Predicting earthquakes by analyzing accelerating precursory seismic activity

1989 ◽  
Vol 130 (4) ◽  
pp. 661-686 ◽  
Author(s):  
David J. Varnes
Keyword(s):  
Seismic Activity ◽  
Precursory Seismic Activity

Historical accounts of pre-eruption seismicity of Katla, Hekla, Öræfajökull and other volcanoes in Iceland

JOKULL ◽  
2020 ◽  
Vol 69 ◽  
pp. 35-52
Author(s):  
Páll Einarsson
Keyword(s):  
Seismic Activity ◽  
Wide Spectrum ◽  
Local Population ◽  
Volcanic Hazards ◽  
Ambient Conditions ◽  
Short Term ◽  
Volcanic System ◽  
Instrumental Observations ◽  
Historical Accounts ◽  
Precursory Seismic Activity

Detecting unusual activity leading to the outbreak of a volcanic eruption is of vital importance for the short-term warning to the local population of an impending eruption. The varied volcano types of Iceland and range of ambient conditions at which eruptions occur offer an unusually wide spectrum of volcanic phenomena and volcanic hazards during the initial phase of eruptions. A recent study of eruptions in Iceland during the last four decades of instrumental observations has revealed that all the eruptions had a detectable precursory seismic activity, that under favourable conditions can be used to issue short-term warnings to the surrounding communities. Considerable documentary data also exist for pre-instrumental times extending several centuries back in time, that can be compared to the instrumental experience. This is true in particular for two of the most active volcanoes, Katla and Hekla, that are sufficiently close to the populated areas of the country. All seven confirmed eruptions of Katla since 1625 were preceded by felt earthquakes, beginning one to nine hours before the eruption was detected and two to over twelve hours before a jökulhlaup from this partly sub-glacial volcano reached the inhabited areas. The behaviour of Hekla is quite different. Large eruptions from the main edifice of Hekla since 1510 were generally accompanied by rather weak seismic activity. Earthquakes are usually felt only minutes before the first explosion occurs, in the 1947 case even several minutes after the first explosion of the volcano. Eruptions of the Hekla volcanic system outside the main edifice are, on the other hand, accompanied by considerable seismic activity, and the precursor times may be more than three hours, even much longer. The two historical eruptions of Öræfajökull, in 1362 and 1727, were apparently preceded by felt seismicity, sufficient to alarm the local population.

Patterns of local seismicity preceding the petatlan earthquake of 14 March 1979

1981 ◽  
Vol 71 (3) ◽  
pp. 761-769
Author(s):  
J. F. Gettrust ◽  
V. Hsu ◽  
C. E. Helsley ◽  
E. Herrero ◽  
T. Jordan
Keyword(s):  
Spatial Distribution ◽  
Seismic Activity ◽  
Main Shock ◽  
Plate Boundary ◽  
Diagnostic Value ◽  
Seismic Network ◽  
Local Seismicity ◽  
Continental Plate ◽  
Time Period ◽  
Precursory Seismic Activity

abstract Local seismic activity (M > 2.3) during the 412-day period preceding the Petatlan earthquake of 14 March 1979 (Ms = 7.6) was monitored by a seismic network deployed by the Hawaii Institute of Geophysics. These data allow us to revise the location of that event, and to study its pattern of foreshocks. The foreshock hypocenters are concentrated above the ocean/continent plate boundary and landward of the hypocenter of the main shock. The spatial distribution of foreshocks suggests that the foreshocks occurred along existing zones of weakness within the continental plate. During the 112-day period preceding the Petatlan event, foreshocks were concentrated within 100 km of the epicenter of that earthquake. The pattern of precursory seismic activity we observed during that period is similar to that observed during the same time period prior to the Oaxaca earthquake of 29 November 1978. However, the 17-hr period of seismic quiescence (for events with M > 2.8) preceding the Oaxaca earthquake is not found in our data where a magnitude 4 foreshock occurs within 28 min of and 2 km from the Petatlan event. This suggests that the spatially larger set of foreshocks may have greater diagnostic value than does the sequence of precursory events within 30 km of the main shock.

Shale, Quakes, and High Stakes: Regulating Fracking-Induced Seismicity in Oklahoma, USA and Lancashire, UK

2019 ◽  
Vol 3 (1) ◽  
pp. 1-14
Author(s):  
Miriam R. Aczel ◽  
Karen E. Makuch
Keyword(s):  
United States ◽  
Hydraulic Fracturing ◽  
Shale Gas ◽  
Seismic Activity ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
High Volume ◽  
The United States ◽  
Horizontal Drilling ◽  
Induced Seismic Activity

High-volume hydraulic fracturing combined with horizontal drilling has “revolutionized” the United States’ oil and gas industry by allowing extraction of previously inaccessible oil and gas trapped in shale rock [1]. Although the United States has extracted shale gas in different states for several decades, the United Kingdom is in the early stages of developing its domestic shale gas resources, in the hopes of replicating the United States’ commercial success with the technologies [2, 3]. However, the extraction of shale gas using hydraulic fracturing and horizontal drilling poses potential risks to the environment and natural resources, human health, and communities and local livelihoods. Risks include contamination of water resources, air pollution, and induced seismic activity near shale gas operation sites. This paper examines the regulation of potential induced seismic activity in Oklahoma, USA, and Lancashire, UK, and concludes with recommendations for strengthening these protections.

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