Francesco Grigoli

Francesco Grigoli
Università di Pisa | UNIPI · Department of Earth Sciences

PhD in Geophysics
Development of new methods for the robust and fully automated analysis of seismicity at different scales

About

53
Publications
27,191
Reads
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1,279
Citations
Citations since 2016
35 Research Items
1210 Citations
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2016201720182019202020212022050100150200250
Introduction
My research focus on the development of innovative (machine-learning based) methods for the characterization of massive seismicity datasets. I am particularly interested in applying such new techniques for the analysis of both natural and induced seismicity sequences to better understand the physical mechanisms governing earthquakes.
Additional affiliations
November 2019 - March 2020
Stanford University
Position
  • Researcher (Visiting)
October 2016 - March 2021
ETH Zurich
Position
  • Senior Researcher
August 2015 - September 2016
National Institute of Oceanography and Applied Geophysics - OGS
Position
  • Researcher
Education
July 2010 - March 2014
Universität Potsdam
Field of study
  • Seismology
October 2007 - May 2010
Università di Pisa
Field of study
  • Exploration Geophysics

Publications

Publications (53)
Article
Full-text available
Accurate and automated locations of microseismic events are desirable for many seismological and industrial applications. The analysis of microseismicity is particularly challenging because of weak seismic signals with low signal-to-noise ratio. Traditional location approaches rely on automated picking, based on individual seismograms, and make no...
Article
Full-text available
Due to the deep socioeconomic implications, induced seismicity is a timely and increasingly relevant topic of interest for the general public. Cases of induced seismicity have a global distribution and involve a large number of industrial operations, with many documented cases from as far back to the beginning of the 20th century. However, the spar...
Article
Full-text available
The monitoring of induced seismicity is a common operation in many industrial activities, such as conventional and non-conventional hydrocarbon production or mining and geothermal energy exploitation, to cite a few. During such operations, we generally collect very large and strongly noise-contaminated data sets that require robust and automated an...
Article
Full-text available
Triggering quakes in a geothermal space Enhanced geothermal systems (EGSs) provide a potentially clean and abundant energy source. However, two magnitude-5 earthquakes recently occurred in South Korea during EGS site development. Grigoli et al. and Kim et al. present seismic and geophysical evidence that may implicate the second of these earthquake...
Article
Full-text available
Earthquake location is one of the oldest problems in seismology, yet remains an active research topic. With dense seismic monitoring networks it is possible to obtain reliable locations for microearthquakes; however, in many cases dense networks are lacking, limiting the location accuracy, or preventing location when there are too few observations....
Article
Full-text available
Induced seismicity is one of the main factors that reduces societal acceptance of deep geothermal energy exploitation activities, and felt earthquakes are the main reason for closure of geothermal projects. Implementing innovative tools for real-time monitoring and forecasting of induced seismicity was one of the aims of the recently completed COSE...
Article
Full-text available
Robust automatic event detection and location is central to real-time earthquake monitoring. With the increase of computing power and data availability, automated workflows that utilize machine learning (ML) techniques have become increasingly popular; however, ML-based classical workflows still face challenges when applied to the analysis of micro...
Article
Full-text available
Despite advanced seismological techniques, automatic source characterisation for micro-seismic earthquakes remains difficult and challenging since current inversion and modelling of high-frequency signals are complex and time consuming. For real-time applications such as induced seismicity monitoring, the application of standard methods is often no...
Article
Full-text available
A R T I C L E I N F O Keywords: Cyclic soft stimulation Multi-stage hydraulic stimulation Zonal isolation Realtime seismic monitoring Fluid injection induced seismicity Adaptive traffic light system enhanced geothermal systems (EGS) A B S T R A C T Reykjavik is almost entirely heated by geothermal energy. Yet, recent growth of the city significantl...
Article
Full-text available
The 2013 seismic sequence at the Castor injection platform offshore Spain, including three earthquakes of magnitude 4.1, occurred during the initial filling of a planned Underground Gas Storage facility. The Castor sequence is one of the most important cases of induced seis- micity in Europe and a rare example of seismicity induced by gas injection...
Article
Full-text available
This report summarizes the seismicity in Switzerland and surrounding regions in the years 2017 and 2018. In 2017 and 2018, the Swiss Seismological Service detected and located 1227 and 955 earthquakes in the region under consideration, respectively. The strongest event in the analysed period was the ML 4.6 Urnerboden earthquake, which occurred in t...
Article
Full-text available
Geothermal systems in the Hengill volcanic area, SW Iceland, started to be exploited for electrical power and heat production since the late 1960s. Today the two largest operating geothermal power plants are located at Nesjavellir and Hellisheiði. This area is a complex tectonic and geothermal site, located at the triple junction between the Reykja...
Article
Full-text available
The rapid increase in energy demand in the city of Reykjavik has posed the need for an additional supply of deep geothermal energy. The deep-hydraulic (re-)stimulation of well RV-43 on the peninsula of Geldinganes (north of Reykjavik) is an essential component of the plan implemented by Reykjavik Energy to meet this energy target. Hydraulic stimula...
Article
Full-text available
Understanding fracturing processes and the hydromechanical relation to induced seismicity is a key question for enhanced geothermal systems (EGS). Commonly massive fluid injection, predominately causing hydroshearing, are used in large-scale EGS but also hydraulic fracturing approaches were discussed. To evaluate the applicability of hydraulic frac...
Article
Full-text available
Hydraulic injection by the Pohang enhanced geothermal systems (EGS) has been suspected to trigger the 2017 moment magnitude (MW) 5.5 Pohang earthquake in South Korea. The last stimulation experiment in the EGS was conducted only two months before the disaster, which has led to this suspicion. In this study, we conducted a seismic analysis on the ea...
Preprint
Full-text available
The rapid increase in energy demand in the city of Reykjavik has posed the need for an additional supply of deep geothermal energy. The deep hydraulic (re-)stimulation of well RV-43 on the peninsula of Geldinganes (north of Reykjavik) is an essential component of the plan implemented by Reykjavik Energy to meet this energy target. Hydraulic stimula...
Conference Paper
Full-text available
One of the main challenges in seismic monitoring in geothermal fields, is to automatically detect and locate induced microseismicity using dense networks. Manual detection and picking is a reliable method, however as the number of stations increases, this strategy becomes inefficient, slow and time consuming. To overcome these problems, several app...
Poster
Since the end of 2013, the region around the volcanoes Masaya and Momotombo, which includes Nicaraguan capital Managua, has shown unusually high seismic and volcanic activitiy. On April 10, 2013, a M6.3 earthquake occured near Momotombo volcano followed by intense aftershock activitiy and a migration of seismicity towards Managua. In the following...
Poster
Full-text available
The DBSCAN (Ester et al. 1996) is a popular data-clustering algorithm. The algorithm processes in arbitrary order every point Pk in the dataset, skipping every point already assigned to a cluster by the previous iterations. If at least N points are within distance R from Pk (including it), then Pk is called a Core Point and the points within distan...
Article
Full-text available
A crucial issue to characterize hydraulic fractures is the robust, accurate and automated detection and location of acoustic emissions (AE) associated with the fracture nucleation and growth process. Waveform stacking and coherence analysis techniques are here adapted using massive datasets with very high sampling (1 MHz) from a hydraulic fracturin...
Presentation
Full-text available
Microseismic monitoring is common operation in different georesources related industrial activities, such as oil&gas and mining operations or geothermal energy exploitation. In microseismic monitoring operations we generally deal with large dataset requiring robust automated analysis procedures. Such seismic datasets are often characterized by mult...
Article
A recent paper in Reviews of Geophysics examined the increasing incidence of seismic events caused by industrial activities. link to the article https://eos.org/editors-vox/the-challenges-posed-by-induced-seismicity#.WT2daTH0ncw.facebook
Conference Paper
Full-text available
On August 24, 2016 a Mw 6.0 earthquake struck Central Italy near the town of Amatrice and claimed the lives of 300 people. Two months later, the intensity of the aftershock sequence suddenly increased, when on its northern sector two seismic events of Mw 5.9 and Mw 6.5 indicated the activation of a new fault system. The latter event of Oct 30, 2016...
Conference Paper
Full-text available
On August 24, 2016, a Mw6.0 earthquake struck Central Italy near the town of Amatrice and claimed the lives of 300 people. Two months later, the intensity of the aftershock sequence suddenly increased, when on its northern sector two seismic events of Mw5.9 and Mw6.5 indicated the activation of a new fault system. The latter event of October 30, 20...
Conference Paper
Full-text available
Microseismic monitoring is common operation in different georesources related industrial activities, such as oil&gas and mining operations or geothermal energy exploitation. In microseismic monitoring operations we generally deal with large dataset requiring robust automated analysis procedures. Such seismic datasets are often characterized by mult...
Conference Paper
Full-text available
The increasing population and the society’s increasing energy demand implicates that production plants move noticeably closer to the inhabited areas. Dense seismic networks and arrays reveal that anthropogenic activities – as e.g. extraction and reinjection of fluids - can induce or trigger seismic activity. This becomes significant in geothermal a...
Article
Full-text available
One of the most critical problems affecting seismological data acquisition is related to possible misorientation of three-component seismic sensors. This generally happens when their orientation cannot be measured directly, as in the case of sensors deployed in boreholes. We describe here the sensor reorientation procedure of the Collalto Seismic N...
Article
Full-text available
The April 1, 2014, Mw 8.1 Iquique (Chile) earthquake struck in the Northern Chile seismic gap. With a rupture length of less than 200 km, it left unbroken large segments of the former gap. Early studies were able to model the main rupture features but results are ambiguous with respect to the role of aseismic slip and left open questions on the rem...
Article
Full-text available
One of the most critical problems affecting geophysical data acquisition procedures is related to the misorientation of multi-component sensors with respect to a common reference system (generally geographical North). In many applications, misoriented sensors affect data analysis procedures, leading to errors in results and interpretations. These...
Conference Paper
Full-text available
In the last decade a permanent seismic network of 30 broadband stations, complemented by dense temporary deployments, covered Portugal. This extraordinary network coverage enables now the computation of a high-resolution image of the seismicity of Portugal, which in turn will shed light on the seismotectonics of Portugal. The large data volumes ava...
Article
Full-text available
The observation of microseismicity has raised the interest of the seismological and geoengineering communities in the last decades, and a significant effort has been spent to develop or improve methodologies able to perform seismological analysis for weak events at a local scale. This effort was accompanied by the improvement of monitoring systems,...
Conference Paper
Full-text available
The Armutlu peninsula is located in the Eastern Marmara region, Turkey, which is exposed to hazards from major earthquakes on segments of the North Anatolian Fault (NAF). The seismotectonic setting is complex, due to the interaction of fault branches of the NAF, pull apart basins, and different crustal fault mechanisms. Precise locations of microea...
Article
Full-text available
A spatially localized seismic sequence originated few tens of kilometres offshore the Mediterranean coast of Spain, close to the Ebro river delta, starting on 2013 September 5, and lasting at least until 2013 October. The sequence culminated in a maximal moment magnitude Mw 4.3 earthquake, on 2013 October 1. The most relevant seismogenic feature in...
Thesis
Full-text available
Automated location of seismic events is a very important task in microseismic monitoring operations as well for local and regional seismic monitoring. Since microseismic records are generally characterised by low signal-to-noise ratio, such methods are requested to be noise robust and sufficiently accurate. Most of the standard automated location r...
Chapter
During the last thee years, the MINE project has developed and successfully applied seismological tools, addressing different aspects of the monitoring of mining environments, as dynamic local-scale systems. The human interaction with the shallow underground mining environment, can lead to rock mass weakening or locally induce stress perturbations....
Article
Full-text available
Automated location of seismic events is a very important task in microseismic monitoring operations as well for local and regional seismic monitoring. Since microseismic records are generally characterised by low signal-to-noise ratio, automated location methods are requested to be noise robust and sufficiently accurate. Most of the standard automa...
Conference Paper
Full-text available
Locating seismic events is one of the oldest problem in seismology. In microseismicity application, when the number of event is very large, it is not possible to locate earthquake manually and automated location procedures must be established. Automated seismic event location at different scales is very important in different application areas, inc...
Article
Full-text available
Determining the relative orientation of the horizontal components of seismic sensors is a common problem that limits data analysis and interpretation for several acquisition setups, including linear arrays of geophones deployed in borehole installations or ocean bottom seismometers deployed at the seafloor. To solve this problem we propose a new in...
Conference Paper
Full-text available
Microearthquake and microcrack detection and location are important challenges in reservoir monitoring and characterization. Detection tools are important to improve catalogue completeness, while high resolution location of microearthquakes allows to estimate the distribution and the orientation of the faults and pore pressure changes inside the re...

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