As of the 12th June 2015 there have been 36 earthquakes worldwide with a moment magnitude (Mw) of 5.0 or larger according to GEOFON (GFZ Potsdam) in this month. This number includes four events of moment magnitude 6.0 or larger, all of which in fact have been moment magnitude 6.0 earthquakes. These have struck in the following locations:
- Borneo, Malaysia (4th June, depth 14km, Mw 6.0) - killed 18 people
- Offshore Hokkaido, Japan (8th June, depth 58km, Mw 6.0)
- Antofagasta, Northern Chile (10th June, depth 122km, Mw 6.0)
- South of Samoa (12th June, depth 49km, Mw 6.0)
Of the 36 events, only 3 have actually been onshore - the Mw 6.0 Borneo Earthquake on the 4th June, the Mw 6.0 Antofagasta Earthquake on the 10th June & the Mw 5.0 Borneo Earthquake on the 12th June (an aftershock of the 4th June event). This means that there have been no Mw 5.0 or larger events, which would be aftershocks, striking Nepal so far this month. My expectations for Nepal are that there is a 50/50 chance of a Mw 5.0 or larger event striking before the end of the month.
Globally my expectations are the following for the month of June 2015 (as qualifying & recorded by GEOFON):
- Mw 5.0 or larger: 84-96 events
- Mw 6.0 or larger: 8-10 events
- Mw 7.0 or larger: 0-2 events
- Largest magnitude: M6.7-7.6 (most likely at a guess is ~M7.0)
In terms of long-term global expectations I expect there to be at least two more Mw 7.0 or larger earthquakes; the current total of seven is a little below average annual totals of ten events.
There are some regions which have not suffered significant seismic activity thus far this year. Europe is a key region which has only seen a single event over Mw 6.0 (16th April, 29km depth, Mw 6.1: Crete, Greece). In all honesty I do not expect an event of such size to occur this month, but I do expect at least one more to strike somewhere in Europe this year, with likely locations being Greece, Italy & Turkey.
Another region with few events this year is Indonesia. There have been very few large events at shallow depths this year; a Mw 6.9 (27th February, depth 544km) struck the Flores Sea, a Mw 6.2 (3rd March, depth 30km) struck west of Southern Sumatra, a Mw 6.0 (15th March, depth 24km) struck the Minahassa Peninsula, Sulawesi & a Mw 6.2 (17th March, depth 38km) struck the Northern Molucca Sea. Since the Northern Molucca Sea Earthquake there have been no earthquakes over Mw 6.0, the largest in Indonesia since that event was either the Mw 5.9 in Sulawesi (28th March, depth 132km) or the Mw 5.9 in Southern Sumatra (15th May, depth 143km). Therefore this is a likely region to expect a Mw 6.0 or larger event this month.
Again, the Philippines have had relatively few earthquakes; there have only been 11 events of Mw 5.0 or larger, the largest a Mw 5.8 on the 10th January striking offshore of Luzon. This is quite unusual to have so few events in the Philippines, and like my expectations for Europe, I believe there will be a Mw 6.0 or larger event this year, though not necessary this month.
For my two countries of specific interest the past five and a bit months have been relatively interesting. The United Kingdom saw a Mw 3.7 (Ml 4.2) earthquake strike near Ramsgate, Kent, on the 22nd May, the largest earthquake to strike the country since the 2008 Market Rasen Earthquake. I do not expect any further earthquake with a magnitude 4.0 (of any kind), but there may yet be a small number (below six) of M3-3.9 events.
New Zealand has seen three significant earthquakes strike onshore; a Mw 5.6 on the 5th January near Arthur's Pass, South Island; a Mw 6.1 on the 24th April near St Arnaud, South Island; & a Mw 5.6 on the 4th May near Wanaka, South Island. The largest earthquake on the North Island was a Mw 4.6 near Ruatoria on the 14th April.
By a very simple process of deduction (by the simple absence of such events so far this year) I believe there will be at least one Mw 4.8 or larger event which will strike the North Island of New Zealand. Such events may be shallow earthquakes near Whanganui, Wellington, Hawkes Bay or Gisborne, or alternatively moderate depth (70-300km) events beneath the North Island.
My final region of interest is the Pacific West Coast of the United States. I still believe that the next Mw 6.0 or larger event to hit the Los Angeles region is due within the next three years. Currently my focus is on the Newport-Inglewood Fault, which has seen an unusual increase in small magnitude tremors recently. Other parts of the Pacific West Coast at risk of decent earthquake (M5.0 or greater) include the San Francisco Bay Area - in particular the Concord Fault - Cape Mendocino & the vast central area of the San Andreas system, particularly around Soledad & Coalinga.
As a note, these are personal opinions and no official forecasts. They definitely are NOT predictions!
Written by J H Gurney, 14:20 BST, 13th June 2015.
