Job Opening at Manila Observatory: Project Research Assistant for Focal Mechanism Research

Focal mechanisms of an earthquake (source: Wikipedia)

Focal mechanisms of an earthquake (source: Wikipedia)


Company Profile: The Manila Observatory (MO) is a scientific research institution established in 1865, by the Jesuit mission in the Philippines. By then, it was already engaged in pre-disaster science doing atmospheric studies, weather and earthquake observations until it became the official institution for weather forecasting and later,
the Philippine Weather Bureau. At the turn of the 21st century, the Institute finds itself addressing new challenges on the global concern for environment and development. With a continuing focus on pre-disaster science that impacts directly on man’s well being, MO undertakes research in the areas of climate change, urban air quality, and disaster risk reduction and management.



Job Description:

  • Collection, processing and encoding of data on seismology
  • Analysis of focal mechanism or fault plane solution and seismograms
  • Assist in the integration and packaging of research studies/project reports
  • Networking with appropriate agencies, both public and private


  • College graduate and /or Graduate students in the fields of Natural
  • Science or Engineering preferably, with physics and math background
  • No required related experience
  • Knowledge of computer programming
  • Proficient with MS Office or similar suites
  • Proficient in oral and written communication skills
  • Good interpersonal skills and a team worker
  • Keen interest in earth sciences

Interested candidates are invited to personally submit a letter of application with resume, transcript of records and recent passport size photograph at the Human Resource Office, Manila Observatory, Ateneo de Manila Campus, Loyola Heights, Quezon City. Or you may also get in touch with us through e-mail address:

For more information about the company, you can visit our website:


Earthquake intensity and magnitude scales of Phivolcs

by Quirino Sugon Jr.

I am working on earthquake risk measurements.  To measure risks, we have to determine earthquake energies: how they are measured and how they die down as a function of distance.  Here are some reference notes:

In the Philvocs website, the earthquake values are obviously magnitude not intensity scales, since we cannot have fractional intensity scales.  Intensity scales are subjective, as seen from the Phivolcs Earthquake Intensity Scale.  The Phivolcs scale is a Richter scale.

From the

As stated above, the Richter scale itself is a logarithmic mathematical formula which is calibrated so that a ten fold increase in amplitude relates to a single whole number increase on the scale (e.g. an earthquake with a Richter magnitude of 5 has seismic waves with a maximum amplitude 10 times larger than those for a magnitude 4). It has a number of practical limitations, in that it is poor at recording earthquakes with magnitudes greater than 7 and at distances greater than 650 km from a seismometer.

The equation for calculating the Richter magnitude (MR) is shown below:

MR = (Log10A) – (Log10A0)

A = maximum zero to peak amplitude of seismic wave (mm) recorded.
A0 = Empirical function derived from the distance from seismometer station to earthquake epicentre

Log10A0 From 0 to 200 km distance:
Log10A0 = 0.15 – 1.6 log(distance in km)

Between 200 and 600 km distance by:
Log10A0 = 3.38 – 3.0 log(distance in km)

Due to the limitations described above (distance and maximum size of measurable earthquake), it has since been replaced by the Moment Magnitude Scale in the measurement of large earthquakes – for information on this, please see the related question.


Does anybody know what would be the empirical function for each point in the Philppines?

Seismology as a Jesuit Science

by Quirino Sugon Jr.

I would like to benchmark what we do at Manila Observatory, with what other Jesuit Observatories do, especially in the fields of Seismology, Geomagnetism, and Ionosphere research. I shall start first with a review of Jesuit involvement in Seismology.


This is a good reference:

The Jesuit Contribution to Seismology by
Agustin Udías and William Stauder (from Seismological Research Letters, Vol. 67, No. 3, pp. 10-19; May/June 1996)

This has a table of the Jesuit observatories participating in seismic research, but this era is about to come to a close.

“It may be intriguing to some that a religious order dedicated so much effort to a science like seismology. From the very early years of the its foundation in the 16th century by Ignacio de Loyola, the Society of Jesus dedicated itself primarily to educational work through its many colleges and universities. From the beginning of these institutions science was an important subject in the curriculum. A key figure in this development was Christopher Clavius (1537-1612), Professor of Mathematics in the Collegio Romano. Clavius was instrumental in incorporating a serious program of mathematics, astronomy, and natural sciences not only in his own college but also in all Jesuit colleges and universities (MacDonnell, 1989). Secondly, in the 17th and 18th centuries a number of astronomical observatories were established in these institutions. In a number of these, meteorological observations also were made. Finally, in a particularly notable page of this history, Jesuits were appointed Directors of the Astronomical Observatory in Beijing, China (Udías, 1994). This tradition forms the background of modern Jesuit scientific work. Since the middle of the 19th century, as many as forty geophysical observatories were created by Jesuits around the world and in many of these seismological stations were installed (Udías and Stauder, 1991).”

The article also notes that “From 1868, the approximate date of the installation of the first seismograph by the Jesuits in Manila, to the present many members of this religious order have dedicated their time and efforts to seismology.”

Another good reference is

Seismology, The Jesuit Science: Some Jesuits and Their Geophysical Observatories

“Much of this narration is taken from the work of William Stauder, S.J. of St. Louis University and Augustin Udias. The underlying seismic principles are taken from The Random House Encyclopedia.

“Jesuits have contributed so much to the development of seismology and seismic prospecting that Seismology has been called The Jesuit Science, and prompted by Dr. Turner, once president of the British Seismological Association, the Society has been congratulated for dominating the field of seismology in America. Daily reports from the Jesuit network were teletyped to the US Coast and Geodetic Survey in Washington and were published annually in the Bulletin of the Seismological Society of America under the title “The Report Or the Jesuit Seismological Association.” This Jesuit report was read throughout the world and was highly esteemed even in countries such as Norway where the Jesuits themselves were not allowed. Not only earthquake seismology owes much to Jesuit research, but even more indebted is the field of seismic prospecting, now 60 years old which claims as one of its chief authorities and organizers, Daniel Linehan, S.J. who first put the theories of shallow refraction into practice. Two principal factors contributed to the interest of Jesuits in geophysical phenomena: the educational work of the Jesuits in colleges and universities and their missionary endeavors in remote lands.”

There are historical details presented here about the 54 Jesuit observatories.