C8416 - LABORATORY OF SEISMOLOGY

Learning outcomes

At the end of the course, students will gain scientific and practical knowledge on some aspects of experimental methods and statistical techniques used in seismology and in the assessment of seismic hazard. In particular, students will: - understand the operating principles of mechanical and electromagnetic seismometers and to carry out experiments to quantify the fundamental characteristics of an electromagnetic seismometer; - read and interpret the fundamental aspects of seismograms and use them to localize earthquakes; - apply statistical methods to the study of earthquake occurrence properties, to probabilistic and deterministic forecasting and to the assessment of seismic hazard and risk.

Course contents

Module 1

● Seismometry

○ Theory. Seismometers: operating principles. The seismometer equation for mechanical and electromagnetic seismometers. The constants of a seismometer. Damping regimes. Response curves of mechanical and electromagnetic seismometers. Examples of historical mechanical and electromagnetic seismometers. Feedback circuits and force-balanced seismometers. Accelerometers. Noise in a seismometer.

○ Laboratory. Determination of the natural period, the critical resistance, the seismometer constant and the response curve of the electromagnetic seismometers available in the laboratory.

● Earthquake location

○ Theory. Hypocentral coordinates and origin time. Interpretation of a seismogram: reading and picking. Graphical methods for location. Inversion algorithm: the linearized least-squares method. Errors and precision of the location.

○ Laboratory. Selection of a recent earthquake that occurred in Italy, for which a sufficient number of seismograms are available. Reading of the seismograms and picking of the P and S waves. Use of the Hypocenter software for inversion and location. Parametric study of the location quality as the model parameters vary.

 

Module 2

● Statistical Seismology

○ Theory. Commonly used definitions of seismic magnitude and their homogenization with the definition of seismic moment magnitude through least-squares regressions with errors in both variables. Occurrence properties of earthquakes, Gutenberg-Richter and Omori laws, and determination of the related parameters through maximum likelihood methods.

○ Laboratory. Development of computer codes to perform a least-squares regression between magnitudes with errors in both variables and the determination of the parameters of the Gutenberg-Richter and/or Omori laws through maximum likelihood methods.

 

Prerequisites:

Module 1: basic knowledge of linear algebra, ordinary differential equations, mechanics (in particular the physics of the harmonic oscillator) and electromagnetics.

Module 2: basic knowledge of statistical methods and of a programming language (Matlab, Python, Fortran, ...)

 

Readings/Bibliography

Each lecture is accompanied by the projection of a PowerPoint file.

The set of files provides a comprehensive presentation of the syllabus and can serve as a textbook for studying the subject. The files, in PowerPoint and PDF format, are made available by the teachers on Virtuale.

Should they wish to explore the topics covered in the course in greater depth, students may consult the following texts:

Module 1:

· Havskov, J. and Alguacil, G. (2016). Instrumentation in Earthquake Seismology, 2nd Ed., Springer.

Havskov, J., Bormann, P., Schweitzer, J. (2011). Seismic source location. https://gfzpublic.gfz-potsdam.de/rest/items/item_43361/component/file_816919/content

 

Teaching methods

Classroom lectures held in person; laboratory sessions held in person.

Attendance at the classroom lectures is not compulsory, but it is strongly recommended both for the learning process and because of the close connection with the laboratory sessions.

The laboratory sessions are compulsory: the teachers will collect the attendance signatures at the beginning of each session.

In consideration of the types of activity and teaching methods adopted, attendance of this training activity requires the prior completion of modules 1 and 2 in e-learning mode and participation in module 3 of specific training on health and safety in study places. Information on the dates and attendance arrangements for module 3 can be found in the dedicated section of the degree programme website.

Assessment methods

Students, divided into groups, will have to produce three written reports, one for each of the experiences carried out in the laboratory (seismometry, earthquake location, statistical seismology).

The three reports must be sent to the teachers in PDF format within 15 days of the end of the course and, in any case, before being able to sit the exam.

The discussion of the reports will be an integral part of the final exam, which may also include questions on the theoretical aspects covered during the course and connected to the laboratory experiences.

The final exam will be a single exam covering both modules, in oral form, lasting on average about one hour.

 

 

Teaching tools

In the classroom: projector.

In the laboratory:

· two PCs with free software for data processing and visualization;

· two long-period vertical electromagnetic seismometers;

· two data acquisition boards.

For the lab experiences related to earthqiake location (Module 1) and statistical seismology (Module 2), students are allowed to use their own laptop.

 

Students with Specific Learning Disorders (SLD) or with temporary or permanent disabilities are advised to contact the relevant University office in due time (https://site.unibo.it/studenti-con-disabilita-e-dsa/it): the office will propose possible adjustments to the students concerned, which must in any case be submitted, 15 days in advance, to the approval of the teacher, who will assess their suitability also in relation to the learning objectives of the course.

Office hours

See the website of Alberto Armigliato

See the website of Paolo Gasperini