Updated Apparent Rotation of Geographic North (*)

Important notice:
This research was done before network operators published the (mis)alignment of the horizontal components,
so the values given here are absolute values.
The results of some more recent work (e.g. Harvard web page) summarize angles that are with respect to the rotations
given by the network operators (e.g. 5deg for PPT, 20deg for ISA) and hence their values are different!


IDA STATIONS
Station# Rayl data# Love dataNORTH (deg)
AAK(1)5252-6.84± 0.59
ALE66691.41± 0.47
ABKT(0)---
ARU(0)---
ASCN(2)220± 3
BFO(0)---
BORG(0)---
BRVK--9.22± 0.95
CMLA(0)---
COCO(0)---
EFI(0)---
ERM(4)40540.22± 0.53
ERM(44)3543-2.03± 0.92
ESK108137-0.28± 0.36
FFC(0)---
GAR(00)<5<5-
HOPE(0)---
JTS(0)---
KDAK(0)---
KIV(0)---
KURK(0)---
LVZ(00)<5<5-
MSEY22< 5
MSVF(0)---
NIL(0)---
NNA841171.02± 0.51
NRIL(00)<5<5-
NVS(00)<5<5-
OBN(0)---
PFO991100.04± 0.35
RAYN(0)---
RPN5947-1.92± 0.56
SHEL(6)22> -35
SUR69720.94± 0.44
TAU(0)---
TLY3737-3.71± 0.57
WRAB(0)---

GEOSCOPE STATIONS
Station# Rayl data# Love dataNORTH (deg)
AGD1613-0.47± 0.99
AIS(0)---
ATD(0)---
BNG29383.38± 0.80
CAN1241500.47± 0.36
CAY3265-2.80± 0.86
CRZF26371.36± 0.85
ECH(00)<5<5-
DRV26281.64± 0.79
HDC216162.09± 1.47
HYB21190.63± 0.75
INU116145-0.06± 0.37
KIP1461691.77± 0.30
KOG(0)---
MBO38390.12± 0.76
NOC(00)<5<5-
NOUC33421.30± 0.77
PAF51590.98± 0.63
PCR(0)---
PEL(0)---
PPT(7)9277-6.03± 0.45
PVC(0)---
RER3233-2.19± 0.66
SCZ(7)128134-4.07± 0.32
SEY24301.13± 0.54
SSB1091161.90± 0.37
SPB(0)---
TAM24301.13± 0.54
UNM34460.23± 0.71
WFM134176-0.02± 0.36
WUS4865-0.92± 0.47









Green station names indicate more than 50 measurements for each wave type, hence more reliably determined orientations.
Maroon values for apparent North indicate significant station misalignment by more than 3°.
Red values for apparent North indicate significant station misalignment by more than 10°.
(*) Positive values mean a clockwise rotation of NORTH (anticlockwise rotation of instrument)
(0) ABKT, AIS, ATD, ARU, BFO, BORG, CMLA, COCO, EFI, FFC, HOPE, JTS, KDAK, KIV, KOG, KURK, MSVF, NIL, OBN, PCR, PEL, PVC, RAYN, SPB, TAU, WRAB not yet analyzed
(00) ECH, NOC, GAR, LVZ, NRIL, NVS: less than 5 data (not used in inversion)
(1)AAK: station fixed 011,94; N-component was off by +6°
(2)ASCN: vault seismometer has N at approx. +3° while borehole is at -3° (not included in inversion)
(3)BRVK: data used were from 244.94 - 092.95 (not included in inversion), instrument was re-oriented by +9° on 093.95
(4)ERM: before 081.94: in addition to the 45° reported by the operators
(44)ERM: after 081.94: in addition to the 180° reported by the operators
(5)MSEY: vault seismometer misrotated, has N at -20° relative to borehole (not included in inversion)
(6)SHEL: borehole seismometer has N at approx. -3° relative to vault seismometer (not included in inversion)
(7)PPT: -5° confirmed by the operators

Results not included in the inversion are only preliminary!

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SOME IU,TS OR OTHER STATIONS
Station# Rayl data# Love dataNORTH (deg)
ANMO127147-1.64± 0.34
BJI5677-0.93± 0.44
CCM45542.09± 0.61
CMB20172.22± 0.98
COL49730.13± 0.43
COR83100-0.19± 0.35
CTAO5357-0.98± 0.62
ENH2740-0.87± 0.67
GSC36542.20± 0.53
GUMO25371.44± 1.06
HIA881090.54± 0.37
HRV1051110.00± 0.41
ISA343716.02± 0.65
KIP(1)1051202.11± 0.34
KMI100123-1.64± 0.42
KONO49721.27± 0.44
LSA28435.11± 0.91
LZH701031.60± 0.49
MAJO7799 6.00± 0.45
MDJ3333-2.14± 0.61
NWAO(2)1723-4.70± 1.20
PAS93104-0.02± 0.34
PFOT(3)9120.32± 0.73
QIZ1724-1.02± 1.09
SBC2224-0.10± 0.76
SNZO3645-4.57± 0.64
TATO(4)16139.90± 1.83
TUC1516-1.46± 0.84
WMQ101112-0.46± 0.38
YSS1220-1.94± 0.76
(1) KIP: same sensor as GEOSCOPE but separate datalogger
(2) NWAO: data from Nov26.92
(3) PFOT: (TERRASCOPE) same sensor as IDA but separate datalogger
(4) TATO: uncertain due to lack of data, data from Sep26.92

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USNSN STATIONS (data from 97 through 99)
Station# Rayl data# Love dataNORTH (deg)
AAM 60 73 3.29± 0.51
AHID21 27 0.90± 0.57
BINY15 20 4.58± 0.94
BLA 47 55 8.87± 0.48
BW0664 62 -27.43± 0.48
CBKS28 32 0.71± 0.62
CEH 29 29 13.08± 1.13
DUG 40 46 -0.14± 0.47
ELK(1) 26 28 30.81± 0.57
ELK1(2)57 58 -5.66± 0.41
EYMN43 43 1.71± 0.49
GOGA36 37 8.22± 0.75
GWDE25 24 2.30± 1.36
HLID(3)2 2 -± -
HWUT29 35 -0.32± 0.55
ISCO71 85 -0.84± 0.28
JFWS23 27 -0.14± 1.04
KNB 50 61 -2.41± 0.59
LBNH73 75 0.58± 0.38
LKWY(3)11 13 -± -
LSCT22 19 2.00± 0.92
MCWV26 29 6.61± 0.78
MIAR12 12 -3.06± 1.25
MNV 38 37 3.80± 0.72
MYNC35 35 5.27± 0.90
NEW 52 55 -3.15± 0.39
OXF 29 32 -1.10± 0.71
TPNV22 26 1.60± 0.73
WMOK19 20 -15.69± 0.74
WVOR31 37 -18.45± 0.68
WUAZ(3)4 5 -± -
YSNY13 18 4.56± 1.12
Green station names indicate more than 50 measurements for each wave type, hence more reliably determined orientations.
Maroon values for apparent North indicate significant station misalignment by more than 5°.
(NB: This is more than for GSN and other global stations!)
Red values for apparent North indicate significant station misalignment by more than 10°.
(1) ELK: ELK before 97.254 (Sep. 11)
(2) ELK1: ELK after 97.300 (Oct. 27)
(3) not enough data

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CNSN (96-99)
Station# Rayl data# Love dataNORTH (deg)
DRLN194 210 -0.24± 0.23
FRB 86 98 0.90± 0.43
GAC 48 62 5.25± 0.81
INK 102 129 0.23± 0.41
MBC 38 46 1.45± 0.66
PMB 76 94 -3.52± 0.46
RES 87 113 -1.29± 0.42
SCHQ(1)39 44 -20.71± 0.65
SCH1(2)26 26 -2.56± 0.89
WHY 123 138 0.45± 0.35
YKW3182 209 -0.62± 0.24
Green station names indicate more than 50 measurements for each wave type, hence more reliably determined orientations.
Maroon values for apparent North indicate significant station misalignment by more than 3°.
Red values for apparent North indicate significant station misalignment by more than 10°.
(1) SCHQ: before 98.158
(2) SCH1: SCHQ after 98.190
Network operators report a misalignment of -23.1° for SCHQ the whole period.

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Temporary Saudi Seismic Network (95/96)
Station# Rayl data# Love dataNORTH (deg)
AFIF43 37 -4.22± 0.66
BISH(1)4 4 0.52± 1.35
HALM16 16 -1.65± 0.84
RANI18 21 -2.76± 0.96
RAYN19 21 1.71± 0.87
RIYD(2)4 5 0.70± 1.34
SODA70 78 -2.72± 0.54
TAIF(2)7 10 -4.01± 1.66
UQSK(2)3 8 -4.04± 2.52
(1) uncertain; stolen after 2 weeks
(2) uncertain; late installation

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Gabi Laske ( glaske@ucsd.edu)

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