Focus
Shaken crust
- Focus
- August 2013 Volume 6 No 8 pp585-672
(Image credited to David Cole / Alamy)
Earthquakes have long been known to trigger more earthquakes, as well as volcanic eruptions and landslides. In this web focus, we present opinion pieces and primary research articles that document and discuss a range of additional, less obvious links between earthquakes and other geological spectacles — such as volcano sinking, seafloor gas-hydrate escape and a mud eruption — that have only now come into focus.
Editorial
Quake after-effects - p585
doi:10.1038/ngeo1917
How the Earth's crust — rather than just buildings or humans — responds to the violent shaking of an earthquake has been observed for centuries. Nevertheless, the wide range of geological impacts continues to surprise.
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News & Views
Volcanology: Sunken volcanoes - pp591-592
Sigurjón Jónsson
doi:10.1038/ngeo1876
Subduction zone earthquakes cause the overriding plate to stretch and subside. Excessive subsidence of volcanoes during the large quakes in Chile in 2010 and Japan in 2011 highlight an unexpected response of volcanic areas to the sudden tectonic pull.
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Natural hazards: Triggered mud eruption? - pp592-593
Paul Davis
doi:10.1038/ngeo1899
The Indonesian government ruled that the Lusi mud eruption was triggered by drilling and held an oil company responsible. Instead, a curved rock layer capping the mud reservoir may have amplified passing seismic waves and the trigger may have been natural.
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Letters
Subsidence at southern Andes volcanoes induced by the 2010 Maule, Chile earthquake - pp632-636
M. E. Pritchard, J. A. Jay, F. Aron, S. T. Henderson & L. E. Lara
doi:10.1038/ngeo1855
Large earthquakes in subduction zones can affect nearby volcanoes. Analysis of ground deformation following the 2010 earthquake in Maule, Chile, shows that some volcanoes subsided by up to 15 cm, probably because of quake-triggered release of hydrothermal fluids.
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Volcanic subsidence triggered by the 2011 Tohoku earthquake in Japan - pp637-641
Youichiro Takada & Yo Fukushima
doi:10.1038/ngeo1857
The 2011 Tohoku earthquake caused high levels of crustal deformation in Japan. Analysis of satellite radar and GPS data show that the earthquake caused nearby volcanic regions to subside instantaneously, creating elliptical depressions that are parallel to the direction of quake-induced crustal extension.
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Lusi mud eruption triggered by geometric focusing of seismic waves - pp642-646
M. Lupi, E. H. Saenger, F. Fuchs & S. A. Miller
doi:10.1038/ngeo1884
The Lusi mud eruption in Indonesia has been ongoing since 2006. Numerical simulations show that a parabolic-shaped layer in the rock surrounding the site of the Lusi eruption could have amplified and focussed incoming seismic energy from an earthquake, which then triggered the mud eruption.
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Subduction zone earthquake as potential trigger of submarine hydrocarbon seepage - pp647-651
David Fischer, José M. Mogollón, Michael Strasser, Thomas Pape, Gerhard Bohrmann, Noemi Fekete, Volkhard Spiess & Sabine Kasten
doi:10.1038/ngeo1886
Methane is abundant in marine sediments. Analysis of sediment cores and seismic images of marine sediments obtained off the coast of Pakistan show fracturing of gas hydrates and an increase in upward methane flux in the decades following a large earthquake in the Arabian Sea in 1945, suggesting that quakes can trigger hydrocarbon seepage.
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From the archive
Commentary
The landslide story -
Runqiu Huang & Xuanmei Fan
doi:10.1038/ngeo1806
The catastrophic Wenchuan earthquake induced an unprecedented number of geohazards. The risk of heightened landslide frequency after a quake, with potential secondary effects such as river damming and subsequent floods, needs more focused attention.
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Feature
Megathrust surprises -
Kelin Wang
doi:10.1038/ngeo1682
Numerous earthquakes have occurred at subduction zones in the past 5 years, and some were devastating. Kelin Wang describes what we have learned about the seismicity of the shallow zone.
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Research Highlights
Volcanology: Earthquake interaction -
Amy Whitchurch
doi:10.1038/ngeo1519
A large earthquake near the Yasur Volcano, on the south Pacific island of Vanuatu, altered the shallow crust that hosts the volcano's magma conduit, but didn't result in a change in eruptive activity, a seismic study suggests.
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Second wave -
Anna Armstrong
doi:10.1038/ngeo1316
The 2011 Tohoku earthquake that occurred off the Pacific coast of Japan triggered a devastating tsunami. The tsunami, in turn, generated a series of atmospheric waves, according to an analysis of atmospheric pressure data.
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News & Views
Earthquakes: Casting stress shadows -
Andrew M. Freed
doi:10.1038/ngeo1489
Earthquakes may trigger or retard quakes on nearby faults, but such relationships are difficult to verify. Observations showing that the Landers earthquake in California shut down aftershocks from a preceding event validate such relationships.
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Volcanology: Throwing mud -
Debi Kilb
doi:10.1038/ngeo299
The causes of the catastrophic eruption of the Lusi mud volcano in Indonesia are hotly debated. Data from a nearby exploration well and a new look at the stress regime suggest that drilling operations, and not an earthquake set the eruption off.
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Letters
Mass wasting triggered by the 2008 Wenchuan earthquake is greater than orogenic growth -
Robert N. Parker, Alexander L. Densmore, Nicholas J. Rosser, Marcello de Michele, Yong Li, Runqiu Huang, Siobhan Whadcoat & David N. Petley
doi:10.1038/ngeo1154
Shallow earthquakes lead to the uplift of mountain ranges, but also trigger landslides that remove mass. An analysis of the 2008 Wenshuan earthquake suggests that more material was removed from the orogen by widespread landslides than was added by coseismic uplift.
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Absence of remotely triggered large earthquakes beyond the mainshock region -
Tom Parsons & Aaron A. Velasco
doi:10.1038/ngeo1110
Earthquakes trigger damaging aftershocks in nearby regions, but whether they also trigger large earthquakes over significant distances has been unclear. Analysis of seismic data since 1979 suggests that earthquakes triggered more large shocks only over distances of about 1,000 km, and did not increase the seismic hazard risk on a global scale.
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Localized damage caused by topographic amplification during the 2010 M7.0 Haiti earthquake -
Susan E. Hough, Jean Robert Altidor, Dieuseul Anglade, Doug Given, M. Guillard Janvier, J. Zebulon Maharrey, Mark Meremonte, Bernard Saint-Louis Mildor, Claude Prepetit & Alan Yong
doi:10.1038/ngeo988
Microzonation maps use local geological conditions to characterize seismic hazard, but do not generally consider topography. Ground motions during the Haiti earthquake are found to have been significantly amplified along a high topographic ridge, which caused substantial structural damage, indicating that topography can play an important role in seismic hazard.
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Global ubiquity of dynamic earthquake triggering -
Aaron A. Velasco, Stephen Hernandez, Tom Parsons & Kris Pankow
doi:10.1038/ngeo204
Surface waves that were generated by 12 out of 15 earthquakes with magnitudes greater than 7 since 1990 led to a global increase in the number of small earthquakes. This suggests that dynamic triggering of earthquakes is common and is independent of the tectonic environment.
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