Weather for San José:
High 27° / Low 19°
Click here for six-day forecast for 16 communities across Costa Rica!
Banco BAC
Banco BCR
Banco Nacional
Banco Popular
Banco Scotiabank

Pacific plate Earthquakes and fault lines: Costa Rica and California

Share this article

costa rica earthquake

The week of 5-11 September was a relatively quiet period seismically. The United States Geological Survey’s interactive map, showing the week’s earth tremors, recorded a relatively modest 414 tremors of greater than M2.5 – of which just 35 were above M5.0, and just four larger than M6.0.

Significant Earthquakes

The largest earthquake recorded in the week was the M7.6 event which took place in Costa Rica on 5 September; the result of faulting along a subduction zone which lies to the west of Central America. Here, the Cocos Plate is forced beneath the Caribbean Plate, and earthquakes (and volcanic activity) are a regular result. The data available show just one significant aftershock, an M5.6 which occurred three days later, on 8 September.

The three other noteworthy tremors in terms of magnitude all occurred along the eastern boundary of the Pacific Plate and were associated with its subduction. They were:

-An M6.1 event in Indonesia, where the convergence of the Australian and Pacific plates is complicated by the presence and relative movement of numerous micro plates

-An M6.0 event in Vanuatu, hundreds of miles further east along the same plate boundary, again where the Pacific Plate is subducted beneath Australasia

-An M6.0 event off the tip of the Kamchatka peninsula in the north west Pacific where the Pacific Plate is subducted beneath an outlying arm of the North American Plate

Smaller Tremors Worldwide

While the USGS data set includes all major earthquakes worldwide, it shows earthquakes below M4.0 only for the United States area. Looking at a map of all 1386 recorded events, therefore, not only underestimates the total number of tremors to have occurred but may also give the misleading impression that America is more seismically active than elsewhere.

To illustrate this further, comparison of USGS data with the European Mediterranean Seismological Centre’s own interactive map of European earth movements, for example, shows that even the largely tectonically stable continent of Europe experienced 313 recorded earth tremors – though just four of these appear on the USGS map.

Earth Tremors and Fault Lines

Examination of all earthquake activity in the States can provide useful illustrations of earthquake patterns and activity. The association of earthquakes with fault zones, for example, is well known and is beautifully exemplified by the pattern of earthquake activity along the San Andreas Fault in central California, where a multitude of small earth tremors occurred on or very close to the fault. Here, the mechanism is sideways movement of two tectonic plates.

Similarly, examination of the small tremors and faults in Alaska shows a different pattern, with the clusters clearly associated with, though not directly following, fault lines. In this case the explanation for the spatial distribution of tremors is due to the ‘ripple’ effect from the northward-moving Pacific Plate being forced under the North American Plate. This movement, together with the complications arising from the subduction of a much smaller sliver of subducting crust, causes faulting and associated earth movements at a distance from the main subduction zone.

Earthquake Overview

Even in a week that might be termed relatively quiet seismologically, the Earth is still moving and is generating, in total, many thousands of earthquakes associated with tectonic plate movements and fault lines – though only a small proportion of these are of any significance or cause much damage.

Source: Decoded Science

Print Friendly

Related Articles

Chinese Tech Giant Xiaomi Unveils Smart Bike

Chinese tech firm Xiaomi unveiled Thursday its first smart bicycle, an electric and foldable prototype [...]

Eco-Friendly Coffee Rust Fungicide Being Shipped to Costa Rica

Phoenix, June 22, 2016 (GLOBE NEWSWIRE) — BioNovelus, Inc. (PINKSHEETS: ONOV) is pleased to [...]

Medical Imaging Diagnostics App Gets Certified in Costa Rica

CALGARY, Alberta–(BUSINESS WIRE)— Calgary Scientific Inc., a company known for creating [...]

Three Crew Members Return From International Space Station

Moscow, Jun 18 (EFE).– The descent module of Russian spaceship Soyuz TMA-19M, with three crew [...]

Costa Rica’s Zanate: A Very Smart and Problematic Bird

University of Cambridge Media Release – Have humans underestimated the intelligence of birds? A new [...]

Costa Rica’s Jungle River Sharks Swim to Discovery en Español

MIAMI, June 15, 2016 /PRNewswire/ — The most ‘fintastic’ time of the year is back and [...]

New, Sustainable Food and Energy System Developed in Costa Rica

San Isidro, Costa Rica – PermaCube Revolution is possibly the most practical solution to address [...]

U.S. Biotech Firm Chooses Costa Rica as Central America HQ

PHOENIX, AZ / ACCESSWIRE / June 9, 2016 / BioNovelus, Inc.  is pleased to announce the creation of [...]