DOI: 10.1029/96gl01233. Mapping the B‐value anomaly at 100 km depth in the Alaska and New Zealand Subduction Zones

Mapping the B‐value anomaly at 100 km depth in the Alaska and New Zealand Subduction Zones

10.1029/96gl01233

Crossref journal-article

American Geophysical Union (AGU)

Geophysical Research Letters (13)

Abstract

A positive anomaly in the frequency‐magnitude distribution (b‐value) is detected at approximately 90–100 km depth in two subduction zones. The b‐value in this anomalous zone is 40% higher than in adjacent volumes. We use regional catalogs with a magnitude of completeness of 2.6 (Central Alaska and Cook Inlet), 2.0 (Shumagin Islands), and 3.5 (New Zealand). To resolve the b‐value as a function of space in more detail, we project all earthquakes onto planes perpendicular to the strike of the slab. These cross‐section views of the b‐value distribution locate the high b‐value anomalies at a depth of 90–100 km, on the upper surface of the Wadati‐Benioff Zone. At these depths, slab dehydration may increase pore pressure, thus lowering the effective stress and increasing the b‐value. Increased pore pressure would also lower the liquidus in the overlying asthenosphere, giving rise to the volcanism that occurs directly above this zone.

Bibliography

Wiemer, S., & Benoit, J. P. (1996). Mapping the Bâvalue anomaly at 100 km depth in the Alaska and New Zealand Subduction Zones. Geophysical Research Letters, 23(13), 1557â1560. Portico.

Authors 2

Stefan Wiemer (first)
John P. Benoit (additional)

References 25 Referenced 155

10.1029/93JB03107
10.1080/00288306.1994.9514633
10.1029/JB085iB03p01389
10.1785/BSSA0730030831 / Bull. Seismol. Soc. Am. / Maximum likelihood estimation of b‐values for magnitude grouped data by Bender B. (1983)
10.1126/science.263.5144.212
Fogleman K. A.J. C.LahrC. D.StephensR. A.Page Earthquake locations determined by the Southern Alaska seismograph network for October 1971 through May 1986 Open File Rep. 93‐309USGS 1993 (10.3133/ofr93309)
{'key': 'e_1_2_1_8_1', 'series-title': 'USGS Bull.', 'first-page': '59', 'volume-title': 'Geologic studies in Alaska by the USGS during 1994', 'author': 'Fogleman K. A.', 'year': '1996'} / Geologic studies in Alaska by the USGS during 1994 / USGS Bull. by Fogleman K. A. (1996)
10.1029/92JB01891
10.1007/978-3-642-68012-0
{'issue': '1', 'key': 'e_1_2_1_11_1', 'first-page': '1', 'article-title': 'Magnitude and energy of earthquakes', 'volume': '9', 'author': 'Gutenberg B.', 'year': '1954', 'journal-title': 'Ann. Geof.'} / Ann. Geof. / Magnitude and energy of earthquakes by Gutenberg B. (1954)
10.1029/95GL01772
{'key': 'e_1_2_1_13_1', 'first-page': '443', 'article-title': 'Observations sur les seisms enregistre par le microseismograph construit dernierment', 'volume': '17', 'author': 'Ishimoto M.', 'year': '1939', 'journal-title': 'Bull. Earthquake Res. Inst. Tokyo Univ.'} / Bull. Earthquake Res. Inst. Tokyo Univ. / Observations sur les seisms enregistre par le microseismograph construit dernierment by Ishimoto M. (1939)
10.1029/GM056p0119
10.1029/95JB03036
{'key': 'e_1_2_1_16_1', 'first-page': '831', 'article-title': 'Magnitude‐frequency relation for elastic shocks accompanying fractures of various materials and some related problems in earthquakes', 'volume': '40', 'author': 'Mogi K.', 'year': '1962', 'journal-title': 'Bull. Earthq. Res. Inst.'} / Bull. Earthq. Res. Inst. / Magnitude‐frequency relation for elastic shocks accompanying fractures of various materials and some related problems in earthquakes by Mogi K. (1962)
10.1130/0016-7606(1993)105<0684:TIOBED>2.3.CO;2
10.1029/95JB02506
Ratchkovsky N. A. Relocation of earthquakes in the Cook Inlet area south‐central Alaska using the joint hypocenter determination method M. S. thesis Univ. of Alaska Fairbanks pp. 1995.
10.1785/BSSA0580010399 / Bull. Seis. Soc. Amer. / The frequency‐magnitude relation of microfracturing in rock and its relation to earthquakes by Scholz C. H. (1968)
10.1785/BSSA0720051677 / Bull. Seis. Soc. Amer. / The standard error of the magnitude frequency b value by Shi Y. (1982)
10.1029/JB075i023p04455
{'key': 'e_1_2_1_23_1', 'first-page': '900', 'article-title': 'Seismic quiescence before the 1993 M=7.5 Landers and M=6.5 Big Bear (California) earthquakes', 'volume': '84', 'author': 'Wiemer S.', 'year': '1994', 'journal-title': 'Bull. Seis. Soc. Amer.'} / Bull. Seis. Soc. Amer. / Seismic quiescence before the 1993 M=7.5 Landers and M=6.5 Big Bear (California) earthquakes by Wiemer S. (1994)
{'key': 'e_1_2_1_24_1', 'first-page': '456', 'article-title': 'ZMAP‐a software package to analysis seismicity (abstract', 'volume': '75', 'author': 'Wiemer S.', 'year': '1994', 'journal-title': 'EOS, Trans., AGU'} / EOS, Trans., AGU / ZMAP‐a software package to analysis seismicity (abstract by Wiemer S. (1994)
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Dates

Type	When
Created	21 years, 6 months ago (Feb. 3, 2004, 11:36 p.m.)
Deposited	1 year, 9 months ago (Nov. 22, 2023, 12:32 p.m.)
Indexed	1 month, 4 weeks ago (July 2, 2025, 12:53 p.m.)
Issued	29 years, 2 months ago (June 15, 1996)
Published	29 years, 2 months ago (June 15, 1996)
Published Online	29 years, 2 months ago (June 15, 1996)
Published Print	29 years, 2 months ago (June 15, 1996)

Funders 0

None

BibTeX

@article{Wiemer_1996, title={Mapping the B‐value anomaly at 100 km depth in the Alaska and New Zealand Subduction Zones}, volume={23}, ISSN={1944-8007}, url={http://dx.doi.org/10.1029/96gl01233}, DOI={10.1029/96gl01233}, number={13}, journal={Geophysical Research Letters}, publisher={American Geophysical Union (AGU)}, author={Wiemer, Stefan and Benoit, John P.}, year={1996}, month=jun, pages={1557–1560} }

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