The 2011 east coast earthquake felt by people from Georgia to Canada likely originated from a fault “junction” just outside of Mineral, Virginia, according to new U.S. Geological Survey research published in the Geological Society of America’s Special Papers.
Following the August 23, 2011 event, USGS scientists conducted low-altitude geophysical (gravity and magnetic) flight surveys in 2012 over the epicenter, located about eight miles from the quake’s namesake. Maps of the earth’s magnetic field and gravitational pull show subtle variations that reflect the physical properties of deeply buried rocks. More research may reveal whether geologic crossroads such as this are conducive to future earthquakes in the eastern United States.Caption: In map view, magnetic data were filtered (colors) to highlight geologic features near the earthquake depth. One contrast (blue dotted line) is aligned with aftershocks (black dots). The other crosses at an angle. They suggest that the earthquake (yellow star) occurred near a “crossroads,” or a complex intersection of different types of rock.
“These surveys unveiled not only one fault, which is roughly aligned with a fault defined by the earthquake’s aftershocks, but a second fault or contact between different rock types that comes in at an angle to the first one,” said USGS scientist and lead investigator, Anji Shah. “This visual suggests that the earthquake occurred near a ‘crossroads,’ or junction, between the fault that caused the earthquake and another fault or geologic contact.”
Deep imaging tools were specifically chosen because the earthquake occurred about five miles beneath the earth. Looking at faults in this way can help scientists better understand earthquake hazards in the eastern United States.
The USGS and partner scientists are also interested in why seismic events occur in certain parts of the central and eastern United States, like the Central Virginia seismic zone, since there are no plate boundaries there, unlike the San Andreas Fault in California, or the Aleutian Trench in Alaska.
USGS scientists still have remaining questions: Could this happen elsewhere? How common are such crossroads? Shah and other scientists are also trying to understand whether and why a junction like this might be an origin point for earthquakes.
“Part of it might be the complex stress state that arises in such an area. Imagine you have a plastic water bottle in your hand, and it has a cut (fault) in it the long way. When you squeeze the bottle, it pops (ruptures) where the cut is. The long cut is comparable to an ancient fault – it’s an area of weakness where motion (faulting and earthquakes) is more likely to happen. Multiple intersecting cuts in that bottle produce zones of weakness where fault slip is more likely to happen, especially where two cuts intersect,” said Shah.
The situation near the fault on which the magnitude 5.8 Mineral earthquake occurred is more complex than that. For example, the fault may separate different types of rocks with varying densities and strengths, as suggested by the gravity data. This contributes to a complex stress field that could also be more conducive to slip.
Additional science data about the 2011 Mineral, Virginia, earthquake may be found online.
NASA in partnership with the U.S. Geological Survey (USGS) is offering more than $35,000 in prizes to citizen scientists for ideas that make use of climate data to address vulnerabilities faced by the United States in coping with climate change.
The Climate Resilience Data Challenge, conducted through the NASA Tournament Lab, a partnership with Harvard University hosted on Appirio/Topcoder, kicks off Monday, Dec. 15 and runs through March 2015.
The challenge supports the efforts of the White House Climate Data Initiative, a broad effort to leverage the federal government’s extensive, freely available climate-relevant data resources to spur innovation and private-sector entrepreneurship in order to advance awareness of and preparedness for the impacts of climate change. The challenge was announced by the White House Office of Science and Technology Policy Dec. 9.
According to the recent National Climate Assessment produced by more than 300 experts across government and academia, the United States faces a number of current and future challenges as the result of climate change. Vulnerabilities include coastal flooding and weather-related hazards that threaten lives and property, increased disruptions to agriculture, prolonged drought that adversely affects food security and water availability, and ocean acidification capable of damaging ecosystems and biodiversity. The challenge seeks to unlock the potential of climate data to address these and other climate risks.
“Federal agencies, such as NASA and the USGS, traditionally focus on developing world-class science data to support scientific research, but the rapid growth in the innovation community presents new opportunities to encourage wider usage and application of science data to benefit society,” said Kevin Murphy, NASA program executive for Earth Science Data Systems in Washington. “We need tools that utilize federal data to help our local communities improve climate resilience, protect our ecosystems, and prepare for the effects of climate change.”
“Government science follows the strictest professional protocols because scientific objectivity is what the American people expect from us,” said Virginia Burkett, acting USGS associate director for Climate Change and Land Use. “That systematic approach is fundamental to our mission. With this challenge, however, we are intentionally looking outside the box for transformational ways to apply the data that we have already carefully assembled for the benefit of communities across the nation.”
The challenge begins with an ideation stage for data-driven application pitches, followed by storyboarding and, finally, prototyping of concepts with the greatest potential.
The ideation stage challenges competitors to imagine new applications of climate data to address climate vulnerabilities. This stage is divided into three competitive classes based on data sources: NASA data, federal data from agencies such as the USGS, and any open data. The storyboarding stage allows competitors to conceptualize and design the best ideas, followed by the prototyping stage, which carry the best ideas into implementation.
The Climate Resilience Data Challenge is managed by NASA's Center of Excellence for Collaborative Innovation at NASA Headquarters, Washington. The center was established in coordination with the Office of Science and Technology Policy to advance open innovation efforts for climate-related science and extend that expertise to other federal agencies.
For additional information and to register (beginning Dec. 15), visit the Climate Resilience Data Challenge website.