 deg Central Mid-Atlantic Ridge 2014/08/10 12:12:24 GMT (0.7, -26.0) 10 km 5.1 MW, 5.0 mb
42.92101 88.1 deg 58.894 deg Southeast Of Ryukyu Islands 2014/03/26 08:49:41 GMT (28.2, 131.5) 10 km 5.6 MWP, 1.0 MI, 5.4 MWC, 5.5 MWW
42.81749 56.9 deg 4.576 deg Northern And Central Iran 2017/04/05 06:09:12 GMT (35.8, 60.4) 13 km 6.1 Mww
42.187946 88.7 deg 96.178 deg Eastern New Guinea Reg., P.N.G. 2014/12/17 03:09:47 GMT (-6.3, 146.8) 95 km 4.6 mb, 4.1 mb, 4.3 mb1, 4.1 mb1mx, 4.5 mbtmp, 3.2 MS, 3.2 Ms1, 2.9 ms1mx
40.184513 76.0 deg 73.893 deg Mindanao, Philippines 2014/06/02 01:04:10 GMT (9.5, 126.6) 59 km 5.1 MW
39.322006 91.7 deg 92.156 deg Admiralty Islands Region, P.N.G. 2017/08/27 04:17:51 GMT (-1.4, 148.1) 10 km 6.6 Mi
34.79439 95.7 deg 98.407 deg Solomon Islands 2015/08/16 21:05:11 GMT (-5.8, 154.1) 68 km 5.2 MW