Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A Look at the Mantle Aids in Arc-Continental Collision Studies

09.04.2008
The application of mantle tomography to seismic intensity data gathered in Central Philippines by researchers from the University of the Philippines Diliman offers new insights into the collision in ancient times between the Palawan Microcontinental Block and the Philippine Mobile Belt in Central Philippines.

A study conducted by a group of researchers led by Dr. Carla B. Dimalanta of the National Institute of Geological Sciences, University of the Philippines Diliman investigates the site of convergence between the Palawan Microcontinental Block and the Philippine Mobile Belt in Central Philippines.

Entitled Delineating the Collision Zone Between Palawan and Central Philippines Using Seismic Intensity Data Inversion (2005), the study uses seismic intensity data inversion to produce tomographic images of the subsurface.

The collision between the Palawan Microcontinental Block and the Philippine Mobile Belt as observed in Central Philippines is a significant event in the evolution of the archipelago. According to Dr. Dimalanta, previous studies (Mitchell et al.,1985 and McCabe et al.,1985) report that the collision boundary is located in southwest Mindoro, Buruanga peninsula in Panay and Tablas Island. However, the presence of collision-related metamorphic rocks in the islands of Tablas, Romblon, and Sibuyan (Yumul et al., 2003) implies that the collision site may be extended east of the Romblon group of Islands (See Fig. 4). The group of Dr. Dimalanta tried a new approach to study this ancient collision. They utilized the inversion of seismic intensity data to produce a cross-section of the mantle in the study area. Moreover, the hypocenter data (or the point where ground rupture starts during an earthquake) and seismic reflection profiles (or the reflections of seismic waves in the seismograph which provide information on the internal structure of the earth) offered additional constraints in the interpretation.

Seismic intensity data in central Philippines were collected from the Southeast Asia Association of Seismology and Earthquake Engineering (SEASEE) Bulletin and the Philippine Institute of Volcanology and Seismology (PHIVOLCS). The group of Dr. Dimalanta evaluated tomographic or cross-sectional images of the mantle based on data gathered from 114 earthquakes that occurred from 1913 to 2003. Three-dimensional images of the mantle below the central Philippine region revealed a generally NE-SW trending high attenuation pattern. This pattern usually indicates that subduction, or the thrusting of a tectonic plate under an adjacent plate, has occurred. However, analysis of the hypocenter data indicates that there are no features that would correspond to a subducted slab. Compressional features such as faults and folds are detected in seismic reflection profiles which are more prominent in the vicinity of Tablas island. Researchers, thus, suggest slab tearing and mantle plumes, or the upwelling of hot rocks from the mantle, as possible causes of this attenuation pattern.

For the researchers, the use of mantle tomography is an important contribution to the application of geophysical methods in geoscience research in the Philippines. There are very few tomographic investigations done in the Philippines after the first work done by Dr. Glenda Besana and colleagues. The results of this investigation offer additional insights into understanding the collision event that has affected Central Philippines. Aside from this tomography work, additional geological, geochemical and geophysical investigations are currently being carried out in northwest Panay and Mindoro island.

Dr. Carla B. Dimalanta is an Associate Professor at the National Institute of Geological Sciences whose field of expertise is geophysics. She is a co-author of the article entitled “Collision, subduction and accretion events in the Philippines: a synthesis” published last 2003 in the ISI journal Island Arc.

This paper won the first Island Arc Award given out by the Island Arc and Blackwell Publishing in 2007.

| ResearchSEA
Further information:
http://www.ovcrd.upd.edu.ph
http://www.researchsea.com

More articles from Earth Sciences:

nachricht Predicting unpredictability: Information theory offers new way to read ice cores
07.12.2016 | Santa Fe Institute

nachricht Sea ice hit record lows in November
07.12.2016 | University of Colorado at Boulder

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>