Statistical Analysis of Intraplate Seismic Clusters: The Case of the NW Iberian Peninsula

Crespo-Martín, Cristina; Martín-González, Fidel

doi:10.1007/s00024-021-02834-8

Cited by 3 publications

(1 citation statement)

References 76 publications

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“…It incorporates two empirical laws, the Omori-Utsu law [38] and the productivity law used to explain the distribution of aftershocks, as well as a stable Poissonian rate for the background seismicity. Our work utilizes the estimated parameters of the ETAS model to investigate regional variabilities in the productivity of the sequences and gain insights into the involved triggering mechanisms [39][40][41].…”

Section: Introductionmentioning

confidence: 99%

Identification and Temporal Characteristics of Earthquake Clusters in Selected Areas in Greece

2022

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The efficiency of earthquake clustering investigation is improved as we gain access to larger datasets due to the increase of earthquake detectability. We aim to demonstrate the robustness of a new clustering method, MAP-DBSCAN, and to present a comprehensive analysis of the clustering properties in three major seismic zones of Greece during 2012–2019. A time-dependent stochastic point model, the Markovian Arrival Process (MAP), is implemented for the detection of change-points in the seismicity rate and subsequently, a density-based clustering algorithm, DBSCAN, is used for grouping the events into spatiotemporal clusters. The two-step clustering procedure, MAP-DBSCAN, is compared with other existing methods (Gardner-Knopoff, Reasenberg, Nearest-Neighbor) on a simulated earthquake catalog and is proven highly competitive as in most cases outperforms the tested algorithms. Next, the earthquake clusters in the three areas are detected and the regional variability of their productivity rates is investigated based on the generic estimates of the Epidemic Type Aftershock Sequence (ETAS) model. The seismicity in the seismic zone of Corinth Gulf is characterized by low aftershock productivity and high background rates, indicating the dominance of swarm activity, whereas in Central Ionian Islands seismic zone where main shock-aftershock sequences dominate, the aftershock productivity rates are higher. The productivity in the seismic zone of North Aegean Sea vary significantly among clusters probably due to the co-existence of swarm activity and aftershock sequences. We believe that incorporating regional variations of the productivity into forecasting models, such as the ETAS model, it might improve operational earthquake forecasting.

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Section: Introductionmentioning

confidence: 99%

Identification and Temporal Characteristics of Earthquake Clusters in Selected Areas in Greece

2022

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Testing potential trigger mechanisms for seismicity in Sarria-Triacastela-Becerreá (Lugo seismic sequences) NW Iberian Peninsula, Spain

Crespo-Martín

Martín-González²,

Hainzl³

et al. 2022

J Seismol

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The unprecedented and long-lasting seismicity of Triacastela (over 25 years) attracted the interest of the research community on this stable continental region (SCR), particularly after the anomalously high 5.1 and 4.9 Mw earthquakes compared to the regional standards. The high rainfall and tide rates of this region compared to the rest of the Iberian Peninsula, in addition to the recognized existence of thermal springs and crustal fluids, motivated us to test these sources of hydroseismicity as a potential trigger mechanism for the observed seismicity in Triacastela. Based on network upgrades, we have gathered the seismic catalog in two periods for analysis (before and after year 2002). Before 2002, neither a diffusion-type earthquake migration nor any significant statistical correlation between the seismicity rates and rainfall or tides is found. After 2002, some clusters migrate to the south, suggesting the presence of fluid migration during earthquake swarms, but no diffusion-type migration is observed on longer time scales. Furthermore, we find correlation coefficients close to zero, indicating that rainfall and tides can be excluded as driving mechanisms. However, the seismic upward migration, a high b-value (1.2), and a low aftershock-productivity parameter (α=0.9) observed in this period support the hypothesis of upward fluid migration through fracture zones. The presence of Mantellic helium-3 along the seismogenic faults and the increase of geochemical precursors in the groundwater previously to 1995 and 1997 mainshocks further support deep fluids as a source for the observed induced fluid migration seismicity in Triacastela. Article Highlights:• Swarms, upward migration, high b-value, and low α-value after 2002 suggest a fluid influence on Triacastela seismicity.• Pearson correlations close to zero reject rainfall and tides as driving mechanisms of Triacastela seismicity.• The mantellic helium-3 in groundwaters, the geochemical precursors rise and elements mobility over faults evoke deep fluids migration.

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Understanding seismicity and seismotectonics in a stable continental region (NW Iberian Peninsula): Implications for the nature of intraplate seismicity

Martín-González

Crespo-Martín

Cesca

et al. 2023

Global and Planetary Change

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Statistical Analysis of Intraplate Seismic Clusters: The Case of the NW Iberian Peninsula

Cited by 3 publications

References 76 publications

Identification and Temporal Characteristics of Earthquake Clusters in Selected Areas in Greece

Identification and Temporal Characteristics of Earthquake Clusters in Selected Areas in Greece

Testing potential trigger mechanisms for seismicity in Sarria-Triacastela-Becerreá (Lugo seismic sequences) NW Iberian Peninsula, Spain

Understanding seismicity and seismotectonics in a stable continental region (NW Iberian Peninsula): Implications for the nature of intraplate seismicity

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