shyam nandan | Swiss Federal Institute of Technology (ETH) (original) (raw)

Papers by shyam nandan

Research paper thumbnail of The 2020 European Seismic Hazard Model: Overview and Results

Research paper thumbnail of Supplementary material to "The 2020 European Seismic Hazard Model: Overview and Results

In this supplementary materials section, we provide a comprehensive exploration of the difference... more In this supplementary materials section, we provide a comprehensive exploration of the differences of the earthquake rate forecasts of ESHM20 and ESHM13. Additionally, we present a series of trellis plots to facilitate a comparative analysis of the ground motion characteristics models.

Research paper thumbnail of Modelling injection induced seismicity in the Hengill geothermal field

<p><span>The Hellisheiði Geothermal ... more <p><span>The Hellisheiði Geothermal Field is situated in Southwest Iceland and composes the Southern part </span><span>of the Hengill Volcanic System. This area is characterized by a complex triple junction between three </span><span>tectonic features: the Reykanes Peninsula rifting, South Iceland Volcanic Zone and West Volcanic  </span><span>Zone. Reinjection of spent geothermal fluids is distributed mostly in two areas (Gráuhnúkar and </span><span>Húsmúli), comprising respectively 6 and 5 active injection wells. The Húsmúli reinjection area, </span><span>commissioned in September 2011 and has seen significant seismicity associated with drilling and </span><span>injection operations.</span><br><span>In the framework of the Geothermica project COSEISMIQ (http://www.coseismiq.ethz.ch/en/home/), </span><span>a dense temporary network was installed to monitor the seismicity in the Hengill region between </span><span>December 2018 and August 2021. With this enhanced network, novel analysis and relocation </span><span>techniques, a high resolution relocated catalogue was curated and comprises over 3600 events in </span><span>the Húsmúli area.</span><br><span>We use numerical models, some purely statistical (ETAS and Seismogenic index) and a hybrid model </span><span>(TOUGH2-Seed) to reproduce observed seismicity in the Húsmúli reinjection area during the </span><span>COSEISMIQ project. We employ a pseudo-forecasting approach and compare models performances </span><br><span>and fit to the recorded data.</span></p>

Research paper thumbnail of Significant Hot Hand Effect in International Cricket

Social Science Research Network, 2020

We investigate the hot hand effect in the game of cricket by analyzing the complete recorded hist... more We investigate the hot hand effect in the game of cricket by analyzing the complete recorded history of international cricket. We introduce an original temporal representation of performance streaks, which is suitable to be modelled as a self-exciting point process. We confirm the presence of hot hands across the players' careers. We show that the self-excitation patterns in performance clusters can be exploited for predicting future performances. This paper contributes to recent historiographical debates concerning the presence of hot hands in the sequence of successes in individual performances. The introduction of several metrics and methods can be useful to test and exploit the clustering of performance in the study of human behavior and the design of algorithms for predicting success.

Research paper thumbnail of A robust, flexible and automatic framework for joint estimation of magnitude of completeness, b-value, magnitude binning and their time variation

EGU General Assembly Conference Abstracts, Apr 1, 2019

Research paper thumbnail of Estimating Spatially Variable Parameters of the Epidemic Type Aftershock Sequence (ETAS) in California

EGU General Assembly Conference Abstracts, Apr 1, 2016

Research paper thumbnail of Foreshocks and Their Potential Deviation from General Seismicity

Bulletin of the Seismological Society of America, Dec 4, 2018

Research paper thumbnail of Significant hot hand effect in the game of cricket

Scientific Reports, Jul 8, 2022

We investigate the predictability and persistence of individual and team performance (hot-hand ef... more We investigate the predictability and persistence of individual and team performance (hot-hand effect) by analyzing the complete recorded history of international cricket. We introduce an original temporal representation of performance streaks, which is suitable to be modelled as a self-exciting point process. We confirm the presence of predictability and hot-hands across the individual performance and the absence of the same in team performance and game outcome. Thus, Cricket is a game of skill for individuals and a game of chance for the teams. Our study contributes to recent historiographical debates concerning the presence of persistence in individual and collective productivity and success. The introduction of several metrics and methods can be useful to test and exploit clustering of performance in the study of human behavior and design of algorithms for predicting success.

Research paper thumbnail of Rx TimeMachine: A global pseudoprospective earthquake forecast database for training and ranking predictive algorithms

This page was generated automatically upon download from the ETH Zurich Research Collection. For ... more This page was generated automatically upon download from the ETH Zurich Research Collection. For more information, please consult the Terms of use.

Research paper thumbnail of Embracing Data Incompleteness for Better Earthquake Forecasting

Research paper thumbnail of The Effect of Declustering on the Size Distribution of Mainshocks

Seismological Research Letters, Feb 17, 2021

Declustering aims to divide earthquake catalogs into independent events (mainshocks), and depende... more Declustering aims to divide earthquake catalogs into independent events (mainshocks), and dependent (clustered) events, and is an integral component of many seismicity studies, including seismic hazard assessment. We assess the effect of declustering on the frequency-magnitude distribution of mainshocks. In particular, we examine the dependence of the b-value of declustered catalogs on the choice of declustering approach and algorithm-specific parameters. Using the catalog of earthquakes in California since 1980, we show that the b-value decreases by up to 30% due to declustering with respect to the undeclustered catalog. The extent of the reduction is highly dependent on the declustering method and parameters applied. We then reproduce a similar effect by declustering synthetic earthquake catalogs with known b-value, which have been generated using an epidemic-type aftershock sequence model. Our analysis suggests that the observed decrease in b-value must, at least partially, arise from the application of the declustering algorithm on the catalog, rather than from differences in the nature of mainshocks versus fore-or aftershocks. We conclude that declustering should be considered as a potential source of bias in seismicity and hazard studies.

Research paper thumbnail of Synchronized Bursts of Productivity And Success In Individual Careers

Research Square (Research Square), Oct 25, 2021

Despite a significant understanding of epidemic processes in biological, social, financial, and g... more Despite a significant understanding of epidemic processes in biological, social, financial, and geophysical systems, little is known about the contagion behavior in individual productivity and success. Here we uncover synchronized bursts in individual productivity and success. We introduce an epidemic model to study the contagion of scholarly productivity and YouTube success. Our analysis reveals the strong influence of network externalities in individual careers. The observed synchronization of individual productivity and success is likely mediated by sustained flows of information within the network.

Research paper thumbnail of The 2020 European Seismic Hazard Model: Milestones and Lessons Learned

Springer proceedings in earth and environmental sciences, 2022

Research paper thumbnail of Joint resolving of the fault plane ambiguity and anisotropic earthquake triggering in Southern California

Research paper thumbnail of Testing physics and statics based hybrid ETAS models

Research paper thumbnail of Using likelihood tests to derive space-time windows for catalog declustering: Application to the 2020 European Seismic Hazard Model (ESHM20)

Research paper thumbnail of Uncovering predictability of individual and team success: Significant Hot Hand Effect in International Cricket

Research Square (Research Square), Nov 9, 2021

We investigate the predictability and persistence (hot-hand effect) of individual and team perfor... more We investigate the predictability and persistence (hot-hand effect) of individual and team performance by analyzing the complete recorded history of international cricket. We introduce an original temporal representation of performance streaks, which is suitable to be modelled as a self-exciting point process. We confirm the presence of predictability and hot-hands across the individual performance and the absence of the same in team performance and game outcome. Thus, Cricket is a game of skill for individuals and a game of chance for the teams. Our study contributes to recent historiographical debates concerning the presence of persistence in individual and collective productivity and success. The introduction of several metrics and methods can be useful to test and exploit clustering of performance in the study of human behavior and design of algorithms for predicting success.

Research paper thumbnail of Status, Milestones and Next Activities on the Development of the 2020 European Seismic Hazard Model (ESHM20)

EGU General Assembly Conference Abstracts, Apr 1, 2019

Research paper thumbnail of Question-Driven Ensembles of Flexible ETAS Models

Seismological Research Letters

The development of new earthquake forecasting models is often motivated by one of the following c... more The development of new earthquake forecasting models is often motivated by one of the following complementary goals: to gain new insights into the governing physics and to produce improved forecasts quantified by objective metrics. Often, one comes at the cost of the other. Here, we propose a question-driven ensemble (QDE) modeling approach to address both goals. We first describe flexible epidemic-type aftershock sequence (ETAS) models in which we relax the assumptions of parametrically defined aftershock productivity and background earthquake rates during model calibration. Instead, both productivity and background rates are calibrated with data such that their variability is optimally represented by the model. Then we consider 64 QDE models in pseudoprospective forecasting experiments for southern California and Italy. QDE models are constructed by combining model parameters of different ingredient models, in which the rules for how to combine parameters are defined by questions ...

Research paper thumbnail of Significant hot hand effect in the game of cricket

Scientific Reports

We investigate the predictability and persistence of individual and team performance (hot-hand ef... more We investigate the predictability and persistence of individual and team performance (hot-hand effect) by analyzing the complete recorded history of international cricket. We introduce an original temporal representation of performance streaks, which is suitable to be modelled as a self-exciting point process. We confirm the presence of predictability and hot-hands across the individual performance and the absence of the same in team performance and game outcome. Thus, Cricket is a game of skill for individuals and a game of chance for the teams. Our study contributes to recent historiographical debates concerning the presence of persistence in individual and collective productivity and success. The introduction of several metrics and methods can be useful to test and exploit clustering of performance in the study of human behavior and design of algorithms for predicting success.

Research paper thumbnail of The 2020 European Seismic Hazard Model: Overview and Results

Research paper thumbnail of Supplementary material to "The 2020 European Seismic Hazard Model: Overview and Results

In this supplementary materials section, we provide a comprehensive exploration of the difference... more In this supplementary materials section, we provide a comprehensive exploration of the differences of the earthquake rate forecasts of ESHM20 and ESHM13. Additionally, we present a series of trellis plots to facilitate a comparative analysis of the ground motion characteristics models.

Research paper thumbnail of Modelling injection induced seismicity in the Hengill geothermal field

<p><span>The Hellisheiði Geothermal ... more <p><span>The Hellisheiði Geothermal Field is situated in Southwest Iceland and composes the Southern part </span><span>of the Hengill Volcanic System. This area is characterized by a complex triple junction between three </span><span>tectonic features: the Reykanes Peninsula rifting, South Iceland Volcanic Zone and West Volcanic  </span><span>Zone. Reinjection of spent geothermal fluids is distributed mostly in two areas (Gráuhnúkar and </span><span>Húsmúli), comprising respectively 6 and 5 active injection wells. The Húsmúli reinjection area, </span><span>commissioned in September 2011 and has seen significant seismicity associated with drilling and </span><span>injection operations.</span><br><span>In the framework of the Geothermica project COSEISMIQ (http://www.coseismiq.ethz.ch/en/home/), </span><span>a dense temporary network was installed to monitor the seismicity in the Hengill region between </span><span>December 2018 and August 2021. With this enhanced network, novel analysis and relocation </span><span>techniques, a high resolution relocated catalogue was curated and comprises over 3600 events in </span><span>the Húsmúli area.</span><br><span>We use numerical models, some purely statistical (ETAS and Seismogenic index) and a hybrid model </span><span>(TOUGH2-Seed) to reproduce observed seismicity in the Húsmúli reinjection area during the </span><span>COSEISMIQ project. We employ a pseudo-forecasting approach and compare models performances </span><br><span>and fit to the recorded data.</span></p>

Research paper thumbnail of Significant Hot Hand Effect in International Cricket

Social Science Research Network, 2020

We investigate the hot hand effect in the game of cricket by analyzing the complete recorded hist... more We investigate the hot hand effect in the game of cricket by analyzing the complete recorded history of international cricket. We introduce an original temporal representation of performance streaks, which is suitable to be modelled as a self-exciting point process. We confirm the presence of hot hands across the players' careers. We show that the self-excitation patterns in performance clusters can be exploited for predicting future performances. This paper contributes to recent historiographical debates concerning the presence of hot hands in the sequence of successes in individual performances. The introduction of several metrics and methods can be useful to test and exploit the clustering of performance in the study of human behavior and the design of algorithms for predicting success.

Research paper thumbnail of A robust, flexible and automatic framework for joint estimation of magnitude of completeness, b-value, magnitude binning and their time variation

EGU General Assembly Conference Abstracts, Apr 1, 2019

Research paper thumbnail of Estimating Spatially Variable Parameters of the Epidemic Type Aftershock Sequence (ETAS) in California

EGU General Assembly Conference Abstracts, Apr 1, 2016

Research paper thumbnail of Foreshocks and Their Potential Deviation from General Seismicity

Bulletin of the Seismological Society of America, Dec 4, 2018

Research paper thumbnail of Significant hot hand effect in the game of cricket

Scientific Reports, Jul 8, 2022

We investigate the predictability and persistence of individual and team performance (hot-hand ef... more We investigate the predictability and persistence of individual and team performance (hot-hand effect) by analyzing the complete recorded history of international cricket. We introduce an original temporal representation of performance streaks, which is suitable to be modelled as a self-exciting point process. We confirm the presence of predictability and hot-hands across the individual performance and the absence of the same in team performance and game outcome. Thus, Cricket is a game of skill for individuals and a game of chance for the teams. Our study contributes to recent historiographical debates concerning the presence of persistence in individual and collective productivity and success. The introduction of several metrics and methods can be useful to test and exploit clustering of performance in the study of human behavior and design of algorithms for predicting success.

Research paper thumbnail of Rx TimeMachine: A global pseudoprospective earthquake forecast database for training and ranking predictive algorithms

This page was generated automatically upon download from the ETH Zurich Research Collection. For ... more This page was generated automatically upon download from the ETH Zurich Research Collection. For more information, please consult the Terms of use.

Research paper thumbnail of Embracing Data Incompleteness for Better Earthquake Forecasting

Research paper thumbnail of The Effect of Declustering on the Size Distribution of Mainshocks

Seismological Research Letters, Feb 17, 2021

Declustering aims to divide earthquake catalogs into independent events (mainshocks), and depende... more Declustering aims to divide earthquake catalogs into independent events (mainshocks), and dependent (clustered) events, and is an integral component of many seismicity studies, including seismic hazard assessment. We assess the effect of declustering on the frequency-magnitude distribution of mainshocks. In particular, we examine the dependence of the b-value of declustered catalogs on the choice of declustering approach and algorithm-specific parameters. Using the catalog of earthquakes in California since 1980, we show that the b-value decreases by up to 30% due to declustering with respect to the undeclustered catalog. The extent of the reduction is highly dependent on the declustering method and parameters applied. We then reproduce a similar effect by declustering synthetic earthquake catalogs with known b-value, which have been generated using an epidemic-type aftershock sequence model. Our analysis suggests that the observed decrease in b-value must, at least partially, arise from the application of the declustering algorithm on the catalog, rather than from differences in the nature of mainshocks versus fore-or aftershocks. We conclude that declustering should be considered as a potential source of bias in seismicity and hazard studies.

Research paper thumbnail of Synchronized Bursts of Productivity And Success In Individual Careers

Research Square (Research Square), Oct 25, 2021

Despite a significant understanding of epidemic processes in biological, social, financial, and g... more Despite a significant understanding of epidemic processes in biological, social, financial, and geophysical systems, little is known about the contagion behavior in individual productivity and success. Here we uncover synchronized bursts in individual productivity and success. We introduce an epidemic model to study the contagion of scholarly productivity and YouTube success. Our analysis reveals the strong influence of network externalities in individual careers. The observed synchronization of individual productivity and success is likely mediated by sustained flows of information within the network.

Research paper thumbnail of The 2020 European Seismic Hazard Model: Milestones and Lessons Learned

Springer proceedings in earth and environmental sciences, 2022

Research paper thumbnail of Joint resolving of the fault plane ambiguity and anisotropic earthquake triggering in Southern California

Research paper thumbnail of Testing physics and statics based hybrid ETAS models

Research paper thumbnail of Using likelihood tests to derive space-time windows for catalog declustering: Application to the 2020 European Seismic Hazard Model (ESHM20)

Research paper thumbnail of Uncovering predictability of individual and team success: Significant Hot Hand Effect in International Cricket

Research Square (Research Square), Nov 9, 2021

We investigate the predictability and persistence (hot-hand effect) of individual and team perfor... more We investigate the predictability and persistence (hot-hand effect) of individual and team performance by analyzing the complete recorded history of international cricket. We introduce an original temporal representation of performance streaks, which is suitable to be modelled as a self-exciting point process. We confirm the presence of predictability and hot-hands across the individual performance and the absence of the same in team performance and game outcome. Thus, Cricket is a game of skill for individuals and a game of chance for the teams. Our study contributes to recent historiographical debates concerning the presence of persistence in individual and collective productivity and success. The introduction of several metrics and methods can be useful to test and exploit clustering of performance in the study of human behavior and design of algorithms for predicting success.

Research paper thumbnail of Status, Milestones and Next Activities on the Development of the 2020 European Seismic Hazard Model (ESHM20)

EGU General Assembly Conference Abstracts, Apr 1, 2019

Research paper thumbnail of Question-Driven Ensembles of Flexible ETAS Models

Seismological Research Letters

The development of new earthquake forecasting models is often motivated by one of the following c... more The development of new earthquake forecasting models is often motivated by one of the following complementary goals: to gain new insights into the governing physics and to produce improved forecasts quantified by objective metrics. Often, one comes at the cost of the other. Here, we propose a question-driven ensemble (QDE) modeling approach to address both goals. We first describe flexible epidemic-type aftershock sequence (ETAS) models in which we relax the assumptions of parametrically defined aftershock productivity and background earthquake rates during model calibration. Instead, both productivity and background rates are calibrated with data such that their variability is optimally represented by the model. Then we consider 64 QDE models in pseudoprospective forecasting experiments for southern California and Italy. QDE models are constructed by combining model parameters of different ingredient models, in which the rules for how to combine parameters are defined by questions ...

Research paper thumbnail of Significant hot hand effect in the game of cricket

Scientific Reports

We investigate the predictability and persistence of individual and team performance (hot-hand ef... more We investigate the predictability and persistence of individual and team performance (hot-hand effect) by analyzing the complete recorded history of international cricket. We introduce an original temporal representation of performance streaks, which is suitable to be modelled as a self-exciting point process. We confirm the presence of predictability and hot-hands across the individual performance and the absence of the same in team performance and game outcome. Thus, Cricket is a game of skill for individuals and a game of chance for the teams. Our study contributes to recent historiographical debates concerning the presence of persistence in individual and collective productivity and success. The introduction of several metrics and methods can be useful to test and exploit clustering of performance in the study of human behavior and design of algorithms for predicting success.