scholarly journals Why Do Great Earthquakes Follow Each Other at Subduction Zones?

Eos ◽  
2017 ◽  
Author(s):  
Terri Cook
Keyword(s):  
South America ◽  
Subduction Zones ◽  
Great Earthquake ◽  
Strain Accumulation ◽  
Gps Measurements ◽  
Great Earthquakes ◽  
Enhanced Strain ◽  
Continuous Gps

A decade of continuous GPS measurements in South America indicates that enhanced strain accumulation following a great earthquake can initiate failure along adjacent fault segments.

The great Lisbon earthquake and tsunami of 1755: lessons from the recent Sumatra earthquakes and possible link to Plato's Atlantis

2006 ◽  
Vol 14 (2) ◽  
pp. 181-191 ◽  
Author(s):  
M.-A. GUTSCHER
Keyword(s):  
Subduction Zone ◽  
Subduction Zones ◽  
Coarse Grained ◽  
Great Earthquake ◽  
Seismic Profiles ◽  
Great Earthquakes ◽  
Lisbon Earthquake ◽  
Southern Iberia ◽  
High Resolution Bathymetry ◽  
Sumatra Earthquakes

Great earthquakes and tsunami can have a tremendous societal impact. The Lisbon earthquake and tsunami of 1755 caused tens of thousands of deaths in Portugal, Spain and NW Morocco. Felt as far as Hamburg and the Azores islands, its magnitude is estimated to be 8.5–9. However, because of the complex tectonics in Southern Iberia, the fault that produced the earthquake has not yet been clearly identified. Recently acquired data from the Gulf of Cadiz area (tomography, seismic profiles, high-resolution bathymetry, sampled active mud volcanoes) provide strong evidence for an active east dipping subduction zone beneath Gibraltar. Eleven out of 12 of the strongest earthquakes (M>8.5) of the past 100 years occurred along subduction zone megathrusts (including the December 2004 and March 2005 Sumatra earthquakes). Thus, it appears likely that the 1755 earthquake and tsunami were generated in a similar fashion, along the shallow east-dipping subduction fault plane. This implies that the Cadiz subduction zone is locked (like the Cascadia and Nankai/Japan subduction zones), with great earthquakes occurring over long return periods. Indeed, the regional paleoseismic record (contained in deep-water turbidites and shallow lagoon deposits) suggests great earthquakes off South West Iberia every 1500–2000 years. Tsunami deposits indicate an earlier great earthquake struck SW Iberia around 200 BC, as noted by Roman records from Cadiz. A written record of even older events may also exist. According to Plato's dialogues The Critias and The Timaeus, Atlantis was destroyed by ‘strong earthquakes and floods … in a single day and night’ at a date given as 11,600 BP. A 1 m thick turbidite deposit, containing coarse grained sediments from underwater avalanches, has been dated at 12,000 BP and may correspond to the destructive earthquake and tsunami described by Plato. The effects on a paleo-island (Spartel) in the straits of Gibraltar would have been devastating, if inhabited, and may have formed the basis for the Atlantis legend.

scholarly journals Estimation of crustal deformation parameters and strain build-up in Northwest Himalaya using GNSS data measurements

2021 ◽  
Vol 51 (3) ◽  
pp. 225-243
Author(s):  
Abhishek YADAV ◽  
Suresh KANNAUJIYA ◽  
Prashant Kumar CHAMPATI RAY ◽  
Rajeev Kumar YADAV ◽  
Param Kirti GAUTAM
Keyword(s):  
Seismic Hazard ◽  
Strain Rate ◽  
Accumulation Rate ◽  
Himalayan Region ◽  
Compression Rate ◽  
Strain Accumulation ◽  
Gps Measurements ◽  
Baseline Method ◽  
Maximum Shear Strain ◽  
Continuous Gps

GPS measurements have proved extremely useful in quantifying strain accumulation rate and assessing seismic hazard in a region. Continuous GPS measurements provide estimates of secular motion used to understand the earthquake and other geodynamic processes. GNSS stations extending from the South of India to the Higher Himalayan region have been used to quantify the strain build-up rate in Central India and the Himalayan region to assess the seismic hazard potential in this realm. Velocity solution has been determined after the application of Markov noise estimated from GPS time series data. The recorded GPS data are processed along with the closest International GNSS stations data for estimation of daily basis precise positioning. The baseline method has been used for the estimation of the linear strain rate between the two stations. Whereas the principal strain axes, maximum shear strain, rotation rate, and crustal shortening rate has been calculated through the site velocity using an independent approach; least-square inversion approach-based triangulation method. The strain rate analysis estimated by the triangulation approach exhibits a mean value of extension rate of 26.08 nano-strain/yr towards N131°, the compression rate of –25.38 nano-strain/yr towards N41°, maximum shear strain rate of 51.47 nano-strain/yr, dilation of –37.57 nano-strain/yr and rotation rate of 0.7°/Ma towards anti-clockwise. The computed strain rate from the Baseline method and the Triangulation method reports an extensive compression rate that gradually increases from the Indo-Gangetic Plain in South to Higher Himalaya in North. The slip deficit rate between India and Eurasia Plate in Kumaun Garhwal Himalaya has been computed as 18±1.5 mm/yr based on elastic dislocation theory. Thus, in this study, present-day surface deformation rate and interseismic strain accumulation rate in the Himalayan region and the Central Indian region have been estimated for seismic hazard analysis using continuous GPS measurements.

scholarly journals Investigation of correlation of the variations in land subsidence (detected by continuous GPS measurements) and methodological data in the surrounding areas of Lake Urmia

2012 ◽  
Vol 19 (6) ◽  
pp. 675-683 ◽  
Author(s):  
K. Moghtased-Azar ◽  
A. Mirzaei ◽  
H. R. Nankali ◽  
F. Tavakoli
Keyword(s):  
Time Series ◽  
Land Subsidence ◽  
Salt Lake ◽  
Linear Trend ◽  
Groundwater Resources ◽  
Time Interval ◽  
Gps Measurements ◽  
Lake Urmia ◽  
North West ◽  
Continuous Gps

Abstract. Lake Urmia, a salt lake in the north-west of Iran, plays a valuable role in the environment, wildlife and economy of Iran and the region, but now faces great challenges for survival. The Lake is in immediate and great danger and is rapidly going to become barren desert. As a result, the increasing demands upon groundwater resources due to expanding metropolitan and agricultural areas are a serious challenge in the surrounding regions of Lake Urmia. The continuous GPS measurements around the lake illustrate significant subsidence rate between 2005 and 2009. The objective of this study was to detect and specify the non-linear correlation of land subsidence and temperature activities in the region from 2005 to 2009. For this purpose, the cross wavelet transform (XWT) was carried out between the two types of time series, namely vertical components of GPS measurements and daily temperature time series. The significant common patterns are illustrated in the high period bands from 180–218 days band (~6–7 months) from September 2007 to February 2009. Consequently, the satellite altimetry data confirmed that the maximum rate of linear trend of water variation in the lake from 2005 to 2009, is associated with time interval from September 2007 to February 2009. This event was detected by XWT as a critical interval to be holding the strong correlation between the land subsidence phenomena and surface temperature. Eventually the analysis can be used for modeling and prediction purposes and probably stave off the damage from subsidence phenomena.

Seismic imaging evidence that forearc underplating built the accretionary rock record of coastal North and South America

2019 ◽  
Vol 158 (1) ◽  
pp. 104-117 ◽  
Author(s):  
David W. Scholl
Keyword(s):  
South America ◽  
Subduction Zones ◽  
Seismic Imaging ◽  
Southern Chile ◽  
Late Palaeozoic ◽  
Aleutian Arc ◽  
Seaward Edge ◽  
Metamorphic Facies ◽  
North And South America ◽  
North And South

AbstractThe submerged forearcs of Pacific subduction zones of North and South America are underlain by a coastally exposed basement of late Palaeozoic to early Tertiary age. Basement is either an igneous massif of an accreted intra-oceanic arc or oceanic plateau (e.g. Cascadia(?), Colombia), an in situ formed arc massif (e.g. Aleutian Arc) or an exhumed accretionary complex of low and high P/T metamorphic facies of late Palaeozoic (e.g. southern Chile, Patagonia) and Mesozoic age (e.g. Alaska). Seismic studies at Pacific forearcs image frontal prisms of trench sediment accreted to the seaward edge of forearc basement. Frontal prisms tend to be narrow (10–40 km), weakly consolidated and volumetrically small (∼35–40 km3/km of trench). In contrast, deep seismic imaging of submerged forearcs commonly reveals large volumes (∼2000 km3/km of trench) of underplated material accreted at subsurface depths of ∼10–30 km to the base of forearc basement. Underplates have been imaged below the southern Chile, Ecuador–Colombia, north Cascade, Alaska, and possibly the eastern Aleutian forearcs. Deep underplates have also been observed below the Japan and New Zealand forearcs. Seismic imaging of northern and eastern Pacific forearcs supports the conclusion drawn from field and laboratory studies that exposed low and high P/T accretionary complexes accumulated in the subsurface at depths of 10–30 km. It seems significant that imaged underplated bodies are characteristic of modern well-sedimented subduction zones. It also seems likely that large Pacific-rim underplates store a significant fraction of sediment subducted in Cenozoic time.

Active deformation in Algeria from continuous GPS measurements

2019 ◽  
Vol 217 (1) ◽  
pp. 572-588 ◽  
Author(s):  
Amina Bougrine ◽  
Abdel Karim Yelles-Chaouche ◽  
Eric Calais
Keyword(s):  
Gps Measurements ◽  
Active Deformation ◽  
Continuous Gps

scholarly journals New constraints on the 1922 Atacama, Chile, earthquake from Historical seismograms

2019 ◽  
Vol 219 (1) ◽  
pp. 645-661 ◽  
Author(s):  
Hiroo Kanamori ◽  
Luis Rivera ◽  
Lingling Ye ◽  
Thorne Lay ◽  
Satoko Murotani ◽  
...  
Keyword(s):  
Subduction Zones ◽  
Source Region ◽  
Plate Boundary ◽  
Spatial Proximity ◽  
Motion Data ◽  
Megathrust Earthquakes ◽  
Great Earthquakes ◽  
Chile Earthquake ◽  
Earthquake Research ◽  
Earthquake Research Institute

SUMMARY We recently found the original Omori seismograms recorded at Hongo, Tokyo, of the 1922 Atacama, Chile, earthquake (MS = 8.3) in the historical seismogram archive of the Earthquake Research Institute (ERI) of the University of Tokyo. These recordings enable a quantitative investigation of long-period seismic radiation from the 1922 earthquake. We document and provide interpretation of these seismograms together with a few other seismograms from Mizusawa, Japan, Uppsala, Sweden, Strasbourg, France, Zi-ka-wei, China and De Bilt, Netherlands. The 1922 event is of significant historical interest concerning the cause of tsunami, discovery of G wave, and study of various seismic phase and first-motion data. Also, because of its spatial proximity to the 1943, 1995 and 2015 great earthquakes in Chile, the 1922 event provides useful information on similarity and variability of great earthquakes on a subduction-zone boundary. The 1922 source region, having previously ruptured in 1796 and 1819, is considered to have significant seismic hazard. The focus of this paper is to document the 1922 seismograms so that they can be used for further seismological studies on global subduction zones. Since the instrument constants of the Omori seismographs were only incompletely documented, we estimate them using the waveforms of the observed records, a calibration pulse recorded on the seismogram and the waveforms of better calibrated Uppsala Wiechert seismograms. Comparison of the Hongo Omori seismograms with those of the 1995 Antofagasta, Chile, earthquake (Mw = 8.0) and the 2015 Illapel, Chile, earthquake (Mw = 8.3) suggests that the 1922 event is similar to the 1995 and 2015 events in mechanism (i.e. on the plate boundary megathrust) and rupture characteristics (i.e. not a tsunami earthquake) with Mw = 8.6 ± 0.25. However, the initial fine scale rupture process varies significantly from event to event. The G1 and G2, and R1 and R2 of the 1922 event are comparable in amplitude, suggesting a bilateral rupture, which is uncommon for large megathrust earthquakes.

The Ordered Network Structure of M≥8 Great Earthquakes and their Prediction in Mainland China

2012 ◽  
Vol 67 (5) ◽  
pp. 308-316
Author(s):  
Kepei Men
Keyword(s):  
Network Structure ◽  
Mainland China ◽  
Practical Method ◽  
Great Earthquake ◽  
Self Organized ◽  
Great Earthquakes ◽  
Chinese Characteristics ◽  
Unique Effect ◽  
Network Feature ◽  
Long Term Prediction

China is one of the countries which have the most earthquake disasters in the world. A total of 23 M ≥ 8 earthquakes occurred in Mainland China from 1303 to 2010. The seismic activity of M ≥ 8 earthquakes has had an obvious self-organized orderliness. The main ordered values are 252~258 a, 108~112 a, 94~98 a, 44~47 a, 24~25 a, 16~19 a, and 11~14 a. According to the information forecasting theory of Wen-Bo Weng and combining ordered analysis with complex network technology, we build an informational ordered network structure of M ≥ 8 great earthquakes in Mainland China and try to explore the practical method for M ≥ 8 great earthquake prediction with Chinese characteristics. In this paper, we have summarized the prediction research on two great earthquakes (the 2001 Kunlunshan M8.1 and the 2008 Wenchuan M8.0 earthquake) during the beginning of the 21st century in western Mainland China. At last, with the method of ordered network structure, we present a new prediction opinion: the future M ≥ 8 great earthquakes will happen in 2026 and 2065 pre and post in Mainland China. The results show that a M ≥ 8 great earthquake could be predicted and the network feature is the formation mechanism of great earthquakes. The ordered network method has a unique effect on moderate term and long term prediction for M ≥ 8 great earthquakes.

Multipath Mitigation of Continuous GPS Measurements Using an Adaptive Filter

GPS Solutions ◽  
2000 ◽  
Vol 4 (2) ◽  
pp. 19-30 ◽  
Author(s):  
Linlin Ge ◽  
Shaowei Han ◽  
Chris Rizos
Keyword(s):  
Adaptive Filter ◽  
Gps Measurements ◽  
Multipath Mitigation ◽  
Continuous Gps
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