Long Island, Willapa Bay - WA129
Additional information
David Yamaguchi
Reference:
Yamaguchi, D.K., B.F. Atwater, D.E. Bunker, B.E. Benson, and M.S. Reid. 1997.
Tree-ring dating the 1700 Cascadia earthquake.
Nature, Vol. 389, pp. 922 - 923, 30 October 1997.
Supplementary information for "Tree-ring dating the 1700 Cascadia earthquake"
published in Nature, Scientific Correspondence
David K. Yamaguchi, Dept. of Environmental Health,
University of Washington, Box 354695, Seattle, Washington 98195, USA
(TrRingzRUs@aol.com, fax 1-206-616-4875)
Brian F. Atwater, U.S. Geological Survey at Dept. of Geological Sciences,
University of Washington, Box 351310, Seattle, Washington 98195, USA
(atwater@u.washington.edu, fax 1-206-553-8350)
Daniel E. Bunker, Boyd E. Benson & Marion S. Reid
Test of validity of Long Island series.
To check for missing rings/1,2 at Long Island (46.42 N, 123.95 W),
we compared its series with one previously obtained from 4-8 old-growth redcedar
about 200 km to the north near Ozette/3 (about 48.2 N, 124.7 W). (The exact size
of the Ozette sample is unknown to us.) The two series overlap between 993 and 1978.
Although the correlation is weak (r = .17, t = 5.3, P < 0.0000001; see Statistical significance),
weak correlation is common between moist-site trees. We found no reason to doubt that the
Long Island chronology is complete.
Correlation between Long Island and snags.
The dating is supported by alignment of narrow rings, which are especially useful in
tree-ring dating/1,2; statistical comparisons with alternative matches/4; strong matching
of ring patterns among snags at each estuary; and best correlation nearest Long Island,
at Willapa Bay (Table S1). (Similarity in tree growth declines with distance/5.)
To convert ring-width measurements into indices we removed long-term trends/6 by
sequential fitting of decay curves and 128-year cubic splines, with division of
measurements by curve values after each fitting, followed by time-series modeling/7.
Signals were enhanced by arithmetically averaging detrended series among samples from
different radii of individual trees or, at Long Island only, among trees.
With one exception, each reported correlation is the strongest obtained along the
entire 994-year Long Island series (or along its local analog, below).
(The correlation for the exception, CP-790, is the fourth highest.)
Each correlation also corresponds to the position that gives the highest
within-estuary correlation (Table S1). All samples are chain-sawed wedges except
for cores from the trunk of CP-GF2. All samples correlated directly with Long Island
are from trunks except for roots of PX-J6; combined trunk series from this snag
contain only 124 rings, too few for firm dating.
Test of tree-ring dating by high-precision radiocarbon dating.
From one snag trunk (PX-782), we obtained a high-precision radiocarbon age--241±11 C-14 yr BP
(QL-4411)--on rings pattern-matched to 1645-1655. With calibration to calendric time/8 and a
probably generous laboratory error multiplier of 1.6 (ref. 9), the 95-percent confidence
interval corresponding to this C-14 age is 1648-1671.
Statistical significance of correlations.
The probability (P) of obtaining each correlation by chance was calculated from three
interim statistics. First, we converted each r value to a Student's t value that weights
the correlation (r) for ring overlap (n, in years; commonly equal to sample length):
t = r /{sq rt of [(1-r**2)/(n-2)]}. Next, we obtained an alpha probability for the t value
using a calculator (Hewlett-Packard 48G) having a built-in, continuous t distribution.
Last, we adjusted that probability for the number of reasonable alternative dates evaluated, m,
from P = 1 - (1-alpha)**m (refs. 4, 10). Note that probability estimation depends heavily
on selecting an appropriate value for exponent m. This value rests on inferred endpoints for dating.
In the case of trunk samples, we used AD 1192 and 1720 as endpoints for the date of the
outer ring in each sample. These are based on an estimated minimum overlap of 200 years
for detecting significant correlation at the 993 start of the Long Island series, and on
radiocarbon evidence for death by 1720 (ref. 1 of printed Scientific Correspondence).
(An exception is CH-764, for which short sample length set the minimum overlap.)
Root samples were more tightly constrained in time by the outer-rings dates of eroded
trunk samples (Table 1 of Scientific Correspondence). For both trunks and roots,
probabilities of P < 10**(-10) were obtained from the approximation, P = m alpha (ref. 4).
A time-series model was fitted to the previously detrended Ozette/3 series before correlation
with Long Island (m = 1 for the special case of comparing modern series such as these).
Correlation among adjacent snags.
In these matches, we assumed minimum ring overlaps of 150 years for detecting correlation.
This minimum is based on relationships among n, r, and P.
Correlation between trunk and root.
We traced distinctive rings in vertical slices that extend from trunk to root in seven trees
(T in Table S1). In addition, we matched long series of ring patterns between trunk and root
in four trees (Tables 1 and S1). Flexible 60-year cubic splines/7, along with time-series models,
were used to detrend the root series, which are less regular than those in trunks.
Comparison with season of death recorded by Sitka spruce.
The complete 1699 rings of the redcedar roots contrast with the incomplete outer rings of roots
of Sitka spruce killed by the same submergence at Copalis River and at Willapa Bay/6.
The difference probably reflects temporary survival of spruce for a few months to years
after submergence. Sitka spruce tolerates more flooding than does redcedar/11.
Archival of ring-width data.
Ring-width measurements will be deposited in the International Tree-Ring Data Bank
(http//:www.ngdc.noaa.gov/paleo.treering.html).
Acknowledgements. We are grateful to the persons noted in Table 1, to Erich Eipert for
loans of sanders, and to Minze Stuiver for advice on dating. We thank Alan Nelson, John Clague,
David Stahle, Katherine Reed, and a shy seismologist for critical reviews.
Support was provided by the U.S. Geological Survey, through the
National Earthquake Hazards Reduction Program, and by the National Research Council
(research associateship to D.K.Y.).
1. Stokes, M. A. & Smiley, T. L. An Introduction to Tree-Ring Dating
(Univ. Chicago, 1968; reprinted by Univ. Arizona Press, 1996).
2. Schweingruber, F. H. Tree Rings, Basics and Applications of dendrochronology, Boston, Reidel (1988).
3. Jozsa, L. A., Parker, M. L., Johnson, S. G. & Bramhall, P. A. Ozette
Dendrochronological Studies (ed Gleeson, P.F.) 27-56
(Laboratory of Anthropology, Wash. State Univ., Pullman, Wash., 1983).
4. Yamaguchi, D. K., Can. J. For. Res. 22, 1215-1221 (1992).
5. Cropper, J. C., & Fritts, H. C. Tree-Ring Bull. 42, 3-9 (1982).
6. Atwater, B. F., & Yamaguchi, D. K. Geology 19, 706-709 (1991).
7. Cook, E. R., & Briffa, K. R. in Methods of Dendrochronology,
Applications in the Environmental Sciences,
(eds Cook, E. R., & Kairiukstis, L. A.) 97-162 (Kluwer, Boston, 1990).
8. Stuiver, M. & Becker, B. Radiocarbon 35, 35-67 (1993).
9. Stuiver, M. & Pearson, G. W. Radiocarbon 28, 805-838 (1986).
10. Yamaguchi, D. K. Can. J. For. Res. 24, 427-429 (1994).
11. Brink, V. C. Ecology 35, 94-95 (1954).
------------------------------------------------------------------------
Table S1 Dating of redcedar snags
------------------------------------------------------------------------
Trunk Root
--------------------------- -------------------------------
L
e Outer Mean Outer
e pre- r with ring
g served Correlation other Height against
Estu- t ring with Long snags relative bark Correlation
ary h (yr Island at es- to high yr with trunk
& tree (yr) AD) (r, t, log P) tuary tide (m) AD) (r, n, t)
------------------------------------------------------------------------
Copalis River
CP-789 347 1677 .21 3.9 -1.52* .35 +0.1 to -0.2 >1680 T
CP-790 327 1632 .16 3.0 -0.24* .38 -- -- --
CP-791 283 1680 .28 4.9 -3.39 .43 +0.2 to -0.3 1708 T
CP-793 325 1664 .28 5.3 -4.11 .40 -- -- --
CP-794 271 1599 .26 4.4 -2.29 .44 -- -- --
CP-GF2 255C 1675 .21 3.4 -0.74* .31 -0.7 to -1.2 1699L .57 255 11
------------------------------------------------------------------------
Grays Harbor
CH-764 150C 1682 .38 5.0 -3.30 .27 -- -- --
JN-560 295 1674 .26 4.6 -2.68 .26 -0.2 to -0.6 1699L T
JN-561 263C 1678 .44 7.9 -10.54 .33 ca -0.5 1699L .35 227 5.6
JN-566 227 1685 .30 4.7 -2.89 .28 -- -- --
------------------------------------------------------------------------
Willapa Bay
BN-915 286 1684 .32 5.7 -5.00 .42 -- -- --
PXnt778 357C 1682 .37 7.6 -10.15 .41 -0.1 to -0.3 >1670 T
PX-779 289 1677 .42 7.8 -10.48 .41 -0.4 to -0.8 -- --
PX-782 239C 1681R .52 9.5 -15.53 .63 -0.2 to -0.6 1699L .42 239 7.1 T
PX-783 340 1675 .30 5.9 -5.59 .43 -0.2 to -0.7 1699L .63 194 11 T
PX-J6 208 1699 .23 3.3 -0.54# .29 -0.8 to -1.2 1699 --
------------------------------------------------------------------------
Columbia River
GR-578 336 1676 .21 3.8 -1.39@ .46 -- -- --
GR-580 222 1658 .36 5.8 -5.17 .50 -- -- --
GR-582 220C 1691 .30 4.7 -2.92 .59 -- -- --
GR-776 244 1675 .22 3.5 -0.82@ .50 -- -- --
GR-777 378C 1671 .27 5.4 -4.52 .41 -0.7 to -0.9 1699L .28 62 ns T
------------------------------------------------------------------------
Notes. Sample length is number of rings used in correlation analysis; a few additional,
innermost rings were lost to fitting of time-series models. Statistics and letter codes
follow text above or Table 1 of Scientific Correspondence. Specific tree locations are in Table S2.
Trunks: C, length combined from 2-3 trunk samples on different radii. R, dating checked by radiocarbon.
Roots: Series are averaged from 3-10 radii. High tide denotes present mean higher high water,
as estimated from depth below present tidal wetland surface (all sites), from leveling tied to one
(CP-789, CP-791, CP-GF2, JN-560, GR-777) or three (PX) tidal cycles, and from tide tables.
Limiting (">") dates are from roots retaining bark solely on radii toward which tapering rings disappear.
n, ring overlap; ns, not significant at P < 0.01.
* Correlations with local master series derived from CP-791, -793, and -794:
CP-789, r =.32 (n = 347, t = 6.3, log P = -6.92); CP-790, r = .25 (n = 303, t = 4.4, log P = -2.77);
CP-GF2, n = 255, t = 4.7.
# Correlations with local master from trunks of all other dated Willapa Bay snags:
n = 181, t = 4.1.
@ Correlations with local master from Gr-580, -582, and -777:
GR-578, r = .48, n = 336, t = 10 (log P = -17.82);
GR-776, r = .41, n = 244, T = 6.9 (log P = -8.28).
------------------------------------------------------------------------
Table S2 Locations of dated snags
------------------------------------------------------------------------
Estu- 7.5-minute
ary Stream quadrangle Tree Latitude N Longitude W
------------------------------------------------------------------------
Copa- -- Moclips CP-789 47 07.74' 124 09.61'
lis R. Moclips CP-790 47 07.77' 124 09.68'
Moclips CP-791 47 07.76' 124 09.56'
Moclips CP-793 47 07.76' 124 09.70'
Moclips CP-794 47 07.76' 124 09.70'
Moclips CP-GF2 47 07.83' 124 09.71'
Grays Chehalis R. Central Park CH-764 46 56.83' 123 43.67'
Har- Johns R. Hoquiam JN-560 46 52.89' 123 57.01'
bor Johns R. Hoquiam JN-561 46 52.87' 123 57.01'
Johns R. Hoquiam JN-566 46 52.89' 123 57.06'
Wil- Bone River Bay Center BN-915 46 39' 123 53'
lapa S.Fk. Palix R. Nemah PX-nt778 46 34.31' 123 53.92'
Bay S.Fork Palix R. Nemah PX-779 46 34.36' 123 53.91'
S.Fork Palix R. Nemah PX-782 46 34.30' 123 53.95'
S.Fork Palix R. Nemah PX-783 46 34.29' 123 53.96'
S.Fork Palix R. Nemah PX-J6 46 34.30' 123 53.93'
Colum- Seal Slough Rosburg GR-578 46 19.36' 123 40.08'
bia R. Seal Slough Rosburg GR-580 46 19.86' 123 39.79'
Crooked Creek Rosburg GR-582 46 17.53' 123 39.60'
Grays River Rosburg GR-776 46 19.30' 123 39.97'
Seal Slough Rosburg GR-777 46 19.62' 123 39.97'
------------------------------------------------------------------------
COFECHA
File_name Date Time_span Series Spline Seg Lag N_Seg Probs Prob% XCorr MnSens C/Var MnMsmt MnStDv MnACorr
wa129.rwl 25May06 991 1986 21 32 50 25 359 123 34.26 .387 .182 32.73 1.737 .901 .846
Run LONG Title: Long Island, Willapa Bay
PART 5: CORRELATION OF SERIES BY SEGMENTS: Long Island, Willapa Bay 14:27 Thu 25 May 2006 Page 5
-----------------------------------------------------------------------------------------------------------------------------------
Correlations of 50-year dated segments, lagged 25 years
Flags: A = correlation under .3281 but highest as dated; B = correlation higher at other than dated position
Seq Series Time_span 1025 1050 1075 1100 1125 1150 1175 1200 1225 1250 1275 1300 1325 1350 1375 1400 1425 1450 1475 1500
1074 1099 1124 1149 1174 1199 1224 1249 1274 1299 1324 1349 1374 1399 1424 1449 1474 1499 1524 1549
--- -------- --------- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
1 LIDY701 1323 1986 .56 .55 .47 .42B .52 .64 .33B .21B .48
2 LI702O 991 1368 .45 .22A-.13B .03B .14B .30A .38 .32A .32B .16B .10B .62 .70
3 LI745 1408 1933 .41 .33 .40 .64 .65
4 LI751 1486 1893 .43 .53
6 LI753 1417 1986 .25A .22B .41 .42 .49
7 LI754 1452 1986 .12B .09B .30A
8 LI755 1425 1873 .52 .58 .45 .47
9 LI756 1424 1923 .61 .61 .40 .31B .68
10 LI757 1515 1911 .59
11 LI758 1419 1922 .35 .34 .34 .46 .52
14 LI761 1289 1874 .18B .49 .63 .48 .40 .37 .29A .40 .31A .45
15 LI762 1411 1756 .39 .34 .44B .54 .49
16 LI766I 1350 1582 .30B .28A .40 .53 .64 .51 .61
17 LI766O 1515 1986 .70
18 LI767I 1036 1535 .45 .22A-.13B .03B .14B .30A .38 .32A .32B .27A .29A .44 .57 .30B .18B .27B .24A .45 .39 .46
Av segment correlation .45 .22 -.13 .03 .14 .30 .38 .32 .32 .21 .19 .53 .61 .39 .32 .40 .41 .41 .40 .53
PART 5: CORRELATION OF SERIES BY SEGMENTS: Long Island, Willapa Bay 14:27 Thu 25 May 2006 Page 6
-----------------------------------------------------------------------------------------------------------------------------------
Correlations of 50-year dated segments, lagged 25 years
Flags: A = correlation under .3281 but highest as dated; B = correlation higher at other than dated position
Seq Series Time_span 1525 1550 1575 1600 1625 1650 1675 1700 1725 1750 1775 1800 1825 1850 1875 1900 1925 1950
1574 1599 1624 1649 1674 1699 1724 1749 1774 1799 1824 1849 1874 1899 1924 1949 1974 1999
--- -------- --------- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
1 LIDY701 1323 1986 .56 .36 .28B .32A .25A .46 .48 .24B .45 .53 .27A .28B .44 .34 .27A .02B-.10B .05B
3 LI745 1408 1933 .63 .40 .37 .52 .58 .58 .45 .34 .45 .50 .27A .04B .14B .38B .61 .61
4 LI751 1486 1893 .66 .33 .28A .43 .30A .28A .36 .06B .35 .57 .58 .56 .51 .59
5 LI752 1680 1986 .41 .38 .40 .47 .37B .27B .38 .62 .62 .46 .42 .45
6 LI753 1417 1986 .33 .27B .44 .45 .59 .67 .57 .35 .40 .37 .34 .41 .61 .61 .52 .53 .41 .35
7 LI754 1452 1986 .33 .19B .29A .49 .53 .47 .45 .25B .31B .47 .23B .16B .31A .37 .44 .51 .38 .30A
8 LI755 1425 1873 .49 .43 .47 .50 .46 .48 .45 .30A .32A .55 .45 .19B .36
9 LI756 1424 1923 .70 .37 .22B .28A .40 .40 .18B .14B .53 .65 .58 .43 .44 .60 .48
10 LI757 1515 1911 .63 .27A .05B .13B .39 .45 .37 .36 .49 .50 .36 .17B .15B .15B .11B
11 LI758 1419 1922 .51 .30A .24B .23A .24A .39 .43 .27A .40 .45 .45 .31A .16B .38 .20A
12 LI759 1746 1986 .25A .48 .48 .36 .45 .47 .42 .52 .53 .42
13 LI760 1722 1986 .31A .36 .65 .56 .21B .57 .66 .58 .48 .44 .38
14 LI761 1289 1874 .61 .55 .40 .52 .56 .50 .36 .14B .51 .62 .48 .33 .38
15 LI762 1411 1756 .32A .26B .29A .15B .23A .29A .37 .47 .49
16 LI766I 1350 1582 .59 .49
17 LI766O 1515 1986 .71 .24B .08B .33A .43 .49 .56 .40 .40 .57 .60 .42 .42 .59 .47 .28A .34 .42
19 LI767O 1544 1917 .48 .48 .37 .26B .27A .36 .34 .14B .42 .48 .39 .39 .56 .64 .57
20 LIDY768 1528 1986 .33A .32A .11B .13B .07B .28A .35 .19B .25B .24A .24A .34 .51 .57 .44 .32B .51 .40
21 LI769 1634 1986 .28B .37 .37 .19B .46 .74 .58 .28A .16B .30A .38 .33 .29A .26A
Av segment correlation .52 .35 .28 .34 .37 .43 .41 .27 .40 .52 .42 .30 .39 .48 .44 .41 .36 .34
PART 7: DESCRIPTIVE STATISTICS: Long Island, Willapa Bay 14:27 Thu 25 May 2006 Page 11
-----------------------------------------------------------------------------------------------------------------------------------
Corr //-------- Unfiltered --------\\ //---- Filtered -----\\
No. No. No. with Mean Max Std Auto Mean Max Std Auto AR
Seq Series Interval Years Segmt Flags Master msmt msmt dev corr sens value dev corr ()
--- -------- --------- ----- ----- ----- ------ ----- ----- ----- ----- ----- ----- ----- ----- --
1 LIDY701 1323 1986 664 27 13 .345 1.47 4.48 .547 .789 .176 2.56 .289 -.009 1
2 LI702O 991 1368 378 13 9 .279 1.08 2.61 .298 .806 .132 2.56 .277 -.023 2
3 LI745 1408 1933 526 21 4 .445 1.88 5.89 .891 .865 .192 2.62 .317 -.017 2
4 LI751 1486 1893 408 16 4 .420 2.07 6.69 .944 .771 .187 2.53 .314 -.030 1
5 LI752 1680 1986 307 12 2 .443 2.59 11.44 2.570 .944 .243 2.73 .396 -.011 1
6 LI753 1417 1986 570 23 3 .437 1.35 5.72 .980 .928 .158 2.63 .379 -.055 1
7 LI754 1452 1986 535 21 11 .324 2.10 5.26 .755 .870 .152 2.46 .274 -.005 4
8 LI755 1425 1873 449 17 3 .432 1.99 8.56 .989 .805 .217 2.67 .277 .012 1
9 LI756 1424 1923 500 20 5 .445 1.42 7.27 1.000 .875 .207 2.61 .291 -.031 3
10 LI757 1515 1911 397 16 7 .322 1.65 4.68 .744 .879 .138 2.56 .385 -.005 1
11 LI758 1419 1922 504 20 8 .334 2.13 5.85 .939 .883 .172 2.62 .375 -.006 1
12 LI759 1746 1986 241 10 1 .454 3.71 13.56 3.059 .939 .216 2.60 .352 -.025 1
13 LI760 1722 1986 265 11 2 .486 2.17 7.89 1.339 .889 .190 2.55 .296 -.029 1
14 LI761 1289 1874 586 23 4 .432 1.92 10.02 1.152 .874 .180 2.68 .355 -.031 2
15 LI762 1411 1756 346 14 7 .362 1.90 6.26 .921 .894 .173 2.68 .338 -.018 1
16 LI766I 1350 1582 233 9 2 .458 1.87 4.96 .811 .859 .176 2.58 .393 -.026 3
17 LI766O 1515 1986 472 19 4 .434 1.49 3.49 .676 .892 .157 2.64 .307 -.017 1
18 LI767I 1036 1535 500 20 13 .276 .97 2.50 .414 .812 .216 2.53 .316 -.034 1
19 LI767O 1544 1917 374 15 3 .403 .86 1.56 .271 .697 .207 2.56 .353 .006 1
20 LIDY768 1528 1986 459 18 11 .316 1.11 2.39 .372 .726 .199 2.55 .315 -.008 1
21 LI769 1634 1986 353 14 7 .367 2.27 6.13 .852 .819 .165 2.53 .342 -.014 2
--- -------- --------- ----- ----- ----- ------ ----- ----- ----- ----- ----- ----- ----- ----- --
Total or mean: 9067 359 123 .387 1.74 13.56 .901 .846 .182 2.73 .327 -.018