Table 1. Pinatubo radiocarbon data.

["Age" and "Standard dev." are the radiocarbon determination, in radiocarbon years. The ages of all but the oldest two eruptive periods were calibrated to calendar rather than radiocarbon years before 1950 by use of calibration curves developed by Stuiver and Reimer (1993). "Calib age" is the statistically-most-likely equivalent in calendar years before 1950, and "calib min" and "calib max" mark 1-sigma confidence limits for the calendar equivalence probability distribution. Sample locations are shown in fig. 7; the approximate stratigraphic position of each sample is shown in fig. 6]

Sample

Field number

Lab
number

Latitude
(N.)

Longitude
(E.)

Material

Occurrence

Drainage

Section in figure 6

Age

Standard
dev.

Calibration age

Calibration minimum

Calibration maximum

Significance
Deposits of Buag age

1

NM-N1W4-1

WW-111

1504'

12016'

Charcoal

Cultural layer

Marella

N

    397

    70

    476

    318

    511

Dates latest occupation; settlement on old lahar deposit.

2

CN-P-33

WW-26

1516.8'

12022.7'

Wood

Fluvial deposit.

O'Donnell

B

    400

    80

    477

    315

    515

Latest major filling of Crow Valley.

3

CN-P-18

W-6478

1509.2'

12034.4'

Wood (in growth
position).

Soil overlying stream gravel.

Abacan

I

    410

    55

    485

    331

    511

After high-energy stream; before latest
pre-1991 lahars.

4

Alonso et al.

W-6314

1509'

ca. 12024'

Charcoal

Pyroclastic-flow deposit

upper Sacobia.

G

    460

    30

    509

    501

    518

Youngest pre-1991 pyroclastic flow in
Sacobia.

5

TP-Sabo4

Beta

1510.5'

12029.5'

Wood (in growth
position).

Post
pyroclastic-flow soil.

Abacan

G

    470

    50

    512

    494

    530

Start of latest pre-1991 fluvial deposition in Abacan.

6

JU-BL-2

W-6509

1459.9'

12015.5'

Charcoal

Lahar deposit

Marella

O

    560

    60

    545

    519

    635

Covered by 1992 lahars.

7

CN-P-16

WW-25

158.2'

12028.8'

Wood

Sediment of small lake.

Pasig-Potrero.

J

    560

    70

    545

    517

    640

Latest fill in the north fork, Pasig-Potrero.

8

CN-P-17d

WW-21

1509.7'

12033.4'

Charcoal

Silt over lahar deposit.

Abacan

I

    570

    70

    547

    519

    643

Age of terrace by Friendship Bridge, south edge, Clark Air Base.

9

JU-BL-1

W-6505

1459.9'

12015.6'

Charcoal

Lahar deposit

Marella

O

    600

    60

    617

    539

    648

Covered by 1992 lahars.

10

CN-P-46

WW-29

1508.2'

12028.7'

Uncharred root (in situ).

Fluvial
deposits.

Pasig-Potrero.

J

    630

    70

    597

    545

    658

After latest pre-1991 downcutting; before major siltation.

11

1275-17

Ebasco

1503.3'

12017.0'

Wood

Lahar deposits

Marella

N

    635

    80

    593

    543

    661

Lahar just below toe of morphologically youngest pre-1991 pyroclastic-flow deposit.

12

CN-P-30

WW-28

1518.5'

12035.7'

Wood

Flood-plain deposits.

Bamban

F

    660

    80

    648

    550

    668

Sedimentation across broad Bamban-Capas flood plain.

13

KSR-P-61

WW-107

1516.03'

12005.3'

Charcoal

Hyperconcentrated flow deposit.

Bucao

Q

    730

    80

    665

    577

    710

Latest major sedimentation in Bucao;
overtopped in 1993.

14

JU-AL-1

W-6504

1459.9'

12016.6'

Charcoal

Fluvial
deposits.

Marella

O

    760

    60

    673

    657

    721

Covered by 1993 lahars.

15

RPH-22592-
2/1.

WW-31

1508'

12029'

Wood

Lahar deposit

Pasig-
Potrero.

J

    950

    70

    800

    787

    925

 
Deposits of Maraunot age

16

376-1G

Ebasco

1503.3'

12017.0'

Charcoal

Pyroclastic-flow deposit.

Marella

N

    2,330

    110

    2,342

    2,157

    2,462

 

17

RPH-91-2

W-6316

1516.1'

12022.2'

Charcoal

Pyroclastic-flow deposit.

O'Donnell

B

    2,640

    50

    2,754

    2,743

    2,772

Same unit as sample 22; underlies
sample 31.

18

RPH-3792-3/1

WW-32

1511.2'

12030.2'

Charcoal

Fluvial deposit.

Clark Air Base.

D

    2,660

    70

    2,759

    2,745

    2,793

Maximum age for surface of Clark Air Base.

19

CN-P-45b

WW-13

1510.7'

12018.5'

Charcoal

Pyroclastic-flow deposit.

Maraunot

P

    2,820

    70

    2,914

    2,617

    2,985

 

20

KS-TP

Beta47404

1509.6'

12036.2'

Wood (in growth
position).

Lahar deposit

Abacan

I

    2,860

    80

    2,953

    2,660

    3,076

 

21

CN-P-36

WW-23

1506.8'

12031.9'

Slightly charred wood.

Lahar deposit

Pasig-Potrero.

K

    2,860

    70

    2,953

    2,866

    3,071

Maximum age for sediments forming Porac fan.

22

RPH-3592-1/4

WW-34

1516.1'

12022.2'

Charcoal (growth position.)

Pyroclastic-flow deposit.

O'Donnell

B

    2,870

    100

    2,958

    2,856

    3,147

Outer part of charred stump.

23

JU-CL-1

W-6508

1558.3'

12012.9'

Charcoal

Lahar deposit

Marella

O

    2,880

    70

    2,971

    2,877

    3,103

Surface leading to Castillejos.

24

CN-P-22

WW-20

1512.6'

12031.0'

Charcoal

Fluvial
deposits.

Sacobia

D

    2,930

    70

    3,070

    2,954

    3,207

 

25

JU-DL-1

W-6506

1459.8'

12016.0'

Charcoal

Sandy, fluvial silt.

Marella

O

    2,930

    80

    3,070

    2,949

    3,209

Probably covered by 1993 lahars.

26

JU-PL-1

W-6507

1459.5'

12014.9'

Charcoal

Fluvial
deposits.

Marella

O

    2,950

    50

    3,084

    2,993

    3,206

1.7 m above 1992 lahars; 3 m below highest pre-1991 lahars.

27

CN-P-43

WW-19

1510.1'

12028.1'

Charcoal

Pyroclastic-flow deposit.

Sacobia

G

    2,950

    70

    3,084

    2,971

    3,212

Latest big valley-filling pyroclastic flow in the Sacobia.

28

JU-Dal-1a

WW-112

1500.0'

12016.0'

Charcoal

Pyroclastic-flow deposit.

Marella

O

    2,990

    70

    3,192

    3,066

    3,320

Largest pyroclastic flow known in the Marella drainage.

29

CN-P-2b

W-6311

1510.2'

12028.2'

Charcoal

Pyroclastic-flow deposit.

Sacobia

G

    2,990

    80

    3,192

    3,012

    3,326

 

30

CN-P-45a

WW-27

1510.7'

12018.5'

Charcoal

Pyroclastic-flow deposit.

Maraunot

P

    3,030

    30

    3,214

    3,167

    3,320

Lowest exposed pyroclastic-flow deposit in Maraunot.

31

RPH-3592-1/2

WW-33

1516.1'

12022.2'

Charcoal

Pyroclastic-flow deposit.

O'Donnell

B

    3,260

    70

    3,467

    3,385

    3,563

Questionable age; overlies sample 22.

32

CN-P-11

W-6375

1511.0'

12029.8'

Charcoal

Pyroclastic-flow deposit.

Sacobia

C

    3,390

    90

    3,629

    3,477

    3,709

 

33

CN-P-39

WW-12

1502.7'

12017.3'

Charcoal

Pyroclastic-flow deposit.

Marella

N

    3,590

    110

    3,875

    3,707

    4,070

Toe of Marella pyroclastic-flow fan;
apparently low in section.
Deposits of Crow Valley Age

34

CN-P-3a

W-6312

1511.2'

12028.8'

Charcoal

Pyroclastic-flow deposit.

Sacobia

C

4,450

    70

    5,004

    4,875

    5,259

 

35

CN-P-12

WW-11

1511.5'

12029.3'

Charcoal

Pyroclastic-flow deposit.

Sacobia

C

4,800

    60

    5,503

    5,468

    5,597

Terrace outside Mactan Gate, Clark Air Base.

36

RHP-91-1

W-6315

1513.6'

12021.2'

Charcoal

Pyroclastic-flow deposit.

O'Donnell

A

4,890

    80

    5,612

    5,583

    5,716

 

37

RHP-22392-4

WW-30

1510.8'

12028.5'

Charcoal

Pyroclastic-flow deposit.

Sacobia

C

4,890

    70

    5,612

    5,586

    5,705

 

38

RHP-3592-1/5

WW-35

1516.1'

12022.2'

Charcoal

Pyroclastic-flow deposit.

O'Donnell

B

4,930

    80

    5,651

    5,594

    5,738

 

39

CN-P-31b

WW-17

1514.9'

12022.0'

Charcoal

Pyroclastic-flow deposit.

O'Donnell

A

4,960

    70

    5,693

    5,612

    5,841

Overlies sample 42.

40

CN-P-32b

WW-16

1514.8'

12021.8'

Charcoal

Pyroclastic-flow deposit.

O'Donnell

A

    5,010

    80

    5,736

    5,652

    5,892

Big dissected pyroclastic-flow deposit, north side of Pinatubo.

41

CN-P-50

WW-104

1525.0'

12039.0'

Charcoal

Fluvial deposit

O'Donnell

B*

    5,080

    70

    5,807

    5,737

    5,916

Major inundation of Tarlac Province.

42

CN-P-31a

WW-14

1514.9'

12022.0'

Charcoal

Pyroclastic-flow deposit.

O'Donnell

A

    5,100

    70

    5,782

    5,745

    5,924

May overlie sample 40.

43

CN-P-41c

WW-22

1515.7'

12010.1'

Charcoal

Silt interbedded with lahar.

Bucao

Q

    5,130

    80

    5,907

    5,753

    5,940

Major filling of the Bucao River valley.

44

CN-P-3b

W-6313

1511.2'

12028.8'

Charcoal

Pyroclastic-flow deposit.

Sacobia

C

    5,140

    100

    5,911

    5,749

    5,985

 

45

CN-P-51

WW-105

1520'

12040'

Charcoal

Fluvial deposit.

O'Donnell

B*

    5,160

    60

    5,918

    5,778

    5,980

Major inundation of Tarlac Province.

46

CN-P-53

WW-106

1525'

12040'

Charcoal

Fluvial deposit.

O'Donnell

B*

    5,280

    70

    6,079

    5,939

    6,176

Major inundation of Tarlac Province.
Deposits of Pasbul Age

47

975-9W-2

Ebasco

1511.8'

12014.8'

Charcoal

Pyroclastic-flow deposit.

Maraunot

P

    8,050

    130

    8,979

    8,655

    9,187

 

48

CN-P-42

WW-18

1502.3'

12027.2'

Charcoal

Pyroclastic-flow deposit.

Gumain

L

    8,380

    80

    9,414

    9,259

    9,447

Deep pyroclastic-flow fill in Gumain; much deeper than in 1991.
Deposits of Sacobia Age

49

CN-P-21

WW-24

1513.4'

12032.2'

Charcoal

Silt overlying lahar deposit.

Sacobia

D

    14,480

    130

    17,347

    17,179

    17,516

A debris-flow/fluvial sediment pair underlying Clark Air Base.
Deposits of Inararo Age

50

CN-P-27a

WW-15

1510.5'

12029.9'

Charcoal

Pyroclastic-flow deposit.

Abacan

G

    30,390

    890

     

     

     

Biggest pyroclastic flow of Pinatubo
history.

51

WS-31392-1/1

W-6487

1510.5'

12029.25'

''Charcoal

Pyroclastic-flow deposit.

Abacan

G

    >35,000

     

     

     

     

Biggest pyroclastic flow of Pinatubo
history.

* Hacienda Luisita.