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New streams and springs after the 2014 Mw6.0 South Napa earthquake.

Wang CY, Manga M - Nat Commun (2015)

Bottom Line: Since the new flows were not contaminated by pre-existing surface water, their composition allowed unambiguous identification of their origin.The estimated total amount of new water is ∼ 10(6) m(3), about 1/40 of the annual water use in the Napa-Sonoma area.Our model also makes a testable prediction of a post-seismic decrease of seismic velocity in the shallow crust of the affected region.

View Article: PubMed Central - PubMed

Affiliation: Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA.

ABSTRACT
Many streams and springs, which were dry or nearly dry before the 2014 Mw6.0 South Napa earthquake, started to flow after the earthquake. A United States Geological Survey stream gauge also registered a coseismic increase in discharge. Public interest was heightened by a state of extreme drought in California. Since the new flows were not contaminated by pre-existing surface water, their composition allowed unambiguous identification of their origin. Following the earthquake we repeatedly surveyed the new flows, collecting data to test hypotheses about their origin. We show that the new flows originated from groundwater in nearby mountains released by the earthquake. The estimated total amount of new water is ∼ 10(6) m(3), about 1/40 of the annual water use in the Napa-Sonoma area. Our model also makes a testable prediction of a post-seismic decrease of seismic velocity in the shallow crust of the affected region.

No MeSH data available.


Related in: MedlinePlus

Stable isotope data for the studied streams and spring.Shown are measurements of δD versus δ18O for the new streams and Spencer Spring, the Napa River from 1984 to 1987, and three major perennial streams in foothills. Measurement errors are smaller than the size of symbols used. Solid line shows the GMWL. Data from this study define a local meteoric water line parallel to, but shifted slightly to the left of the GMWL. Notice that the isotopic compositions of each flow, sampled at different times (Supplementary Table 3), cluster together, while the isotopic compositions of different flows span a broad range along the local meteoric water line. During rainy seasons (normally November to March) the isotopic composition of the Napa River falls mostly close to the GMWL; during dry seasons, the Napa River composition becomes significantly heavier and falls to the right of the line due to evaporation and recharge by evaporated surface water.
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f3: Stable isotope data for the studied streams and spring.Shown are measurements of δD versus δ18O for the new streams and Spencer Spring, the Napa River from 1984 to 1987, and three major perennial streams in foothills. Measurement errors are smaller than the size of symbols used. Solid line shows the GMWL. Data from this study define a local meteoric water line parallel to, but shifted slightly to the left of the GMWL. Notice that the isotopic compositions of each flow, sampled at different times (Supplementary Table 3), cluster together, while the isotopic compositions of different flows span a broad range along the local meteoric water line. During rainy seasons (normally November to March) the isotopic composition of the Napa River falls mostly close to the GMWL; during dry seasons, the Napa River composition becomes significantly heavier and falls to the right of the line due to evaporation and recharge by evaporated surface water.

Mentions: The stable isotopes of hydrogen and oxygen of the new waters (Supplementary Table 3) define a linear relation on a δD versus δ18O plot (Fig. 3), parallel to, but slightly shifted to the left of, the global meteoric water line (GMWL)23. The slight shift from GMWL may reflect differences in humidity and temperature that affect secondary evaporation as rain falls from clouds24. The isotopic compositions of each flow, sampled at different times (Supplementary Table 3), cluster closely together (Fig. 3), suggesting that each flow came from a distinct source of constant composition. Different flows, on the other hand, span a broad range of isotopic composition (Fig. 3), suggesting different sources recharged by meteoric water at different elevations (Fig. 4a). Also plotted are the isotopic compositions of the Napa River determined at various times of year from 1984 to 1987 (ref. 25). From November to March, normally the rainy season, the isotopic composition of Napa River falls mostly close to the GMWL; during dry seasons, on the other hand, it becomes significantly heavier and falls to the right of the GMWL. The latter may reflect the evaporation of river water and recharge from shallow groundwater or reservoirs in the valley during dry seasons21.


New streams and springs after the 2014 Mw6.0 South Napa earthquake.

Wang CY, Manga M - Nat Commun (2015)

Stable isotope data for the studied streams and spring.Shown are measurements of δD versus δ18O for the new streams and Spencer Spring, the Napa River from 1984 to 1987, and three major perennial streams in foothills. Measurement errors are smaller than the size of symbols used. Solid line shows the GMWL. Data from this study define a local meteoric water line parallel to, but shifted slightly to the left of the GMWL. Notice that the isotopic compositions of each flow, sampled at different times (Supplementary Table 3), cluster together, while the isotopic compositions of different flows span a broad range along the local meteoric water line. During rainy seasons (normally November to March) the isotopic composition of the Napa River falls mostly close to the GMWL; during dry seasons, the Napa River composition becomes significantly heavier and falls to the right of the line due to evaporation and recharge by evaporated surface water.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4510671&req=5

f3: Stable isotope data for the studied streams and spring.Shown are measurements of δD versus δ18O for the new streams and Spencer Spring, the Napa River from 1984 to 1987, and three major perennial streams in foothills. Measurement errors are smaller than the size of symbols used. Solid line shows the GMWL. Data from this study define a local meteoric water line parallel to, but shifted slightly to the left of the GMWL. Notice that the isotopic compositions of each flow, sampled at different times (Supplementary Table 3), cluster together, while the isotopic compositions of different flows span a broad range along the local meteoric water line. During rainy seasons (normally November to March) the isotopic composition of the Napa River falls mostly close to the GMWL; during dry seasons, the Napa River composition becomes significantly heavier and falls to the right of the line due to evaporation and recharge by evaporated surface water.
Mentions: The stable isotopes of hydrogen and oxygen of the new waters (Supplementary Table 3) define a linear relation on a δD versus δ18O plot (Fig. 3), parallel to, but slightly shifted to the left of, the global meteoric water line (GMWL)23. The slight shift from GMWL may reflect differences in humidity and temperature that affect secondary evaporation as rain falls from clouds24. The isotopic compositions of each flow, sampled at different times (Supplementary Table 3), cluster closely together (Fig. 3), suggesting that each flow came from a distinct source of constant composition. Different flows, on the other hand, span a broad range of isotopic composition (Fig. 3), suggesting different sources recharged by meteoric water at different elevations (Fig. 4a). Also plotted are the isotopic compositions of the Napa River determined at various times of year from 1984 to 1987 (ref. 25). From November to March, normally the rainy season, the isotopic composition of Napa River falls mostly close to the GMWL; during dry seasons, on the other hand, it becomes significantly heavier and falls to the right of the GMWL. The latter may reflect the evaporation of river water and recharge from shallow groundwater or reservoirs in the valley during dry seasons21.

Bottom Line: Since the new flows were not contaminated by pre-existing surface water, their composition allowed unambiguous identification of their origin.The estimated total amount of new water is ∼ 10(6) m(3), about 1/40 of the annual water use in the Napa-Sonoma area.Our model also makes a testable prediction of a post-seismic decrease of seismic velocity in the shallow crust of the affected region.

View Article: PubMed Central - PubMed

Affiliation: Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA.

ABSTRACT
Many streams and springs, which were dry or nearly dry before the 2014 Mw6.0 South Napa earthquake, started to flow after the earthquake. A United States Geological Survey stream gauge also registered a coseismic increase in discharge. Public interest was heightened by a state of extreme drought in California. Since the new flows were not contaminated by pre-existing surface water, their composition allowed unambiguous identification of their origin. Following the earthquake we repeatedly surveyed the new flows, collecting data to test hypotheses about their origin. We show that the new flows originated from groundwater in nearby mountains released by the earthquake. The estimated total amount of new water is ∼ 10(6) m(3), about 1/40 of the annual water use in the Napa-Sonoma area. Our model also makes a testable prediction of a post-seismic decrease of seismic velocity in the shallow crust of the affected region.

No MeSH data available.


Related in: MedlinePlus