Statistical evidence indicates that some triggering or promotion forward in time can occur in regions which are under high stress due to additional stress events of  small size. Among these are surface and body waves passing through a region.  Triggering may be dynamic with the promoted earthquake occurring at the same time as the stress event or delayed with an earthquake occurring later in time but still related to the stress event through water lubrication or other various geophysical effects on the faults. We have argued in this report for the past 35 years that this effect is most observable where the seismic waves are largest.  In general this occurs at distances from the rupture ends of  the earthquake producing those waves (mainshock) which we have termed nodal distances. These are defined by the formula D=360*m/n where D is the distance in degrees and m<=m where n an m are small integers. These are also the locations of  the maximum corrections to magnitude in the standard Jeffreys-Bullen tables. In addition there is focusing of  seismic energy from reflections and refractions of f the core-mantle and the inner-outer core boundary of  the earth. This focuses energy at the surface in the distance between 101 and 108 degrees (core-mantle) and 141-148 degrees (inner-outer core boundary). In this report we monitor seismicity at these distances following major earthquakes as experience has shown that strong and/or unusual earthquake are much more likely to occur at these distance from the mainshock. 



Antipodal (~180 degrees)


Sumatra to northern Colombia, 

O'Higgins Chile to Qinghai, China, 

Southern California to

Banda Sea to

Halmahera to

Kermadec Islands to

Peru to Nias, Sumatra, Indonesia, 

Ecuador to Nias, Sumatra, Indonesia, 


Outer shadow zone edge (141-148 degrees)


Sumatra to Oklahoma, Central Chile,  

O'Higgins Chile to Mariana Islands, Sumatra, Minahassa, Molucca, Kuril Is, 

Southern California to

Halmahera to

Banda Sea to Costa Rica, Chile, 

Kermadec Islands to Azerbaijan, Central mid-Atlantic, 

New Britain to Dominican Republic, Haiti, Puerto Rico, 

New Guinea to Dominican Republic, Puerto Rico, Virgin Islands, 

Peru to Papua, Honshu, Japan, Mariana Islands, Uzbekistan, Northern Territory, Australia, Ryukyu Islands, Papua New Guinea, Honshu, Japan, Pakistan,  

Ecuador to Papua, Northern Territory, Australia, Mid-Indian Ridge, Kyushu, Japan, Gujarat, India, Ryukyu Islands, New Guinea,  Western Australia,

Loyalty Islands to South Atlantic, Crete,


Node 3 (120 degrees)


Sumatra to  Vancouver,

O'Higgins Chile to Fox Islands, Aleutians, Turkey, Romania, Northern Territory, Australia, New Britain, 

Southern California to

Halmahera to South Sandwich Islands,

Banda Sea to Algeria, 

Kermadec Islands to Madagascar, Mayotte, Pakistan, Puerto Rico,

New Britain to South Sandwich Islands, Quebec, El Salavador, Dodecanese Islands, Nicaragua, Central Chile

New Guinea to Chiapas, Mexico, Albania, El Salavador, Gulf of California, Sonora, Mexico

Peru to Iran, Kuril Islands, Near Islands,  Solomon Islands,

Ecuador to Iran, Reykjanes Ridge, 


P- and S- shadow zone edge and node 7 (101-110 degrees)


Sumatra to Anchorage,  Kodiak, Alaska, Hawaii, 

O'Higgins Chile to Vanuatu, SE Alaska,

Southern California to Azerbaijan, Crete, Turkey, Hindu Kush, Taiwan, Northern Territory, Australia, Yunnan, Northern Philippines, Assam, India, Snares, South Island, New Zealand, Crete, Iraq, Halmahera, Tajikistan, Iran, Hindu Kush, Molucca Sea, Philippines, Northern Australia, Papua, New Guinea, Pacific-Antarctic Ridge, 

Halmahera to Coast of Oregon, Washington State, Central California, 

Banda Sea to Turkey, Greece, Southeast Pacific Rise, Coast of Oregon, Queen Charlotte Island, Svalbard, Coast of Northern California,  

Kermadec Islands to Mississippi, China, Assam, India, Alberta, Canada, Panama, Kansas, Colombia, Texas, 

New Britain to Azerbaijan, Iran, Svalbard, Western Texas, East Pacific Rise,  Alamosa, Colorado, Kansas, Baffin Bay, Iran, Michoacan, Jalisco, Mexico,  Greenland Sea, Mayotte, Southern Colorado, Iran, Gulf of Aden, Caucasus, Arctic Ocean, Idaho, Montana, Nevada, Oklahoma,

New Guinea to Iran-Iraq, Nevada, Madagascar, Jalisco, Oklahoma, South Pacific, East Central Pacific Rise, Alberta, California, Owen Ridge, Idaho, 

Peru to Turkey, East Africa, Snares, South Island, New Zealand, Crete, Greece, Swaziland, Andreanof Is, Alaska, Fiji, Kermadec Is, South Island, New Zealand, Arctic Ocean, Turkey, Albania, Greenland Sea, Ukraine, Fiji, New Zealand, Dodecanese Islands, Congo, Turkey, Unimak, Alaska, Fiji, Northern Alaska, Fiji, Aegean Sea, Hungary, 

Ecuador to Greece, Crete, Swaziland, Komandorsky Is, Snares, South Island, New Zealand,  Turkey, Ukraine, Mediterranean Sea, Severnaya Zemlya, North Island, New Zealand, Congo, South Africa, Turkey, Crete, Kermadec Islands, Rat Islands, Near Islands, Aegean Sea, Fiji,  South Africa, Ionian Sea, Macquarie Islands, Fiji, New Zealand, Crete, 


Node 4 (90 degrees)


Sumatra to

O'Higgins Chile to Fiji, Tonga,

Southern California to Kermadedc, Loyalty Is., Vanuatu, New Britain, 

Halmahera to

Banda Sea to Iran,

Kermadec Islands to Southern California, Arizona, Panama, Coast of Oregon, Sichuan, China, Western Texas, 

New Britain to Coast of No. California, Nevada, Central, Southern California, 

New Guinea to Coast of Oregon,

Peru to France, South Africa, Kodiak, Alaska, Jan Mayen Is,, 

Ecuador to Beaufort Sea, Northern Alaska, 


Node 5 (72 degrees)


Sumatra to Azerbaijan,

O'Higgins Chile to Western Texas,

Southern California to

Halmahera to

Banda Sea to

Kermadec Islands to Flores, Indonesia,

New Britain to

New Guinea to

Peru to Idaho, Northern Mid-Atlantic, Northern, Central California, 

Ecuador to Reykjanes Ridge, 


Node 6 (60 degrees)


Sumatra to

O'Higgins Chile to Jalisco, Mexico, Northern Mid-Atlantic,

Southern California to East Pacific Rise, Iceland, Jan Mayen, 

Halmahera to

Banda Sea to

Kermadec Islands to  Molucca Sea, Halmahera,

New Britain to Komandorsky Is, Nicobar Islands, India, 

New Guinea to

Peru to  Montana, Southern Mid-Atlantic, Central California, South Sandwich Islands, 

Ecuador to Northern, central California, Azores, 


Node 7 (52 degrees)


Sumatra to

O'Higgins Chile to Puerto Rico, Chiapas, Mexico,

Southern California to

Halmahera to South Island, New Zealand,

Banda Sea to Fiji,

Kermadec Islands to Papua, New Guinea, 

New Britain to Sumatra, 

New Guinea to

Peru to Central Mid-Atlantic, Alamosa, Colorado, New York, Baja California, North Atlantic Ocean, North Carolina, Drake Passage, Quebec,, 

Ecuador to Arizona, Nevada, Northern Mid-Atlantic, Utah, Wyoming, Southern California,